Posterior rhythmic slow activity in eeg after eye closure

Abstract

During a 20 month period, EEGs in 7 patients, ages 6–16 years, showed a distinctive posterior rhythmic slow (PRS) activity brough on by eye closure. Following eye opening for 5–10 sec, eye closure on command was followed by a rhythmic high amplitude (100–250 μV) slow wave discharge of 3–4 c/sec lasting for 1.5–3 sec after a latency of 300–500 msec. Its distribution was limited to the occipital, posterior temporal and parietal regions. It was always bilaterally synchronous, accurred symmetrically or asymmetrically and fatigued easily. Of the 7 initial EEGs, only 2 had other EEG abnormalities. One patient, in a subsequent EEG, developed spontaneous PRS unrelated to eye closure. Clinical histories on the 7 patients showed 5 with various types of seizures disorders. 1 with attention deficit disorder, and 1 with Tourette syndrome. Neurological examination was normal in all patients, while computerized tomography or radioisotope brain scan was normal in 4. We suggest that PRS after eye closure represents sents a variant of the non-specific spontaneously occurring PRS described by Aird and Gastaut and others. It was found only in children and was not found to be helpful in diagnosing a seizure disorder order or structural abnormality. Furthermore, such a discharge should not be interpreted as epileptiform activity.