Risk factors for the recurrence of chronic subdural hematomas in patients undergoing burr-hole drainage

Chronic subdural hematoma (cSDH) is a common neurosurgical disease, particularly in the elderly. The recurrence of cSDH remains a clinical challenge, with several risk factors postulated. Although adjunctive treatments to surgery exist, such as steroids, statins, and middle meningeal artery embolization, the number needed to treat is high, and patient selection remains unclear. This retrospective study aimed to identify risk factors for recurrence after burr hole drainage of cSDH. A single-center retrospective study included consecutive patients undergoing burr-hole drainage for cSDH between February 2012 and May 2023. The primary outcome was surgical recurrence, defined as cSDH recurrence requiring reoperation within six months. Clinical characteristics, preoperative radiological findings, comorbidities and medications, and postoperative findings were assessed as potential risk factors using univariate analysis and, after imputation, multivariable analysis.A total of 766 patients with a recurrence rate of 11.2% (86/766) were included. Significant preoperative risk factors for recurrence included subacute and separated hematoma types (p = 0.02), larger hematoma volume (p = 0.004), greater midline shift (MLS) (p = 0.006), lower Glasgow Coma Scale (GCS) (p < 0.001) and higher Markwalder score (p = 0.012). Postoperative findings significantly associated with recurrence were larger cavity volume (p = 0.005), greater MLS (p = 0.01), a higher Markwalder score (p = 0.01) and modified Rankin Scale (mRS) score (p < 0.001) at discharge. After multivariable logistic regression, subacute hematoma age (OR 2.097, p = 0.036), absence of hypertension (OR 1.937, p = 0.012), larger postoperative cavity volume (OR 1.012, p = 0.016), greater postoperative MLS (OR 1.179, p < 0.001), and higher mRS at discharge (OR 1.959, p = 0.002) remained independently associated with recurrence. We found subacute hematoma, larger postoperative subdural cavity volume, higher mRS at discharge, greater postoperative MLS, and the absence of hypertension as factors significantly associated with surgical recurrence within six months.