BACKGROUND: Midline shift in trauma relates to the severity of head injury. Large craniectomies are thought to help resolve brain shift but can be associated with higher rates of morbidity. This study explores the relationship between craniectomy size and subtemporal decompression for acute subdural haematomas with the resolution of brain compression and outcomes. No systematic study correlating these measures has been reported. METHOD: A retrospective study of all adult cases of acute subdural haematomas that presented to a Major Trauma Centre and underwent a primary decompressive craniectomy between June 2008 and August 2013. Data collection included patient demographics and presentation, imaging findings and outcomes. All imaging metrics were measured by two independent trained assessors. Compression was measured as midline shift, brainstem shift and cisternal effacement. RESULTS: Thirty-six patients with mean age of 36.1 ± 12.5 (range 16-62) were included, with a median follow-up of 23.5 months (range 2.2-109.6). The median craniectomy size was 88.7 cm2 and the median subtemporal decompression was 15.0 mm. There was significant post-operative resolution of shift as measured by midline shift, brainstem shift and cisternal effacement score (all p < .00001). There was no mortality, and the majority of patients made a good recovery with 82.8% having a Modified Rankin Score of 2 or less. There was no association between craniectomy size or subtemporal decompression and any markers of brain shift or outcome (all R2 < 0.05). CONCLUSIONS: This study suggests that there is no clear relationship between craniectomy size or extent of subtemporal decompression and resolution of brain shift or outcome. Further studies are needed to assess the relative efficacy of large craniectomies and the role of subtemporal decompression
