Ocular Flutter in Acute Doxylamine Intoxication

Ocular flutter consists of bursts of high-frequency, low-amplitude, conjugate saccadic oscillations without normal intersaccadic interval and confined to the horizontal plane. Ocular flutter can be present during sleep, eyelid closure, attempted fixation, and volitional eye movements. Cerebellar fastigial nuclei disinhibition and/or inhibition of pontine omnipause cells disturb the excitatory/inhibitory balance of brainstem saccadic burst neurons, ultimately leading to saccadic oscillations including ocular flutter.1 The most common causes of ocular flutter in adults are paraneoplastic and parainfectious. Toxic metabolic etiologies are rare and include medications such as phenytoin and venlafaxine. Cerebellar and brainstem lesions have been reported, but the etiology remains unknown in approximately half of these patients.1,2 We present a case of ocular flutter in the setting of acute doxylamine intoxication. Doxylamine is a first-generation antihistamine widely available over the counter (OTC) as a sedative sleep aid, often combined with antitussives and decongestants.