Stimulus-induced generalized epileptiform discharges: an unrecognized EEG pattern in refractory nonconvulsive status epilepticus.

PURPOSE: To report an unrecognized EEG pattern occurring in patients with coma with nonconvulsive status epilepticus (NCSE) treated with thiopental and characterized by a high amplitude generalized sharp wave that was induced by isolated or repetitive low frequency photic or tactile stimulation (stimulus-induced generalized epileptiform discharges).

METHODS

Review of clinical and EEG records of 4 patients with stimulus-induced generalized epileptiform discharges identified among patients admitted to an intensive care unit (ICU) of our institution who underwent EEG monitoring between July 2011 and January 2013.

RESULTS

Four patients had refractory NCSE secondary to hepatic encephalopathy, brain tumor, immunomediated encephalopathy, or anti-NMDA encephalitis. All of them were treated with several antiepileptic drugs and anesthetics, but stimulus-induced generalized epileptiform discharges were only recorded after control of NCSE with thiopental. The discharges occurred without associated clinical manifestations. Two patients died in the ICU, and two had a favorable outcome. Stimulus-induced generalized epileptiform discharges were not recorded in 240 critically ill patients admitted to the ICU who had an EEG recorded during this period. Twenty-two of them were in NCSE, and only one was treated with thiopental.

CONCLUSIONS

Stimulus-induced generalized epileptiform discharges is an EEG pattern occurring in patients with NCSE treated with thiopental. The clinical relevance and pathophysiology of stimulus-induced generalized epileptiform discharges remain to be clarified.