Utility of Clinical Features for the Diagnosis of Seizures in the Intensive Care Unit

Seizures in the intensive care unit are often subtle, and may have little or no clinical correlate. This study attempts to determine what clinical features are most strongly associated with the presence of electrographic seizures on continuous EEG (cEEG) monitoring.

A retrospective review for all patients who underwent cEEG monitoring between January 2003 and March 2009 for either characterization of clinical events or altered mental status was performed. Clinical events were categorized as (1) limb myoclonus/tremor, (2) extremity weakness, (3) eye movement abnormalities, (4) facial/periorbital twitching, and (5) other abnormal movements. The presence of associated dyscognitive event features was also recorded.

Records from 626 patients who underwent cEEG were reviewed-154 for event characterization and 472 for altered mental status. Seizures were captured in 48 patients (31.2%) undergoing cEEG monitoring for characterization of clinical events. This was not significantly different from the incidence of seizures in patients undergoing cEEG for altered mental status (N = 133, 28.2%). Patients undergoing cEEG monitoring for facial/periorbital twitching were significantly more likely to have electrographic seizures (78.9%, P < 0.005) than patients undergoing cEEG for altered mental status or characterization of other types of events.

The incidence of seizures in patients in the intensive care unit with clinical events is generally not significantly higher than the incidence of seizures in patients in the intensive care unit with altered mental status. However, the presence of facial/periorbital twitching was associated a higher incidence of electrographic seizures.