Neurosurgery for chronic neuropathic pain Jung Y Park MD PhD 1,2 , Andres M Lozano MD PhD FRCSC 1,2 C hronic pain has been defined as pain that lasts longer than three to six months or, as proposed by the Interna- tional Association for the Study of Pain. It is pain that out- lasts the period of normal healing of an acute abnormality (1). Any acute pain has the potential to become chronic, and this conversion can follow different temporal courses for dif- ferent problems. Pain of primarily neural origin is termed neuropathic pain. Common features of chronic neuropathic pain include spontaneous burning, paroxysmal jabbing or shocking pain, hyperpathia, hyperalgesia, and allodynia or touch-evoked pain. These features may occur alone or in combination. Causes of neuropathic pain include injuries to the nervous system, whether by trauma, ischemia or metabolic dysfunc- tion. Neuropathic pain is idiosyncratic; not every patient who suffers neural injury develops this type of pain. The inci- dence of neuropathic pain may also vary according to the site of neural injury. It is classified as ‘peripheral type’ when it re- sults from neural injury or dysfunction from peripheral sources or as ‘central type’, when it arises from dysfunction in the brain and spinal cord. Neuropathic pain, in contrast to somatic or nociceptive pain, usually occurs without ongoing physiological activation of nociceptors. However, neuro- pathic and nociceptive pain may have overlapping features, and both types may at times be complicated by psychological and psychosocial factors. Table 1 lists the broad range of causes of peripheral and central neuropathic pain. Only patients with chronic neuropathic pain that fails to respond to medical treatment are considered potential candi- dates for surgical treatment. Hence, neurosurgeons are called upon to treat these often difficult pain syndromes. The goal here is to describe neurosurgical treatments for the chronic, intractable neuropathic pain states and to provide a brief out- line of current neurosurgical approaches in these settings. Pain Res Manage Vol 5 No 1 Spring 2000 101 JY Park, AM Lozano. Neurosurgery for chronic neuropathic pain. Pain Res Manage 2000;5(1):101-106. Neurosurgery can play a role in the management of patients with refractory chronic neuropathic pain. However, selecting patients as candidates for surgery and choosing the most appropriate surgi- cal procedure is challenging, and surgical interventions often have limited efficacy. When considering surgery, neuroaugmentative or neuromodulative procedures (eg, peripheral, spinal, motor cortex or deep brain stimulation) are generally preferred over ablative procedures as initial modalities. With better understanding of spe- cific pain mechanisms, surgery will have more to offer patients with chronic neuropathic pain. Key Words: Chronic neuropathic pain; Surgery La neurochirurgie pour la douleur neuropathique chronique RÉSUMÉ : La neurochirurgie peut jouer un rôle dans la prise en charge des patients souffrant d’une douleur neuropathique chronique réfractaire. Cependant, la sélection des patients comme candidats à la chirurgie et le choix de l’intervention chirurgicale la mieux appropriée restent un défi, et les interventions chirurgicales ont souvent une efficacité limitée. Si l’on envisage une chirurgie, les interventions qui ont un effet neuromodulateur ou neuroamplificateur (par exemple, une stimulation cérébrale profonde, ou celle du cortex moteur ou une stimulation spinale ou bien périphérique) sont généralement préférables à des méthodes ablatives comme méthodes de premier choix. Avec une meilleure compréhension des mécanismes de la douleur, la chirurgie aura plus à offrir aux patients atteints d’une douleur neuropathique chronique. Toronto Western Hospital, University of Toronto, Toronto, Ontario Correspondence and reprints: Dr Andres M Lozano, 1 The Toronto Hospital, Western Division, McLaughlin Pavilion 2-433, 399 Bathurst Street, Toronto, Ontario M5T 2S8. Telephone 416-603-6200, fax 416-603-5298, e-mail [email protected]NEUROLOGY AND CHRONIC PAIN
7
Embed
75 Neurosurgery for chronic - Hindawi Publishing …downloads.hindawi.com/journals/prm/2000/682131.pdfTue Apr 18 15:56:50 2000 Color profile: EMBASSY.CCM - Scitex Scitex Composite
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Neurosurgery for chronicneuropathic pain
Jung Y Park MD PhD1,2, Andres M Lozano MD PhD FRCSC1,2
Chronic pain has been defined as pain that lasts longerthan three to six months or, as proposed by the Interna-
tional Association for the Study of Pain. It is pain that out-lasts the period of normal healing of an acute abnormality(1). Any acute pain has the potential to become chronic, andthis conversion can follow different temporal courses for dif-ferent problems. Pain of primarily neural origin is termedneuropathic pain.
