Histopathological spectrum of outer and inner membrane of the chronic subdural hematoma at a tertiary care centre

Abstract

Background: Chronic subdural hematoma is a common neurosurgical condition, particularly in the elderly, characterized by the gradual accumulation of blood in the subdural space. Its pathogenesis involves recurrent microbleeding, inflammation, and neovascularization within encapsulating membranes. Histopathological evaluation of both the outer and inner membranes helps determine disease chronicity, activity, and potential for recurrence. This study was done to analyze the histopathological spectrum of the outer and inner membranes in chronic subdural hematoma and classify them based on inflammatory activity, fibrosis, vascular proliferation, and hemorrhagic changes.

Materials and Methods: A retrospective observational study was conducted over one year in the Department of Pathology, Siddaganga Medical College and Research Institute. Outer and inner membrane samples obtained during burr-hole evacuation were examined histologically and classified into four types: Type I (non-inflammatory), Type II (inflammatory), Type III (hemorrhagic inflammatory), and Type IV (scar inflammatory). Data were analyzed using descriptive statistics, with categorical variables reported as frequencies and percentages.

Results: Among the 36 chronic subdural hemorrhage cases, the outer membrane most frequently exhibited an inflammatory pattern (Type II) in 48.4% of cases. The inner membrane predominantly showed hemorrhagic inflammatory (Type III) in 35.5%. Overall, most membranes displayed active inflammation and vascular proliferation, indicating ongoing membrane activity and potential risk for recurrence. Statistical analysis confirmed a significant difference in the distribution of membrane types between outer and inner membranes (p < 0.05).

Conclusions: This study shows that inflammatory and hemorrhagic inflammatory patterns are the predominant histopathological findings in both the outer and inner membranes of chronic subdural hematoma. Type II membranes were most frequently observed in the outer membrane, while Type III membranes predominated in the inner membrane.