Regarded as a chronic, progressive condition of the brain, moyamoya disease occurs when the carotid artery in the skull becomes blocked or narrowed, reducing blood flow to your brain. The term “moyamoya” describes the appearance of tiny vessels that form to compensate for the blockage. In this condition, as the normal blood vessels narrow and become blocked, it may cause a ministroke (transient ischemic attack), stroke or bleeding in the brain. It can also affect the important functions of the brain and cause cognitive and developmental delays or disability. The brain tries to compensate for the reduced blood flow by growing new blood vessels called “collaterals”. Even though these blood vessels can temporarily help increase blood supply, they eventually stop working. There are currently no medications that can stop or reverse the progression of this condition. Treatment involves managing symptoms with medicine or surgery. The treatment also focuses on reducing the risk of stroke and restoring blood flow to the brain. Once the process of blockage (vascular occlusion) begins, it tends to continue and a major stroke or bleeding could occur resulting in permanent loss of function. It is important to treat this condition promptly. Neurologists, neurosurgeons and other specialists who treat this progressive condition of the brain need to correctly document the same in the patient’s medical records. Opting for medical billing services from an established medical billing company can help simplify the documentation process.

Generally, moyamoya disease affects children; however, adults may also experience this condition. It is slightly more common in children of Asian descent than in other ethnic backgrounds. This disease is most prevalent in Japan, but has also been diagnosed among people throughout the world. In the United States, the risk of developing this condition is less than 1 in 100,000. It can occur at any time, but is most commonly diagnosed in children aged between 5-15 years and in adults in their early 40s. Females have a higher risk of developing this condition.

Identifying the Causes and Symptoms

The exact cause of this condition is unknown. Reports suggest that about seven percent of children with moyamoya are believed to have an inherited gene defect. However, in at least half of all known cases of moyamoya, the disease has no identifiable cause. The condition is often associated with other disorders like neurofibromatosis type 1, sickle cell disease and Down syndrome and hyperthyroidism. The complications that occur as part of the disease are associated with the effects of stroke, such as – movement disorders, vision problems and learning or developmental issues.

One of the initial symptoms of moyamoya disease usually appears with a stroke or recurrent transient ischemic attack (TIA), especially in children. During a TIA, a blockage interrupts the flow of oxygen-carrying blood to the brain. Other related symptoms include: –

  • Headache
  • Visual disturbances
  • Seizures
  • Progressive difficulty in thinking and remembering due to repeated strokes and bleeding
  • Involuntary movements
  • Hemiparesis (Weakness, numbness or paralysis in the face, arm or leg, typically on one side of the body)
  • Epilepsy
  • Difficulties with speaking or understanding others (aphasia)
  • Developmental delays

The above symptoms can be triggered by exercise, crying, coughing, straining or fever.

How Is Diagnosis of Moyamoya Disease Made?

If a person experiences stroke-like symptoms, he/she may be referred to a neurosurgeon. Before beginning the diagnosis, the surgeon will review the patient symptoms, current and previous medical problems, medications taken and medical history. A detailed physical examination will be performed. Several diagnostic tests may be necessary to analyze the symptoms and other underlying conditions. Common diagnostic imaging tests include – Magnetic resonance imaging (MRI), Computerized tomography (CT) scan, Transcranial Doppler ultrasound, Electroencephalogram (EEG), cerebral angiogram and Positron emission tomography (PET) scan or single-photon emission computerized tomography (SPECT). These imaging tests are performed to correctly detect the nature of arterial narrowing and collateral blood vessels of moyamoya that have the appearance of a “puff of smoke.” Imaging studies can also reveal evidence of multiple small strokes.

By performing these tests, physicians will evaluate the patient’s condition and determine the most appropriate treatment. Treatment modalities may primarily focus on reducing the impact of symptoms, improve blood flow, and reduce the risk of other serious complications such as an ischemic stroke (caused by a lack of blood flow, bleeding in your brain (intracerebral hemorrhages) or death. Treatment modalities comprise medications (like blood thinners, calcium channel blockers and anti-seizure medications) that help reduce the risk of stroke or help in seizure control. However, if the symptoms become worse or if any tests show evidence of low blood flow, physicians may recommend revascularization surgery. In this surgical procedure, surgeons bypass blocked arteries to help restore blood flow to your brain. They may use direct or indirect revascularization procedures, or a combination of both the procedures. In order to address the physical and mental effects of this condition, physicians may recommend other therapies like physical and occupational therapy. Cognitive behavioral therapy may also be prescribed to address emotional issues related to having moyamoya disease and ways to coping with the fears and uncertainties about future stroke.

Neurologists, Neurosurgeons or other physicians who diagnose, screen and treat moyamoya disease must carefully document these tests and procedures using the correct medical codes. Billing and coding services offered by established medical billing and coding companies can help physicians in using the correct codes for their medical billing process. In ICD-10, code 167 and its complete sub-categories offer more specific representation of the other cerebrovascular diseases –

  • 167.5 – Moyamoya disease

The prognosis for patients with moyamoya is quite complex to predict. The condition can progress slowly with occasional TIAs or strokes, or it can involve rapid decline. The overall prognosis for patients with this condition is based on the extent of vascular blockage and the patient’s ability to develop effective collateral circulation, the age of the patient at onset of symptoms, and the severity of disability resulting from a stroke. The patient’s neurologic condition at the time of treatment is an important factor in determining the long-term outcome of the disease.

Billing and coding for cerebrovascular disorders is challenging. Outsourced medical billing services can help physicians ensure the correct medical codes on their claims, and optimal reimbursement.