Deep Spaces, Paranasal Sinuses, & Nasopharynx

7/28/2019 Deep Spaces, Paranasal Sinuses, & Nasopharynx

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DEEP SPACES, PARANASAL SINUSES, AND NASOPHARYNX

Wade Wong, D.O.

Evaluation of the head and neck has developed significantly with the advent of CT and MRI. These modalities have greatly complimented the physical and endoscopic examinations byrevealing possible b lind areas such as nonpalpable adenopathy, cartilage invasion, bone marrow invasion, contralateral involvement, and distant metastases. MRI has some majoradvantages over CT. Superior soft tissue contrast is possible with MRI leading to better definition between tumor and adjacent structures. Multiplanar imaging can be extremely helpful inappreciating and confirming the extent of disease. There is a lack of beam hardening artifacts which are encountered with CT when dental fillings are present. In patients who can not

tolerate intravenous iodine contrast, MRI with gadolinium can still be performed. In order to optimally evaluate the head and neck for pathological processes, one must first have a clearunderstanding of the anatomy of the head and neck.

Anatomical Considerations:

In addition to understanding basic anatomical structures such as the tongue, the tonsilar fossa, the epiglottis, the paranasal sinuses, the nasal cavity, and the larynx, one must also be awareof certain anatomical spaces which are delineated by fascial planes. These anatomical spaces throughout the head and neck represent potential vertical highways for tumor spread ofpathological processes.

Pharyngeal Mucosal Space:

This space is located very superficially along the pharyngeal mucosal walls. It includes the mucosa of the pharynx, Waldeyer's ring, the cartilaginous eustachian tube, the pharyngobasilarfascia, the levator and constrictor muscles. Common tumors seen in this space would include squamous cell cancer, lymphoma, and sometimes adenocarcinoma, adenoid cystic carcinoma, andjuvenile angiofibromas. Thornwaldt cysts and mucous retention cysts can also be found along this space. It represents a very superficial layer for which tumors often will develop before theyspread to deeper l ayers. This space is p robably less important from an imaging standpoint than the deeper spaces as an endoscopist can usually detect tumor spread along this spacewithout difficulty.

Pharyngeal Mucosal Space

* Most superficial layer includes the pharyngeal mucosa, Waldeyer's Ring, eustachian tube, constrictor and levator muscles.

* Common masses:

Squamous Cell CarcinomaAdenoid Cystic Carcinoma

LymphomaJuvenile Nasal AngiofibromaThornwaldt's Cyst


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Parapharyngeal Space:

This is an important vertical highway which extends from the skull base to the hyoid bone. Tumors that may arise along the pharyngeal mucosal space such as squamous cell cancer of thetonsilar fossa, can spread to the next deeper layer which is often the parapharyngeal space. Once in the parapharyngeal space, it can spread in a vertical manner very quickly. Theparapharyngeal space contains primarily fat, branches of the trigeminal nerves, and the pterygoid veins. Lesions that are frequently encountered in this space include metastatic lesionsfrom squamous cell cancer, particularly from the base of the tongue, tonsilar fossa, and larynx. Salivary gland tumors may also be encountered in this space as a result of direct extension.Branchial cleft cysts can develop or cross through this space. Lipomas may arise denovo from the fat within this space. Infections can also run rampant in this space in a very rapid manner.

Parapharyngeal Space

* Fat filled space with some twigs of the fifth nerve and pterygoid veins.

* Extends from skull base down to the hyoid bone.

* METS (squamous cell cancer), infection, li pomas, pleomorphic adenomas, branchial cleft cysts.


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Carotid Space:

This is another major highway through which tumors can race vertically up and down from the skull base down to the aortic arch., This space includes the extracranial carotid artery, thejugular vein, portions of cranial nerves 9 through 11, the internal jugular chain of nodes. Metastatic lesions from squamous cell cancer can frequently be found in this space. Popular sites oforigin for squamous cell cancer to invade the carotid space include the larynx, the tongue base, the tonsilar fossa, and the nasal pharynx. Other lesions that can be found in the carotidspace would include neurofibromas, Schwannomas, paragangliomas, and lymphomas. Infections which may be harbored, particularly in the internal jugular nodes, can also be detected inthe carotid space. Involvement of the carotid space may be an indica tor for nonresectability, particularly if the carotid artery is encased.

