What is Moyamoya Disease?
Moyamoya disease is a rare, progressive cerebrovascular disorder characterized by the narrowing or blockage of the internal carotid arteries and their main branches in the brain. This leads to reduced blood flow and the formation of abnormal, fragile blood vessels that resemble a puff of smoke (which is what moyamoya means in Japanese) on imaging studies. The carotid arteries are the blood vessels that supply oxygenated blood to the head.
Causes and Risk Factors of Moyamoya Disease
The exact cause of Moyamoya disease is unknown, but it is believed to have a genetic component, particularly in East Asian populations. It is also associated with certain conditions such as sickle cell disease, Down syndrome, hyperthyroidism, and neurofibromatosis type 1.
Symptoms of Moyamoya Disease
Moyamoya disease can present with different symptoms, depending on age and severity, including the following:
- Transient ischemic attacks (TIAs) or strokes
- Seizures
- Cognitive impairment
- Developmental delays
- Headaches
- Speech or vision problems
- Weakness or paralysis in one part of the body
- Involuntary movements
Diagnosis of Moyamoya Disease
Diagnosis of moyamoya disease typically involves the following:
- MRI and MRA (Magnetic Resonance Imaging/Angiography): To visualize narrowed arteries and collateral vessels
- CT Angiography (CTA): Useful for detecting bleeding or infarctions
- Cerebral Angiography: The gold standard for diagnosing Moyamoya, showing the characteristic collateral networks
- PET or SPECT scans: To assess brain perfusion
Treatment for Moyamoya Disease
Since Moyamoya disease is a progressive condition, treatment focuses on improving cerebral blood flow, preventing strokes, and managing symptoms. Treatment options include medications, surgical interventions, and supportive therapies.
Medications (Symptomatic Management)
- Antiplatelet drugs (Aspirin, Clopidogrel): To reduce the risk of stroke
- Anticoagulants: Used in some cases, but with caution due to the bleeding risk
- Calcium Channel Blockers (e.g., Nimodipine): These may help relieve headaches and prevent vasospasms
Surgical Treatments (Revascularization Procedures)
Surgery is the most effective treatment to restore blood flow. Common procedures include the following:
- Direct Bypass (STA-MCA Bypass): Connects the superficial temporal artery (STA) to the middle cerebral artery (MCA) for immediate blood flow improvement
- Indirect Bypass (EDAS, EMS, or Omental Transposition): Creates new pathways for gradual revascularization by rerouting scalp or muscle arteries
Supportive and Rehabilitation Therapy
- Physical/Occupational Therapy: For stroke recovery and mobility improvement
- Speech/Cognitive Therapy: For speech or cognitive impairment
- Avoidance of hyperventilation, dehydration, or extreme stress: To mitigate the risk of stroke and worsening symptoms
