The risk of rebleeding after external lumbar drainage in patients with untreated ruptured cerebral aneurysms

Background. Does continuous external lumbar CSF drainage before aneurysm repair in patients with aneurysmal subarachnoid hemorrhage increase the risk of rebleeding? Method. The study population, consisting of 18 patients treated by External Lumbar Drainage (ELD) after SAH before aneurysm repair, was compared with an independent control group of 324 SAH patients treated in another clinic. Control patients were selected for not being treated for the ruptured aneurysm yet and not having undergone any form of CSF drainage during the exposure time in the case patients. We calculated hazard ratios with the Cox regression model, adjusted for age and clinical condition on admission and hydrocephalus. Findings. The cox regression analysis shows a non-adjusted hazard ratio of 2.1 (95% CI 0.8 to 5.3) in the model with 5 rebleedings in 18 patients. Adjustment for age, clinical condition on admission and hydrocephalus did not alter the hazard ratio estimate importantly in either analyses. Conclusions. An increased risk of rebleeding by external lumbar drainage in the acute phase after aneurysmal SAH could not be confirmed, but the data are too imprecise to rule out an increased risk. The potential benefits of early drainage should be weighed against the risks if the aneurysm is not occluded before or early after the start of drainage.