VIIIth nerve vascular compression syndrome: vestibular paroxysmia.

Neurovascular cross-compression of the root entry zone of the Vth, VIIth and IXth cranial nerves causes symptoms of trigeminal neuralgia, hemifacial spasm and glossopharyngeal neuralgia. It is reasonable to search for a group of patients presenting with typical paroxysmal vestibular and/or cochlear symptoms, analogously caused by neurovascular compression of the VIIIth cranial nerve. Since no pathognomonic sign or test has yet been established, the diagnosis of 'vestibular paroxysmia' secondary to neurovascular cross-compression is based on four characteristic features: (1) short attacks of rotational to-and-fro vertigo lasting seconds to minutes; (2) attacks frequently dependent on particular head positions and modification of the duration of the attack by changing head position ('disabling positional vertigo'); (3) hyperacusis or tinnitus permanently or during the attack; and (4) measurable auditory or vestibular deficits by neurophysiological methods. Carbamazepine is a most effective drug. In medically intractable cases, retromastoid craniotomy and microvascular decompression is a recommended procedure once the side of disorder has been identified.