The Pathogenesis of Chronic Subdural Hematomas: A Study on the Formation of Chronic Subdural Hematomas and Analysis of Computed Tomography Findings.

Background: The origin of chronic subdural hematomas (CSDH) and the pathophysiology of its enlargement remain unknown. The chemical fluid composition of CSDH, the contribution of cerebrospinal fluid (CSF) to its enlargement, and the relationship to its appearance on computed tomography (CT) also are not entirely clear.

Methods: In this prospective study, 58 samples in 41 patients treated surgically for CSDH were analyzed. CSDHs were evaluated for the presence of CSF via β-2 transferrin and substances related to cell breakdown and hemolysis. These were compared with normal value of those substances in the serum and the CT appearances of the CSDH.

Results: In this study, 24% of the samples contained β-2 transferrin, which was statistically significant. Total protein, lactate dehydrogenase, total bilirubin, and red blood cells also were statistically different when compared with their normal serum concentration, indicating an active process of rebleeding and hemolysis rather than plasma ultrafiltration; however, their concentrations did not correlate with specific CT scan appearance. The absence of CSF in CSDH in 76% of cases did not support the theory that most CSDHs originate from subdural hygromas. The presence of hemolysis and cell breakdown, byproducts supports the hypothesis that the primary enlargement of CSDH develops through neomembrane and neovascular formation, rebleeding, and inhibition of the blood coagulation process. Our study did not test for serum transudation as a component of the enlargement of CSDH.

Conclusions: Our study confirms that the origin and enlargement of CSDH is multifactorial, but the contribution of individual factors and condition under which it occurs still remains unclear. CT scan findings do not correlate with the chemical composition or the presence of CSF in the CSDH.