Abstracts

Rationale: Numerous studies have established that patients in the intensive care unit (particularly neurologic intensive care units) are at high risk for developing seizures, with seizure rates ranging from 19-31%. The majority of these seizures are nonconvulsive seizures, which can present in a wide variety of ways. Although the clinical manifestations of seizures in the outpatient setting has been widely described in the existing literature, there is little information on the clinical features associated with electrographic seizures in the ICU. Methods: A retrospective chart review was conducted on 770 patients in the neurologic ICU placed on continuous EEG monitoring (cEEG) between January 2003 and March 2009. Of these patients, 152 (19.7%) were placed on cEEG in order to characterize a specific type of clinical event. Events were characterized as: episodic loss of consciousness (LOC), extremity myoclonus/tremor, other stereotyped movements, extremity weakness, increased ICP, eye deviation or other abnormal eye movements, episodic agitation or confusion, aphasia or speech disruption, hallucinations, facial or eye twitching, or other symptoms. Many patients had more than one type of event. Results: The most common type of event was myoclonus /tremor, seen in 53 patients, followed by aphasia / speech disruptions (27 patients), episodic agitation/ confusion (22 patients), episodic LOC (22 patients), extremity weakness (21 patients), facial / eye twitching (19 patients), and eye deviation / eye movement abnormalities (15 patients.) Other events were relatively uncommon. Seizures were present in 31.2% of patients. Seizures were most common in patients with eye / facial twitching (78.9%), followed by aphasia / speech disturbance (40.7%), extremity weakness (38.1%), hallucinations (33.3%), myoclonus / tremor (32.1%), episodic agitation / confusion (31.8%), episodic loss of consciousness (22.7%), eye deviation or eye movement abnormalities (13.3%), and other stereotyped movements (10.0%.) Patients who had only one symptom were less likely to have seizures than patients who had two or three symptoms (31.2% versus 38.1 and 40.0%, respectively.) Conclusions: Manifestations of seizures in the ICU are typically subtle, and are most commonly associated with facial or eye twitching. Episodic aphasia, agitation or confusion should also raise suspicion for nonconvulsive seizure activity. The majority of myoclonus, tremor and stereotyped movements seen in the ICU are not caused by seizure activity.