What is moyamoya disease?

Moyamoya disease is a rare progressive cerebrovascular disorder characterized by a narrowing and occlusion of the internal carotid arteries at their origins within the skull, resulting in the formation of abnormal small collateral vessels (moyamoya vessels) in the area surrounding the circle of Willis.

Here's an overview of moyamoya disease:

Causes:

The exact cause of moyamoya disease is unknown, but it is considered a multifactorial condition influenced by genetic and environmental factors. Some cases are associated with specific genetic mutations, while others occur sporadically.

Pathogenesis:

In moyamoya disease, the internal carotid arteries, which are major blood vessels supplying the brain, develop a progressive narrowing (stenosis) or complete blockage (occlusion). The narrowing or occlusion restricts blood flow to the brain, leading to insufficient oxygen supply (ischemia) in the cerebral tissues.

To compensate for the reduced blood flow, the brain responds by forming abnormal small blood vessels (moyamoya vessels or collateral vessels) in an attempt to bypass the occluded arteries and restore blood flow to the affected brain areas. These newly formed vessels are often fragile and prone to rupture or thrombosis.

Symptoms:

The symptoms of moyamoya disease vary depending on the severity and location of the affected vessels. Common symptoms include:

1. Headaches: Headaches can be recurrent, severe, and throbbing in nature.

2. TIA's (Transient Ischemic Attacks): Episodes of temporary neurological symptoms similar to stroke, such as weakness or numbness on one side of the body, slurred speech, or visual disturbances.

3. Strokes: Moyamoya disease significantly increases the risk of ischemic strokes (caused by a lack of blood flow) or hemorrhagic strokes (caused by ruptured vessels) in both children and adults.

4. Developmental delay: In children, moyamoya disease can affect cognitive development and may result in developmental delays.

5. Epilepsy: Seizures can be a symptom of moyamoya disease, especially if the decreased blood flow affects areas of the brain responsible for controlling epileptic activity.

Diagnosis:

Moyamoya disease is diagnosed based on the patient's symptoms, physical examination findings, medical history, and imaging tests. Magnetic Resonance Angiography (MRA) and Computed Tomography Angiography (CTA) allow visualization of the cerebral blood vessels and help identify the narrowed or occluded arteries and collateral vessel formation characteristic of moyamoya disease.

Treatment:

The primary treatment for moyamoya disease aims to improve brain perfusion (blood flow) and prevent strokes. Two common approaches include:

1. Revascularization surgery: Surgical procedures such as direct bypass or indirect vascular reconstruction are performed to bypass the occluded vessels and restore blood flow to the affected brain areas.

2. Medical management: Medications, such as antiplatelet agents, anticoagulants, and calcium channel blockers, may be prescribed to reduce the risk of blood clot formation and improve blood flow.

Moyamoya disease can be a challenging condition, but proper management and timely intervention can significantly improve the outcomes and prevent serious complications.