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Clinical results of an extra-intracranial arterial bypass (EIAB) procedure for cerebral ischemia are assessed in 65 patients. The 5-year-study suggests that the EIAB procedure has a protective effect against further clinically significant cerebrovascular accidents in properly selected patients. Correlation with angiography and regional cerebral blood flow (rCBF) studies are discussed. It is felt that rCBF measurements offer the best diagnostic test to determine which patients are suitable for surgery by revealing if an ischemic or relative ischemic focus is present. The surgical procedure is contraindicated in acute cerebral ischemia and when the rCBF study reveals general reduction of cerebral blood flow as opposed to a localized ischemic focus.

Extracranial intracranial arterial anastomosis is gaining acceptance as a form of treatment in selected cases with ischemic cerebrovascular disease. To establish indications for this operation and to provide an objective assessment of postoperative results, regional cerebral blood flow (rCBF) studies were performed in 110 patients with cerebrovascular insufficiency considered for extra-intracranial bypass surgery. The 133Xe intracarotid injection method with 16 externally placed detectors was used for measuring rCBF. Postoperatively, rCBF was measured in 40 patients. From these results our present criteria for surgery have evolved. The probability of a good postoperative result is best in patients who showed focal cerebral ischemia or a moderate general reduction of CBF with an additional ischemic focus. The operation is contraindicated in patients with either normal or severely reduced CBF values (less than 60% of normal).

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Computed tomography and serial scintigraphy with 99mTc-pertechnetate (radionuclide angiography and early and late static imaging) were compared in 214 patients with cerebrovascular disease. CT correctly identified 151 (95.0%) of 159 patients with completed ischemic stroke but was positive in only 11 (25%) of 44 patients with asymptomatic stenosis, transient ischemic attacks (TIA), or prolonged reversible ischemic neurological deficit (PRIND). Scintigraphy was positive in 93.1% of patients with completed stroke. CT detected 175 territories of vascular supply involved, scintigraphy 164. In patients with asymptomatic stenosis, TIA, or PRIND, scintigraphy was correct in 77.3% of cases. The combined evaluation offered a sensitivity of 97.5% in patients with completed stroke and 86.4% in those with asymptomatic stenosis, TIA, or PRIND. The rate of true-positive scintigraphic findings in patients with completed stroke did not change as the interval between ictus and study increased. In patients with intracerebral hematoma, CT was far more specific than scintigraphy. If cerebrovascular disease is suspected, radionuclide angiography should be performed first.