Makindo Medical Notes

Related Subjects: |Subarachnoid Haemorrhage |Haemorrhagic stroke

Moyamoya disease is a non-inflammatory vasocclusive disease of the ICA, MCA, and ACA, leading to both ischemic and hemorrhagic stroke. The characteristic net-like vessels seen on cerebral angiograms resemble "moyamoya," a Japanese word for something hazy, like drifting cigarette smoke. The term was popularized by Jiro Suzuki [Suzuki J et al. 1983].

About

• First described in 1957 in Japan as "hypoplasia of the bilateral internal carotid arteries." Named "Moyamoya" in 1965.
• Incidence: 10 per 100,000 in Japan; 1 per 1,000,000 in the USA.
• Increased levels of Basic fibroblast growth factor have been associated with the disease.
• Causes progressive intracranial internal carotid artery occlusion, with fragile collateral vessels that may bleed.
• Both sporadic and familial cases exist, leading to ischemic and hemorrhagic stroke.

Genetics

• Most common in Asians (Japanese, Chinese, and Koreans) but also seen in non-Asian populations.
• Ten times more common in Japanese, Chinese, and Koreans compared to White Europeans and Americans.
• Familial cases are linked to a gene on Chromosome 17.

Aetiology

• Affects distal internal carotid artery, MCA, and ACA stems.
• Leads to extensive collateralization with lenticulostriate and transdural anastomoses between cortical branches of the meningeal and scalp arteries.
• Non-inflammatory; fragile collateral arteries can bleed.
• Similar disease patterns may appear with atherosclerosis and diabetes.

Associations

• Sickle cell disease, beta thalassemia, Neurofibromatosis type I.
• Other associations: Fanconi anemia, hereditary spherocytosis, homocystinuria, APS, Grave's Disease, and SLE.

Clinical Presentation

• Commonly affects young people and may present in childhood.
• Symptoms: recurrent sudden hemiplegia, cognitive impairment, silent infarcts, seizures, chorea, and hemorrhage.

Investigations

• Blood tests are usually unremarkable (non-inflammatory vasculopathy).
• CT Imaging: Shows cortical/subcortical infarction, potential volume loss, and hemorrhages.
• MRI/MRA: Preferred for diagnosis; shows carotid narrowing or occlusion, "puff of smoke" appearance due to fragile collaterals.
• MRI Gradient Echo: Detects hemorrhages and dilated collateral vessels in the basal ganglia and thalamus, known as the "ivy sign" on FLAIR images.
• Transcranial Doppler: Non-invasive evaluation of intracranial hemodynamics and artery stenosis.
• EEG: Characteristic in children with Moyamoya syndrome, showing a "re-build-up phenomenon" after hyperventilation.
• Perfusion Studies: Highlight ischemic areas at risk of infarction.

Management

• Managed in specialized centers with both medical and surgical options.
• Medical management is largely unproven; includes vasodilators and generally avoiding antiplatelets in older patients.
• Blood pressure management is essential; surgery is generally considered for symptomatic patients.
• Surgical Treatments: Direct bypass (e.g., STA to MCA anastomosis) and indirect methods like multiple burr holes for revascularization. Surgical treatments for Moyamoya can reduce hemorrhagic risk, with recent studies favoring direct approaches.
• Aspirin is used for children but discontinued in adults to reduce bleeding risk.
• Haemorrhagic lesions are the most common cause of death in Moyamoya patients.

Further Reading

• [1] Moyamoya Disease and Moyamoya Syndrome. N Engl J Med 2009;360:1226-37.
• [2] Moyamoya Disease: Treatment and Outcomes. J Stroke. 2016 Jan; 18(1): 21-30.
• [3] Characteristic EEG findings in childhood moyamoya syndrome. Neurosurg Rev 1992;15(1):57-60.
• [4] Comparison of MR Perfusion Weighted Imaging and CT Perfusion Imaging in Assessing Haemodynamics of Patients with Moyamoya Disease. Sichuan Da Xue Xue Bao Yi Xue Ban. 2018 Sep;49(5):749-753.
• [5] How I do it: Operative nuances of multiple burr hole surgery for Moyamoya disease and syndrome. Acta Neurochir (Wien). 2018 Nov 24.