Independent predictors for functional outcome after drainage of chronic subdural hematoma identified using a logistic regression model.

BACKGROUND: Chronic subdural hematoma (CSDH) is a common indication for undergoing neurosurgery, but the outcome may remain limited despite timely surgical treatment. The factors potentially associated with the functional outcome have not been sufficiently investigated. We set out to identify independent predictors associated with the functional outcome after surgical treatment of CSDH, avoiding arbitrary classifications and thresholds or subjective imaging assessment.

METHODS: We retrospectively reviewed 197 consecutive surgical cases of CSDH. Univariate and multivariate analyses were performed to identify the relationship between clinical plus radiographic factors and outcome. Imaging analysis was performed using computer-assisted 3D-volumetric analysis.

RESULTS: One-hundred and sixty four (83.2%) patients had a favorable (GOS grade 5 and 4) and 33 (16.8%) an unfavorable clinical outcome (GOS grade 1-3). The multivariate logistic regression analysis determined 4 independent prognostic factors: age over or under 77 years, preoperative clinical condition (Markwalder Score), recurrence and surgical technique applied. Patients treated with mini-craniotomy procedures had worse outcomes than those treated with single or two burr-hole craniostomies. The percentage of the hematoma drained correlated strongly with recurrence and was by itself not an independent predictor for outcome.

CONCLUSIONS: In our study age, pre-operative neurological status, surgical technique and recurrence were found to be independent prognostic factors for the functional outcome in patients with CSDH.