Restoration of Vasoreactivity in Patients with Symptomatic ICA Occlusion after Extracranial-Intracranial Bypass Surgery

Kang, Sung Don; Park, Jong Tae; Moon, Seong Keun

Abstract

OBJECTIVE
The purpose of this study is to investigate changes of vasoreactivity after STA-MCA anastomosis in patients who develop hemodynamic cerebral ischemia associated with ICA or MCA occlusion.
METHODS
Twenty-five patients with hemodyamic infarction due to symptomatic ICA or MCA occlusion were treated with extracranial-intracranial bypass surgery (EIAB). Of these, we enrolled 17 patients who underwent follow-up SPECT and follow-up angiogram. To test vasomotor reactivity, we measured relative regional cerebral blood flow (rrCBF) with SPECT both at rest and after diamox infusion. rrCBF were calculated using the following equation: (lesional radioactivity/contralateral radioactivity) x100. We performed EIAB in patients with impaired vasomotor reactivity. To evaluate changes in vasomotor reactivity after surgery, follow-up brain SPECT was performed 1-6 months after surgery and compared rrCBF before and after surgery.
RESULTS
Base line radioactivity ratios did not change after surgery. These ratios after diamox challenge were 59.8+/-4.2%, however, 1-6 months after surgery, ratios increased to 77.7+/-.6% (p<0.05, Paired T-test). Preoperative degree of angiographic collateral circulation did not influence the restoration of vasoreactivity. All but two patients showed good collateral circulation through the bypass. There were no cerebral accidents in any these patients at 6 months to 2 years follow-up.
CONCLUSION
These results demonstrate the restoration of vasomotor reactivity distal to the occluded ICA or MCA after EIAB, and also show that measurement of rrCBF using SPECT are useful indicators of the clinical and hemodynamic improvement.