Surgery for acute subdural haematoma: replace or remove the bone flap?

OBJECTIVE: In surgery for acute subdural haematoma (ASDH), the bone flap can be fixed onto the skull, or left "riding" to provide partial skull decompression, or removed. This study assessed whether removing the bone flap improved outcome.

METHODS: We conducted an observational study in consecutive patients who were operated for ASDH in our hospital from July 2011 to June 2014. We retrospectively collected data on demographics, injury severity, predicted and observed outcomes at six months. The cohort was divided into two groups based on whether the bone flap was replaced (fixed and riding flap craniotomy) or removed (decompressive craniectomy). The differences in functional status, postoperative control of intracranial hypertension and number of cranial reoperations were analysed. A subgroup analysis compared decompressive craniectomy to riding flap craniotomy alone.

RESULTS: Data were obtained for 99 patients; 69 had decompressive craniectomy, 17 had riding flap and 13 had fixed flap craniotomy. The decompressive craniectomy group had statistically worse injuries, more predicted poor outcomes (69% v 57%, p=0.013), more observed poor outcomes (59% v 37%, p=0.037), equivalent control of intracranial hypertension and similar number of reoperations compared to the craniotomy groups. Subgroup analysis between decompressive craniectomy and riding flap craniotomy showed no significant difference in baseline characteristics and outcomes.

CONCLUSION: Our study concluded that removing the bone flap after ASDH evacuation was not associated with a better outcome. We recommend replacing the bone flap if brain conditions allow. Further research is required to evaluate the role of skull decompression in surgery for ASDH.