Bilateral Chronic Subdural Hematoma is Associated with Rapid Progression and Poor Clinical Outcome.

Chronic subdural hematoma (CSDH) has been recognized as a benign disease, but its clinical outcome is not well documented. This study aims to expand the knowledge base regarding the outcome of CSDH. We retrospectively reviewed clinical characteristics of CSDH operated in the Kobe City Medical Center General Hospital between June 2005 and June 2012. Variants included age at onset, sex, laterality, presence of headache, consciousness level, and risk factors for hemorrhage such as malignancy or intake of anticoagulants. A total of 368 cases were analyzed. Six patients (1.4%) had a poor outcome, defined as any morbidity or mortality at 7 days postoperatively. Bilateral hematoma was significantly associated with a poor outcome (p = 0.041). Warfarin use and malignancy, albeit statistically not significant, were more frequently observed in patients with a poor outcome. Bilateral CSDH was observed in 53 patients (14.4%). Age at onset, sex, history of malignancy, anticoagulant use, and antiplatelet use did not differ between bilateral and unilateral CSDH. Recurrence rate was not different between bilateral and unilateral CSDH (14.2% vs. 11.3%), but poor outcome as a result of brain herniation was significantly higher in bilateral than in unilateral hematomas (5.7% vs. 0.3%, p = 0.01). Bilateral CSDH was associated with rapid progression and showed worse outcome as a result of brain herniation in comparison with unilateral CSDH. Urgent trephination surgery for decompression of hematoma pressure may be recommended for bilateral CSDH.