Cerebral blood flow in patients with subarachnoid haemorrhage studied with an intravenous isotope technique. Its clinical significance in the timing of surgery of cerebral arterial aneurysm.

The cerebral blood flow state has been evaluated in a series of 207 patients suffering from subarachnoid haemorrhage and with proved arterial aneurysms. Particular interest was focussed on 160 in grade I or II according to Botterell. An intravenous isotope method was used with 131-I Hippuran or 99-Tc pertechnetate as indicators. 133 of the 160 patients were operated on. 78 were also examined postoperatively. The radioactivity was recorded by two gamma detectors place bilaterally over the skull. The heights of the curves were taken as an index of the cerebral blood flow. Transit time was determined by dividing the area of the curve by its height. The results showed that even patients with no or slight neurological symptoms could have a depressed cerebral blood flow. Alterations in the blood flow seemed to precede a change in the clinical picture. Postoperatively, most patients had a further decrease in flow, but some others remained unchanged or even improved. With a normal or only slightly disturbed cerebral blood flow in the preoperative period, the morbidity and mortality of intracranial aneurysm surgery was estimated at 8%. For patients with a low preoperative blood flow value, i.e. more than a 40% reduction, the morbidity and mortality was much higher, about 30%. The results indicate that an analysis of the cerebral blood flow status represents an additional diagnostic parameter of great clinical significance, increasing the possibility of predicting to outcome of the operative treatment of an intracranial arterial aneurysm.