Focal motor seizures induced by alerting stimuli in critically ill patients.
OBJECTIVE
We have previously demonstrated that it is common for alerting stimuli to induce electrographic seizures and other periodic or rhythmic patterns in the critically ill; however, only 1 of the first 33 patients we reported with this phenomenon had a detectable clinical correlate.


METHODS
Review of charts and video EEG findings in critically ill patients in a neurological ICU at a tertiary care medical center in Manhattan.


RESULTS
We identified nine patients who had focal motor seizures repeatedly induced by alerting stimuli. All patients were comatose, and 8/9 had nonconvulsive status epilepticus at some point during their acute illness. Imaging abnormalities involved bilateral thalami in three patients, upper brainstem in one, and the perirolandic region in five.


CONCLUSIONS
We hypothesize that in encephalopathic patients, alerting stimuli activate the arousal circuitry, and, when combined with hyperexcitable cortex, result in epileptiform activity or seizures. This activity can be focal or generalized, and is usually nonconvulsive, as is true of seizures in general in the critically ill. However, when the cortex is hyperexcitable in a specific region only, focal EEG findings arise. If the electrographic seizure activity is adequately synchronized and involves motor pathways, this can present as focal motor seizures, as seen in these nine patients. Alerting can induce seizures in encephalopathic/comatose patients. The observation of clear focal clinical seizures removes the last remaining doubt that these stimulus-induced patterns are indeed seizures by any definition, not simply abnormal arousal patterns.
Hirsch
Lawrence J
LJ
Department of Neurology, Comprehensive Epilepsy Center, Neurological Institute, Columbia University, College of Physicians and Surgeons, New York, New York 10032, USA. ljh3@columbia.edu
Pang
Trudy
T
Claassen
Jan
J
Chang
Craig
C
Khaled
Karine Abou
KA
Wittman
John
J
Emerson
Ronald G
RG
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000927:Anticonvulsants / Q000009:adverse effects / Q000627:therapeutic use; D001143:Arousal / Q000502:physiology; D001925:Brain Damage, Chronic / Q000175:diagnosis; D001933:Brain Stem / Q000473:pathology; D002648:Child; D003422:Critical Care; D004292:Dominance, Cerebral / Q000502:physiology; D004569:Electroencephalography / Q000187:drug effects; D020938:Epilepsy, Partial, Motor / Q000175:diagnosis* / Q000188:drug therapy; D020195:Epilepsy, Reflex / Q000175:diagnosis* / Q000188:drug therapy; D005260:Female; D005625:Frontal Lobe / Q000473:pathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D013375:Substance Withdrawal Syndrome / Q000175:diagnosis; D013702:Temporal Lobe / Q000473:pathology; D013788:Thalamus / Q000473:pathology; D014741:Video Recording
D000927:Anticonvulsants