Moyamoya Disease

Overview

Moyamoya disease is a rare vascular disorder in which the carotid artery in the skull becomes blocked or narrowed, reducing blood flow to your brain. Tiny blood vessels then open up at the base of the brain in an attempt to supply the brain with blood. It most commonly affects children, but adults may also have the condition. It is found all over the world but is most commonly seen in Japan, Korea and China.

Symptoms

The first symptom of moyamoya disease is usually stroke or recurrent transient ischemic attack (TIA), especially in children. Adults may also experience hemorrhagic stroke (bleeding in the brain) in addition to these symptoms.

 

Accompanying signs and symptoms include:

  • Headache

  • Seizures

  • Weakness, numbness or paralysis in face, arm or leg, typically on one side of the body

  • Visual disturbances

  • Aphasia (Difficulties with speaking or understanding others)

  • Developmental delays

  • Involuntary movements

Causes and Risk Factors

Although the cause of moyamoya is unknown, certain factors can increase the risk of getting this disease. These risk factors include:

  • Being an Asian descent: Researchers believe the greater prevalence in these Asian countries strongly suggests a genetic factor in some populations.

  • Having a family history of moyamoya disease.

  • Having a certain medical condition: Moyamoya disease sometimes occurs in association with another disorder, such as neurofibromatosis type 1, sickle cell disease and Down syndrome.

  • Being female

  • Being young: Children under 15 are most commonly affected.

Diagnosis

  • In most patients, the diagnosis of moyamoya is based on magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA).

  • Cerebral arteriography will confirm the diagnosis, establish the exact degree of blood vessel narrowing, demonstrate the existing blood flow patterns to various areas of the brain, and allow treatment decisions to be made.

  • Catheter angiography can help with the identification of important blood vessels called “transdural collaterals,” which are present in some cases and can markedly influence surgical planning and prognosis. 

 

Treatments

Medications

  • Aspirin: prevent or reduce the development of small blood clots developing within the narrowed vessels

  • Anti-seizure medications: when indicated because of a patient’s seizure disorder.

  • In rare instances, anticoagulants such as lovenox or coumadin are administered in very unstable patients having frequent symptoms, but because of the obvious risk of cerebral bleeding in this condition, they are rarely indicated as long-term measures.

  • Calcium channel blockers: carefully used to help reduce headache and symptoms related to transient ischemic attacks. However, calcium channel blockers can also lower blood pressure, which may increase stroke risk.

 

There is no medication available which will stop the progression of the cerebral artery narrowing and the disease will continue to progress in most patients regardless of treatment.

Surgical procedures

Indirect procedures

Usually carried out in children and younger patients and involves the placement of vascularized structures from the scalp and/or the membranes that surround the brain onto the brain surface to induce the growth of new blood vessels into the brain.

Direct procedures

Direct suturing of the superficial temporal artery to a middle cerebral artery branch on the brain surface. Long-term results following surgery of either type have been quite good, with long-term prevention of strokes seen in published series of both pediatric and adult patients.

References:

“Moyamoya Disease - Symptoms and Causes.” Mayo Clinic, 8 Dec. 2020, www.mayoclinic.org/diseases-conditions/moyamoya-disease/symptoms-causes/syc-20355586.

Kondo, Takeshi. “Moyamoya Disease.” Canadian Medical Association Journal, vol. 190, no. 46, 2018, p. E1364. Crossref, doi:10.1503/cmaj.180681.

NORD - National Organization for Rare Disorders. “Moyamoya Disease.” NORD (National Organization for Rare Disorders), 8 May 2018, rarediseases.org/rare-diseases/moyamoya-disease.

Resources by Judy Zhu