ch05

C H A P T E R F I V E

Pathophysiology

A dysfunctional Eustachian tube system is either tooclosed or too open, or abnormal pressure is present ateither end.

Dysfunction of the Eustachian tube system plays an importantrole in the pathogenesis of middle-ear disease. However, otherfactors are involved because the pathogenesis and etiology aremultifactorial and include genetic, infectious, immunologic,allergic, environmental, and social factors (as discussed inChapter 1, Introduction; see Figure 17). A functionally andstructurally immature Eustachian tube and an immatureimmune system are probably the most important factors relat-ed to the increased incidence of otitis media in infants andyoung children. Human infants are born about 12 months tooearly compared with our immediate mammalian ancestors.1 Agenetic predisposition is also critical in many infants and chil-dren.2,3 When they are exposed to upper respiratory tract infec-tions, otitis media is a common complication.

As demonstrated in intranasal viral challenge studies inadults in our department, and as described in detail in Chapter6, Pathogenesis, the pathogenesis of otitis media has the fol-lowing sequence of events in adults and children4,5: the patienthas an upper respiratory tract viral infection resulting in con-gestion of the respiratory mucosa of the nose, nasopharynx, andEustachian tube. Congestion of the mucosa in the Eustachiantube obstructs the narrowest portion of the tube, the isthmus.This obstruction causes negative middle-ear pressure followedby a middle-ear effusion, but the susceptibility to develop thissequence of events is related to the individuals underlyingEustachian tube function; those whose tubes are dysfunctionalare more likely to develop middle-ear underpressures and effu-sion than those whose function is basically normal.4,6 Themucosal secretions of the middle ear have no way out and accu-mulate there; clearance is impaired. If the effusion is relativelyasymptomatic (without the signs and symptoms of acute infec-tion), it is termed otitis media with effusion. However, during anupper respiratory infection, the viruses causing the primaryinfection and the potentially pathogenic bacteria that colonizethe nasopharynx can be refluxed, aspirated, or insufflated into

the middle ear through the Eustachian tube and cause an acuteotitis media. Because the middle ear has negative pressure, aspi-ration of nasopharyngeal organisms into the middle ear is mostlikely. Also, the inflammation can progress distally in themucosa of the Eustachian tube and into the middle ear. Acuteotitis media is characterized by the signs and symptoms of acuteinfection: fever and otalgia.4 For patients with recurrentepisodes of acute otitis media and recurrent and chronic otitismedia with effusion, preexisting pathophysiology of theEustachian tube appears to be one of the most important fac-tors, especially in infants and children.

My colleagues and I initially described some of the con-cepts related to the pathologic mechanisms of the Eustachiantube many years ago but have refined these pathophysiologicfactors over the past 30 years.7,8 The pathophysiology of theEustachian tube system can be summarized as follows: the tubewill not open; the tube is too closed, too floppy, too open, tooshort, or too stiff; or at either end of the Eustachian tube, thesystem is either too closed or too open, or there is abnormalpressure at either end of the system (Figure 51).9 More pre-cisely, the pathophysiology can be classified into

Impairment of pressure regulation

Loss of protective function

Impairment of clearance

FIGURE 51. Evidence-based, simplified classification of Eustachian tubedysfunction. The Eustachian tube system may be too closed or too open, orthere is abnormal pressure at either end.

Figure 52 depicts some of the types of Eustachian tubedysfunction, which are described in more detail below.Table 51 provides the classification of the pathophysiology (ordysfunction) of the Eustachian tube system.

Impairment of Pressure RegulationThe pressure regulation function of the middle-earmastoidcells can be impaired by

Anatomic obstruction of the Eustachian tube system (thesystem is too closed)

Failure of the opening mechanism of the Eustachian tube(the tube will not open)

As described below, the tube constricting during swallow-ing as opposed to dilating and opening

Anatomic Obstruction

The Eustachian tube can be anatomically (mechanically)obstructed in the cartilaginous or osseous portions of the tubeor at either end of the system, regardless of the status of thestructure and function of the Eustachian tube itself (obstructionof the middle ear or nasopharynx).

Obstruction of the Eustachian Tube

When an anatomic obstruction involves the tube, it can be

Intraluminal (intramural)

Periluminal (mural)

Peritubal (extramural) (the tube is too closed)

Obstruction of the lumen or within the periluminal tissues(intrinsic obstruction) can be due to inflammation secondary toinfection (viral, bacterial)6,10,11 or allergy.12 Congenital oracquired stenosis of the Eustachian tube has also been diag-nosed in adults but is a rare finding in children.13 Peritubal(extramural) obstruction of the cartilaginous portion of thetube (extrinsic obstruction) can be the result of compressioncaused by a tumor1416 or an adenoid mass.1721 Figure 53shows a computed tomographic scan in which congenitalcholesteatomas in the base of the skull anatomically (extrinsi-cally, extramurally) obstructed the Eustachian tube, whichcaused long-standing chronic otitis media with effusion.

68 / Eustachian Tube: Structure, Function, Role in Otitis Media

FIGURE 52. Examples of some of the types of dysfunction of theEustachian tube. The tube may be abnormally patent or obstructed. Whenobstruction is present, it may be due to failure of the opening mechanism(functional), or it may be anatomic (mechanical); the latter conditionmay be due to intrinsic or extrinsic causes. TVP = tensor veli palatinimuscle.

Table 51. Classification of Pathophysiology (Dysfunction) of

the Eustachian Tube System

Impairment of pressure regulation

Anatomic obstruction

Obstruction of Eustachian tube

Intraluminal (intramural)

Periluminal (mural)

Peritubal (extramural)

Obstruction at either end of system

Middle earmastoid

Nasopharynx

Failure of opening mechanism (functional obstruction)

Functional obstruction of Eustachian tube

Functional obstruction at either end of system

Middle earmastoid

Nasopharynx-nose-palate

Loss of protective function

Abnormal patent Eustachian tube

Short Eustachian tube

Abnormal gas pressures at either end of system

Middle earmastoid

Nasopharynx

Nonintact middle earmastoid

Impairment of clearance

Mucociliary

Muscular

Anatomy of system

Pathophysiology / 69

Obstruction at Either End of the System

At either end of the Eustachian tube system, anatomic obstruc-tion may be present even when the tube itself functions normal-ly. Obstruction at the middle-ear end of the tube (the system atthe distal end of the Eustachian tube is too closed) may be dueto acute or chronic inflammation of the mucosal lining and mayalso be associated with polyps or a cholesteatoma. A congenitalcholesteatomanot secondary to tubal dysfunctioncanobstruct the middle ear end (osseous portion) of the Eustachiantube in the face of a normally functioning cartilaginous portion.Likewise, at the proximal end of the systemin the nasophar-ynxthe tubal orifice can be anatomically obstructed evenwhen the Eustachian tube itself is patent and functions normal-ly. This can be due to a variety of etiologies, including adenoids,a foreign body (eg, packing), or a tumor; the nasopharynx is tooclosed.

Failure of the Opening Mechanism (FunctionalObstruction)

One of the most common types of Eustachian tube dysfunctionis when the lumen of the cartilaginous portion of the tube failsto open during swallowing activity (the Eustachian tube will notopen). This may be due to

Persistent collapse of the Eustachian tube owing toincreased tubal compliance (lack of stiffness or the tube istoo floppy)

An inefficient active opening mechanism

Both defects coexisting

This has also been termed functional obstruction; the tubeis not anatomically obstructed but is functionally obstructed.This was first described in infants with unrepaired palatal cleftswho had had chronic otitis media with effusion (seeDysfunction Related to Cleft Palate).22 Failure of the openingmechanism of the Eustachian tube is common in infants andyounger children without a cleft palate or a history of middle-ear disease but is more common in children with middle-eardisease.2328 We demonstrated that inactivation of the tensor, byeither transection or expunging the belly through the palate29 orinjecting botulinum toxin into the muscle, will inactivate theopening mechanism and result in middle-ear underpressuresand effusion. Even though tumor usually anatomicallyobstructs the Eustachian tube, as described above, tumor thatinactivates the tensor veli palatini muscle can also cause func-tional tubal obstruction owing to failure of the active openingmechanism (see Chapter 7, Pathology).30

Floppy Eustachian Tube Cartilage

The Eustachian tubes failure to open can be caused by persist-ent collapse of the tubal cartilage because there is less cartilagein infants than in older children and adults. Cartilage cell den-sity changes with advancing age can affect the stiffness of thetubal cartilage in the infant and young child.31,32 If the tubal car-tilage lacks stiffness (the tube is too floppy), the lumen may notopen when the tensor veli palatini muscle contracts. Also, thedensity of elastin in the cartilage is less in the infant, andOstmanns fat pad is less in volume in the infant than in theadult (see Chapter 3, Anatomy).33,34 Figure 54 graphicallydepicts the theory that if the Eustachian tube cartilage is floppyin children, it will collapse into the lumen when the tensor velipalatini contracts. But, to date, experimental confirmation ofthis hypothesis is lacking. Low and colleagues studied patientswho had nasopharyngeal carcinoma with the aid of magneticresonance imaging to determine if the cartilage of theEustachian tube was eroded and concluded that in somepatients, tubal compliance was altered by extension of thetumor into the cartilage.35

