Improving diagnostics and treatment of moyamoya vasculopathy

Improving the Diagnosis and Treatment of Moyamoya: A Cerebrovascular Disease with Serious Implications

Moyamoya is a rare but severe condition affecting the major arteries in the brain, primarily impacting children and young adults. It leads to an increased risk of transient ischemic attacks (TIAs), strokes, and brain hemorrhages, which can significantly affect daily life, causing paralysis, cognitive issues, and overall a reduced quality of life.

What is Moyamoya?
In moyamoya disease, the internal carotid artery and middle cerebral artery gradually narrow or completely occlude. As a compensatory response, fragile, thin blood vessels form around the stenosis or occlusion to maintain blood flow. On an angiography, this network of vessels appears as a "puff of smoke," which is the meaning of the Japanese term "moyamoya." The exact cause remains unknown, though abnormal growth of muscle cells in the blood vessels is thought to play a role. The disease is more common in women and is diagnosed more frequently in Asian countries than in Western regions. Symptoms also differ: Asian patients are more prone to brain hemorrhages, while Western patients more often experience strokes and cognitive problems.

Treatment
Currently, no cure exists to halt or reverse arterial narrowing in moyamoya. Treatment focuses on symptom relief and preventing further brain damage. Blood thinners (e.g., aspirin) and lifestyle advice are often recommended. In many cases, revascularization surgery is needed to restore blood flow to the brain. This is done by an extracranial to intracranial bypass.

Research into Treatment Effects
At UMC Utrecht, we studied the impact of surgery and medication on symptoms and cognitive function. We found that surgery did not improve cognition, but did stabilize the symptoms. Furthermore we discovered that a unilateral operation can benefit both sides, so it is not always necessary to treat both hemispheres.

Advances in Imaging
Accurately mapping of cerebral blood flow and reactivity is essential for diagnosis and treatment. While PET scans were traditionally used, a new MRI-based technique has been developed, avoiding radioactive substances and reducing the need for additional tests. This method is now the standard at UMC Utrecht for evaluating moyamoya patients. Furthermore we found that inhalation of CO2-enriched air reduced the CMRO2, which is important to take into account when using BOLD-imaging. When scanning patients under anesthesia, this greatly impacts their cerebrovascular reactivity, so caution is warranted with the interpretation of patients scanned under anesthesia.

Conclusion
Moyamoya remains a complex disease with many unanswered questions, particularly regarding optimal surgical timing and patient selection. Improved imaging is the first step in enhancing treatment. Future research aims to develop better therapies and refine patient selection for surgery to maximize benefits and reduce complications.