Trigeminal Neuralgia

Trigeminal neuralgia, also known as tic douloreux, manifests as recurrent attacks of abrupt, unilateral, severe stabbing (or electric-like) pain in the distribution of the trigeminal nerve. Typically, the mandibular or maxillary region is involved, with the ophthalmic region only rarely affected. Pain persists for seconds to 2 minutes, then resolves. Episodes may recur multiple times per day. Symptoms are often triggered by chewing, brushing teeth, touching the face, or eating or drinking. Detailed neurological examination should demonstrate no abnormalities, specifically including no sensory loss in the distribution of the trigeminal nerve between attacks, and normal trigeminal nerve motor function (e.g., muscles of mastication). If abnormalities are present on examination, an alternative diagnosis should be considered. Trigeminal neuralgia may be idiopathic or due to a compressive or demyelinating lesion; brain magnetic resonance imaging with contrast can be performed to exclude secondary causes. Symptomatic treatment is generally similar regardless of the presence of an underlying identifiable cause.

A.

The mainstay of treatment is carbamazepine, which is effective at controlling pain in about 75% of patients. A low dose should be started, with upward titration until good symptomatic relief is achieved. Oxcarbazepine is an alternative, and appears to have similar efficacy.
B.

Other agents that can be used in addition to or instead of carbamazepine include gabapentin, baclofen, and lamotrigine, though evidence for efficacy of these drugs is weaker.
C.

For refractory cases unresponsive to medical therapy or in cases where medications result in severe side effects, surgical procedures can be considered to relieve pain. These include microvascular decompression, percutaneous rhizotomy, and stereotactic radiosurgery (gamma knife radiosurgery). Of these, microvascular decompression is the only one that is not an intentionally destructive procedure. Through an incision behind the ear, the surgeon explores the cerebellopontine angle to identify sites of physical compression of the trigeminal nerve, typically caused by an adjacent vessel, and relieves the compression. Microvascular decompression appears to produce the most durable response of the surgical procedures for trigeminal neuralgia, but is also the most invasive procedure. Percutaneous rhizotomy is an intentionally destructive procedure with direct injury (heat, chemical, or mechanical) targeted to the trigeminal nerve via a needle placed through the face into the gasserian ganglion. Pain relief is often accompanied by numbness, but it produces near immediate results. It is recommended for patients who are deemed poor surgical candidates or who experience recurrent pain despite microvascular decompression. Stereotactic radiosurgery is also a destructive procedure; in this case utilizing high doses of focused radiation to damage the trigeminal nerve root. It is the least invasive procedure, but pain relief takes weeks to months to fully develop.