Inefficient Tensor Veli Palatini

Also, failure of the Eustachian tubes opening mechanism maybe due to an inefficient tensor veli palatini muscle, which isrelated to the effect of age on the craniofacial base. The angle ofa childs tube is different from that of the adult. In the adult, thetube is approximately 45 related to the horizontal plane. Ininfants, this inclination is only 10.36 Some think that this dif-ference in the angle is related to possible clearance problems inchildren, but this hypothesis has not been confirmed. What ismore likely is that this difference in angulation affects the func-

FIGURE 53. Computed tomographic (CT) scan (coronal view) of a 15-year-old male who had almost lifelong chronic otitis media with effusionin the left ear requiring permanent tympanostomy tubes. Eustachiantube function tests revealed total obstruction of the Eustachian tube. TheCT scan shows multiple congenital cholesteatomas in the base of the skullobstructing the Eustachian tube (arrow).

tion of the active opening mechanism (tensor veli palatini mus-cle contraction). Swarts and Rood found that the angular rela-tionship between the tensor veli palatini muscle and the carti-lage varies in the infant but is relatively stable in the adult (seeChapter 3).37 Also, the tensor veli palatini muscle can be inacti-vated, by tumor or surgery, in the palate or skull base, resultingin functional obstruction.38,39

Abnormal Pressures at Either End of the System

Another pathogenic mechanism whereby the Eustachian tubecan be functionally obstructed is when sudden high negativepressure develops at either end of the Eustachian tube system.This is graphically demonstrated by the flask model (seeChapter 4, Physiology, Figure 411). One of the major differ-ences between a flask with a rigid neck and a biologic tube, suchas the Eustachian tube, is that the cartilaginous portion of thehuman tube is compliant. The effect of applied negative pres-sure in a flask with a compliant neck is shown in Figure 55.Flow of fluidshown as a liquid for graphic purposesthrough the neck does not occur until negative pressure is slow-ly applied to the bottom of the flask. When the negative pressurewithin the middle-ear pressure is gradual, such as occurs duringa viral upper respiratory tract infection, equilibration of a slow-ly developing middle-ear underpressure can be accomplishedduring swallowing. However, if the negative pressure is appliedsuddenly, temporary locking of the compliant neck prevents theliquid (air) from flowing. This is called the locking phenomenonof the Eustachian tube (active muscle dilation by swallowing isimpaired).40 Therefore, the speed with which the negative pres-sure is applied and the compliance in the cartilaginous portionof the tube are critical factors in whether the tubal lumen

becomes severely functionally obstructed. This phenomenoncan occur during unphysiologic activities when there are rapidalterations in atmospheric pressure, such as descent in an air-plane, during diving in water (especially scuba), or duringhyperbaric treatment in a pressure chamber (see Swimming,Diving, and Air Flight). Also, locking of the Eustachian tube canoccur during testing of the ventilatory function of theEustachian tube (see Chapter 8, Diagnosis and Tests ofFunction). Humans did not evolve with the capability of open-ing the Eustachian tube following sudden application of nega-tive pressure when engaging in these unphysiologic activities.

Abnormal negative pressures at the nasopharyngeal endof the Eustachian tube might also prevent physiologic openingof the tube, such as during habitual thumb sucking with thenose obstructed,41 sucking on a pacifier (Figure 56), or closed-nose swallowing, which I have termed the Toynbee phenomenon(see Toynbee Phenomenon). It has been suggested by someinvestigators that habitual sniffing can cause abnormalnasopharyngeal negative pressures that can adversely affect thetube and even cause middle-ear disease. They postulated abnor-mal tubal patency and poor active opening function as possiblepredisposing factors.42 Also, middle-ear underpressures havebeen recorded in infants during bottle feeding, with conven-tional nonventilated bottles, which was presumably due tohigh negative nasopharyngeal pressures generated during thefeeding.43

As shown in Figure 57, a floppy tube would not only bemore susceptible to collapsing (or sucking in) owing to negativepressure than a tube that is stiff, but a highly compliant (floppy)tube would also be more likely to distend than a stiff tube. Thislatter mechanism may be related to crying in the infant becausethe tube is floppy in babies. It is a common occurrence to wit-ness (hear) infants crying during descent in an airplane, whichis most likely a compensatory mechanism to insufflate air intothe middle ear. Most likely, all infants have some degree of dys-function of active muscular opening of the tube, especiallywhen attempting to equilibrate negative middle-ear pressure inan airplane during descent (see Swimming, Diving, and AirFlight). It is not uncommon to examine the tympanic mem-brane of an infant who is crying and, on pneumatic otoscopy,visualize a bulging (with gas) tympanic membrane. This obser-vation has been documented by tympanometry; the positivemiddle-ear pressure can last for an abnormal amount of timebecause infants have difficulty equalizing positive, as well asnegative, middle-ear pressures. In contrast to infants with anintact palate, infants with an unrepaired cleft palate are lesslikely to be able to insufflate nasopharyngeal air into the mid-dle ear because the palate is open (the system is too open) atthe proximal end of the tube. Thus, infants with a cleft palateare most likely unable to insufflate air into the middle ear as acompensatory mechanism in the face of poor Eustachian tubefunction. In the studies of Eustachian tube function in infants

FIGURE 54. Cartoon showing the hypothetical Eustachian tube function-al obstruction occurring during contraction of the tensor veli palatini inthe infant owing to floppy cartilage support compared with a normaltubal opening in the adult when the cartilage is stiffer.


FIGURE 55. The flask model of the Eustachian tube system for fluidflow through a flask with a compliant neck (see Figure 411). A,Fluid stopped in the neck of the flask. B, Effect of negative pressureapplied slowly to the bottom of the flask. C, Effect of negative pres-sure applied suddenly to the bottom of the flask (the locking phe-nomenon).

FIGURE 56. Illustration showing the proposed effect of suckingon a pacifier on the function of the Eustachian tube, with theresultant possible middle-ear disease. The negative pressure gen-erated by the sucking when the nose is obstructed (eg, viralupper respiratory tract infection) could cause nasopharyngealnegative pressures, which could impair active opening of theEustachian tube and result in middle-ear underpressures. Also,during swallowing, positive pressure immediately followed bynegative pressure would be in the nasopharynx, which couldeither create negative middle-ear pressure or insufflate nasopha-ryngeal secretions into the middle ear. This is termed theToynbee phenomenon.

FIGURE 57. Illustration demonstrating that applied positivepressure can distend a collapsible tube and applied negativepressure can collapse (or suck in) a tube when it is floppy, asdepicted with a balloon.


with an unrepaired cleft palate, using fluoroscopy andradiopaque dye instilled into the nose, no dye was visualizedentering the pharyngeal end of Eustachian tube, even when thenose was pinched off. By contrast, infants with a normal palatehad insufflation of the contrast media into the tube, and insome infants, dye was forced into the middle ear when the nosewas pinched off (see Dysfunction Related to Cleft Palate andChapter 8).

Abnormal pressures at either end can also be related toloss of the protective function, as described below.

Constriction of the Eustachian Tube during SwallowingRecently, we reported a very significant finding after testing thefunction of the Eustachian tube in older children, adolescents,and adults who had otitis media when compared with normalindividuals: the Eustachian tube constricted during swallow-ing.44 Table 52 summarizes the outcome of this study and ourother investigations in humans showing that constriction of theEustachian tube occurs in individuals with otitis media and not

normal (control) subjects without middle-ear disease.4450

Figure 58 compares normal Eustachian tube dilation on swal-lowing with abnormal tubal constriction.

In our laboratory, experiments in the monkey model ofEustachian tube dysfunction and otitis media showed similarfindings in some models but not others. In the monkey models,tubal dysfunction when the tensor veli palatini muscle was sev-ered was characterized by paradoxical constriction of theEustachian tube during swallowing activity as opposed to dila-tion. However, animals that had botulinum injected into thetensor muscle also developed the sequence of events that led tothe accumulation of a middle-ear effusion, but they did notexhibit constriction. Table 53 summarizes the outcomes ofexperiments in the monkey.29,45,46,5157

The underlying cause of constriction of the Eustachiantube during swallowing is uncertain at present but may be relat-ed to abnormalities in the muscles of the tube (levator palatini,tensor veli palatini, or tubal cartilage support). These findingsare a current research direction in the laboratory. It is hoped


Table 52. Eustachian Tube Function Test Results Related to Tubal Constriction in Humans

Eustachian Tube Function Tests

Procedure Reference Number of Inflation- Tubal Forced Compliance Constriction

Subjects Deflation Dilation Response

Normal adults Cantekin et al, 6 Normal Normal Normal ND No

traumatic perforations 197946

Normal adult volunteers Swarts et al, 6 Normal Normal Normal Normal No

(myringotomy) unpublished data,

2003

Chronic perforations in Cantekin et al, 5 Abnormal No Abnormal ND Yes

adults 197946

Recurrent AOM/chronic Lildholdt et al, 40 Abnormal No Abnormal ND Yes

OME in children 198247

(tympanostomy tubes)

Chronic OME in Cantekin, 198548 87 Abnormal No Abnormal ND Yes

children (tympanostomy

tubes)

Chronic OME/recurrent Swarts and 38 Abnormal No Abnormal ND Yes

Bluestone, 200344

AOM in older children,

teenagers, and adults


Chronic OME in infants Doyle et al, 198449 31 Abnormal No Abnormal ND Yes

with unrepaired CP


Chronic OME/recurrent White et al, 198450 14 Abnormal No Abnormal ND Yes

AOM in Down syndrome


Adapted from Bluestone CD.45

AOM = acute otitis media; CP = cleft palate; ND = not done; OME = otitis media with effusion.


that possible interventions can be developed to prevent thisabnormal function and possibly prevent otitis media (seeChapter 11, Future Directions).

