Evaluation of the Otolithic Organs Function in Patients Suffering From Benign Paroxysmal Positional Vertigo (BPPV) by Vestibular Evoked Myogenic Potentials (VEMP).

Benign Paroxysmal Positional Vertigo (BPPV) is the most frequent cause of vertigo of peripheral vestibular origin with life time incidence of 2.4%. BPPV is characterized by bouts of acute whirling vertigo lasting less than one minute provoked by changes in head position in relation to the gravitational vector. The vertigo is accompanied by typical rotational or horizontal nystagmus that is often demonstrated by the Dix-Hallpike maneuver and less frequently by testing for positional nystagmus. BPPV pathogenesis is currently explained by the fall of otoconia (calcium-carbonate crystals) or otoconial debris from the tectorial membrane of the otolithic organs into the dependant semicircular canals (canalithiasis) or adherence of such particles to the semicircular canal's cupula (cupulithiasis). Under these circumstances, the semicircular canal which normally responds only to angular velocity and acceleration is stimulated by gravity. Otoconial remnants as free floating particles inside the semicircular canal arms or attached to the cupula have been observed by few investigators. Although the presence of such particles explains most characteristics of the positioning nystagmus described in BPPV, it does not account for the dizziness and disequilibrium which are described by many patients even without changes in head position and the continuation of such symptoms after successful treatment of BPPV as evidenced by the resolution of positional vertigo and nystagmus.

The study hypothesis is that otolithic pathology is an important component in the pathogenesis of BPPV explaining these symptoms, BPPV recurrence, and the refractoriness of some BPPV cases to the vastly employed particles repositioning treatments. In the present study the Vestibular Evoked Myogenic Potentials (VEMP) testing would be employed to measure the function of one of the otolithic organs - the saccule. The study objectives are: 1. To investigate possible malfunction of the saccule in patients suffering from BPPV. 2. To look for association between saccular pathology and BPPV recurrence and between such pathology and BPPV treatment failure. 3. To study possible relation between saccular pathology and continuation of dizziness and disequilibrium despite the resolution of positional vertigo.