Paroxysmal Positional Nystagmus in Acoustic Neuroma Patients.

The association between acoustic neuroma and positional vertigo with paroxysmal positional nystagmus is relatively rare, but, when present, it certainly represents a challenge for the otoneurologist. There are few reports in the literature on this particular issue, and some questions are still unanswered, particularly regarding the characteristics of positional nystagmus that may distinguish between a true benign paroxysmal vertigo and a positional nystagmus associated with the tumor. We present the videonystagmographic patterns of seven patients with acoustic tumor who had paroxysmal positional nystagmus and analyzed its features. A concomitant true benign paroxysmal positional vertigo may be present during the follow-up of a non-treated patient, as the paroxysmal positional vertigo may be the first symptom of the tumor, and it may show characteristics that are very similar to a posterior semicircular canal canalolithiasis or a horizontal canal "heavy or light cupula". The possible mechanisms are discussed.