Evaluation of cerebral vasospasm in patients with subarachnoid hemorrhage using single photon emission computed tomography.

Cerebral vasospasm (CVS) occurs as a result of the breakdown in cerebral autoregulation mechanisms. Because cerebral vasospasm can occur after subarachnoid hemorrhage (SAH), it is important to evaluate borderline perfusion. Evaluation of borderline vascular insufficiency is important to reduce ischemic complications. In this study 25 patients with SAH were investigated by somatosensory evoked potentials (SEP), computed tomography (CT), digital subtraction angiography (DSA) and single photon emission computed tomography (SPECT) in order to predict borderline ischemic areas. Clinical grades were also correlated with these investigations. Thirteen patients had symptomatic vasospasm and 15 patients had angiographic vasospasm. SPECT showed hypoperfusion in 22 out of 25 patients. CT predicted CVS in 8 of these 22 patients. Our study shows that brain perfusion SPECT is a non-traumatic, non-invasive, non-allergic, inexpensive method for the prediction of cerebral vasospasm. We conclude that brain SPECT with Tc-99m HM-PAO is an accessible technique that can demonstrate varying degrees of regional tissue hypoperfusion in patients with delayed ischemic deficits due to CVS following SAH.