Read more about this disease, some with Classification – Types – Signs and symptoms – Genetics – Pathophysiology – Diagnosis – Screening – Prevention – Treatment and management – Cures and much more, some including pictures and video when available.
Moyamoya disease is an extremely rare disorder characterized by progressive intracranial vascular stenoses of the circle of Willis, resulting in successive ischemic events. Hemorrhagic events can also occur. The condition leads to irreversible blockage of the carotid arteries to the brain as they enter into the skull. It is a disease that tends to affect children and adults in the third to fourth decades of life. In children it tends to cause strokes or seizures. In adults it tends to cause bleeding or strokes. The clinical features are cerebral ischaemia (strokes), recurrent TIAs, sensorimotor paralysis (numbness in the extremities), convulsions and/or migraine-like headaches.
The condition is believed to be hereditary and linked to q25.3, on chromosome 17[1]. In Japan the overall incidence is higher (0.35 per 100,000).[1] In North America, women in the third or fourth decade of life are most affected. These women frequently experience transient ischemic attacks (TIA), cerebral hemorrhage or no symptoms. They have a higher risk of recurrent stroke and may be experiencing a distinct underlying pathophysiology compared to patients from Japan. Data suggest a potential benefit with surgery if early diagnosis is made.[2] The pathogenesis of Moyamoya disease is unknown.
The process of blockage (vascular occlusion) once it begins tends to continue despite any known medical management. In some people this leads to repeated strokes and severe functional impairment or even death. In others, this blockage may not cause any symptoms.
Moyamoya can be either congenital or acquired. Patients with Down syndrome, neurofibromatosis, or sickle cell disease can develop Moyamoya malformations. It is more common in women than in men.[3] Brain radiation therapy in children with neurofibromatosis increases the risk of its development.
The diagnosis is initially suggested by CT, MRI, or angiogram. In fact, the name derives from its angiographic image; the “puff of smoke,” which is how moyamoya loosely translates from Japanese, refers to the appearance of multiple compensatorily dilated striate vessels seen on angiography. Contrast-enhanced T1-weighted images are better than FLAIR images for depicting the leptomeningeal ivy sign in Moyamoya disease. MRI and MRA should be performed for the diagnosis and follow-up of Moyamoya disease. Diffusion-weighted imaging can also be used for following the clinical course of children with Moyamoya disease, in whom new focal deficits are highly suspicious of new infarcts.
Often nuclear medicine studies such as SPECT (single photon emission computerized tomography) are used to demonstrate the decreased blood and oxygen supply to areas of the brain involved with Moyamoya disease. Conventional angiography provided the conclusive diagnosis of Moyamoya disease in most cases and should be performed before any surgical considerations.
There are many operations that have been developed for the condition, but currently the most favored are the in-direct procedures EDAS, EMS, and multiple burr holes and the direct procedure STA-MCA. Direct superficial temporal artery (STA) to middle cerebral artery (MCA) bypass is considered the treatment of choice, although its efficacy, particularly for hemorrhagic disease, remains uncertain. Multiple burr holes have been used in frontal and parietal lobes with good neovascularisation achieved.
The EDAS (encephaloduroarteriosynangiosis) procedure requires dissection of a scalp artery over a course of several inches and then making a small temporary opening in the skull directly beneath the artery. The artery is then sutured to the surface of the brain and the bone replaced.
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