Polysomnography reveals nystagmus from benign paroxysmal positional vertigo

Images: polysomnographic findings of nystagmus caused by a midbrain hemorrhagic stroke

Brainstem strokes can present with an array of ophthalmologic findings depending on the location of the lesion. Eye movements are recorded on electrooculogram during polysomnography for sleep staging. We present the case of a patient with a dorsal midbrain hemorrhagic stroke and nystagmus with distinct findings on the electrooculogram during polysomnography. These eye movements from nystagmus differed in many aspects (frequency and amplitude) from the classic findings of other eye movements recorded during different stages of sleep. These polysomnography findings have not been reported in the setting of midbrain stroke. Future studies comparing nystagmus in multiple sleep stages in stroke patients would be of interest.

CITATION

Shoukat U, Glick DR, Chaturvedi S, Diaz-Abad M. Images: Polysomnographic findings of nystagmus caused by a midbrain hemorrhagic stroke. J Clin Sleep Med. 2022;18(5):1479-1482.

The eyes wake up: Screening for benign paroxysmal positional vertigo with polysomnography

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.