BENIGN PAROXYSMAL POSITIONAL VERTIGO OF THE HORIZONTAL CANAL

Objectives-To review the clinical features, electronystagmography find ings, the possible mechanism, and a possible therapeutic approach to b enign paroxysmal positional vertigo (BPPV). Methods-Sixty three cases of BPPV of the horizontal canal type have been reviewed. It is charact erised by horizontal nystagmus and an intense vertigo, provoked by rot ation of the head in a supine patient. The horizontal nystagmus beats towards the ground on both sides, becomes more pronounced when lying o n the pathological side, and then the nystagmus often changes directio n. Results-Forty eight patients underwent electronystagmography. On th e pathological side, the first phase nystagmus had a mean latency of t hree seconds and a mean duration of 31.6 seconds. Nystagmus inversion occurred in 36 patients after a nystagmus free interval. The mean seco nd phase nystagmus duration lasted 33.4 seconds. On the healthy side, the nystagmus had a mean latency of 3.4 seconds and a mean duration of 39.5 seconds. Fatigue was seen in six patients. Simultaneous involvem ent of the posterior canal was present in 16 patients. A liberatory ma noeuvre was successful in six patients. Conclusions-The liberatory man oeuvre should be tried in patients with horizontal canal vertigo. It s hould not be performed in patients with severe cervical arthrosis, ver tebrobasilar insufficiency, or when the patient has neck pain during t he manoeuvre.