medwireNews: The total time spent having seizures, rather than their presence per se, is linked to outcomes after subarachnoid haemorrhage (SAH), say researchers.
“Assuming that seizure in SAH is not just a marker of initial severity, but a primary source of secondary brain injury, earlier therapeutic interventions may lead to ameliorated outcomes”, say Gregory Kapinos (Hofstra North Shore–LIJ School of Medicine, New York, USA) and Julius Gene Latorre (State University of New York, Upstate University Hospital, Syracuse, USA) in an editorial accompanying the study in Neurology.
But they note that some previous studies also found a link between electroencephalogram (EEG) findings not related to seizures and outcomes, casting doubt on whether seizure activity reflects developing or existing brain damage.
The study, by Jan Claassen (Columbia University, New York, USA) and co-workers, included data from 402 SAH patients who underwent continuous EEG for an average duration of 96 hours during hospital admission. Of these, 12% had nonconvulsive seizures lasting a median of 6 hours.
Three-month outcomes were known for 77% of the patients, and, as anticipated, were unfavourable (modified Rankin Scale 4–6) in more patients with than without seizures, at 81% versus 54%. The association between seizures and poor outcomes persisted after accounting for confounders and was strongest for nonconvulsive status epilepticus.
Furthermore, each additional hour of cumulative seizure activity during monitoring increased the risk of an unfavourable outcome by 10%, after accounting for potential confounders.
Older age, higher Hunt and Hess grade, and aneurysm size larger than 10 mm also predicted unfavourable outcomes.
Seizure burden was also significantly associated with cognitive outcomes, which were available for 121 participants. Each additional hour of cumulative seizure activity was associated with an 0.19-point reduction in 3-month Telephone Interview for Cognitive Status score. The presence of seizures per se, by contrast, did not predict cognitive outcomes.
In their editorial, Kapinos and Latorre say that the “notion of seizure burden should encourage clinicians to escalate anticonvulsive therapy even for discrete short-lived but accumulating seizures”, although they caution that “overzealous treatment” of all single seizures may not be necessary.
“Using this gauging system of incremental cumulative effect of seizures seems more appropriate”, they say. “This seizure burden study suggests that every hour counts and thus, one can no longer accept making intensivists aware of electrographic seizures many hours after the occurrence.”
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