339 Preliminary Analysis of 10 Year Institutional Experience With Cortical Spreading Depolarization Following Surgical Evacuation of Chronic Subdural Hematoma

INTRODUCTION: The surgical management of chronic subdural hematoma (cSDH) is complicated by the development of transient neurologic deficits (TND) without underlying electrographic or radiographic correlates. This phenomenon, known as cortical spreading depolarization (CSD), is estimated to occur in nearly 25% of patients who undergo surgical evacuation of a cSDH. Although CSD can lead to unnecessary testing and increased length of stay the long-term clinical outcomes and potential risk factors for CSD have not been well-established. METHODS: Patients with concomitant subdural hygroma, previous epilepsy diagnosis, and incomplete data were excluded. CSD was defined as a post-operative TND without underlying hematoma expansion, infarct, or epileptiform activity on EEG. Chi-square tests with odds ratios were conducted for categorical variables and independent samples t-tests were conducted for continuous variables. RESULTS: 220 patients managed with surgical intervention for cSDH were included. 23 patients (10.4%) had clinically suspected CSD. Patients who presented with a speech deficit had increased odds of developing a CSD (odds ratio=3.2; p=0.026). Patients who developed CSD had greater midline shift (mean difference=+2.1 mm; p=0.046) and were more likely to have had a left-sided surgery (52.2%). 91.2% of patients who developed CSD were treated with mini craniotomy though this did not reach statistical significance, however the rate of burr holes was greater in the non-CSD group (CSD, 8.7% vs non-CSD 19.7%). There was no statistically significant impact of CSD on mortality (6 months; p=0.29, 12 months; p=0.17). CONCLUSIONS: Preliminary analysis of factors that contribute to CSD following the surgical evacuation of cSDH has identified several interesting trends including an association between larger midline shift and speech deficits on presentation. Surgery type did not significantly impact the likelihood of CSD.