Common features of chronic neuropathic pain include
spontaneous burning, paroxysmal jabbing or shocking pain,
hyperpathia, hyperalgesia, and allodynia or touch-evoked
pain. These features may occur alone or in combination.
Causes of neuropathic pain include injuries to the nervous
system, whether by trauma, ischemia or metabolic dysfunc-
tion. Neuropathic pain is idiosyncratic; not every patient who
suffers neural injury develops this type of pain. The inci-
dence of neuropathic pain may also vary according to the site
of neural injury. It is classified as ‘peripheral type’ when it re-
sults from neural injury or dysfunction from peripheral
sources or as ‘central type’, when it arises from dysfunction
in the brain and spinal cord. Neuropathic pain, in contrast to
somatic or nociceptive pain, usually occurs without ongoing
physiological activation of nociceptors. However, neuro-
pathic and nociceptive pain may have overlapping features,
and both types may at times be complicated by psychological
and psychosocial factors. Table 1 lists the broad range of
causes of peripheral and central neuropathic pain.
Only patients with chronic neuropathic pain that fails to
respond to medical treatment are considered potential candi-
dates for surgical treatment. Hence, neurosurgeons are called
upon to treat these often difficult pain syndromes. The goal
here is to describe neurosurgical treatments for the chronic,
intractable neuropathic pain states and to provide a brief out-
line of current neurosurgical approaches in these settings.
Pain Res Manage Vol 5 No 1 Spring 2000 101
JY Park, AM Lozano.Neurosurgery for chronic neuropathic pain.Pain Res Manage 2000;5(1):101-106.
Neurosurgery can play a role in the management of patients withrefractory chronic neuropathic pain. However, selecting patientsas candidates for surgery and choosing the most appropriate surgi-cal procedure is challenging, and surgical interventions often havelimited efficacy. When considering surgery, neuroaugmentative orneuromodulative procedures (eg, peripheral, spinal, motor cortexor deep brain stimulation) are generally preferred over ablativeprocedures as initial modalities. With better understanding of spe-cific pain mechanisms, surgery will have more to offer patientswith chronic neuropathic pain.
Key Words: Chronic neuropathic pain; Surgery
La neurochirurgie pour la douleurneuropathique chroniqueRÉSUMÉ : La neurochirurgie peut jouer un rôle dans la prise encharge des patients souffrant d’une douleur neuropathique chroniqueréfractaire. Cependant, la sélection des patients comme candidats à lachirurgie et le choix de l’intervention chirurgicale la mieux appropriéerestent un défi, et les interventions chirurgicales ont souvent uneefficacité limitée. Si l’on envisage une chirurgie, les interventions quiont un effet neuromodulateur ou neuroamplificateur (par exemple, unestimulation cérébrale profonde, ou celle du cortex moteur ou unestimulation spinale ou bien périphérique) sont généralementpréférables à des méthodes ablatives comme méthodes de premierchoix. Avec une meilleure compréhension des mécanismes de ladouleur, la chirurgie aura plus à offrir aux patients atteints d’unedouleur neuropathique chronique.
Toronto Western Hospital, University of Toronto, Toronto, Ontario
Correspondence and reprints: Dr Andres M Lozano, 1The Toronto Hospital, Western Division, McLaughlin Pavilion 2-433, 399 Bathurst Street,
Color profile: EMBASSY.CCM - Scitex ScitexComposite Default screen
0
5
25
75
95
100
0
5
25
75
95
100
0
5
25
75
95
100
0
5
25
75
95
100
Detailed review is not intended, but rather an attempt is made
to establish a framework within which the practising clini-
cian can add insights when providing care to these patients.
