Use of a split dura for revascularization of ischemic hemispheres in moyamoya disease.

A new technique of indirect revascularization using the dural arterial supply to provide donor vessels is presented together with the results of an assay performed to determine the angiogenic activity of the dura. At surgery, a portion of the dura near the branches of the middle meningeal artery was split into outer and inner layers, and the split surface of the outer layer was attached to the cortical surface. This procedure, combined a with standard encephaloduroarteriosynangiosis, was applied to 25 hemispheres in 18 patients with pediatric moyamoya disease (mean age 6 years). All of the patients were symptom free by 1.5 years after surgery. The follow-up period ranged from 1 to 12 years (mean 6.5 years). Thirteen (81%) of 16 patients were able to lead normal lives and three were mildly handicapped due to mental retardation that existed preoperatively. Postoperative superselective angiograms demonstrated effective cortical revascularization through the dural arteries as well as from the scalp arteries. A histological study of the dura in cases of moyamoya disease showed an increased number of blood vessels in the outer layer. Angiogenic activity determined by chorioallantoic membrane assay was higher in the split surface of the dura than in the internal surface of the dura (the natural interface between the dura and cortex). The split duroencephalosynangiosis described in this report is a useful addition to indirect revascularization techniques, allowing extension of the area of revascularization in the ischemic hemispheres of patients with moyamoya disease.