Loss of Protective FunctionThe Eustachian tube system can lose its protective function when

The lumen of the tube is abnormally patent (the tube istoo open)

The tube is shorter than normal (the tube is too short)

Abnormal gas pressures develop at either end of the tubalsystem

There is a nonintact middle ear, for example, perforation(or tympanostomy tube) of the tympanic membrane,resulting in a loss of the middle-ear gas cushion (the sys-tem is too open) at the middle-ear end of the Eustachiantube system

The system is also too open at the pharyngeal end whenthere is an open cleft palate; not only is the proximal end of thetube exposed to the oropharyngeal contents during swallowing,but nasopharyngeal pressures are altered (see DysfunctionRelated to Cleft Palate). Each of these pathophysiologic charac-teristics is described in detail below.

Abnormally Patent Eustachian Tube

The lumen of the Eustachian tube can be abnormally open, andin the extreme, it is open even at rest. This is called an abnor-mally patent, or patulous, Eustachian tube; it is too open. Lesserdegrees of abnormal patency result in a semipatulous tube thatis closed at rest but with a lumen that has low resistance to the

flow of gas or liquids compared with the normal tube.58

Increased patency of the tube may be due to abnormal tubalgeometry or to a decrease in the peritubal pressure that canoccur after weight loss or as a result of periluminal factors.59

The flask model is illustrative of the loss of the protectivefunction of the Eustachian tube when the tubal lumen is tooopen. As shown in Chapter 4 (see Figure 411), liquid flowincreases as the radius of the narrow neck of the flask increases,to the fourth power. As shown in Figure 59, when comparedwith a flask with a narrow neck, reflux of liquid into the body ofthe flask occurs if the neck is excessively wide. This is analogousto an abnormally patent human Eustachian tube in which thereis free flow of air and nasopharyngeal secretions from thenasopharynx into the middle ear. The result is reflux otitismedia. Another important difference between the flask modeland the Eustachian tube is that the narrowest portion of thehuman tube, the isthmus, aids in prevention of liquid flow intothe middle ear, assuming that the isthmus portion is not floppy.Also as described below, liquid (nasopharyngeal secretions) willmore likely be aspirated or insufflated into the middle ear if thelumen of the tube is abnormally wide.

The Eustachian tube may be abnormally patent even whenthe caliber of the lumen appears to be normal when collapsed atrest. It can also be functionally hyperpatent, making it less pro-tective of the middle ear. Because the cartilaginous portion ofthe Eustachian tube is distensible (compliant), fluid (gas or liq-uid) can be forced into the middle ear by abnormally high posi-tive nasopharyngeal pressure, which can occur during noseblowing, with Valsalvas maneuver, or during closed-nose swal-lowing (the Toynbee phenomenon) (see Toynbee Phenomenon).The ability to insufflate the middle ear during these activitiesdepends on the amount of positive pressure developed in the

FIGURE 58. Cartoon showing a forced-response manometricfunction test when Eustachian tube dilates normally on swal-lowing compared with an abnormal tube that constricts dur-ing swallowing. ET = Eustachian tube; P = pressure, Q = flow.

nasopharynx and the degree of compliance (lack of stiffness) ofthe tube. Because the Eustachian tube has been found to be high-ly compliant (the tube is too floppy) in infants and young chil-dren, this increase in distensibility of the tube may result inabnormal patency, especially when there is high nasopharyngealpressure, possibly during crying (see Figure 59). A highly dis-tensible tube can easily permit nasopharyngeal secretions to beinsufflated into the middle ear, as radiographic studies in infantswith middle-ear disease have demonstrated.22,23 Figure 510shows a radiograph obtained in a child who had recurrent acuteotitis media, in which radiopaque contrast material was insuf-flated into the middle ear during swallowing while the nose waspinched closed. High intranasal and nasopharyngeal positivepressure forced the dye into the highly compliant (floppy)Eustachian tube and into the middle ear. This abnormal findingdid not occur in children without otitis media, especially olderchildren.

The flask model is used to illustrate this phenomenonwhen the neck of the flask is rigid; liquid is insufflated into thebulbous portion of the flask when positive pressure is applied atthe mouth of the flask (Figure 511). But if the narrow portionof the flasks neck is compliant, making it more consistent withthe human Eustachian tube, applying positive pressure at themouth of a flask will distend the neck and enhance fluidgasand liquidflow into the vessel. Thus, less positive pressure is

needed to insufflate liquid into the vessel if the neck is floppy. Inhumans, insufflating nasopharyngeal secretions into the middleear occurs more readily if the Eustachian tube is abnormally dis-tensible (has increased compliance or is floppy).

Patulous Eustachian Tube

The patulous Eustachian tube has been found to be too stiff inteenagers and adults when compared with normal individualswhose tubal compliance was assumed to be normal.60 This hasrecently been shown to be associated with chronic middle-earinflammation.61 A patulous Eustachian tube is too open andusually permits gas to flow readily from the nasopharynx intothe middle ear, effectively regulating middle-ear pressure.62

However, unwanted secretions from the nasopharynx can morereadily gain access (reflux or be insufflated) to the middle earwhen the tube is abnormally patent. Figure 512 is a compari-son between the normally functioning Eustachian tube and onethat is patulous.

Certain special populations have been found to haveEustachian tubes that are too open, including Native Americansand patients who have Down syndrome and middle-ear dis-ease.50,63 Chronic suppurative otitis media is a common diseasein certain special populations around the world, includingAustralian Aborigines, North American Inuits, and NativeAmericans.64

Table 53. Outcomes Following Surgical and Nonsurgical Procedures on the Paratubal Muscles of the Eustachian Tube Related to

Tubal Constriction in Monkeys

Eustachian Tube Function Tests

Number of Inflation- Tubal Forced

Procedure Reference Animals Deflation Dilation Response Compliance Constriction

Normal controls Cantekin et al, 197751 5 Normal Yes ND ND NA

Normal controls Cantekin et al, 198029 12 Normal Yes Normal ND No

Normal controls Cantekin et al, 198252 15 Normal Yes Normal ND No

Electrical stimulation Cantekin et al, 197946 5

TVP NA Yes ND ND No

LVP NA No ND ND Yes

Internal pterygoid muscles NA No ND ND Yes?

Transposition of TVP Cantekin et al, 198029 5 Slightly abnormal Yes Slightly abnormal ND No

Transection of TVP Abnormal No Abnormal ND Yes

Excision of TVP Abnormal No Abnormal ND Yes

Excision of LVP Cantekin et al, 198353 5 Normal Yes Normal ND No

Botulinum in TVP Casselbrant et al, 198854 2 Abnormal No Abnormal ND No

Botulinum in TVP Ghadiali et al, 200355 12 ND No Abnormal Increased No

Cleft of soft/hard palate Doyle et al, 198056 9 Abnormal No Abnormal ND Yes

Cleft of soft palate Casselbrant et al, 198557 8 Abnormal No Abnormal ND Yes

Adapted from Bluestone CD.45

LVP = levator palatini muscle; NA = not applicable; ND = not done; TVP = tensor veli palatini muscle.


FIGURE 510. Radiograph (submental-vertex view spot film taken duringfluoroscopy) of a young child who had recurrent acute otitis media.During installation of radiopaque contrast material into the nasal cavity,during swallowing with the nose closed, dye distended the cartilaginousportion of the Eustachian tube and was insufflated into the middle ear(black arrow). Note that even the narrowest portion of the cartilaginousportion of the tube, the isthmus (open arrow), is also distended.

FIGURE 59. The flask model is illustrative of how an abnor-mally patent lumen of the neck of the flask can enhance liquidflow because as the radius of the lumen increases, flow increas-es to the fourth power.


FIGURE 511. The flask model illustrating the effect of positivepressure at the mouth of the flask on the flow of liquid into theflask. The liquid is insufflated into the bulbous portion of theflask. Unlike a flask with a rigid neck, the Eustachian tube iscompliant, which would enhance flow because the liquid underpositive pressure distends a collapsible tube.

