Critical postcraniotomy cerebrospinal fluid hypovolemia: Risk factors and outcome analysis

OBJECTIVE: Critical cerebrospinal fluid (CSF) hypovolemia may cause acute postoperative clinical deterioration in aneurysmal subarachnoid hemorrhage patients after craniotomy for microsurgical aneurysm clipping. We sought to identify risk factors for critical CSF hypovolemia and determine this syndrome's effect on clinical outcome. METHODS: Between April 2001 and June 2004 at Columbia University Medical Center, 16 aneurysmal subarachnoid hemorrhage patients were diagnosed with postoperative critical CSF hypovolemia, whereas 151 patients who underwent craniotomy for clipping were not. The demographics, as well as the presenting radiographic and clinical characteristics, of these groups were evaluated. In addition, a 2:1 matched case-control comparison of patients with and without critical CSF hypovolemia was completed using clinical data, operative variables, and outcome data. Outcome analysis was performed with a battery of tests designed to assess global outcome, cognitive function, independence, and quality of life. RESULTS: There was no difference in clinical grade, Fisher score, age, and sex distribution between patients diagnosed with critical CSF hypovolemia and the general aneurysmal subarachnoid hemorrhage population at Columbia University Medical Center. Subsequent 2:1 matched case-control comparison demonstrated a higher incidence of global cerebral edema on admission computed tomographic scans (75 versus 31%; P < 0.01) and a significantly longer operative time for patients with critical CSF hypovolemia (5 h 18 min versus 4 h 22 min; P < 0.03). No significant differences were observed between groups in outcome assessments at the time of hospital discharge or the 3-month follow-up examination. CONCLUSION: Risk factors associated with an increased incidence of critical CSF hypovolemia after aneurysm surgery include the presence of global cerebral edema on admission head computed tomographic scans and prolonged operative time. In such patients, heightened suspicion of CSF hypovolemia is crucial because rapid and appropriate management obviates excess morbidity and mortality.