Decreased CSF output as a clinical indicator of cerebral vasospasm following aneurysmal subarachnoid hemorrhage

Objective: Vasospasm is a significant cause of morbidity and mortality among those with aneurysmal subarachnoid hemorrhage (aSAH). Treating increased intracranial pressure by drainage of cerebral spinal fluid through an external ventriculostomy is routine practice. The objective of this study is to evaluate the trends of CSF output in patients who experience vasospasm.

Methods: Electronic medical charts were reviewed to identify two groups of patients with aSAH, 75 consecutive patients who developed vasospasm and 75 matched patients who did not develop vasospasm. CSF output was recorded within 3 days before and 3 days after the occurrence of vasospasm. CSF output was recorded for the same days after SAH in matched patients with no vasospasm.

Results: Total CSF output was lower in patients with vasospasm as compared to patients without vasospasm matched for the same day (p<0.001). In patients with vasospasm, CSF output recordings were significantly higher prior to the occurrence of vasospasm (438ml/day) than the period following vasospasm (325.7ml/day), with a consistent decrease in CSF drainage from day 3 before vasospasm to day 3 after vasospasm (p=0.012). Decreasing CSF output was significantly associated with the occurrence of vasospasm (p=0.017). Youden indices demonstrated that daily CSF drainage <160ml was significantly associated with the occurrence of vasospasm. The sensitivity of this test was 64.79% and the specificity was 55.38%.

Conclusions: In addition to clinical exam findings, observation of a CSF output decline to less than 160ml/day may be used as additional support for the diagnosis of vasospasm.