Electro-otolithography: new insight into benign paroxysmal positioning vertigo
Abstract
Early vestibular evoked potentials were recorded with an extratympanic electrode. The recording principle was adding responses phase locked to a recording frequency. The recording frequency was empirically determined to match harmonically an individual response frequency and thus allowing averaging. This new technique was evaluated in benign paroxysmal positioning vertigo. Normal data were obtained from 12 patients without vestibulo-cochlear symptoms, and compared with 18 symptomatic patients diagnosed with benign paroxysmal positioning vertigo. All symptomatic patients were treated with a canalith repositioning manoeuvre, and all responded in that they had no longer attacks of vertigo. Five patients could be reassessed. They had no longer attacks of vertigo, but three complained of persisting postural imbalance. Repeat electro-otolithography continued to be abnormal in these patients, whereas the remaining two patients had normal responses being consistent with the treatment outcome. The results suggest that electro-otolithography is a valuable addition to the otoneurological test battery. Successful canalith repositioning can abolish attacks of vertigo, but not necessarily a persisting imbalance, which the patient frequently describes as a temporary and momentary instability. This is most likely related to a remaining otolithic deficit.