Failure of the Eustachian tubes passive closing mecha-nism (the tube is too open) has been postulated to be related tosniff-induced middle-ear disease (see Other Causes ofEustachian Tube Dysfunction).65

Short Tube

The Eustachian tube that is too short may lose its protectivefunction, such as in all infants and young children and in cer-tain special populations.

Infants and Young Children

Because one of the most important structural differences of theEustachian tube between infants and young children and olderchildren and adults is the length of the tube, this developmentaldifference can contribute to the high incidence of otitis mediain infants and young children. The tube is shorter in childrenbelow age 7 years (the tube is too short) (see Chapter 3,Table 32).31 The effect of a short Eustachian tube is graphical-ly illustrated in Figure 513. A flask with a short neck would notbe as protective as a flask with a long neck. Accordingly, theEustachian tube that is too short is more likely to reflux secre-tions from the nasopharynx into the middle ear than a tube thatis longer. As the length of the tube (neck) shortens, flow increas-es proportionally. Because infants have a shorter Eustachian

tube than adults, reflux is more likely in the baby. (An analogycan be made to the length of the urethra: females of all ages havemore urinary tract infections than males because the urethra isshorter in the female.) A tube that is too short can be includedin the classification of being too open because secretions fromthe nasopharynx can more easily enter the middle ear thanwhen a tube is of normal length.

Special Populations

Certain special populations may also have shorter tubes thanother groups. Infants and young children with a cleft palate haveEustachian tubes that are statistically shorter than age-matchedcontrols below age 6 years (see Chapter 7, Table 71). The tubeis also shorter in children with Down syndrome.31 The shorterthe tube, the more likely it is that secretions can reflux into themiddle ear in these children. This may be one explanation for thefrequent occurrence of troublesome otorrhea in infants andyoung children, especially those with a cleft palate and Downsyndrome when the tympanic membrane is not intact (there is aperforation or a tympanostomy tube is in place). Cranial anato-my may also play a role in the length of the Eustachian tube.Todd has postulated from studies in cadavers that the longer thecranial base, the longer the Eustachian tube, resulting in lessmiddle-ear disease.66

FIGURE 513. The flask model illustrating the effect of the length of thenarrow neck on the flow of liquid. Liquid is more likely to reflux into thebulbous portion of the flask when the neck is short. Because the Eustachiantube is shorter in infants and children compared with older children andadults, the short tube would enhance the flow and the liquid would refluxinto the middle ear.

FIGURE 512. Cartoon comparing a normally functioningEustachian tube at rest and during swallowing, related to soundpressure and nasopharyngeal gas, compared with a patulous tube.The patulous tube is open even at rest, which allows pressure regu-lation of middle-ear pressure, but sound pressures are transmitted tothe middle ear, causing autophony. EC = external auditory canal;ET = Eustachian tube; MAST = mastoid gas cell system; ME = mid-dle ear; NP = nasopharynx; TVP = tensor veli palatini muscle.



Abnormal Gas Pressures at Either End of the System

A loss of the tubes protective function can also occur whenabnormal pressures develop at either end of the Eustachian tubesystem.

Middle EarMastoid

At the distal end of the system, high negative middle-ear pres-sure, secondary to obstruction of the Eustachian tube that isanatomic (common during a viral upper respiratory tract infec-tion), due to a failure of active opening (functional obstruc-tion), or both may develop and result in aspiration of nasopha-ryngeal secretions into the middle ear. Figure 514 shows howaspiration can occur in the flask model when negative pressureis within the bulbous portion of the flask. In the study thatinvolved an adult volunteer who had an intranasal inoculationof a respiratory virus, the sequence of events from nasal conges-tion, Eustachian tube dysfunction with middle-ear negativepressure, and then development of an acute otitis mediaoccurred extremely rapidly after the onset of the viral upper res-piratory tract infection. The rapid progression of these findingsinfers aspiration of the viral and bacterial pathogens; both wereisolated by tympanocentesis.4 A chinchilla model of this processhas been established (W. J. Doyle, unpublished data, 1989).Although not related to loss of the Eustachian tubes protectivefunction, transudation of fluid into the middle ear and mastoidcan also occur when high negative pressure is present, which canresult in otitis media with effusion, that is, the hydrops ex vacuotheory (see Chapter 6).11,67

Nasopharynx

A loss of the tubes protective function can also occur when highpositive nasopharyngeal pressures develop at the proximal end ofthe Eustachian tube system. This abnormally high pressure, fromblowing the nose, crying in the infant (see Chapter 4, Figure 47),or when nasal or nasopharyngeal obstruction is present, can causenasopharyngeal secretions to be insufflated into the middle ear(see Figure 510). An animal model has been developed in whichhigh positive nasopharyngeal pressure produced by Politzerstechnique can insufflate nasopharyngeal liquids into the middleear (W. J. Doyle, unpublished data, 1990). Rapid alterations inambient pressures, which can occur during swimming, diving,airplane flying, and hyperbaric pressure treatments, can alsoresult in aspiration or insufflation of nasopharyngeal secretions(see Swimming, Diving, and Air Flight).

Toynbee Phenomenon The assessment of middle-ear pressureswhen swallowing while the nose is pinched off is a test ofEustachian tube function called the Toynbee test.68 Although arather crude test of tubal function, the results can be helpful,and even more informative, than Valsalvas or Politizers tests.When performing the Toynbee test, the middle-ear pressuresdeveloped are either positive, negative, or both (see Chapter 8).

But closed-nose swallowing can also occur when there isobstruction in the nose or nasopharynx. Swallowing when thenasal cavities, nasopharynx, or both are obstructed (owing toinflammation or enlarged adenoids) results in an initial positivenasopharyngeal gas pressure followed by a negative pressurephase (Figure 515). These pressures are produced in the meso-and hypopharynx during swallowing activity and are reflectedin the nasopharynx during closed-nose swallowing. When thetube is pliant, positive nasopharyngeal pressure might insufflateinfected secretions into the middle ear, especially when the mid-dle ear has high negative pressure. With negative nasopharyn-geal pressure, a pliant tube could be prevented from openingand could be further obstructed functionally. I originally sug-gested that the effect of swallowing when the nose or nasophar-ynx is obstructed could be related to Eustachian tube dysfunc-tion or middle-ear disease and coined the termed Toynbee phe-nomenon.24 Other investigators have subsequently confirmedthat this phenomenon exists.6971 Nasal packing has also beenidentified as being associated with the Toynbee phenomenon.72

Further evidence of the Toynbee phenomenon was pro-vided by an experiment in our laboratory in which the ferretanimal model of complete nasal obstruction resulted in persist-ent high positive middle-ear pressure (Figure 516), most likelysecondary to insufflation of nasopharyngeal gas into the middleear during swallowing activity.73

Another possible example of the Toynbee phenomenonmay be associated with hypertrophy of the adenoids that com-pletely block the nasal cavities posteriorly. As shown inFigure 517, adenoid hypertrophy not only can cause anatom-ic obstruction of the Eustachian tube, it may also be related totubal functional obstruction or even insufflation of nasopha-

FIGURE 514. The flask model illustrating the effect of negative pressure inthe bulbous portion of the flask when liquid is in the narrow neck. The liq-uid is aspirated into the flask. An analogy can be made when there isunderpressure in the middle ear, which can result in nasopharyngealsecretions being aspirated into the middle ear.

ryngeal secretions into the middle ear during the positive phaseof closed-nose swallowing. Figure 518 shows a radiograph inwhich the hypertrophy of the adenoids obstructs the posteriornasal choanae. It is possible that because the nasopharyngealgas volume is extremely small, when adenoids are very large,the pressures generated in the nasopharynx are greater thanwhen the volume of gas in the postnasal space is large (Boyleslaw).18

Nonintact Middle EarMastoid

Physiologically, protection of the middle ear from unwantednasopharyngeal secretions is provided by the geometry of thetube (isthmus, length, radius, tubal compliance, and other fac-tors described above). But another very important protectivefunction of the Eustachian tube system is the presence of aphysiologic middle earmastoid gas cushion, which helps pre-vent reflux, aspiration, and insufflation of nasopharyngealsecretions into the middle ear and mastoid. The pressure in themiddle earmastoid becomes more positive as the column ofsecretions enters the tubal lumen toward the middle ear, and thepositive middle earmastoid gas acts as a gas cushion (back-pressure of gas) (see Chapter 4). But when there is a perforationof the tympanic membrane (or a tympanostomy tube is inplace) or, in the extreme condition, a radical mastoidectomy ispresent (the eardrum is absent, and the middle ear, mastoid,and ear canal communicate, forming a single cavity), the gascushion is lost, allowing secretions from the nasopharynx toreflux or be insufflated into the middle ear.23,25 Thus, eventhough the anatomy and function of the tube itself may be nor-mal, the system at its distal end is defective (the tubal system istoo open). This concept is important when the surgeon is con-sidering repairing a perforation of the tympanic membrane orremoving a retained tympanostomy tube (see Chapter 9, Rolein Management of Otitis Media).