SURGICAL TREATMENT OF CHRONICNEUROPATHIC PAIN
Before considering any surgical measure to treat patientswith chronic neuropathic pain, appropriate medical thera-peutic approaches should be thoroughly investigated andexhausted. Generally, when neurosurgical therapy is consid-ered, neuroaugmentative or neuromodulative procedures arepreferred over ablative approaches as the initial surgical mo-dality. This is because of their reversibility and low incidenceof significant side effects. These approaches are only un-dertaken after the primary and causative disturbances, forexample compression, tumours, infections and ongoing me-chanical injury, etc, have been addressed.
Pain associated with peripheral nerve abnormalities that is
located primarily in the distribution of a single peripheral
nerve may be treated with peripheral nerve stimulation
(PNS) (2). The mechanism of action of PNS may be central
or peripheral. As with other pain control operations, there
must be a clear cut etiology for the pain, and a correctable pa-
thology (eg, nerve entrapment syndrome) should be ex-
cluded. The surgery is usually done in two phases. Usually, a
site proximal to the injury site is selected for electrode place-
ment. After a skin incision and dissection to free 5 to 6 cm of
nerve, the electrode is placed directly under the nerve and su-
tured in place. The electrode lead is then externalized
through a small stab wound and connected to a temporary
electrical stimulator. The effects of stimulation through the
implanted electrode are evaluated over this trial phase, which
can last two to three days. The settings of the temporary
stimulator are considered satisfactory when the patient re-
ports a fine tingling sensation in the nerve distribution. There
are two potential outcomes of this trial. In patients where
stimulation does not help the pain, the device is removed. On
the other hand, patients who derive substantial pain relief,
usually greater than 50% on a pain visual analogue scale, go
on to permanent implantation in which the stimulating elec-
trode is connected to a battery powered, pacemaker-like, im-
planted pulse generator. Results from a large series (3)
indicated good to excellent pain relief in 70% to 80% of pa-
tients. These devices, like all stimulation implants, are sub-
ject to displacement, infection, breakage of leads and loss of
battery power over time.
Peripheral nerve pain from multiple sources, including
neuropathic pain secondary to neural injury as a consequence
of degenerative disc disease, postamputation pain (eg, phan-
tom limb pain, stump pain), reflex sympathetic dystrophy
(now replaced with the term ‘complex regional pain syn-
drome’ [CRPS] type 1), or causalgia (CRPS type 2), may be
relieved by spinal cord stimulation (SCS) (4,5) (Figure 1). A
relevant animal model of chronic neuropathic pain, showing
apparent relief by SCS, has been developed recently (6). Its
exact mechanism of action of SCS is not fully understood but
may at least partly be mediated via GABAergic and
adenosine-dependent mechanisms, or modulated by influ-
encing the transmission of A fibres and not of c fibres. Some
effects of SCS may be mediated by the sympathetic nervous
102 Pain Res Manage Vol 5 No 1 Spring 2000
Park and Lozano
TABLE 1Various types of peripheral and central neuropathic pain
Peripheral neuropathic pain Central neuropathic pain
Peripheral nerve injury with orwithout sympatheticallymaintained pain
Figure 1) Postoperative thoracolumbar spine x-ray showing spinal cordstimulation electrode with four contacts on T10-11 epidural space. Re-produced with permission from Medtronic Inc, Minneapolis
postherpetic neuralgia, and spinal and peripheral nerve inju-
ries) are thalamic sensory relay nuclei, ventral posterior lat-
eral or ventral posterior medial, and the medial lemniscus or
internal capsule (19). However, implantation of electrodes on
the PVG region may be more suitable for patients with no-
ciceptive pain when other measures fail.
