Abnormal Hemispheric Blood Flow and Metabolism Despite Normal Angiograms in Patients with Stroke

Hemispheric blood flow (HBF) and metabolism were measured using the intracarotid injection of hydrogen-saturated saline in a group of patients with unilateral hemispheric infarction, some of whom had normal angiograms. Blood flow was calculated from the formula derived from the Stewart-Hamilton principle using the clearance curve of hydrogen in the cerebral transverse sinus. Hemispheric metabolic index was estimated using a newly developed formula by assuming that the distribution of hydrogen into each transverse sinus following intracarotid injection indicates the distribution of blood from each hemisphere into each transverse sinus. HBF and oxygen metabolism on the affected side were reduced in all groups, but the reduction was greater in patients with angiographical evidence of vascular occlusion. In many patients, HBF and metabolism on the nonaffected side which angiograms showed to be normal were reduced in the acute phase. It is apparent that by using the hydrogen bolus technique of measuring HBF and metabolism, small disturbances in cerebral circulation can be detected which are not discernible in angiograms.