External ventricular drainage following aneurysmal subarachnoid haemorrhage.

External ventricular drain (EVD) placement is standard of care in the management of aneurysmal subarachnoid haemorrhage-associated hydrocephalus (aSAH). However, there are no guidelines for EVD placement and management after aSAH. Optimal EVD insertion conditions, techniques to reduce the risk of EVD-associated infection and aneurysmal rebleeding, and methods of EVD removal are critical, yet incompletely answered management variables. The present literature consists primarily of small studies with heterogeneous populations and variable outcome measures, and suggests the following: EVDs may increase the risk of rebleeding; EVDs are increasingly placed by non-neurosurgeons with unclear results; intraparenchymal ICP monitors may be safely considered (with or without spinal drainage) in the setting of difficult EVD placement; the optimal timing and manner of EVD removal has yet to be defined; and the efficacy of prophylactic systemic antibiotics and antibiotic-coated EVDs needs further investigation. Nevertheless, there are no definitive practice guidelines for EVD placement and management techniques in aSAH patients. Large prospective randomised trials are needed to definitively address important gaps in our understanding of EVD management principles in the neurocritical care setting.