OBJECTIVE: We investigated the neuro-otological findings, including
nystagmus, and the clinical course of patients with the horizontal canal
variant of benign paroxysmal positional vertigo (HC-BPPV), who showed
spontaneous inversion of nystagmus without a positional change. Furthermore,
we speculated on the possible mechanism of spontaneous inversion of
nystagmus without a positional change.
PATIENTS AND METHODS: The characteristics of spontaneous inversion
of positional nystagmus without a positional change were analyzed in 7
patients with HC-BPPV.
RESULTS: All patients were diagnosed as having HC-BPPV. During the
positional test, the spontaneous inversion of nystagmus was observed in the
same head position in all patients. Spontaneous inversion was observed on
both sides in 5 patients, and only on 1 side in 2 patients. All patients
presented with geotropic nystagmus in the first phase, and ageotropic
nystagmus in the second phase.
CONCLUSIONS: The coexistence of cupulolithiasis and canalolithiasis
appears to be a possible mechanism of the spontaneous inversion of
positional nystagmus.
