Incidence and risk factors for post-traumatic hydrocephalus following decompressive craniectomy for intractable intracranial hypertension and evacuation of mass lesions.

There continues to be a considerable interest in decompressive craniectomy in the management of severe traumatic brain injury (TBI). Though technically straightforward, the procedure is not without significant complications. In this study we assessed the incidence and risk factors for the development of subdural hygroma and hydrocephalus after decompressive craniectomy. A total of 195 patients who had had a decompressive craniectomy for severe TBI between 2004 and 2010 at the two major trauma centers in Western Australia were considered. Of the 166 patients who survived after the acute hospital stay, 93 (56%; 95% confidence interval [CI] 48,63%) developed subdural hygroma; 45 patients (48%) had unilateral and 48 patients (52%) had bilateral subdural hygromas. Of the 159 patients who survived more than 6 months after surgery, 72 (45%; 95% CI 38,53%) developed radiological evidence of ventriculomegaly, and 26 of these 72 patients (36%; 95% CI 26,48%) developed clinical evidence of hydrocephalus and required a ventriculoperitoneal (VP) shunt. Maximum intracranial pressure prior to decompression (p=0.005), subdural hygroma (p=0.012), and a lower admission Glasgow Coma Scale score (p=0.009), were significant risk factors for hydrocephalus after decompressive craniectomy. Hydrocephalus requiring a VP shunt was associated with a higher risk of unfavorable neurological outcomes at 18 months (odds ratio 7.46; 95%CI 1.17,47.4; p=0.033), after adjusting for other factors. Our results showed a clear association between injury severity, subdural hygroma, and hydrocephalus, suggesting that damage to the cerebrospinal fluid drainage pathways contributes to the primary brain injury rather than the margin of the craniectomy as the factor responsible for these complications.