Carotid Space

* Includes carotid artery, internal jugular vein, c ranial nerves 9-11, internal. j ugular chain of nodes.

* Extends from skull base down to aortic arch. Major verticle highway.

* Common tumors:

Metastatic squamous cell cancerLymphomaSchwannomas/NeurofibromasParaganglioma

* Encasement of the carotid artery may mean inoperability.


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Prevertebral Space:

This is a complex space which is enveloped by a deep layer of cervical fascia. It includes not only the longus coli muscles, but also the paraspinous muscles, the vertebra, the vertebralartery, and the spinal cord. Metastatic lesions to the prevertebral space as well as to the carotid space can potentially determine inoperability. For that reason, close scrutiny of tumorextension to the prevertebral space is very important. Common neoplasms that are found in the prevertebral space include metastatic lesions particularly from squamous cell carcinoma ofthe tonsilar fossa, the nasopharynx, the larynx, and the base of the tongue. Chordomas can also be found in this space. Infections from vertebral osteomyelitis and/or prevertebral abscessesmay also be encountered in this area.

Prevertebral Space

* Longus colli muscles, spine, spinal cord, vertebral bodies, paraspinus muscles.

* METS involving the prevertebral space may also mean inoperability as a tumor-free margin can not be obtained.

* Common masses

METSChordomaInfection


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Submandibular Space:

This space contains the submandibular gland, submandibular nodes, and portions of the facial vein and artery as well as the inferior loop of cranial nerve 7. Squamous cell cancer from thebase of the tongue and floor of the mouth can extend into this space. Other types of tumors involving this space may include the variety of salivary gland tumors ranging frommucoepidermoid to adenoid cystic to pleomorphic adenomas.

Submandibular Space* Includes submandibular gland, nodes, facia l vein nerve and artery.

* Malignancies:

Squamous cell cancer from oral cavity and face.LymphomaAdenoid Cystic Carcinoma, Mucoepidermoid carci nomas.

* Benign:

Pleomorphic adenomaWarthin's Tumor

HemangiomaBranchial Cleft CystsEpidermoid


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Parotid Space:

This space contains the parotid gland and the parotid segment of cranial nerve 7. The retromandibular vein in external carotid arteries also pass through this space. Common tumors in thislocation would include pleomorphic adenomas, Warthin's tumors, mucoepidermoid carcinomas, adenoid cystic carci nomas, hemangiomas, and squamous cell carcinomas.

Parotid Space

* Includes parotid gland, cranial nerve 7, external carotid artery, retromandibular vein.

* Common Tumors:

Pleomorphic adenoma, Warthin's Tumors, mucoepidermoid carcinomaAdenoid cystic carcinomaSquamous cell cancer carcinomaHemangioma


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Masticator Space:

This space contains the muscles of mastication. These include the masticator, temporalis, the medial and lateral pterygoids. Metastatic extensions of squamous cell carci noma, particularlyfrom the floor of the mouth, tonsilar fossa, and nasopharynx can be found extending into this space. Salivary gland tumors can also extend into this space. If neoplasm is discovered in thisspace, one should check for extension to the side of the skull as the masticator space extends very high into the suprazygomatic region along the temporalis muscle. One should also check forpossible perineural spread, particularly along the course of the mandibular division of cranial nerve 5. Lymphomas and hemangiomas as well a s cellulitis or abscesses can also be found inthis compartment.

Masticator Space

* Masseter, medial lateral pterygoid muscles, temporalis.

* Common Masses:

Squamous Cell CarcinomaSalivary Gland TumorsLymphomaHemangiomaAbscessRhabdomyosarcoma

* Warning checks:

Perineural spread along V3 (foramen ovale)


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Pterygopalatine fossa to orbital apex and cavernous sinus

Retropharyngeal Space:

This is a posterior potential midline space which can also present a major highway extending cephalad to the skull base or caudad down to approximately the T3 level. Common lesions

which can involve this space would include lymphomas, metastatic tumors, particularly from squamous cell cancer, and infections.

Retropharyngeal Space

* Posterior mid-line potential space extending from skull base to approximately T3.

