Seizure triggered by flicker electroretinogram in a patient with no history of epilepsy

Abstract

Purpose: It is well known that repetitive flash stimulation may trigger seizures in susceptible individuals. Nevertheless, reports of such incidents occurring during recording of a flash electroretinogram (ERG) are extremely rare. Here, we describe the case of a photic-induced seizure triggered during an ERG recording in the absence of a history of epilepsy or other paroxysmal events.

Methods: A 14-year-old male patient presented with reduced visual acuity and impaired mesopic vision. Ophthalmological exams confirmed the patient's complaints but were inconclusive as to the underlying pathophysiology. An ERG recording was performed, during which the 30-Hz flicker stimulus triggered a seizure.

Results: The ERG was essentially normal, with the exception of a 7-Hz rhythm superimposed onto the flicker ERG response that was recorded when the seizure developed.

Conclusions: The present case highlights the possibility that the 30-Hz ERG flash stimulus triggers a seizure in patients with no previous paroxysmal events. Literature evidence suggests that the likelihood of such an incident could be reduced by stimulating monocularly.

Keywords: Electroretinography; Epilepsy; Paroxysmal event; Photic-induced seizure; Safety.

Fig. 1

Scotopic ERGs for flash strengths ranging from 0.001 cd/m² (top) to 10 cd/m² (bottom). Recordings were performed with skin electrodes, and amplitudes were scaled to approximately match recordings with fiber electrodes

Fig. 2

Photopic single-flash ERGs (top) and two recordings of 30-Hz flicker ERGs (middle and bottom). Recordings were performed with skin electrodes, and amplitudes were scaled to approximately match recordings with fiber electrodes. All responses were in the normal range or, in the case of the flicker response in right eye, slightly supranormal. A 7-Hz rhythm is present in the second recording of the flicker ERG. In contrast, normal movement artifacts are only present in the first recording. Note the different abscissal scaling of the single-flash and flicker ERGs