Clinical, Radiological, Laboratory and Matrix Metalloproteinase Profiles Associated with Hematoma Architecture and Recurrence of Chronic Subdural Hematoma

Background/Objectives: Postoperative recurrence of chronic subdural hematoma (CSDH) has been associated with several clinical, laboratory, and radiological factors. However, the biological differences between radiological types of CSDH remain poorly understood. Matrix metalloproteinases (MMPs), particularly MMP-2 and MMP-9, are involved in inflammation, angiogenesis, and extracellular matrix remodeling. This study examined factors associated with CSDH recurrence and explored the relationship between MMP concentrations and hematoma architecture and density. Methods: This retrospective study included 100 consecutive patients who underwent surgery for CSDH. Recurrence was assessed over 3 months. Serum and hematoma MMP-2 and MMP-9 concentrations were measured in a subgroup of 22 patients, with serum concentrations additionally compared with those of 16 controls. Factors associated with recurrence were analyzed using Firth penalized logistic regression. Associations between MMP concentrations and radiological characteristics were examined in an exploratory analysis, with correction for multiple comparisons. Results: Postoperative recurrence occurred in 20 patients (20.0%). Separated hematoma architecture (OR 14.10, 95% CI 4.51–48.82; p < 0.001) and higher neutrophil-to-lymphocyte ratio (OR 1.078, 95% CI 1.011–1.182; p = 0.023) were independently associated with recurrence. Serum MMP-2 concentrations were higher in separated hematomas, while serum MMP-9 concentrations were higher in trabecular hematomas. Hematoma MMP-9 concentrations also differed according to hematoma density. All three associations remained significant after false discovery rate correction (adjusted p = 0.042). Neither serum nor hematoma MMP-2 and MMP-9 concentrations were significantly associated with postoperative recurrence. Conclusions: Separated hematoma architecture and higher NLR were independently associated with postoperative recurrence of CSDH. Differences in MMP-2 and MMP-9 concentrations across radiological hematoma subtypes suggest potential biological heterogeneity, although no significant association with recurrence was demonstrated. These exploratory biomarker findings require confirmation in larger studies, particularly given the small biomarker subgroup and limited precision of some estimates.