Francesca Tinelli, MSc
Moyamoya angiopathy (MA) is a rare cerebrovascular disease characterized by chronic and progressive stenosis of the terminal part of the internal carotid arteries, associated with the compensatory development of an unstable vascular network (MA vessels).
Despite MA pathogenesis being unknown, an increasing number of studies propose alterations in angiogenesis and vasculogenesis as potential disease mechanisms. Moreover, the strong association with variants of Ring Finger Protein 213 (RNF213) gene in East Asian patients strengthens the role of genetic factors in MA pathogenesis.
MA manifests with ischemic or hemorrhagic strokes (about 80% of cases), leading patients to severe neurological deficits, physical disabilities and even death. Since the relationship between the MA onset pattern and risk factors for stroke has not been understood, the authors aimed to look into this association, performing a retrospective analysis on 178 adult patients enrolled at the University of Tokyo Hospital. Subsequently, Hirano Y. et al. investigated whether risk factors for stroke contribute to display symptoms in asymptomatic MA patients. Hypertension, diabetes mellitus and alcohol intake are considered as general risk factors for stroke.
Patients were divided into three groups based on their presenting event: 47% of them were asymptomatic, 40% had ischemic strokes and the remaining 13% had hemorrhagic strokes. The comparison between the three groups showed no significant differences in the prevalence of risk factors for stroke. Interestingly, the magnetic resonance imaging/angiography output revealed that the hemorrhagic group develops more frequently the anterior choroidal artery (AChA) anastomosis and cerebral microbleeds compared to both the ischemic and asymptomatic group.
Among the asymptomatic group, during follow-up, 8.33% became symptomatic. Dyslipidemia, hypertension, and presence of multiple risk factors significantly increased the probability to manifest symptoms and anticipated their onset.
In conclusion, the authors demonstrated that: (i) there is no correlation between the frequency of risk factors for stroke and the MA onset pattern, (ii) the development of AChA anastomosis and cerebral microbleeds is significantly higher in the hemorrhagic group, and (iii) dyslipidemia and hypertension increase the probability of cerebrovascular events in asymptomatic patients.
These findings may help predict and prevent hemorrhagic stroke and may clarify the heterogenic onset and course of MA disease. Future goals are: (i) enlarging the sample size, (ii) including cohorts from several institutions, and (iii) understanding whether the strict medical control of stroke risk factors may prevent the onset of symptoms.
