Abstract
This chapter provides an and in-depth review of the Moya-Moya Syndrome and surgical correction. The authors describe disorders commonly associated with Moya-Moya Disease. The angiographic staging as well as medical and surgical options are presented. A thorough discussion on the perioperative evaluation and anesthetic considerations for this complex disease is presented to the reader.
A three-year-old boy presents for preoperative evaluation prior to pial synangiosis. A recent angiogram under general anesthesia to evaluate his cerebral circulation following recurrent transient ischemic attacks confirmed the diagnosis of Moyamoya disease. Current medications include aspirin. The nurse practitioner calls to determine what work-up and patient recommendations are appropriate prior to surgery.
What Are the Anatomic Changes and Pathophysiology Associated with Moyamoya Disease (MMD)?
Moyamoya is a Japanese word meaning “puff of smoke,” which describes the web-like vascularity depicted when viewing the reticular anastomosis and collateral formations between the internal and external carotid arteries on cerebral angiography (Figure 38.1).
The disease involves a progressive stenosis of the internal carotid artery and its branches with gradual development of collaterals from the base of the brain and through the skull from the external carotid artery. Intimal thickening and hyperplasia result in vascular occlusion and consequent proliferation of collateral vessels at variant planes such as leptomeningeal, basal ganglia, and/or transdural. The result of this collateral vessel formation can be critically diminished blood flow in the cerebral vasculature which can lead to eventual ischemic crisis.
What Is the Epidemiology of MMD?
Moyamoya disease was originally reported by Takeuchi and Shimizui in 1957. In the United States, the ethnically specific breakdown of incidence ratio per 100,000 includes 4.6 in the Asian population, 2.2 for African Americans, and 0.5 for the Hispanic population. MMD is likely genetically inherited as there is a 9–12% incidence in those with a family history of the disease. There is a female predominance, with the female to male ratio being 1.8:1. Though the syndrome is thought to be genetically influenced, radiation and various infectious processes have been suggested as possible causes of pathogenicity.
What Is the Most Likely Age for Presentation?
Disease may be acquired as an autosomal dominant process and can even present in early infancy, while a chronic and progressive disease presentation occurs with the highest incidence within the first decade of life.
Table 38.1 Disorders most commonly associated with Moyamoya development.
| Congenital syndromes | Apert syndrome Hirschsprung disease Marfan syndrome Neurofibromatosis – type 1 Trisomy 21 |
| Immunological disorders | Graves’ disease |
| Hematological disorders | Aplastic anemia Fanconi anemia Sickle cell anemia Thalassemia |
| Neoplasia | Wilms tumor Craniopharyngiomas |
| Infectious | Tuberculous meningitis Leptospirosis |
| Vascular disorders | Atherosclerotic disease Cardiomyopathy Coarctation of the aorta Hypertension |
| Others | Radiation Pulmonary sarcoidosis Nephrotic syndrome |
What Are the Signs and Symptoms of MMD?
In early childhood, MMD usually presents with ischemic symptoms, whereas adults may present with intracranial hemorrhage. In children, MMD often manifests with transient ischemic attacks or ischemic strokes. Symptoms may include headache, dizziness, and seizures, although some patients are asymptomatic. Decline in neurological function and/or cognition, choreiform movements, growth hormone deficiency, and visual impairment may occur as the disease progresses.
What Are the Disease Stages of MMD?
The dynamic and continual disease process is a slow progression ultimately leading to complete occlusion of the internal carotid artery. Early on, suprasellar carotid stenosis occurs followed by formation of basal collaterals. As stenosis worsens to include occlusion at the Circle of Willis vessels, extracranial collaterals form. With progressing stenosis, these extracranial collaterals enlarge and eventually provide nearly all flow.
What Factors Affect Prognosis?
A worse prognosis is associated with younger age at presentation (under six years), severe neurological deficits at presentation, and advanced angiographic changes.
How Is MMD Diagnosed?
If intracranial hemorrhage is suspected, then computed tomography (CT) of the head is indicated. Acute and chronic infarcts and areas of cortical ischemia will be revealed by magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) with roughly 90% sensitivity. Angiography is the gold standard for diagnosis, allowing for assessment of the internal and external carotid systems independently.
What Are the Angiographic Stages of MMD?