* Common Masses:

METSLymphomasInfections


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Lymph Node Evaluation:

We consider nodes to be suspicious for metastatic di sease by size. In the jugular digastric region (levels 1, 2, and 3 or submandibular and upper internal jugular c hain)nodes that arelarger than 1.5 centimeters in diameter should be considered very suspicious for metastasis. Nodes in all other levels of the neck exceeding 1 centimeter in size, should be consideredabnormal. Nodes with necrosis should also be considered abnormal regardless of size. One should also pay attention to nodes that have ill defined borders as there may be extracapsularextension with infiltration of the surrounding fat planes or encasement of vessels such as the carotid.

Abnormal supraclavicular nodes may represent metastasis from any source, but lung, breast, and esophagus are particularly common sources. Abnormal adenopathy along the inferiorjugular chain may be due to metastatic di sease from the supraglottic l arynx, esophagus, or thyroid. Abnormal adenopathy in the midjugular chain may be related to

metastasis from tongue, pharynx, or supraglottic larynx cancers. Those along the jugular digastric region are often related to metastasis from the pharynx, tonsil, tonsilar fossa, tongue,parotid gland, or supraglottic larynx. Submandibular adenopathy may be related to metastasis from adjacent skin, submaxillary gland, or base of the tongue. Posterior triangle nodesmay be seen with metastasis from the pharynx, the nasopharynx, tongue base, tonsilar fossa, or thyroid.

Lymph Nodes

* Suspicious for malignancy if greater than 1.5 centimeters in juglo-digastric region; 1 centimeter or greater elsewhere.

* Central necrosis makes lymph nodes suspicious for malignancy regardless of size.

* Check for extra capsular extension as this carries a very poor prognosis.


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PATHOLOGY BY LOCATION

Paranasal Sinuses, Nasopharynx, and Nasal Cavity:

Coronal CT is usually the most functional projection for evaluating the paranasal sinuses. The osteomeatal complex represents a common drainage point for the anterior sinuses (frontal,ethnoid, and maxillary). A lesion placed at the osteomeatal complex can strategically obstruct the anterior sinuses.

Osteomeatal Complex: (Strategic point which a lesion can obstruct the anterior sinuses.)

* Components: Infundibulum, uncinate process, ethmoid bulla, hiatus semilunaris, middle meatus, middle turbinate.

* Concha Bullosum may act as an ethmoid air cell and should be reported.

* Haller cell: laterally situated ethmoid cell which can potentially cause structural obstruction of outflow to maxillary sinus.

* Olfactory cleft: obstruction may be a cause of anosmia.

* Mucus retention cysts: obstructed mucus gland. Usually well-rounded and arises from side wall of sinus.

* Mucocele: an obstructed sinus.

Inflammatory and/or allergic processes are usually seen as areas of mucoperiosteal thickening, fluid or airfluid levels filling the paranasal sinuses. In severe or complicated cases, bone

changes (erosion or thickening) may be present.

A mucus retention cyst represents an obstructed gland. It is usually seen as a rounded soft tissue mass attached to the wall of a sinus.

A mucocele is an obstructed sinus. Bone expansion can be present with mucoceles.

Polyps and Papillomas

* Polyps: Inflammatory or allergic etiology.

* Papilloma:

Neoplastic (benign) related to HP virus exposure. (Potential malignant transformation in 10 to 20 percent.)Inverted papilloma: Arises from lateral wall adjacent to middle neatus. Slow growth. Relentless. Obstructs sinuses. May cause bone destruction and

epistaxes.Fungiform papi lloma: Arises from nasal septum.

Malignancies that affect the paranasal sinuses include squamous cell ca rcinoma, non-hodgkins lymphoma, and salivary malignancies.

Nasopharyngeal carcinoma tends to have a predilection for the fossa of Rosenmueller and therefore often presents with unilateral otitismedia or unilateral mastoiditis in adults. This tumorlikes to spread along the spinal accessory chain of nodes and the suspicious node in the posterior triangle may therefore alert one to the presence of nasopharyngeal carcinoma. Likewise,the finding of unilateral otitismedia and/or mastoiditis in an adult, should direct one to the nasopharynx to be sure that there is not an early nasopharyngeal cancer lurking.

Nasal Pharyngeal Squamous Cell Carcinoma* Warning sign: Unilateral otitis media/mastoiditis in adult.


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* Arises at fossa of Rosenmuller.

* May metastasize to spinal accessory nodes in posterior triangle.

