RAMSAY HUNT SYNDROME
Herpes zoster infection of the geniculate (facial) ganglion causes sudden severe facial weakness with a typical zoster vesicular eruption within the external auditory meatus. Pain is a major feature and may precede the facial weakness. Serosanguinous fluid may discharge from the ear.
Deafness may result from VIII involvement. Occasionally, other cranial nerves from V-XII are affected.
Antiviral agents (acyclovir) may help. HEMIFACIAL SPASM
This condition is characterised by unilateral clonic spasms beginning in the orbicularis oculi and spreading to involve other facial muscles. The stapedius muscle can be affected producing a subjective ipsilateral clicking sound.
Contractions are irregular, intermittent and worsened by emotional stress and fatigue. Onset usually occurs in middle to old age and women are preferentially affected. The aetiology remains unknown but 'irritation1 from an adjacent blood vessel (or from a tumour) may cause demyelination and 'short-circuiting' within the nerve. Occasionally hemifacial spasm follows a Bell's palsy or traumatic facial injury.
The clinician must distinguish hemifacial spasm from milder habit spasms or tics which tend to be familial, and also from 'focal' seizures selectively affecting the face. Investigations
CT/MR scan of the posterior fossa excludes the presence of a cerebellar pontine angle lesion and may show an ectatic basilar artery.
Surgery - Posterior fossa exploration and microvascular decompression i.e. dissecting blood vessels off the facial nerve roots and root entry zone, gives excellent results (cure rate 80%), but carries the risk of producing deafness and rarely brainstem damage. Alternative, less successful treatments include phenol injection or partial section of the facial nerve; these methods inevitably cause some facial weakness.
Less common than hemifacial spasm. Occurs with cerebellar pontine angle lesions. It produces tonic elevation of the corner of the mouth with narrowing of the eye. The diagnosis is confirmed by CT/MR scanning and treatment is surgical. FACIAL MYOKYMIA
A rare condition seen most often in multiple sclerosis. Flickering of facial muscles results from spontaneous discharge in the facial motor nucleus. Other brainstem signs arc present. The facial movements respond to carbamazcpine. MYOCLONUS
Rhythmic facial movement associated with similar palatal movements and characteristic of dentate or olivary nucleus disease.
Spasmodic closing or screwing up of eyes (sec page 357). 167
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