[Idiopathic cupulolithiasis: vasomotor reactivity evaluation of the vertebro-basilar artery by transcranial doppler ultrasonography and acetazolamide test].

Benign paroxysmal positional vertigo (BPPV) or cupulolithiasis is one of the more common peripheral vestibular disorders. Diagnosis is made on the observation of typical positioning nystagmus brought about by the Hallpike manoeuver. In most cases of BPPV, etiology is unknown. Microcirculatory disorders have often been considered responsible for idiopathic BPPV. Few reports have been published on this specific aspect of the problem. In our study we evaluated vertebro-basilar haemodynamics and vasomotory reactivity after Acetazolamide administration in 12 patients with idiopathic BPPV. The results obtained reveal the absence of macrocirculatory impairment in the vertebro-basilar district in basal conditions, but significative vasoreactivity variation after acetazolamide, both in vertebral and basilar arteries. Poor vasomotor reactivity in one vertebral artery was observed in 5 patients and, in two cases, in the basilar artery. Altered vasoreactivity in the middle cerebral arteries was not observed in any case. In the light of these findings, we suggest that a possible inadequate response if microcirculation in the labyrinth, in some particular haemodynamic situations, might cause otolithic damage.