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The canalithiasis hypothesis proposes that benign positional vertigo(BPV) is caused by dislodged otoconia that settle in the posterior semicircular canal(PSC).When head position is changed these particles move within the canal and induce abnormal endolymph flow.To clear the PSC from debris we developed a procedure that consists of a full circle of backward head rotation in the exact plane of the canal.Patients were in a three- dimensional motion device that rotated in steps of 110 degrees every 30 seconds.The first part of the study was conducted as an open trial;the second part followed a single-blinded,placebo-controlled design:Forward rotation(placebo)was applied first and backward rotation was applied 1 week later if BPF persisted.All patients were assessed with a symptom diary and,in the controlled trial,also with the Dix-Hallpike maneuver.In the open study 10 of 15 patients became asymptomatic after one treatment session.In the controlled trial all 15 patients remained symptomatic after forward rotation while 10 of 14 undergoing backward rotation were relieved from positional vertigo immediately(p=0.004).The presence of secondary nystagmus during the procedure indicated a favorable outcome.Our findings provide evidence for the efficacy of canal-clearing procedures that validate the canalithiasis hypothesis of BPD. |
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