To evaluate EEG responses to endovascular interventions used to prevent and treat delayed cerebral ischemia

Prior work has associated the development of delayed cerebral ischemia in hospitalized aneurysmal subarachnoid hemorrhage patients with increased incidence of inter-ictal continuum abnormalities and epileptiform discharges on long-term EEG monitoring.

However, to our knowledge no group has compared the frequencies of these EEG abnormalities before and after endovascular interventions used to prevent and treat delayed cerebral ischemia.

We performed a single-center retrospective analysis of EEG recordings from aneurysmal subarachnoid hemorrhage patients admitted to our Neuro-ICU.

EEGs from 50 patients (mean age 56.3 ± 11.6 years, 38 female, median Hunt-Hess 3 and modified Fisher 4) who received a total of 86 endovascular interventions with intra-arterial verapamil (mean dose 22.7 ± 10.3 mg, 9 with angioplasty) were processed using the recently developed Morgoth algorithm for automated detection of EEG abnormalities.

Time intervals from 8 to 2 hours before procedure start and 2 to 8 hours after procedure end were compared for the rates of seconds with high probability of epileptiform activity (LPDs, GPDs, or LRDA), GRDA, seizures, and spikes using matched-paired T-tests.

As compared to the preprocedural time interval, the postprocedural time interval showed a 15.1% average decrease in the frequency of epileptiform activity (p = 0.14), an 8.9% average decrease in the frequency of seizure (p = 0.54), and a 26.3% average decrease in the frequency of spikes (p = 0.06).

The frequency of GRDA stayed essentially constant across time intervals (p = 0.97).

While the decreases seen in the detected incidences of epileptiform abnormalities were individually non-significant, their collective trend suggests a potential benefit of endovascular interventions in reducing neurophysiologic dysfunction in patients at risk for or actively developing delayed cerebral ischemia.

Further work is needed to characterize these findings on the individual patient level.