Local cerebral hemodynamic changes through the angiographic stages of moyamoya disease

In order to elucidate the cerebral hemodynamic changes that occur in Suzuki's six angiographic stages of moyamoya disease, local cerebral blood flow (LCBF) during the stable state and CO2 responsiveness of LCBF (L-CO2R: delta %LCBF/delta PaCO2) were measured by the Xenon CT-CBF method. Nineteen patients with moyamoya disease (mean age: 36.8 +/- 11.6 years) and 11 age-matched normal volunteers were studied. The LCBF during the steady state at all stages was not significantly different from that in normal volunteers. At stage 6, however, the LCBF was slightly decreased in the anterior part of the brain, resulting in loss of "hyperfrontality." On the other hand, the L-CO2R in the anterior part of the brain tended to diminish with progression through the stages. Especially in the frontal cortex, the L-CO2R at stage 5 was significantly less than that in normal volunteers (p < 0.01) or at stage 3 (p < 0.05). In conclusion, the cerebrovascular reserve in the anterior circulation became insufficient after stage 4, although the posterior circulation was well maintained. Revascularization surgery involving the anterior circulation may be crucial to prevent ischemic events.