Intracranial bleeding rates associated with two methods of external ventricular drainage.

We investigated the risk of intracranial haemorrhage with two frequently performed methods of external ventricular drainage (EVD). Haemorrhage is believed to be a rare complication of such procedures, although in most studies reported in the literature standardised evaluation of computed tomography (CT) scans was not performed in all cases. Data were analysed retrospectively for 82 patients who had undergone percutaneous needle trephination and 92 who had undergone classic ventriculostomy. We found an overall bleeding risk with EVD of 9.4%. Most haematomas were small, and only one caused neurological symptoms. Therefore, the risk of symptomatic haemorrhage in this study was low (0.5%). Percutaneous needle trephination was associated with a higher risk of haemorrhage (12.2%) than classic ventriculostomy (6.5%), although differences were not statistically significant. We conclude from our results that small asymptomatic haemorrhages occur far more often after EVD than has generally been suspected. To compare the true risk of bleeding associated with different drainage methods requires controlled studies in which CT scans are evaluated in a standardised way.