Abstract
OBJECTIVE: While positional nystagmus of benign paroxysmal positional vertigo (BPPV) has been shown to be detectable in electrooculography (EOG) tracings of polysomnography (PSG), the frequency of undiagnosed BPPV in patients referred for sleep-wake examination has never been investigated.
METHODS: Prospective evaluation of positional nystagmus in 129 patients, referred to a neurological sleep laboratory for sleep-wake examination with PSG. Both in the evening and morning, patients had diagnostic positioning maneuvers under ongoing EOG-PSG registration, followed by visual inspection of EOG for positional nystagmus.
RESULTS: In 19 patients (14.7%), we found patterns of positional nystagmus, typically appearing few seconds after changes in head position. In 9 of these patients (47%), the nystagmus was also provoked by the positioning maneuvers. Nystagmus only occurred during wakefulness, not during sleep. In a patient with severe cupulolithiasis, we observed disappearance of nystagmus while entering N1 sleep stage. Nocturnal positional nystagmus was independently associated with positive positioning maneuvers.
CONCLUSIONS: Inspection of EOG-PSG demonstrated that positional nystagmus is common, occurring only when wake, and independently associated with positive positioning maneuvers.
SIGNIFICANCE: By routinely searching for positional nystagmus in PSG, sleep physicians may substantially contribute to the identification of patients with so-far undiagnosed BPPV.
Valko, Yulia