[Benign paroxysmal positional vertigo of the horizontal semicircular canal].

OBJECTIVE: Assesment of 8 new cases of benign paroxysmal positional vertigo of the horizontal semicircular canal (BPPV-HC), since this variant of benign positional vertigo occurs rarely. An oculographic study of features in the positional response was carried out. Electrooculograpy (EOG) allows an exhaustive study of positional nystagmus.

MATERIAL AND METHODS: We have studied retrospectively 8 patients with BPPV-HC and positive head rotation manoeuvre registered by EOG techniques. Possible alterations in other EOG tests in the group of patients were analyzed.

RESULTS: Most of the patients (7/8) expressed bilateral horizontal geotropic changing-direction nystagmus. One patient exhibited apogeotropic horizontal nystagmus. 5/8 cases showed caloric hypofunction.

CONCLUSIONS: We have proven that BPPV-HC is an uncommon disorder. In most of the cases, provocative manoeuver generates bilateral horizontal geotropic changing-direction nystagmus that probably is due to canalitiasis of the horizontal semicircular canal. The rest, a few cases, exhibit apogeotropic horizontal response that can be secondary to cupulolitiasis or location particles in the anterior portion of the horizontal canal. A caloric test showed abnormal in many and can help to locatize the affected ear.