Background: Twist drill craniostomy (TDC) is a minimally invasive and cost-effective technique to treat chronic subdural hematomas (CSDHs). Predictors for treatment success such as imaging characteristics, hematoma volume, and drainage volume are not established; thus, they are purpose of this analysis.
Material and methods: We retrospectively evaluated all data of patients with CSDH undergoing TDC in our institution between January 2010 and December 2013. We analyzed imaging characteristics (extension and composition), volumetrically calculated pre- and postoperative hematoma volumes, measured drainage volume, and clinical course. Primary treatment success was defined as sufficient if definitive treatment was achieved via a single TDC (TDC-1) and insufficient if more than one TDC was needed. The need for open surgical evacuation was defined as treatment failure.
Results: Data of 233 patients undergoing 387 TDCs were available for our study. A total of 67% of TDCs treated CSDHs effectively, whereas the remainder required further open surgical evacuation. Via use of the median-split-method, we found that sufficient treatment was achieved more frequently in smaller hematomas (P < 0.05). Treatment effectiveness was neither correlated with hematoma image characteristics (presence of membranes: P = 0.11, extent of chronification: P = 0.55) nor with the respective drainage volume (P = 0.95). Residual hematoma volume was consistently greater than expected by drainage calculation (P < 0.05).
Conclusions: TDC is an effective treatment option for CSDH. Sufficient treatment with single TDC was more common in smaller hematomas with an associated smaller residual hematoma. Failure of brain re-expansion after TDC may increase the treatment failure rates. In these cases, an open surgical evacuation might accelerate treatment and clinical recovery.
Keywords: Chronic subdural hematoma; Hematoma composition; Hematoma volume; Twist drill craniostomy.
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