Introduction
Recently, Japanese extracranial-intracranial (EC-IC) bypass trial has revealed a benefit of EC-IC bypass for preventing stroke in patients with cerebral artery occlusive disease and severe cerebral hemodynamic failure. We previously reported that flow velocity of the superficial temporal artery (STA) was predictive of the extent of bypass flow or the improvement in the regional cerebral blood flow (rCBF) after EC-IC bypass surgery1, 2. The purpose of the present study is compare post-surgical changes in STA blood flow and cerebral hemodynamics between patients with atherothrombotic carotid occlusive disease and moyamoya disease.
Methods
This study included 37 consecutive patients with athrothrombotic carotid occlusive disease (Athero-Group) and 11 consecutive patients with moyamoya disease (Moya-Group) who underwent EC-IC bypass. We adopted the inclusion criteria using single photon emission computed tomography (SPECT) as follows: rCBF <32 ml/100 g/min (80% of the mean value in the normal control subjects) and acetazolamide (ACZ) reactivity <10% in the ipsilateral middle cerebral artery (MCA) territory. STA duplex ultrasonography (STDU) was performed to measure the flow velocity and diameter of the operated STA before and 14 days and 3 months after EC-IC bypass surgery. Relationships between STA mean flow velocity (MFV) 14 days after EC-IC bypass and various clinical and radiological factors were investigated. Changes in parameters of STDU and SPECT were compared between Athero-Group and Moya-Group.
Results
STA MFV was correlated with the rCBF in the ipsilateral MCA territory 14 days after EC-IC bypass surgery (R=0.51, p<0.0001) 14 days after EC-IC bypass. There was no significant difference in any baseline STDU and SPECT parameters between Athero-Group and Moya-Group. Two patients in Moya-Group showed a hemispheric hyperperfusion syndrome within 14 days after EC-IC bypass. In Athero-Group, hyperperfusion syndrome was not observed. Between Moya-Group and Athero-Group, there was a significant difference in STA MFV 14 days after EC-IC bypass (73.2±20.9 vs 55.1±16.7 cm/sec, p<0.01). The rCBF of the ipsilateral MCA territory was also higher in Moya-Group than Athero-Group 14 days after EC-IC bypass (40.0±8.3 vs 34.6±5.8 ml/100g/min, p<0.05). These differences were not observed 3 months after EC-IC bypass. There was no difference in STA diameter 14 days and 3 months after EC-IC bypass between the 2 groups. Changes in STA MFV (42.2±23.7 vs 29.3±13.9 cm/sec, p<0.05) and rCBF (8.7±4.9 vs 5.3±4.3 ml/100g/min, p<0.05) before and 14 days after EC-IC bypass were also higher in Moya-Group than Athero-Group.
Conclusions
In patients with severe cerebral hemodynamic failure, STA MFV is a highly sensitive parameter for predicting rCBF in the ipsilateral MCA territory after EC-IC bypass. In moyamoya disease, changes in STA MFV as well as rCBF were higher than those in atherothrombotic carotid occlusive disease after EC-IC bypass. Hyperperfusion syndrome was observed only in patients with moyamoya disease.