Electrodes are implanted stereotactically when the patient
is under local anesthesia supplemented as necessary by in-
travenous midazolam and/or fentanyl. Electrodes are
introduced according to anatomical targets, based on pre-
operatively obtained anterior commissure and posterior com-
Pain Res Manage Vol 5 No 1 Spring 2000 103
Surgery for chronic neuropathic pain
Figure 2) Configuration of implanted brain electrode and connections toremainder of deep brain stimulation equipment (top) and magnetic reso-nance imaging after implantation of a thalamic deep brain stimulationelectrode (bottom). Reproduced with permission from Medtronic Inc,Minneapolis, Minnesota
Color profile: EMBASSY.CCM - Scitex ScitexComposite Default screen
0
5
25
75
95
100
0
5
25
75
95
100
0
5
25
75
95
100
0
5
25
75
95
100
tively low morbidity; lower cost than that of augmentative
procedures; and lack of need for general anesthesia, they may
be suitable in certain circumstances.
Generally, patients with trigeminal neuralgia are managed
by medical treatment. However, up to 30% of patients will
ultimately require more aggressive therapy. There are two
common mainstays of surgical therapy for these patients (ie,
percutaneous trigeminal gangliolysis and microvascular
decompression), both with similar high success rates (70%
to 90%) of long lasting or even permanent pain relief (28-30).
Recently, radiosurgery with gamma knife for chronic pain
has been used by several investigators with some promising
results (31-34). The role of radiosurgery in disorders such as
trigeminal neuralgia is being studied (35,36). Although it is a
noninvasive procedure to the brain, it may produce unpre-
dictably large lesions, and until well-designed, long term
follow-up studies are available, this technique remains
speculative.
CONCLUSIONSThe main challenge facing the treatment of neuropathic painis the incomplete understanding of its pathogenesis andconsequently the limited success of its treatment. The selec-tion of patients who are likely to respond to surgery and the
choice of the surgical procedure should be carefully decidedbased on diligent evaluation.
Some surgical interventions have substantial potential
morbidity, and this must be considered before deciding to op-
erate. Also, no one neurosurgical procedure can relieve the
pain complaints of all patients, and surgery performed be-
cause there is ‘nothing left to try’ is most likely to fail.
Whichever procedure is chosen or intended, treating neuro-
surgeons should have the necessary neuroscience background
and surgical skills to be an important member of the team car-
ing for these multifaceted, chronically ill patients.
Neurosurgical strategies will be more diverse, and neuro-
surgery will likely offer better and more options for the man-
agement of chronic neuropathic pain syndromes in the future.
These strategies will be driven by a better understanding of
3. Shetter AG, Racz GB, Lewis R, Heavner JE. Peripheral nervestimulation. In: North RB, Levy RM, eds. Neurosurgical Managementof Pain. New York: Springer-Verlag, 1997:261-70.
4. Barolat G, Singh-Sahni K, Staas WE Jr, Shatin D, Ketcik B, Allen K.Epidural spinal cord stimulation in the management of spasms inspinal cord injury: a prospective study. Stereotact Funct Neurosurg1995;64:153-64.
5. North RB, Roark GL. Spinal cord stimulation for chronic pain.Neurosurg Clin N Am 1995;6:145-55.
6. Meyerson BA, Ren B, Herregodts P, Linderoth B. Spinal cordstimulation in animal models of mononeuropathy: effects onthe withdrawal response and the flexor reflex. Pain1995;61:229-43.
7. North RB, Kidd DH, Zahurak M, James CS, Long DM. Spinal cordstimulation for chronic, intractable pain: experience over two decades.Neurosurgery 1993;32:384-94.
8. Kumar K, Toth C, Nath RK. Deep brain stimulation for intractablepain: a 15-year experience. Neurosurgery 1997;40:736-46.
9. Penn RD. Intrathecal drug infusion for pain. In: Youmans JR, ed.Neurological Surgery. Philadelphia: WB Sounders, 1996:3552-9.
10. Hassenbusch SJ, Stanton-Hicks M, Covington EC, Walsh JG,Guthrey DS. Long-term intraspinal infusions of opioids in thetreatment of neuropathic pain. J Pain Symptom Manage1995;10:527-43.
