The objective was to identify unique features of the photoparoxysmal response seen in patients with neuronal ceroid lipofuscinosis type 2 as compared to patients with a photoparoxysmal response associated with other epilepsy syndromes.

Electroencephalograms from patients with neuronal ceroid lipofuscinosis type 2 seen at the authors’ institution in the past 10 years as well as electroencephalograms (EEGs) reported to have a photoparoxysmal response during a single year were reviewed.

A photoparoxysmal response was seen in 60% of the patients with neuronal ceroid lipofuscinosis type 2. This was most commonly seen with low frequency intermittent photic stimulation (76%) which often occurred in a time-locked fashion (63%) and was seen on the patient’s initial EEG (78%). A unique pattern the authors called "sentinel" discharge was identified in 30% of EEGs in patients with neuronal ceroid lipofuscinosis.

Photoparoxysmal responses in patients with neuronal ceroid lipofuscinosis type 2 have features which are distinguishing from photoparoxysmal responses seen in other epilepsies.