Chronic subdural hematoma (CSDH) is fundamentally treatable through surgery, although CSDH recurs in some cases. We have observed several cases of spontaneous resolution of CSDH outer membranes, including in trabecular CSDH, after
trepanation surgery. In this study, we examined the expression of molecules involved in
caspase signaling in CSDH outer membranes. Eight patients whose outer membranes were obtained successfully during
trepanation surgery were included in this study. The expression of Fas; Fas-associated death domain (FADD);
tumor necrosis factor receptor type 1-associated death domain (TRADD);
receptor-interacting protein (RIP);
caspases 3, 7, 8, and 9;
poly-(ADP-ribose) polymerase (PARP);
DNA fragmentation factor 45 (DFF45) and β-actin was examined by Western blot analysis. The expression levels of PARP,
caspase-3, and cleaved
caspase-3 were also examined by immunohistochemistry. Fas; FADD; TRADD; RIP;
caspases 3, 7, 8, and 9; PARP, and DFF45 were detected in nearly all samples.
Caspase-3 and PARP were localized in the endothelial cells of vessels and in fibroblasts in CSDH outer membranes. In addition, cleaved
caspase-3 was detected in fibroblasts. We detected molecules of the
caspase signaling pathway in CSDH outer membranes. In particular, cleaved
caspase-3 was detected, which suggests that apoptosis may occur within these membranes. Thus, during the growth of CSDH outer membranes, the
caspase signaling pathway may be restrained. Once the pathway is activated, gradual resolution of CSDH outer membranes may occur. Therefore, these molecules may be novel therapeutic targets for intractable CSDH.