Hydrocephalus following spontaneous subarachnoid hemorrhage: Its occurrence and implications

Hydrocephalus is a common complication after spontaneous subarachnoid hemorrhage (SAH). It is seen in 15-20% of acute (48-72 hours), 2-3% of subacute (4-13 days) and 10-20% of chronic (after 14 days) cases. SAH patients presenting with poor neurological status and presence of hydrocephalus are known indicators for adverse outcome. Although the exact mechanism for hydrocephalus remains ill-defined, leading theories include obstruction of cerebrospinal fluid (CSF) flow through the ventricles and compromised CSF reabsorption through the arachnoid granulations due to its obstruction by blood products. More recent theories propose fibrosis leading to obstruction of the fourth ventricle and arachnoid granulations, and also increased CSF production resulting in hydrocephalus. Acute hydrocephalus following SAH is usually managed by temporary CSF diversion using external ventricular drain (EVD) or lumbar drain. There are several advantages and disadvantages of the above-mentioned procedures and its placement is determined usually by patient specific issues and local practice. Above-mentioned temporary diversion procedures are gradually weaned over a period of days with the goal of discontinuation once the CSF flow dynamics have normalized. Unfortunately, guidelines are lacking regarding such weaning protocols. The number of patients who undergo permanent CSF diversion procedure is variable depending of neurosurgeons' preference that maybe based on radiological evidence of hydrocephalus versus symptomatic hydrocephalus.