Figure 519 shows that the flask model is helpful in illus-trating how liquid can reflux into the vessel if there is a hole in thebulbous portion of the flask. The nonintact bulbous portion ofthe flask cannot develop positive pressure that could deter refluxof the liquid; the gas cushion is lost. The hole in the flask is anal-ogous to a perforation of the tympanic membrane or the pres-ence of a tympanostomy tube, which can both allow reflux of

nasopharyngeal secretions because the middle ear and mastoidgas cushion is lost. Similarly, following a radical mastoidectomy,a patent Eustachian tube could cause troublesome otorrhea.25

Impairment of Clearance FunctionThe physiologic clearance function of the Eustachian tubemiddleearmastoid is important in maintaining a healthy middle-earcleft (see Chapter 4). Clearance (drainage) of secretions from themiddle ear and Eustachian tube can be adversely affected whenthere is impairment of the mucociliary system, when there isimpairment of the muscular pumping action during opening andclosing of the Eustachian tube, and owing to the anatomy of thesystem in which there is trapping of liquid in the middle earmas-toid portions of the system. Table 54 is a summary of some of theknown factors that can impair middle ear and mastoid clear-ance.23,7483 Most investigators consider an impaired clearancefunction to be related to failure to resolve middle-ear effusions


FIGURE 515. When the nose or nasopharynx is obstructed,unphysiologic pressures can develop in the nasopharynx andadversely affect the Eustachian tube and middle ear, which istermed the Toynbee phenomenon. The left figure shows thatduring closed-nose swallowing, positive pressure is present first inthe nasopharynx, which could result in insufflation of nasopha-ryngeal secretions into the middle ear, followed by (right figure)negative pressure in the nasopharynx, which could cause func-tional obstruction of the Eustachian tube and middle-ear nega-tive pressure.

FIGURE 516. The results of a study in the ferret model in which one groupof animals had unilateral chronic nasal obstruction, another group hadbilateral chronic nasal obstruction, and a third group had no nasalobstruction (controls). Abnormally high positive middle-ear pressures (ontympanometry) occurred only in the animals with bilateral nasal obstruc-tion. Most likely, nasopharyngeal gas was insufflated into the bilaterallyobstructed animals middle ears during swallowing (the Toynbee phe-nomenon).


FIGURE 517. Cartoon showing two possible mechanismsrelated to adenoids and Eustachian tube dysfunction andmiddle-ear disease. The left figure shows that adenoidsmay anatomically obstruct the tube. The right figure showsthat if the adenoid hypertrophy obstructs the nasal cavitiesposteriorly, the Toynbee phenomenon can occur duringswallowing.

FIGURE 518. Submental-vertex radiograph showing hypertro-phied adenoids blocking the posterior nasal choanae (arrow). Nocontrast media instilled in the nasal cavities appeared in thenasopharynx that demonstrated total nasal obstruction.73

FIGURE 519. The left figure shows the flask model when ahole is made in the bulbous portion; liquid refluxes into thebottom of the flask owing to the loss of the backpressure inthe bulbous portion. The right figure shows how reflux ofnasopharyngeal secretions can reflux through theEustachian tube into the nonintact middle earmastoidbecause the physiologic gas cushion is lost.

and not the primary cause of the disease.84 However, patients withciliary dysmotility in their upper respiratory tract mucous mem-brane have been observed to have chronic middle-ear effusions.85

Mucociliary

Ohashi and colleagues conducted studies in guinea pigs anddemonstrated that bacteria, their toxins, and irradiation canimpair ciliary function.74 Park and colleagues demonstratedthat influenza A virus alters the ciliary activity and dye trans-port function in the Eustachian tube of the chinchilla.75 Rheeand colleagues reported that platelet-activating factor, aninflammatory mediator induced by infection, impairs ciliaryclearance in the Eustachian tube.86 Allergic response probablydoes not impair ciliary motility but may alter the mucus blan-ket in the Eustachian tube.87

Muscular

The pumping action of the Eustachian tube is most likely inef-fective when its opening mechanism is inadequate (see Failureof the Opening Mechanism), and this function has beendemonstrated to be impaired when negative pressure is in themiddle ear.80,81 If the Eustachian tube does not dilate duringswallowing activity, passive closure and pumping out of mid-dle-ear liquid is adversely affected (see Chapter 4, Figure 412).

Anatomy of the System

If the physiologic clearance systemmucociliary and pumpingactionis impaired, retained liquid is not likely to drain owingto the negative pressure that develops within the middle ear andmastoid gas cell system. The liquid is trapped in the middleearmastoid. This is because the liquid moves even by gravitytoward the Eustachian tube and into the nasopharynx. This can

be graphically shown using the flask model. Figure 520 showscertain aspects of liquid flow from the middle ear andEustachian tube into the nasopharynx by inverting the flaskmodel. In this case, the liquid trapped in the bulbous portion ofthe flask does not flow out of the vessel because of the relativenegative pressure that develops inside the chamber as the liquidattempts to flow out of the flask. However, if a hole is made inthe vessel, the liquid drains out of the flask because the suctionis broken. Clinically, these conditions occur in cases of middle-ear effusion, that is, pressure is relieved when the tympanicmembrane ruptures spontaneously or by myringotomy.Inflating air into the flask could also relieve the pressure, possi-bly explaining the reputed success of Politzers or Valsalvasmethod in clearing a middle-ear effusion (see Chapter 9).

Even though there are several known mechanisms ofimpairment of the clearance function, this dysfunction general-ly can be included in the simplified classification as being relat-ed to the tubal system being too closed at the distal middle earend. Figure 521 shows a radiograph of a middle ear in whichmucoid effusion was aspirated and contrast media instilled. Thedye did not enter the Eustachian tube owing to inflamedmucosa obstructing the osseous portion of the tube.

Dysfunction Related to Cleft PalateIn infants with an unrepaired cleft palate, otitis media is univer-sally present.88,89 Palate repair appears to improve middle earstatus, but middle-ear disease nonetheless often continues orrecurs even afterward.90,91 Figure 522 shows a radiograph of aninfant in whom radiopaque contrast media failed to enter theEustachian tube during open- and closed-nose swallowing. Ourstudies suggest failure of the Eustachian tubes opening mecha-nism in infants with an unrepaired cleft palate as the primarycause of dysfunction.22,91,92 As described in Chapter 7,histopathologic temporal bone studies have confirmed that theEustachian tube of cleft palate patients is not anatomicallyobstructed, giving credence to a failure of the opening mecha-nism as the underlying defect (functional as opposed toanatomic obstruction). Other anatomic findings, such as theabnormal cartilage and lumen, insertion ratio of the tensor velipalatini muscle into the cartilage, deficient attachment of thetensor veli palatini muscle into the lateral lamina of the carti-lage, and deficient elastin at the hinge portion of the cartilage,most likely explain the functional obstruction identified byradiographic and manometric Eustachian tube function tests(see Chapter 7, Table 71).9397 Also, the craniofacial skeleton isabnormal in children with a cleft palate, which may influenceEustachian tube function, development of otitis media witheffusion, and the hearing loss that is associated with the middle-ear effusion.98,99 Animals whose palates had been surgically splitalso developed middle-ear effusion.49,56,100

Patients with a submucous cleft of the palate appear tohave the same risk of developing middle-ear disease as those


Table 54. Factors Attributed to Impairment of Middle Ear

Eustachian Tube Clearance in Humans and Animals

Factor Reference

Bacteria (and toxins) Ohashi et al, 198974

Virus (influenza A) Park et al, 199375

Middle-ear effusion Takeuchi et al, 199076

Ohashi et al, 199577

Inflammatory mediators

Prostaglandin E2 Herman et al, 199478

Leukotrienes C4, D4 Ganbo et al, 199579

Middle-ear negative pressure Nozoe et al, 198480

Takahashi et al, 199281

Smoking Agius et al, 199582

Inflammatory obstruction Bluestone et al, 197223

of osseous Eustachian tube Niwa et al, 199083

Anatomy of system Bluestone et al, 197223

(trapping effusion in

closed space)


with an overt cleft, which may be related to the underlyingpathology associated with the child with a cleft palate; possibly,a high-arched palate is also related to these problems.93 In addi-tion, a bifid uvula has been associated with a high incidence ofotitis media.101 Both conditions are probably associated withthe same pathophysiologic mechanism related to the pathogen-esis of otitis media found in patients with overt cleft palates(functional obstruction of the Eustachian tube).

Constriction and Pathophysiologic DefectsStudies in humans and animals indicate that the high incidenceof otitis media in children with cleft palate is related to a failureof the tubes opening mechanism and that the tube is function-ally obstructed (the tube will not open). Recently, we identifiedconstriction of the Eustachian tube to be present during swal-lowing in humans with cleft palate and in monkey models ofcleft palate (see Tables 52 and 53). We created an animalmodel of cleft palate in the monkey. Following surgically cleft-ing the palate, dysfunction of the Eustachian tube was docu-mented (including constriction in some), which resulted inmiddle-ear effusion.102.103 In one of these experiments, thepalate was allowed to heal, which resulted in the return of nor-mal tubal function and resolution of the middle-ear disease.57

If the tube constricts during swallowing, dilation and thepressure regulation function are impaired (see Figure 58).

