Independent predictors of shunt-dependent normal pressure hydrocephalus after aneurysmal subarachnoid hemorrhage.

BACKGROUND

Normal pressure hydrocephalus frequently develops after subarachnoid hemorrhage. It can often be difficult, however, to predict shunt dependency. The purpose of this study was to identify predictors of shunt-dependent normal pressure hydrocephalus (SDNPH) after aneurysmal subarachnoid hemorrhage (aSAH).

METHODS

The incidence of SDNPH in 139 consecutive patients who underwent surgery for aSAH in the Department of Neurosurgery Tokyo Medical and Dental University between January 2008 and December 2011 was evaluated. The patientage, Glasgow Coma Score, World Federation of Neurosurgical Societies grade, Hunt and Hess grade, modified Fisher group, modified Rankin Scale, duration of external drainage of cerebrospinal fluid (CSF), gender, aneurysm location, presence of intraventricular hemorrhage, surgical method (clip or coil), and presence of acute hydrocephalus were analyzed.

RESULTS

Forty-seven of 139 patients (33.8%) underwent shunt operation. Fifteen of these 47 patients were assessed to have high-pressure hydrocephalus and excluded. Thirty-two SDNPH patients (23.0%) were compared with 84 patients without hydrocephalus (60.4%). An age of 65 years or over (OR 5.51;95%CI 1.97-15.40), a GCS of 13 or less (OR 3.82;95%CI 1.38-10.60), and CSF drainage for a duration of 12 days or more (OR 3.63;95%CI 1.30-10.14) were independently associated with SDNPH.

CONCLUSIONS

SDNPH after aSAH in our study showed no correlations with three of the parameters previously identified as risk factors for shunt-dependent hydrocephalus, namely, the amount of SAH, the presence of IVH, or acute hydrocephalus. Instead, a longer duration of CSF drainage correlated with SDNPH as an independent factor. These data suggest that a longer duration of CSF drainage may be one of the risk factors for SDNPH after aSAH.