Cerebral blood flow in moyamoya disease. Part 2: Autoregulation and CO2 response.

In order to clarify the cerebrovascular response in Moyamoya disease, the autoregulation and CO2 response was investigated using the 81mKr continuous cerebral blood flow (CBF) measurement technique. A total of 32 measurements were made over the anterior and posterior circulation in 16 Moyamoya patients (seven adults, nine children). CBF measurements were made during four loading trials (hypertension, hypotension, CO2 inhalation and hyperventilation). Study was then made of the vascular response of the frontal lobe, perfused by the internal carotid artery (ICA), and the occipital lobe and cerebellum, perfused by the vertebral artery (VA). Deficits of autoregulation were more severe among the juvenile cases in response to hypotension than to hypertension in both the ICA and VA regions, but the deficits were mild. The CO2 response to hypercapnea in the juvenile cases tended to be abnormal in both the ICA and VA regions. Both adult and juvenile patients showed deficits in the ICA region in response to hyperventilation, some of whom exhibited paradoxial responses. Notable differences in the severity of the deficits of the vascular response in adult and juvenile cases were seen, with the deficits in the response being more severe among the juvenile cases. Moreover, significant regional differences in the deficits were also found.