These pathophysiologic defects would be more likely to result inrelatively asymptomatic middle-ear effusion in the infant withan unrepaired cleft palate, which was the stage of otitis mediadiagnosed in these babies,89 as opposed to recurrent acute otitismedia with little or no effusion between attacks, as is so fre-quently present in infants without a cleft palate. Also, on forced-response function tests, the Eustachian tube had high resistanceto airflow, which could be related to the known pathology of thetube identified from the temporal bone histopathologic studies.It has also been suggested that there is a tubal closing failure inpatients with a cleft palate.65

In comparison with other special populations of patientswho are prone to otitis media (Down syndrome, certain NativeAmerican tribes), individuals with a cleft palate have differentEustachian tube function, which could be an insight into theunderlying cause (see Comparison of Eustachian TubeFunction in Special Populations and Figure 523).

Also, the pathogenesis of recurrent and chronic otitismedia in these patients may be related to another pathology relat-ed to dysfunction, such as the deficient length of the Eustachiantube.31,104 A short tube may permit nasopharyngeal secretions toenter the middle ear, causing otitis media by reflux or aspiration.Troublesome otorrhea is a frequent clinical problem in thesepatients when the tympanic membrane is perforated or there is atympanotomy tube in place; palatoplasty reduces this problem.105

FIGURE 520. The right figures show the flask model inverted. When thereis liquid in the bulbous portion, flow out of the flask does not occur owingto the buildup of negative pressure in the body of the flask as the liquiddrains down the neck (A). An opening made in the bulbous portion allowsthe liquid to flow out because the pressure in the body of the flask is ambi-ent and not negative (B). The left figures show that, normal mucociliaryand muscular pumping clearance functions notwithstanding, the anatomyof the Eustachian tubemiddle earmastoid can impair flow of a middle-ear effusion down the Eustachian tube owing to the development of nega-tive pressure in the middle ear as the effusion attempts to drain down thetube (A). An opening in the tympanic membrane (myringotomy) wouldenhance drainage of the middle-ear effusion down the Eustachian tube (B)(see Chapter 9). ET = Eustachian tube; ME= middle ear; TM = typanicmembrane; Mast = mastoid gas cells.

Another obvious pathophysiologic defect in thesepatients is that when the palatal cleft is unrepaired, there is novelopharyngeal closure during swallowing (and during speech).If infants with an intact palate are able to inflate their middleears during crying, as a physiologic compensatory mechanismfor their ineffective active tubal opening, especially duringdescent in an airplane, then infants with an unrepaired cleftpalate have an additional handicap (the proximal end of theEustachian tube system is too open). It is likely that infants withan intact palate inflate their middle ears during crying in anattempt to regulate middle-ear pressure even at sea level, butthey are also at risk of insufflating infected nasopharyngealsecretions during a viral upper respiratory tract infection. Bycontrast, the baby with an unrepaired cleft has difficulty insuf-flating air into the middle ear during crying but is also probablynot at risk of insufflating nasopharyngeal secretions. This isanother possible reason for recurrent acute otitis media to be rel-atively less common in this age group compared with infantswhose palates are intact. Most likely, the lack of symptomaticacute otitis media in infants with an unrepaired cleft is a major

reason that the diagnosis of the universality of chronic otitismedia was not accepted until the 1960s.88,,89 Of note is the morefrequent occurrence of episodes of acute otitis media followingrepair of the palate, especially when velopharyngeal function isgood; the child can develop positive nasopharyngeal pressure fol-lowing repair. Following palatoplasty, some infants have a reduc-tion in the rate of otitis media, whereas others do not, which hasbeen suggested to be related to the status of Eustachian tube func-tion.102 Also, some clinicians have observed a reduction in otitismedia following pharyngoplasty to improve velopharyngeal func-tion. Investigation into the effect of nasopharyngeal pressures,before and after palate repair, is an important future researchdirection (see Chapter 11).

Complications and Sequelae

Children with a cleft palate have middle-ear disease character-ized by either persistent or recurrent high negative middle-earpressure, effusion, or both. But these children frequently havechronic suppurative otitis media, especially infants. Because


FIGURE 521. Submental-vertex radiograph showinga lack of clearance of radiopaque contrast mediainstilled into the middle ear that had mucoid effusionimmediately after aspiration of the effusion. The dye isblocked at the osseous tube (arrow).

FIGURE 522. Submental-vertex radiograph of aninfant with an unrepaired cleft palate in whomradiopaque contrast media was instilled into thenasal cavities showing no dye entering thenasopharyngeal portion of the Eustachian tubeeven after closed-nose (nasal alae pinched off)swallowing.


these patients are prone to acute otorrhea, chronic suppurativeotitis media can develop if the acute otitis media and otorrheaare not treated appropriately and promptly. Chronic otorrheadoes not occur if acute otorrhea is successfully treated.64 As stat-ed above, troublesome chronic otorrhea may be improved withpalatoplasty. Most likely, providing effective velopharyngeal clo-sure aids in improving the Eustachian tube system, in additionto possible benefits from repairing the muscle sling, which ispurported to improve muscular active opening of the tube.Unfortunately, the best surgical methods to repair the palate, inan effort to improve Eustachian tube function, remain an areaof future research (see Chapter 11).

A frequent clinical finding in children with an unrepaired orrepaired cleft palate is chronic middle-ear negative pressure, whichoften leads to atelectasis of the tympanic membranemiddle ear, especially a retraction pocket in the attic or posterosuperiorquadrant of the pars tensa, which can develop into a retractionpocket or cholesteatoma. Prevention of these sequelae is related toearly and continuous attempts to maintain middle-ear pressure,such as by palate repair and frequent insertion of tympanostomytubes.90 Interestingly, this sequence of events is not the case in cer-tain Native Americans, in whom the Eustachian tube has beenshown to be hyperpatent (to have low tubal resistance; the tube istoo open) (see Chapter 10, Role in Certain Complications andSequelae of Otitis Media).63

Comparison of Eustachian Tube Function inSpecial Populations

From our numerous studies over the years, it has become evi-dent to us that there are different types of Eustachian tube dys-function identified in certain special populations of humanswhen compared with adults with normal function. Figure 523is a somewhat simplistic but interesting conceptual separationof these populations based on the function of their Eustachiantube. Such a conceptual differentiation might help in under-standing the pathophysiology, and subsequently the pathogene-sis, of each of the disease states associated with the individualgroups. As described above, patients with a cleft palate havepoor dilatory function of the Eustachian tube and high resist-ance (pressure/flow) when tested with the forced-responsefunction test.18,22,91, 92 As stated above, these childrens middle-ear disease is characterized by chronic otitis media with effu-sion, atelectasis and retraction pockets, and cholesteatoma.106 Incontrast to the tubal function and middle-ear disease in the cleftpalate population, the other end of the spectrum has the WhiteMountain Apache Native Americans, who were studied byBeery and colleagues.63 This group had function tests that indi-cated semipatulous or patulous Eustachian tubes, but they diddilate the tube on swallowing, indicating function. This group isprone to chronic perforation with chronic suppurative otitismedia without the high incidence of cholesteatoma. Still anoth-er population that is somewhat unique is children with Down

syndrome who had Eustachian tube function tests that indicat-ed that their tubes were too open. Unlike the Native Americans,the patients with Down syndrome could not effectively opentheir tubes during swallowing.50 Children with Down syndromehave chronic middle-ear disease, including cholesteatoma.When comparing these function results with children andadults with recurrent and chronic middle-ear disease, they haveworse function than normal children,23,44,48,107 and normal chil-dren have worse function than normal adults.26,108,109 In func-tion studies of patients who had cholesteatoma (not in a specialpopulation), the Eustachian tube failed to open during swal-lowing, indicating dysfunction.25 It is hoped that these compar-isons will help in identifying the underlying pathophysiology ineach group, which will aid in developing treatment and preven-tive strategies (see Chapter 11).

Dysfunction Related to AllergyAllergy is thought to be one of the pathogenic factors in otitismedia because otitis media occurs frequently in allergic indi-viduals.110 I discuss certain aspects of the possible role of aller-gy in the pathogenesis of middle-ear disease in Chapter 6, but inthis chapter, I present some of the current evidence, for andagainst, of the possible mechanisms (pathophysiology) bywhich allergy might be related to the pathogenesis of otitismedia, even though some of them remain hypothetical andcontroversial.111,112 The possible role that allergy plays in the

FIGURE 523. Conceptual schema of Eustachian tube function and dys-function in selected, special populations compared with normal adultsand children. The long axis is conceptualized as the structure of the tuballumen, and the vertical axis is related to function (whether or not the tubeopens upon swallowing) (see text).

pathogenesis (and etiology) of otitis media may be by one ormore of the following mechanisms:

The middle-ear mucosa functioning as a shock (target)organ

Inflammatory swelling of the Eustachian tube mucosa

Inflammatory obstruction of the nose

Aspiration of bacteria-laden allergic nasopharyngealsecretions into the middle-ear cavity113

Doyle has also proposed another possible mechanism.114

In a clinical study by Bernstein and colleagues, it was sug-gested that the Eustachian tube might be adversely affected byallergy as opposed to the middle ear as a target organ.115 Theyinvestigated the role of immunoglobulin E (IgE)-mediatedhypersensitivity in 100 children with recurrent otitis media. Thechildren were divided into nonallergic and allergic groups basedon their history and physical examination, prick testing forselected antigens, total IgE, and specific IgE radioallergosorbenttesting. Following aspiration of their middle ears and testing forIgE, they concluded that 35% of the 100 children may have hadIgE-mediated allergy as a cause of their effusion and in 8% ofthe children, the middle ear was a possible target organ. In theother 27%, they postulated that the Eustachian tube might havebeen the target organ (Table 55).

