Chronic Subdural Hematomas: Comparison between Unilateral and Bilateral Involvement

OBJECTIVE Chronic subdural hematoma (CSDH) is a common intracranial hemorrhage, encountered in neurosurgical practice. Most CSDHs are unilateral, but some show bilateral involvement. However, the clinical characteristics of bilateral CSDH remain unclear. In this study, we investigated the clinical differences between bilateral and unilateral CSDH. METHODS A retrospective study was performed on 120 patients with CSDH surgically treated at our institute from January 2008 to December 2012. Patients were divided into two groups: the bilateral CSDH and the unilateral CSDH groups. Clinical presentations, precipitating factors, computed tomography (CT) findings, postoperative complications, and outcomes of patients were analyzed. RESULTS Bilateral CSDH was identified in 11 of 120 (10.9%) patients with CSDH. Patients with bilateral CSDH tended to have a lower rate of head injury compared to patients with unilateral CSDH (36.4% vs. 59.6%), but it had no statistical significance (p=0.201). The frequency of marked midline shift on CT scans was significantly greater in unilateral CSDH than in bilateral CSDH (p=0.010). Presenting symptoms, coexisting systemic diseases, postoperative complications, and clinical outcomes were not significantly different between the two groups. CONCLUSION Bilateral CSDH has comparatively similar clinical features and precipitating factors as unilateral CSDH. Patients with bilateral CSDH have significantly lower incidences of midline shift on CT scans, and most patients with either bilateral or unilateral CSDH have good postoperative outcomes.