Moyamoya Disease | Knowledge Brush-Up

J.Adderton, BSN, MSN

I recently cared for a 40 year old male patient diagnosed with moyamoya disease who was being admitted to inpatient rehabilitation. He had a history of recurring hemorrhagic strokes with the last one occurring immediately before admission. I had never heard of the disease and desperately needed to beef up I’d like to share some highlights of what I learned.

What is moyamoya disease?

Moyamoya disease is a rare chronic condition caused by blocked arteries at the base of the brain. It’s also a progressive disease that gets worse over time. The Japanese were the first to describe and name the condition. Moyamoya means “puff of smoke” and describes the hazy appearance of the tiny vessels that compensate blood flow around blocked arteries. These collateral vessels are fragile and break easily causing bleeding in the brain.

What are the causes?

The exact cause of moyamoya disease is unknown. However, family history may play a role, especially in people of Japanese origin. There are several conditions that are associated with moyamoya-like changes, including:

Neurofibromatosis type I
Sickle cell disease
Down’s syndrome

Moyamoya-like changes may also occur in people who have undergone head or neck radiation to treat pituitary tumors and craniopharyngiomas.

Who does it affect?

Moyamoya disease has been diagnosed in people worldwide, however, Asians are more likely to have the condition. Other demographics include:

More likely to occur in females
Risk of developing less than 1 in 100,000
Ages range from 6 months to 67 years, but
More likely in children age 5 to 15, and adults 30 to 40

What are the symptoms?

The symptoms of moyamoya disease usually first appear with a TIA, ischemic or hemorrhagic stroke. The most common symptoms include:

Headache
Limb numbness, weakness or paralysis that is usually on one side of the body
Aphasia- difficulties with speech or understanding others
Visual changes
Developmental delays
Involuntary movements
Seizures

People with recurring strokes may experience difficulty thinking and memory problems that worsen over time.

How is it diagnosed?

To diagnose moyamoya disease, physicians consider the patient’s symptoms, past and present medical problems, the medications they are currently taking and any family history. Diagnostic imaging is performed to identify arterial narrowing and collateral blood vessels that have the “puff of smoke” appearance. A diagnosis is usually made with MRIs showing

Decreased blood flow to the internal carotid artery and cerebral arteries
Collateral blood flow at the brain’s base

The diagnosis is confirmed by an angiogram. Other diagnostic tests include:

Computed Tomography Angiography (CTA)
Computed Tomography Perfusion imaging (CT)
Other cerebral blood flow studies, such as
Transcranial Doppler ultrasonography
Xenon-enhanced CT
Positron emission tomography (PET)
Single photon emission computed tomography (SPECT)

What are the available treatments?

There isn’t an available treatment that reverses artery narrowing and blockage. Therefore, the focus of treatment is aimed at:

Reducing the risk of repeated strokes
Creating a new blood supply to the affected areas of the brain

Medications and surgical interventions are both used to slow the disease progression.

Medication interventions

The type of drug therapy used in treating moyamoya depends on how the disease is manifested.

Antihypertensive are used to control blood pressure in patients with hemorrhagic strokes.
Anticoagulants and antiplatelets are used in patients with ischemic strokes

Surgical interventions

The goal of surgical interventions is to prevent further strokes by revascularizing blood flood to the inside of the brain. Surgical procedures may provide direct or indirect revascularization.

Direct method through cerebral bypass
Indirect methods such as, EDAS, EMS and burr holes

Other treatments

Physical, speech and occupational therapy are used when patients have experienced long-term damage from strokes. These therapies help regain function and develop ways to promote independence.

What is the prognosis?

Predicted moyamoya progression is challenging because causes are not well understood. Prognosis largely depends on how fast arterial blockage occurs and how much damage it causes. The speed of progression depends on the patient’s ability to develop an effective collaborative blood flow, the age symptoms first appeared and the degree of disability. Some patients experience a slow decline with occasional TIAs or strokes, while others experience a more rapid decline.

It’s estimated that 50 to 60 percent of people with untreated moyamoya will experience poor outcomes, such as physical deterioration and irreversible neurological deficits. The prognosis is much better if a patient undergoes surgical intervention before suffering a major stroke.

Have you cared for a patient with Moyamoya disease? What was your experience?

References

Moyamoya Disease

Weill Cornell Brain and Spine Center

Moyamoya Disease Medscape