Neurovascular compression of the eighth nerve: Vestibular paroxysmia

Neurovascular cross-compression of the root entry zone of the eighth nerve induced by pulsatile arteries of the cerebellar pontine angle or the inner ear canal remains an underdiagnosed cause of episodic vertigo. This disorde r is termed vestibular paroxysmia. In recent years neurophysiological metho ds and magnetic resonance tomography of the eighth nerve have greatly helpe d to identify it as a separate clinical entity. The diagnosis of vestibular paroxysmia, analogous to that of trigeminal neuralgia, is based on five ch aracteristic features: 1. short attacks of rotational or to-and-fro vertigo lasting from seconds to minutes; 2. attacks frequently dependent on partic ular head positions and whose duration is modified by changing head positio n; 3. hypacusis or tinnitus permanently or during the attack; 4. measurable auditory or vestibular deficits detected by neurophysiological methods; an d 5. therapeutic efficacy of carbamazepine. The most important criteria for diagnosis are the patient's prompt response to carbamazepine and a relapse after a washout phase.