Non-Hodgkin's lymphoma is the second most common nasopharyngeal malignancy. Most are histiocytic or lymphocytic types of lymphomas. Hodgkin's lymphoma is very uncommon in thehead and neck. Cervical lymph node involvement is common in non-Hodgkin's lymphomas of the head and neck and involvement of Waldeyer's ring is often seen. These tumors tend to be verybulky and can easily cross fascial planes.

Non-Hodgkin's Lymphoma

* Bulky masses.

* Cross fascial plains easily.

* May be accompanied by large cervical nodes.

* May have thickening of Waldeyer's Ring.

* Tends to be destructive rather than blastic.

* May involve a solitary gland such as the thyroid gland with or with out adjacent adenopathy and may arise very rapidly.

Other malignancies that occur in the nasopharynx and paranasal sinuses can include tumors of the minor salivary glands which line the mucosal surfaces of the nasopharynx and paranasalsinuses.

These would i nclude adenoid cystic carcinomas and mucoepidermoid ca rcinomas. Adenocarcinomas and rhabdomyosarcomas are also a possibility. Benign tumors would include invertedpapilloma which arises from the mucous membranes, but invaginates inwardly into the underlying stroma. The common place for an inverted papilloma to arise would be the lateral nasalwall at the middle meatus. The inverted papilloma is a benign, slow growing lesion, which tends to remottle and enlarge the nasal fossa. It tends to grow inwardly, particularly into themaxillary sinuses, causing obstruction and possibly bone destruction. Epistasis can also be associated with this tumor.

Juvenile nasal angiofibroma

s tend to be seen in teenage males and usually originate along the pterygopalatine fossa. They are extremely vascular and can follow blood vessels commonly out to the infratemporalfossa, orbit, and possibly also into the middle cranial fossa. They can represent with nasal obstruction and epistasis. One should check for numerous flow voids and widening of thepterytopalatine foramen.

Juvenile Nasal Angiofibroma

* Juvenile nasal angiofibroma:

* Teenage males.

* Epistaxes and/or nasal obstruction.

* Arises from pterygopalatine fossa with frequent destruction of pterygoid plates.

* Extremely vascular: Check for flow voids on MRI. Do not biopsy unless the tumor has been embolized.

* May spread to infratemporal fossa, orbit, skull base.

* Low grade malignancy.


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* Usually slow growing, relentless, and recurrent.

* Destroys adjacent architecture by direct invasion.

Fibrosarcoma

* Low grade malignancy.

* Slow growing.

* Relentless

Esthesioneuroblastoma

* Arises from neuroectodermal cells a long cribriform pla te, nasal septum, superior turbenates, ethmoid air cell s.

* Very aggressive and malignant, extends through the cribriform plate and may see the CSF.

* A form of PNET like medulloblastoma and pineoblastoma.

* May present as cystic mass intracranially.

References:

1. Harnsberger H, Osborn A. Differential diagnosis of head and neck lesions based on their space of origin. I. The suprahyoid part of the neck. AJR 157:147-154, July 1991.

2. Smoker W, Hansberger H. Differential diagnosis of head and neck lesions based on their space of origin. The infrahyoid portion of the neck. AJR 155:159, J uly 1991.

3. Hesselink JR, Norbash AM. Nasopharynx and Deep Facia l Compartments. in Edelman, Hesselink, Zlatkin & Crues, eds., Clinical Magnetic Resonance Imaging, 3rd edition, Saunders-Elsevier, Philadelphia, 2006, pp 2048-84.

4. Harnsberger HR, Hudgins PA, Wigg ins RH, Davidson HC: Diagnostic Imaging Head and Neck. 1st ed., Saunders, Philadelphia, 2005 .

5. Brown J, Chew F. Inverted papilloma. AJR 159 :278, August 1992.

6. Som P, Shapiro M. MRI of head and neck. Radiologic Clinics NA, vol. 27, #2, March 1989.

7. Som PM, Curtain HD, eds., Head and Neck Imaging, Mosby-Year Book, St. Louis, 1996, pp. 1300-1549.

8. Buetow P, Smirniotopoulos J, Wenig B. Pediatric sinonasal tumors. Applied Radiology 21-28, February 1993.

9. Drawings adap ted from: Harnsberger H, Osborn A. Differential d iagnosis of head and neck lesions based on their space of origin. I . The suprahyoid part of the neck. AJR 157:147-154,July 1991.

Deep Spaces, Paranasal Sinuses, & Nasopharynx

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