Trigeminal Neuralgia

Sashank Prasad, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
Steven L Galetta, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA

Published online: December 2009

DOI: 10.1002/9780470015902.a0022325

Trigeminal neuralgia (TN) is characterized by paroxysmal excruciating unilateral facial pain. Knowledge of the proper diagnosis and management of trigeminal neuralgia is essential to successfully treat these patients. There are several clinical features that are typical of TN, but there may be red flags that should suggest alternative diagnoses. There is convincing evidence that TN develops from focal demyelination at the trigeminal root entry zone with subsequent ephaptic transmission (crosstalk) between axons. Vascular compression of the nerve root causes the demyelination in most patients. Medical management of this condition, with anticonvulsants and other drugs, aims to dampen the abnormal electrical signals and thereby ameliorate the symptoms. Refractory cases may require surgical intervention, such as microvascular decompression of the trigeminal root. Gamma knife therapy is emerging as an alternative treatment for patients with medically refractive TN, particularly the elderly patient with co-morbid conditions.

Key concepts:

  • Trigeminal neuralgia (TN) may be an extremely disabling illness, characterized by a severe, electric, lancinating pain on one side of the face.
  • Most cases of TN are due to demyelination of trigeminal nerve sensory fibres within the proximal nerve root, caused by compression by an overlying blood vessel.
  • TN can also occur in disease of central demyelination (such as multiple sclerosis).
  • Patients with new-onset trigeminal neuralgia should typically undergo an MRI to exclude a tumour, demyelination, stroke or other lesion. MR angiography may help identify vessels compressing the trigeminal nerve.
  • Most patients with TH will require daily prophylactic treatment, most commonly with an antiepileptic drug (such as carbamazepine, gabapentin or oxcarbamazepine).
  • Microvascular decompression is a very effective surgical procedure for the treatment of TN. Other procedures include radiofrequency thermocoagulation, retrogasserian glycerol injection and trigeminal ganglion balloon compression.
  • Stereotactic gamma knife radiosurgery is emerging as an effective alternative, particularly for elderly patients or those with co-morbid conditions.

Keywords: trigeminal neuralgia; tic doloureux; ephaptic transmission; microvascular decompression; gamma knife radiosurgery

Figure 1. Compression of the medial aspect of the trigeminal root entry zone (long arrow) by the superior cerebellar artery (short arrow), identified by magnetic resonance angiography (MRA); axial, coronal and sagittal views. Reproduced with permission from Yoshino N, Akimoto H, Yamada I, et al. (2003) Trigeminal neuralgia: evaluation of neuraligic manifestation and site of neurovascular compression with 3D CISS MR imaging and MR angiography. Radiology 228: 539–545. Copyright© Radiological Society of America.
Figure 2. Anatomic distribution of fibres to V1, V2 and V3 in the trigeminal root entry zone, and typical medial compression by an offending blood vessel. Reproduced with permission from Yoshino N, Akimoto H, Yamada I, et al. (2003) Trigeminal neuralgia: evaluation of neuraligic manifestation and site of neurovascular compression with 3D CISS MR imaging and MR angiography. Radiology 228: 539–545. Copyright© Radiological Society of America.
Figure 3. Trigeminal neuralgia due to vascular compression of the nerve root. (a) Posterolateral surgical approach, and retraction of a vein (arrowheads) reveals an area of indentation (arrow) on the trigeminal nerve by an anteriorly placed artery. (b) The offending artery has been mobilized and repositioned behind the nerve root. (c) Pathologic specimen, of toluidine blue-stained semithin sections from the region of nerve root compression, demonstrates demyelination within the proximal nerve root in the immediate vicinity of the vascular indentation. (d) Electron microscopy confirms large numbers of demyelinated nerve fibres, several in direct apposition (some indicated by arrows). Reproduced from Love S and Coakham HB (2001) Trigeminal neuralgia: pathology and pathogenesis. Brain 124: 2347–2360, with permission from Oxford University Press.
Figure 4. Axial MRI from a patient with multiple sclerosis and trigeminal neuralgia. Left, high signal abnormality along left trigeminal nerve course (arrow). Right, the nerve enhances after gadolinium injection (arrow). Reproduced from Prasad S and Galetta S (2009) Trigeminal neuralgia: historical perspectives and current concepts. Neurologist 15: 87–94, with permission from Elsevier.
Figure 5. Trigeminal neuralgia due to multiple sclerosis. (a) Electron micrograph illustrating a focus of chronic nerve root demyelination in a patient with multiple sclerosis (scale bar=10 m). (b) Higher magnification shows areas of apposition (some indicated by arrows) between several nerve axons (scale bar=2 m). Reproduced from Love S and Coakham HB (2001) Trigeminal neuralgia: pathology and pathogenesis. Brain 124: 2347–2360, with permission from Oxford University Press.
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 Further Reading
    Barker FG II, Jannetta PJ, Babu RP et al. (1996) The long-term outcome of microvascular decompression for trigeminal neuralgia. New England Journal of Medicine 334: 1077–1083.
    Headache Classification Subcommittee of the International headache Society (2004) The international classification of headache disorders, 2nd edition. Cephalalgia 24: 126–136.
    Jorns TP and Zakrzewska JM (2007) Evidence-based approach to the medical management of trigeminal neuralgia. British Journal of Neurosurgery 21: 253–261.
    Katusic S, Beard CM, Bergstralh E and Kurland LT (1990) Incidence and clinical features of trigeminal neuralgia, Rochester, Minnesota, 1945–1984. Annals of Neurology 27: 89–95.
    Lopez BC, Hamlyn PJ and Zakrzewska JM (2004) Systematic review of ablative neurosurgical techniques for the treatment of trigeminal neuralgia. Neurosurgery 54: 973–982.
    Love S and Coakham HB (2001) Trigeminal neuralgia: pathology and pathogenesis. Brain 124: 2347–2360.
    book Prasad S and Galetta S (2007) "The trigeminal nerve". In: Goetz C (ed.) Textbook of Clinical Neurology, 3rd edn, pp. 165–183. Philadelphia: Elsevier.
    Tolle T, Dukes E and Sadosky A (2006) Patient burden of trigeminal neuralgia: results from a cross-sectional survey of health state impairment and treatment patterns in six European countries. Pain Practice 6: 153–160.

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Neurobiology of Disease
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Article Title: Trigeminal Neuralgia
 
How to Cite close
Prasad, Sashank, and Galetta, Steven L(Dec 2009) Trigeminal Neuralgia. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0022325]