11. Glynn C, O’Sullivan K. A double-blind randomised comparison ofthe effects of epidural clonidine, lignocaine and the combination ofclonidine and lignocaine in patients with chronic pain. Pain1996;64:337-43.
12. Gomes JA, Li X, Pan HL, Eisenach JC. Intrathecal adenosine interactswith a spinal noradrenergic system to produce antinociceptionin nerve-injured rats. Anesthesiology 1999;91:1072-9.
13. Middleton JW, Siddall PJ, Walker S, Molloy AR, Rutkowski SB.Intrathecal clonidine and baclofen in the management of spasticity andneuropathic pain following spinal cord injury: a case study.Arch Phys Med Rehabil 1996;77:824-6.
14. Gybels JM, Sweet WH. Neurosurgical Treatment of Persistent Pain.Physiological and Pathological Mechanisms of Human Pain, vol 11.Basel Karger, 1989.
15. Gerhart KD, Yezierski RP, Fang ZR, Willis WD. Inhibition of primatetract neurons by stimulation in ventral posterior lateral (VPLc)thalamic nucleus: possible mechanims. J Neurophysiol1983;49:406-23.
16. Lenz FA. The ventral posterior nucleus of thalamus is involvedin the generation of central pain syndromes. Am Pain Soc J1992;1:42-51.
17. Levy RM, Lamb S, Adams JE. Treatment of chronic pain by deepbrain stimulation: long term follow-up and review of the literature.Neurosurgery 1987;21:885-93.
18. Tasker RR, Vilela Filho O. Deep brain stimulation for neuropathicpain. Stereotact Funct Neurosurg 1995;65:122-4.
19. Young RF, Rinaldi PC. Brain stimulation. In: North RB, Levy RM,eds. Neurosurgical Management of Pain. New York: Springer-Verlag,1997:283-301.
20. Katayama Y, Tsubokawa T, Yamamoto T. Chronic motor cortexstimulation for central deafferentation pain: experience with bulbarpain secondary to Wallenberg syndrome. Stereotact Funct Neurosurg1994;62:295-9.
21. Nguyen JP, Keravel Y, Feve A, et al. Treatment of deafferentation painby chronic stimulation of the motor cortex: report of a series of 20cases. Acta Neurochir Suppl (Wien) 1997;68:54-60.
22. Meyerson BA, Lindblom U, Linderoth B, Lind G, Herregodts P. Motorcortex stimulation as treatment of trigeminal neuropathic pain.Acta Neurochir Suppl (Wien) 1993;58:150-3.
23. Nguyen JP, Lefaucheur JP, Decq P, et al. Chronic motor cortexstimulation in the treatment of central and neuropathic pain.Correlations between clinical, electrophysiological and anatomicaldata. Pain 1999;82:245-51.
24. Tsubokawa T, Katayama Y, Yamamoto T, Hirayama T, Koyama S.
decompression for the surgical management of tic douloureux.Neurosurgery 1981;9:111-9.
31. Kondziolka D, Lunsford LD, Flickinger JC, et al. Stereotacticradiosurgery for trigeminal neuralgia: a multiinstitutional study usingthe gamma unit. J Neurosurg 1996;84:940-5.
32. Pollock BE, Gorman DA, Schomberg PJ, Kline RW. The Mayo Clinicgamma knife experience: indications and initial results.Mayo Clin Proc 1999;74:5-13.
33. Young RF, Vermeulen SS, Grimm P, et al. Gamma knife thalamotomyfor the treatment of persistent pain. Stereotact Funct Neurosurg1995;64:172-81.
34. Lindquist C, Kihlstrom L. Department of Neurosurgery, KarolinskaInstitute: 60 years. Neurosurgery 1996;39:1016-21.
35. Young RF, Vermulen S, Posewitz A. Gamma knife radiosurgery forthe treatment of trigeminal neuralgia. Stereotact Funct Neurosurg1998;70(Suppl 1):192-9.
36. Kondziolka D, Lunsford LD, Flickinger JC. Gamma knife radiosurgeryas the first surgery for trigeminal neuralgia.Stereotact Funct Neurosurg 1998;70(Suppl 1):187-91.