Asymptomatic Mild Hyperperfusion for the Prediction of Clinical Outcome in Postoperative Patients After Subarachnoid Hemorrhage

BACKGROUND Delayed cerebral ischemia (DCI) is one of the main causes of poor outcomes after subarachnoid hemorrhage (SAH). The early identification of DCI by noninvasive imaging modalities would provide valuable information of therapeutic intervention for improving the patient outcomes. We aimed to describe the clinical features of cerebral blood flow (CBF) data obtained from the single-photon emission computed tomography (SPECT) during the risk period for DCI after SAH. MATERIAL AND METHODS Clinical data from 94 SAH patients who underwent surgical clipping of anterior circulation aneurysms were reviewed retrospectively. 99mTc-HMPAO SPECT images were visually and semiquantitatively analyzed on days 7 and 14 after SAH. RESULTS In all cases, the areas of hypoperfusion were found in the middle cerebral artery territories. By contrast, the areas of mild hyperperfusion were always detected on the surgical side, the prevalence which increased from days 7 (n=28; 30%) to 14 (n=48; 51%) without neurological defects. Univariate analysis revealed that the hyperperfusion on day 14 had a significant relationship with functional outcome at 3 months (P=0.04). Multivariate analysis including age, clinical SAH grade, DCI, and hyperperfusion on day 14 showed that DCI (P=0.004; odds ratio [OR], 0.10; 95% confidence interval [CI], 0.02-0.48) and hyperperfusion on day 14 (P=0.002; OR, 2.44; 95% CI, 1.40-4.29) were independently associated with functional outcome at 3 months. CONCLUSIONS Delayed mild hyperperfusion around the surgical site can predict good prognosis after SAH, although it may hinder the CBF diagnosis of focal ischemia attributable to DCI.