Clinical correlations of occipital epileptiform discharges in children

To the Editor:

The report by Libenson et al.1 sought to “determine the frequency of different causes of occipital epileptiform discharges (OEDs) in children … .”1 Their principal finding was that over half of all children with OEDs had symptomatic epilepsies and only 6 (under 7% of the total) had benign childhood epilepsy with occipital paroxysms (BCEOP). This conflicts with other studies, some prospective, suggesting a prevalence of up to 8% of all, not just occipital, childhood epilepsies.2

The principal reason for this discrepancy is probably methodologic. The study by Libenson et al.1 was retrospective and relied on the identification from an EEG database of children with OEDs before 1997. Clinical details, including diagnosis, were then obtained from patient records. The common form of BCEOP (early onset variant or Panayiotopoulos syndrome), although first described almost 20 years ago, has only recently been confirmed worldwide, particularly in Europe, Japan, and South America.3-5 Defining seizure features are liable to be missed or misinterpreted unless the clinician is familiar with this syndrome. It is characterized by a combination of autonomic and behavioral disturbances, vomiting, deviation of the eyes, and usually impairment of consciousness, with some seizures progressing to convulsions. Seizures usually last more than 3 minutes; a quarter last for over an hour.

Moreover, Libenson et al.1 specifically excluded patients whose EEG showed focal discharges in extra-occipital sites. In BCEOP, up to one …