Figure 524 shows one probable mechanism in which theallergic shock organ is the Eustachian tube, but as indicated inthe cartoons in the figure, most likely an individual should havedysfunction of the Eustachian tube as an underlying predispos-ing factor to result in middle-ear disease. As described inChapter 6, studies at the Childrens Hospital of Pittsburghinvolving adult volunteers demonstrated a relationship betweenintranasal challenge with respiratory viruses, antigen challenge,allergic rhinitis, and Eustachian tube obstruction.12,116120 Noneof these allergy studies produced otitis media in the volunteers,but apparently none had preexisting Eustachian tube dysfunc-tion. As discovered in some of the virus studies, adult volunteerswho had preexisting Eustachian tube dysfunction were prone todeveloping Eustachian tube dysfunction and middle-earpathology.6 It is possible that repeated challenge with antigenover a prolonged period of time would cause individuals whoare hypersensitive to the specific antigen and who also have

poor Eustachian tube function to develop middle-ear effusion.Figure 525 depicts another hypothetical sequence of events,but, again, a preexisting abnormality of the Eustachian tube isproposed as a predisposing factor (the tube is too open).

Swimming, Diving, and Air FlightEven though normal swimming is usually not associated withany pathophysiology related to the pathogenesis of middle-eardisease, some individuals do have difficulty equalizing middle-ear pressures during and after swimming, especially when div-ing into water. Swimming is a normal activity that is part of ourevolutionary development, but scuba diving is not. We did notevolve as a species with the need to equalize sudden alterationsin atmospheric pressure. Thus, humans also may have difficul-ty in flying in an airplane, especially ones that do not have cabinpressurization. But most individuals can successfully equalizepositive and negative pressures within the middle ear duringthese activities, but some cannot, such as individuals who havean upper respiratory tract infection or nasal allergy, eventhough they have normally functioning Eustachian tubes, orthose who have preexisting dysfunction of the Eustachian tube.Most commonly, middle-ear dysfunction and disease occurwhen both conditions are present, that is, upper respiratorytract inflammation (infection or allergy) and preexistingEustachian tube dysfunction.

Swimming and DivingSwimming on the surface of the water is usually not associatedwith Eustachian tubemiddle ear problems, but even in the faceof a normally functioning tube, swimming under water only afew feet is sufficient to insufflate infected nasopharyngeal secre-tions into the middle ear during an upper respiratory tract infec-tion (Figure 526). The positive pressure from even a modestdepth may result in middle-ear disease. Most swimming instruc-tors restrict children from swimming when they develop a coldor have moderate to severe nasal allergy. However, diving can bea problem for children and adults depending on the preexistingstatus of their Eustachian tube function, the presence or absenceof an upper respiratory tract infection, and the depth of the dive.Those who have the most discomfort are individuals who havelong-standing Eustachian tube dysfunction who often have otal-gia when the middle ear has a relative negative pressure related

Table 55. Summary of 100 Allergic and Nonallergic Children in Buffalo (NY) with Recurrent Otitis Media

Possible Target Organ Middle Ear/Eustachian Tube

Group Middle Ear Eustachian Tube Probably Not Target Organs Total

Allergic 8 27 0 35

Nonallergic 0 0 65 65

Total 100

Adapted from Bernstein JM et al.115



to acquisition of sudden positive water pressure. Barotrauma canoccur and even severe acute otitis media if the person has a cold.Most experienced scuba divers frequently use the Valsalvamaneuver on descent to prevent locking of the Eustachiantube. Scuba diving in the presence of preexisting dysfunction ofthe tube, when nasal congestion develops, or both are risk factorsfor severe Eustachian tube problems and barotrauma. It is prob-ably not wise for individuals with chronic Eustachian tube dys-function to pursue the sport of scuba diving.

Flying and Pressure ChambersFor most passengers in commercial airplanes, the unphysiolog-ic experience of flying in an airplane is not associated with anymajor problems in their Eustachian tubes ability to equalizemiddle-ear pressure when in a pressurized cabin, usually pres-surized to about 7,000 feet. Figure 527 presents a rather sim-plistic but informative explanation of the events occurring in

the middle ear related to an individual with normal Eustachiantube function during air flight. On ascent, the normal tube willspontaneously, passively openwithout the need to swallowand actively dilate the tubeto equilibrate the relative positivepressure that develops in the middle as the ambient pressurebecomes negative. On descent, the tube does not spontaneous-ly open, and the flyer must actively open the Eustachian tube byswallowing activity to equalize the relative middle-ear negativepressure as the ambient pressure becomes more and more pos-itive. On the other hand, despite an otherwise normally func-tioning tube, a passenger who has nasal congestion may experi-ence some discomfort on ascent because the passive openingpressure will be higher than experienced when a cold is absent.On descent, otalgia is a commonly encountered problem, sec-ondary to the inability to equilibrate the middle-ear negativepressure with the ambient positive pressure in the cabin, owingto inflammation of the tubal lumen. Even locking of the

FIGURE 524. Cartoon showing a possible sequence ofevents in which allergy can affect the Eustachian tube.When upper respiratory allergy is present, anatomicobstruction of the Eustachian tube is possible, secondaryto inflammation of the lumen (intramural). Then mid-dle-ear negative pressure develops, followed by atelectasisof the tympanic membranemiddle ear, otitis media witheffusion, or even acute otitis media (secondary to aspira-tion of bacteria-laden and allergic secretions in thenasopharynx). These events are hypothesized to occurwhen there is preexisting Eustachian tube dysfunction.

FIGURE 525. Cartoon showing another possible mechanism involved inthe role of allergy in the pathogenesis of otitis media. If the Eustachiantube is abnormally patent (too open), nasopharyngeal secretions (associ-ated with nasal allergy) could be refluxed or insufflated into the middleear. Thus, the predisposing factor in this hypothesis is a hyperpatent tube.


Eustachian tube can occur.40 Locking of the tube on descent canlast hours to days. Locking is related to the rate and depth of thedescent. Also, flying an unpressurized aircraft would more like-ly present tubal problems than one that is pressurized.

A well-known related story is that German aviators whoflew the infamous Stuka planes during the Spanish Civil War inthe 1930s would frequently pass out during their very steepstrafing dives owing to their Eustachian tubes locking. To pre-vent this, German flight surgeons performed prophylacticmyringotomies before the pilots took off. Despite the fact thatthese pilots most likely had had normally functioning tubes, thesteep dive could not be equilibrated.

For individuals who have preexisting Eustachian tube dys-function, even flying in commercial aircraft can lead to greatdifficulty in equalizing rather extreme alterations in ambientpressures, and the presence of upper respiratory tract inflam-mation would increase the chance of middle-ear (otitic) baro-trauma. Although rather rare, a person who has a preexistingnarrow tubal lumen, such as the presence of acquired or con-genital stenosis, may have severe discomfort on ascent, given thedifficulty in passively opening the tube (higher opening pres-sures are required for the tube to open). More commonly, indi-viduals who have Eustachian tube dysfunction symptoms andhave had middle-ear disease in the past will have relatively littleproblem in equilibrating positive pressure despite higher passiveopening pressures, but these individuals frequently will havegreat difficulty on descent (Figure 528). The presence of preex-isting Eustachian tube dysfunction can be a real problem forpilots of jet airplanes, which, as well as other investigationsinvolving Eustachian tube function, has been extensively studiedin the past by the research group in Malm, Sweden.121

Alternobaric vertigo can occur in pilots whose passive openingpressure does not occur in both ears at about the same heightduring ascent.122

Similar types of Eustachian tube problems in functioningalso occur in the face of unphysiologic pressure alterationswhen individuals are in pressure chambers (hyperbaric treat-ment). Individuals without a history of Eustachian tube dys-function are more capable of equilibrating changes of pressuresin the chamber than those whose function is poor. Placementof tympanostomy tubes has been recommended as a prophy-lactic measure prior to hyperbaric treatment when a patient hasa history of tubal dysfunction because they frequently cannotequalize the relative middle-ear negative pressure as the cham-ber pressure increases. Otic barotrauma can occur in thesepatients if a pressure-equalizing tympanostomy tube is notpresent.

