Moyamoya disease (MMD) and moyamoya syndrome (MMS), referred to as the moyamoya angiopathy (MMA), is a chronic progressive steno-occlusive angiopathy at the distal portions of internal carotid arteries (ICAs) and their proximal branches, with typical collateral artery formation, called the moyamoya vessels. MMS has similar vascular abnormalities as in MMD, but is associated with other conditions such as Down’s syndrome or neurofibromatosis I (NFI). MMA is more common in East Asia (e.g. Korea and Japan) than in Western countries. Majority of the MMA studies are done in the Asian populations. Typically the clinical presentation age of MMA has a bimodal distribution, and peaks both before the age of 14 and later, at the ages 21-59 years. Women are more affected than men, with a ratio varying from 1:1-3:2. Typical presenting symptoms are ischemic or hemorrhagic strokes, transient ischemic attacks, headaches, and epileptic seizures. In East Asian countries familial form of MMD is more common than in the Western countries and a RNF213 gene has been identified as an important susceptibility gene in East Asian populations. The underlying mechanisms of MMD are still unknown, despite extensive studies. Intimal hyperplasia, medial layer thinness, and the waving of internal elastic lamina are the representative histo-pathological features found in MMD-affected vessels. Revascularization surgery is commonly used to treat MMA, although it does not cure the disease, but it can reduce the risk of an ischemic stroke. Antiplatelet therapy is also commonly used to treat the ischemic form of MMA. For this thesis we collected an MMA database at the Helsinki University Hospital (HUH), including 61 Caucasian patients of Finnish origin treated in the HUH Neurology and Neurosurgery departments between January 1987 and December 2014. The aim of the first study (I) was to investigate the prevalence of MMA in Finland, and the type of the disease, i.e. the clinical manifestations, and treatments used. The incidence of MMA in the HUH district was 0.14 per 100 000. The prevalence in the HUH district was 2.38 per 100 000 in year 2014. There was a female predominance found (ratio 4.5:1). At the time of the diagnosis, 10 patients were children. The most common clinical manifestations were ischemic stroke (51%), hemorrhagic stroke (13%), and headaches (11%). Twenty-six patients underwent revascularization surgery. Seventy percent of the patients were on antithrombotic medication. In the second (II) study our aim was to study the long term prognosis of MMA in the Finnish patient population including all 61 patients of the HUH-MMA registry. The mean follow-up period was 9.5 years. Patient-years summed up to 581. Two-thirds of the patients had no new vascular events during the follow-up period. Eight patients had an ischemic and five patients had a hemorrhagic stroke during the follow-up. The average annual rate of a recurrent stroke from the first event for all the study subjects was 3.5%. Two patients died during the follow-up period. Cause of death was intracerebral hemorrhage in both cases. Patients reported significantly poorer physical and psychological health aspects of quality of life when compared to the general Finnish population. In the third (III) study we performed a follow-up brain MRI and MRA to detect potential radiological changes over time. The mean follow-up time was 64 months between these two MRI/MRA imaging time points and we found new ischemic or hemorrhagic lesions only in one patient. All unilateral cases remained unilateral in the radiological follow-up study including 32 of our registry patients. Ivy sign was observed in 22%, cerebral microbleeds in 6% and white matter lesions in 9% of the patients. The phenotype of MMD in Finland confirms occurrence of the Western phenotype of the disease, with a disease course rather benign in the Finnish patient population, despite the less common, hemorrhagic form, which has a higher mortality.
|Tila||Julkaistu - 2021|
|OKM-julkaisutyyppi||G5 Tohtorinväitöskirja (artikkeli)|
LisätietojaM1 - 61 s. + liitteet
- 3112 Neurotieteet
- 3124 Neurologia ja psykiatria