Nystagmus parameters and subtypes of benign paroxysmal positional vertigo.

CONCLUSION

Although computational models suggest the existence of canalithiasis and cupulolithiasis subtypes of benign paroxysmal positional vertigo (BPPV), these subtypes cannot be distinguished from each other based on characteristics of nystagmus. Therefore, although the subtypes probably exist more information is needed from each patient than is available without invasive procedures. Also, some patients may have clinical syndromes that include both canalithiasis and cupulolithiasis subtypes.

OBJECTIVE

To determine if the parameters of nystagmus provide sufficient information to determine the subtype of nystagmus in a patient with BPPV.

METHODS

Patients (n = 118) had unilateral BPPV of the posterior canal; 15 patients also had BPPV of the lateral canal. The main outcome measures were parameters of nystagmus in response to the Dix-Hallpike maneuver: latency to onset of nystagmus, maximum slow phase velocity, and maximum duration.

RESULTS

Correlations between pairs of variables showed minimal or no relationships. Also, cluster analyses showed no significant subtypes. The contralateral eye moved significantly faster than the ipsilateral eye.