Pregnancy and PubertyDespite the fact that both pregnancy and puberty are consideredto be part of human physiology, some women who are pregnantand a few girls and boys in puberty have Eustachian tube dys-

function during these periods and even develop middle-ear dis-ease. Obviously, pregnancy is solely a female issue, and eventhough both sexes go through puberty, Eustachian tube dys-function during this time is much more common in girls thanin boys. Because women in the third trimester of pregnancy aremost affected and girls are more prone to dysfunction than boysin puberty, the dysfunction in both pregnancy and puberty ismost likely related to hormones, but the underlying causeremains obscure at present.

PregnancyRhinitis and Eustachian tube dysfunction are problems in preg-nancy. It is estimated that up to 30% of pregnant women havesome degree of nasal congestion and dysfunction of the tube.123

Pulec suggested that the tube is patulous (too open) and attrib-uted the cause to hormones.124 In an elegant prospective studyconducted at our medical center, Derkay assessed the functionof the Eustachian tube in three groups of women: 20 pregnantvolunteers who had symptoms of Eustachian tube dysfunction,20 trimester-matched volunteers who were in their thirdtrimester of pregnancy but had no symptoms of tubal dysfunc-tion, and 20 age-matched nonpregnant women (controls).123

Eustachian tube function tests included the nine-stepinflation-deflation tympanometric test and sonotubometry (seeChapter 8). Among the symptomatic pregnant subjects, 80%had Eustachian tube dysfunction compared with only 45% ofasymptomatic pregnant women and 30% of nonpregnant con-trols; these differences were significant. In all three groups, onlya few had evidence of a patulous Eustachian tube, contrary topast assumptions about the type of dysfunction related to preg-nancy. The primary dysfunction diagnosed was failure to openthe tube during swallowing. All of the symptomatic pregnantwomen had resolution of their dysfunction following the birthof their child. Most likely, pregnancy-related Eustachian tubedysfunction is related to hormonal activity, and some have sug-gested that the tubal dysfunction related to taking oral contra-ceptives may have a similar underlying etiology.

Puberty

Although no systematic study of the incidence, sex predilection,and cause of the symptoms of Eustachian tube dysfunctionassociated with puberty has been reported, it is my experiencethat it occurs much more commonly in girls than in boys, ismost likely an abnormality of the tubal opening mechanism,and is almost always relieved following tympanostomy tubeplacement. There are usually no signs of pathology of the tym-panic membrane or middle ear, although negative pressure maybe diagnosed on pneumatic otoscopy and by tympanometry.The symptoms are classic of dysfunction of the Eustachian tube,such as fluctuating hearing, tinnitus characterized by poppingand cracking sounds in the ear, occasional mild recurrent verti-go, and mild recurrent otalgia. Symptoms of a patulous tube,


Still eustachian tubeopens naturally

Swallowing cannotopen abnormaleustachian tube

Persistent negative pressure in middle ear upon landing, which

can be painful

Cruising altitudeAltitude

Take off Landing

Pres

sure

in in

ner e

ar re

lativ

e to

gro

und Positive pressure

Negative pressure

0

+

Negative middle earpressure at cruising altitude

Normal middle ear pressure at ground level

FIGURE 528. Artists drawing explaining how anabnormal Eustachian tube and middle ear respondduring airplane flying. Reproduced with permissionfrom Bluestone CD, Casselbrant ML, Dohar JE.Targeted therapies: otitis media and otitis externa.Hamilton (ON): BC Decker; 2003.

Positive pressureunder water Forces nasal

secretions intoeustachian tube

Eustachian tubeopens naturally

Swallowing opens eustachian tube and

equalizes pressure in ear

Middle ear pressurereturns to normal

Cruising altitudeAltitude

Take off Landing

Pres

sure

in in

ner e

ar re

lativ

e to

gro

und

Normal middle ear pressure at ground level

Positive pressure

Negative pressure

0

+

Negative middle earpressure at cruising altitude

FIGURE 527. Artists drawing explaining how the normal Eustachiantube and middle ear respond during airplane flying. Reproduced withpermission from Bluestone CD, Casselbrant ML, Dohar JE. Targeted ther-apies: otitis media and otitis externa. Hamilton (ON): BC Decker; 2003.

FIGURE 526. Diving into a swimming pool can causeacute otitis media when an upper respiratory infection ispresent. Reproduced with permission from Bluestone CD,Casselbrant ML, Dohar JE. Targeted therapies: otitismedia and otitis externa. Hamilton (ON): BC Decker;2003.

such as autophony, are uncommon. This age-related dysfunc-tion is usually self-limited because it frequently resolves follow-ing passing of the age of puberty. However, some females willhave persistent symptoms into the teenage years. Similar to thepurported etiology of tubal dysfunction related to pregnancy,this is probably a hormonal phenomenon.

Other Causes of Eustachian Tube Dysfunction

Dysfunction of the Eustachian tube has also been associatedwith deviation of the nasal septum (the tubal system is tooclosed at the proximal end); trauma induced by nasogastric andnasal endotracheal tubes (the tube is too closed); trauma to thepalate, pterygoid bone, or tensor veli palatini muscle (the tubewill not open); injury to the mandibular branch of the trigemi-nal nerve (the tube will not open); and trauma associated withsurgical procedures, such as palatal or maxillary resection fortumor (the tube will not open or is too open at the proximalend of the system).38,125129 Benign or malignant neoplastic dis-ease that invades the palate, pterygoid bone, or tensor veli pala-tini muscle can also cause the opening mechanism of the tubeto fail (the tube will not open), causing otitis media.30,38,39,130

Because a cleft of the palate can functionally obstruct theEustachian tube, any child with a craniofacial malformationthat has an associated cleft of the palate will have recurrent andpersistent otitis media. A common example is Robin sequence.However, children with craniofacial anomalies that do notinclude an overt cleft of the palate also have an increased inci-dence of middle-ear disease. Eustachian tube dysfunction hasbeen described in children with Down syndrome and otitismedia.50 Even though there have been no reports of formalEustachian tube function studies in individuals with other dis-orders, such as Turners or Aperts syndrome or Crouzons dis-ease, Eustachian tube dysfunction is the most likely cause of eardisease in these patients. Indeed, patients with chromosomalaberrations have abnormal Eustachian tube anatomy,131 as wellas those who have oculoauriculovertebral spectrum.132 Also,presumably, a defect related to the abnormal craniofacial com-plex, most often at the base of the skull, influences the relation-ship between the Eustachian tube and its associated dysfunc-

tion.133 Other syndromes associated with a high rate of otitismedia and hearing loss, such as has been observed in velocar-diofacial syndrome,134 may also have abnormal function of theEustachian tube as the origin of the middle-ear disease.

Patients with dentofacial abnormalities often have otitismedia or develop middle-ear disease as a result of these abnor-malities. A dental overbite has been associated with otitis mediain children.135 Correction of the defect to relieve the Eustachiantube dysfunction is indicated.

Some individuals, but rarely children, are habitual snif-fers and actually create underpressure within the middle ear bythis act (Figure 529).65 In a study from Japan, Sakakihara andcolleagues evaluated 17 subjects, mean age 16 years, who hadsniff-induced otitis media and found that their Eustachiantubes were excessively patent (the tube is too open) with pooractive opening mechanisms (the tube will not open).42


FIGURE 529. Cartoon showing the effect of sniff-induced negative pres-sure in the middle ear. The negative nasopharyngeal pressure can close ahyperpatent Eustachian tube, and middle ear abnormal underpressurescan also occur.

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a twin and triplet study. JAMA 1999;202:212530.4. Buchman CA, Doyle WJ, Skoner DP, et al. Influenza A virus-induced acute

otitis media. J Infect Dis 1995;171:134851.5. Moody S, Alper CM, Doyle WJ. Daily tympanometry in children during

the cold season: association of otitis media with upper respiratorytract infections. Int J Pediatr Otorhinolaryngol 1998;45:14350.

6. Buchman CA, Doyle WJ, Skoner D, et al. Otologic manifestations ofexperimental rhinovirus infection. Laryngoscope 1994;104:12959.

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9. Bluestone CD. Definitions, terminology, and classification. In: RosenfeldRM, Bluestone CD, editors. Evidence-based otitis media. Hamilton(ON): BC Decker; 1999. p. 85104.

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26. Bylander A, Tjernstrm O, Ivarsson A. Pressure opening and closing func-tions of the Eustachian tube by inflation and deflation in children andadults with normal ears. Acta Otolaryngol (Stockh) 1983;96:25568.

27. Stenstrom C, Bylander-Groth A, Ingvarsson L. Eustachian tube function inotitis-prone and healthy children. Int J Pediatr Otorhinolaryngol1991;21:12738.

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40. Flisberg K, Ingelstedt S, Ortegren U. The valve and locking mechanismof the Eustachian tube. Acta Otolaryngol Suppl (Stockh)1963;182:5768.

41. Lamp CB. Chronic secretory otitis media: etiologic factors and pathologicmechanisms. Laryngoscope 1973;83:27691.

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