Cerebral Blood Flow as a Prognostic Indication in Subarachnoid Hemorrhage

In an investigation of the changes in cerebral blood flow (CBF) in subarachnoid hemorrhage, CBF was monitored in 14 patients who underwent surgery within 3 days of the onset of hemorrhage. On admission, one patient was neurological grade I, one was grade II, seven were grade III, and five were grade IV. Computed tomography showed diffuse, thick subarachnoid hemorrhage with or without intracerebral hematoma in all patients, strongly indicating the possibility of cerebral vasospasm. CBF monitoring was performed by the thermal diffusion technique, in which a small flow probe, 7 mm in diameter and 4 mm in height and containing a Peltier stack, is used. The probe was implanted in the subdural space in the frontotemporal region during surgery. Epidural intracranial pressure was also monitored. Local CBF was measured continuously for 7 to 19 days after surgery. Immediately after surgery, CBF was low in grade IV patients (mean, 25 ml/100 g/min), whereas a variety of CBF rates were observed in grade III patients. Minimal decreases in CBF were noted in the grades I and II patients (mean, 41 ml/100 g/min). The sequential changes in CBF were well correlated with outcome. The two grades I and II patients, who had no appreciable decrease in CBF, had excellent outcomes. In the five (of seven) grade III patients who showed good or excellent recovery, CBF was maintained with only a slight decrease. In two grade III patients, substantial depression of CBF occurred several days after the onset of subarachnoid hemorrhage; one had a poor outcome, and one died. Good recovery of CBF was observed in one grade IV patient, who showed excellent postoperative recovery. The remaining four patients, had moderate to substantial decreases in CBF, with poor postoperative results, including two deaths. These observations indicate that a decrease in CBF due to vasospasm or other causes can be detected early through CBF monitoring. In addition, the outcome of subarachnoid hemorrhage can be predicted on the basis of sequential changes in CBF.