A New Classification Of MMD From The Perspective Of Embryology

Purpose:Moyamoya disease is a chronic cerebrovascular disorder with etiology little known.Here,we proposed a new classification system based on the vessels involved from the perspective of embryology.Materials and Methods:Moyamoya disease patients' digital subtraction angiograms were retrospectively analyzed.Every angiogram was analyzed to find the abnormal vessels and from which part the lesions begin in the posterior cerebral artery.Results:In 262 Moyamoya disease cases,32 pediatrics have posterior cerebral artery involved,of which 17 are male and 15 are female;68 adults have posterior cerebral artery involved,of which 33 are male and 35 are female.The probabilities of the posterior cerebral artery involved are not statistically significant,no matter between the pediatric(35.16%)and the adult(39.77%)(p=0.465>0.05)or between the male(38.76%)and the female(37.59%)(p=0.864>0.05).The initial affected part of posterior cerebral artery between sexes,pediatric and adult,and sides are not statistically significant(p=0.233,p=0.855,p=0.343,respectively).However,all the posterior cerebral artery involved Moyamoya patients have the lesions begin from the second part of the posterior cerebral artery or from the posterior communication artery,which is derived from the caudal ramus of the primitive intracarotid artery,leave the first part of the posterior cerebral artery,which is derived from the primitive vertebral basilar artery,excluded from affection.Conclusion:The Moyamoya disease should classified into primitive intracarotid artery system involved type and primitive vertebral basilar artery system involved type.The reason of the vertebral basilar artery so rarely involved in Moyamoya disease might is its late development into the brain.The symptoms appeared in earlier age of patients' life is likely because of the abnormal vessels' failure in providing adequate blood for the developing brain while in later age of life is more likely because of the atherosclerosis based on the abnormal vessels.