Outcomes of patients with nonepileptic transient neurologic symptoms after subdural hematoma evacuation

Background Patients undergoing a subdural hematoma (SDH) evacuation can experience transient neurological symptoms (TNS) postoperatively. Electroencephalography (EEG) is used to rule out seizures. We aim to characterize patients with TNS and negative epileptiform activity on EEG and compare them to those with positive epileptiform EEG findings. Methods We performed a retrospective study of adult patients who underwent EEG for evaluation of TNS after undergoing SDH evacuation. Patients were stratified based on SDH type (acute and non-acute) and whether or not their EEG demonstrated positive epileptiform activity. A multivariate analysis was performed to identify predictors of negative EEG findings. Results One hundred twenty-nine SDH patients were included (45 (34.9%) acute; 84 (65.1%) non-acute). Overall, 45 (24 acute and 21 non-acute SDH patients) had positive epileptiform EEG findings, and 84 (21 acute and 63 non-acute SDH patients) had a negative EEG. Acute and non-acute SDH patients with positive EEG findings were more likely to suffer from greater than five episodes of TNS, impaired awareness, and motor symptoms, while the negative EEG group was more likely to suffer from negative symptoms. Non-acute SDH patients with positive EEG had longer mean ICU stays (14.6 vs. 7.2; p = 0.005). Both acute and non-acute SDH-positive EEG patients had worse disposition upon discharge ( p < 0.05), worse modified Rankin score at discharge ( p < 0.05), and 3-month follow-up ( p < 0.05) and were more likely to be discharged on more than one antiepileptic drug ( p < 0.001). Conclusion Postoperative acute and non-acute SDH patients with TNS and negative EEG results are likely to have a favorable clinical picture. This distinction is therapeutically and prognostically important as these patients may not respond to typical antiepileptic drugs and they have better functional outcomes.