Prediction of ventriculoperitoneal shunt dependency in patients with aneurysmal subarachnoid hemorrhage.

OBJECT: Patients with subarachnoid hemorrhage treated using external ventricular drainage due to obstructive hydrocephalus commonly remain shunt-dependent. Based on identified risk factors for external ventricular drain (EVD) challenge failure, the authors sought to determine the likelihood that a patient will require a permanent shunt.

METHODS

The authors reviewed 89 consecutive cases of aneurysmal subarachnoid hemorrhage with obstructive hydrocephalus for parameters associated with EVD challenge failure and permanent shunt requirement. Significant parameters were combined in a discriminant function analysis to create a failure risk index (FRI). Linear regression analysis was performed correlating the FRI with the actual rate of shunt dependency.

RESULTS

Patients requiring a permanent shunt had: a larger third ventricular diameter (7.0 vs 5.4 mm; p = 0.02) and a higher Hunt and Hess grade (3 vs 2; p = 0.02) at the time of admission; and a larger third ventricular diameter (6.6 vs 5.2 mm; p = 0.04), a larger bicaudate diameter (31.9 vs 30.2 mm; p = 0.03), and higher CSF protein levels (76.5 vs 40.3 mg/dl; p < 0.0001) at the onset of EVD challenge. These patients were also more likely to be female (p = 0.01) and have a posterior circulation location of their aneurysm (p = 0.01). The FRI score was calculated based on a weighted combination of the above parameters. Linear regression analysis between FRI values and the percentage of patients who required a permanent shunt had a correlation coefficient of 91%; the risk of a permanent shunt requirement increased linearly with a rising FRI score.

CONCLUSIONS

An FRI score created by discriminant function analysis can predict whether or not a permanent shunt is required, even if separate factors are not in agreement with each other or show a weak correlation when considered separately. An increased FRI score was strongly and linearly correlated with the risk of EVD challenge failure. A prospective study is necessary to validate the FRI.