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INTRODUCTION

Disorders of vision and ocular movement are discussed in Chaps. 58 and 63, dizziness and vertigo in Chap. 57, and disorders of hearing in Chap. 63.

FACIAL PAIN OR NUMBNESS [TRIGEMINAL NERVE (V)]

(See Fig. 199-1)

FIGURE 199-1

The three major sensory divisions of the trigeminal nerve consist of the ophthalmic, maxillary, and mandibular nerves.

Trigeminal Neuralgia (Tic Douloureux)

Frequent, excruciating paroxysms of pain in lips, gums, cheek, or chin (rarely in ophthalmic division of fifth nerve) lasting seconds to minutes. Typically presents in middle or old age. Pain is often stimulated at trigger points. Sensory deficit cannot be demonstrated. Must be distinguished from other forms of facial pain arising from diseases of jaw, teeth, or sinuses. Rare causes are herpes zoster or a tumor. Onset in young adulthood or if bilateral raises the possibility of multiple sclerosis (Chap. 202).

TREATMENT Trigeminal Neuralgia

  • Carbamazepine is effective in 50–75% of cases. Begin at 100-mg single daily dose taken with food and advance by 100 mg every 1–2 days until substantial (50%) pain relief occurs. Most pts require 200 mg four times a day; doses >1200 mg daily usually provide no additional benefit.

  • Oxcarbazepine (300–1200 mg bid) is an alternative with less bone marrow toxicity and probably similar efficacy.

  • For nonresponders, lamotrigine (400 mg daily) or phenytoin (300–400 mg/d) can be tried.

  • When medications fail, surgical microvascular decompression to relieve pressure on the trigeminal nerve can be offered.

  • Other options include gamma knife radiosurgery and radiofrequency thermal rhizotomy.

Trigeminal Neuropathy

Usually presents as facial sensory loss or weakness of jaw muscles. Causes are varied (Table 199-1), including tumors of middle cranial fossa or trigeminal nerve, metastases to base of skull, or lesions in cavernous sinus (affecting first and second divisions of fifth nerve) or superior orbital fissure (affecting first division of fifth nerve).

TABLE 199-1TRIGEMINAL NERVE DISORDERS

FACIAL WEAKNESS [FACIAL NERVE (VII)]

(See Fig. 199-2)

FIGURE 199-2

The facial nerve. A, B, and C denote lesions of the facial nerve at the stylomastoid foramen, distal and proximal to the geniculate ganglion, respectively. Green lines indicate the parasympathetic fibers, red lines indicate motor fibers, and purple lines indicate visceral afferent fibers (taste). (Adapted from ...

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