Abstracts

Rationale: We wish to describe a rare case of visually provoked myoclonic epilepsy. Methods: This is a 53-year-old man with childhood-onset undifferentiated generalized tonic-clonic seizures since age twelve, who developed diffuse body tremors and multifocal twitching/jerking waxing and waning throughout wakefulness and sleep for 6-7 years, becoming nearly continuous in the past 1-2 years. He describes dizziness, sensitivity to light, severe anxiety, and vertigo associated with his spells of twitching/jerking. These twitching of limbs occasionally progressed to full body stiffening and jerking with tongue biting, mainly on the left side, followed by postictal fatigue. Events are triggered by visual phenomena including bright lights, vertical patterns (e.g. trees through a car window), and the events are worse on cloudy days. He took Levetericitam for generalized seizures with incomplete effect and no impact on continuous twitches. Routine EEG and brain MRI studies were reportedly normal five years prior to the current presentation. Results: The patient was admitted to our epilepsy service for long term video-EEG monitoring. Initial clinical evaluation revealed multifocal limb and head twitching that was somewhat distractible, suspicious for a nonepileptic phenomenon. Interictal EEG showed frequent generalized paroxysmal fast activity during sleep, occasional independent spike-wave discharges in the left temporal and right parasagittal regions activated in sleep, and occasional independent right and left temporal slowing. Multiple jerking movements involving various body parts were recorded during both wakefulness and sleep, which predominantly did not have an abnormal EEG correlate, but rarely in sleep were time-locked with small spike-wave discharges in the right parasagittal or left temporal regions, indicating a deep cortical origin for myoclonus. Worsening of baseline myoclonus evolving into a myoclonic-tonic-clonic seizure was provoked by visual stimulation with a scrolling parallel line pattern on a smartphone. The scalp EEG only showed myogenic pattern during this epileptic seizure and was diffusely suppressed in the immediate postictal phase. The patient was discharged on Clobazam and titrated to 20 mg daily with complete resolution of daily myoclonus. Conclusions: This report highlights a rare case of reflex myoclonic epilepsy of probably deep cortical origin, provoked by visual stimuli. Video EEG monitoring was necessary for correct diagnosis. Our patient had no response to Levetiracetam and complete response to low-dose Clobazam, suggesting a benzodiazepine responsive syndrome. Funding: No funding