The Long-Term Use of Diagnostic Subdural Electroencephalogram Electrodes and Subdural Hematoma: A Prospective Cohort Study*

Abstract

OBJECTIVES: Seizures and status epilepticus (SE) are frequent complications of acute subdural hematoma (aSDH) associated with increased morbidity and mortality. Therefore, we aimed to evaluate whether invasive subdural electroencephalogram recording leads to earlier seizure detection and treatment initiation in patients with aSDH. DESIGN: Prospective, single-center, cohort trial. SETTING: Neurologic and neurosurgical ICUs of one academic hospital in Germany. PATIENTS: Patients with aSDH undergoing surgical treatment. In total, 76 patients were enrolled in this study, 31 patients (40.8%) were assigned to the invasive electroencephalogram (iEEG) monitoring group and 45 patients (59.2%) to control group. INTERVENTIONS: The electrode group was implanted with a subdural strip electrode providing up to 7 days of real-time electroencephalogram recording in the neurointensive care unit, whereas the control group received regular normal surface electroencephalograms during the 7-day period. The primary outcomes were the prevalence and time to seizures and SE occurrence. Secondary outcomes included neurologic outcomes assessed using the Glasgow Outcome Scale (GOS) at discharge and 6-month follow-up and the prevalence of focal structural epilepsy within 2 years after discharge. MEASUREMENTS AND MAIN RESULTS: The trial was stopped after a study committee meeting when the prespecified criteria were met. The iEEG and control groups were well-matched for clinical characteristics at admission. Frequencies of seizures and SE detection were significantly higher in the iEEG group than in the control group (61% vs 15.6%; p < 0.001 and 38.7% vs 11.1%; p = 0.005). Time to seizure and SE detection was significantly earlier (median 29.2 vs 83.8 hr; p = 0.018 and 17.2 vs 83.8 hr; p = 0.033) in the iEEG group than in the control group. Favorable outcomes (GOS 4–5) were more frequently achieved in the iEEG group than in the control group (58% vs 31%; p = 0.065). No significant differences were detected in long-term mortality or post-traumatic epilepsy. CONCLUSIONS: Invasive subdural electroencephalogram monitoring is valuable and safe for early seizure/SE detection and treatment and might improve outcomes in the neurocritical care of patients with aSDH.