Abstracts

Rationale: Stimulus-induced rhythmic, periodic or ictal discharges (SIRPIDs) is an electrographic pattern that was first reported by Hirsch et al. in 2004 in critically ill patients. We review five patients who exhibited this pattern and their outcome. Methods: We prospectively identified five patients with SIRPIDs who underwent continuous video-EEG monitoring. The pattern was recognized by one of two electroencephalographers and reviewed by both. We evaluated the patients’ history, examination, laboratory work-up, imaging studies and outcome.Results: All five patients (ages 44-72 years; 4 women and 1 man) had multiple medical problems and decreased mental status at the time of continuous video-EEG monitoring. Three patients had a history of seizures or epilepsy. One of the three had progressive dementia of unclear etiology. One of the two patients without history of seizures suffered an anoxic brain injury following resuscitation for cardiopulmonary arrest. Continuous video-EEG monitoring was performed for 2 to 4 days. In all five patients, SIRPIDs were noted at onset of spontaneous stimulation induced by motor activity, eye movements, as well as sensory stimulation often due to nursing care. The electrographic pattern persisted throughout the period of stimulation, ending only after stimulation or movements ceased. Antiepileptic drugs did not appear to affect this electrographic pattern. Four of the five patients’ condition improved. Three were back to their baseline upon discharge, but had to be readmitted approximately a month later with several acute medical problems. The fourth patient, with progressive dementia, was sent back to her nursing home and was seen in follow up one month approximately after her discharge. She never recovered to her baseline status. The patient who suffered anoxic brain injury expired eight days after monitoring was discontinued. Conclusions: Three of our 5 patients with SIRPIDs recovered back to baseline. The electrographic pattern did not respond to antiepileptic medications. This electrographic pattern therefore does not appear to be ictal in origin and its presence may imply a favorable prognosis. Overall prognosis however appears to depend on the initial insult.