Never heard of moyamoya disease? What do you do when this patient presents to your ED?
HPI: The patient is a 32yo female with a history significant for moyamoya disease, ischemic strokes and multiple sclerosis sent from her pcp today for head imaging with concerns for another stroke. She has had a 3 week progression of worsening mental status changes, increasing headaches, and increased sleepiness. Her mother, whom she lives with, has said that she stares off into space at times, does not respond appropriately to her questions, and forgets information that she used to remember. Last night she urinated on herself while asleep and this has never happened before. She denies loss of bowel or bladder function otherwise. She does have a hx of migraines that she says are getting worse and only sleep makes them better. She says she has been slurring her speech at times and feels a left sided facial droop around her cheek. She denies blurry vision, double vision, N/V, SOB, chest pain or pressure, numbness, tingling or pain. Her last stroke was September of 2011. Four months prior she underwent a left superficial temporal artery to middle cerebral bypass with no complications. Her last diagnostic cerebral angiogram was 4/2/12 and no additional changes to her treatment plan were made.
Neurological Exam: Positive for facial asymmetry, speech difficulty and headaches.
Moyamoya disease is a progressive, occlusive disease of the cerebral vasculature with particular involvement of the circle of Willis and the arteries that feed it. The image below is a schematic representation of the circle of Willis, the arteries of the brain, and the brainstem.
The term moyamoya (Japanese for “puff of smoke”) refers to the appearance on angiography of abnormal vascular collateral networks that develop adjacent to the stenotic vessels. The steno-occlusive areas are usually bilateral, but unilateral involvement does not exclude the diagnosis.
Pathologically, moyamoya disease is characterized by intimal thickening in the walls of the terminal portions of the internal carotid vessels bilaterally. The proliferating intima may contain lipid deposits. The anterior, middle, and posterior cerebral arteries that emanate from the circle of Willis may show varying degrees of stenosis or occlusion. This is associated with fibrocellular thickening of the intima, waving of the internal elastic lamina, and thinning of the media.
Children and adults with moyamoya disease may have different clinical presentations. The symptoms and clinical course vary widely, with the disease ranging from being asymptomatic to manifesting as transient events to causing severe neurologic deficits. Adults experience hemorrhage more commonly; cerebral ischemic events are more common in children.
Children may have hemiparesis, monoparesis, sensory impairment, involuntary movements, headaches, dizziness, or seizures. Mental retardation or persistent neurologic deficits may be present.
Adults may have symptoms and signs similar to those in children, but intraventricular, subarachnoid, or intracerebral hemorrhage of sudden onset is more common in adults.
Physical examination findings depend on the location and severity of the hemorrhage or ischemic insult.
Misdiagnosis and delayed diagnosis of moyamoya disease are particular pitfalls in the treatment of patients with this disorder. Misdiagnosis can occur easily if the physician does not incorporate moyamoya disease into the differential diagnosis of any patient presenting with stroke. How high moyamoya disease is ranked in the differential depends on presence of atypical features such as young age and absence of obvious risk factors for stroke.
If moyamoya disease is not considered seriously, then appropriate diagnostic tests may not be performed and a delay in diagnosis could result. Because definitive treatment may be surgery, any delay could allow unnecessary progression of disease.
If an ischemic stroke that is being treated with antiplatelet agents or anticoagulants does not respond to therapy, then moyamoya disease should be considered as a possible etiology. This is especially true if results of a hypercoagulability profile are unremarkable.
Physicians practicing in the community who encounter atypical stroke presentations should not hesitate to seek consultation with a stroke specialist or even to transfer a patient to a facility equipped to care for complex cases.
Cerebral angiography is the criterion standard for the diagnosis of moyamoya disease. The following findings support the diagnosis:
Stenosis or occlusion at the terminal portion of the internal carotid artery or the proximal portion of the anterior or middle cerebral arteries
Abnormal vascular networks in the vicinity of the occlusive or stenotic areas
Bilaterality of the described findings (although some patients may present with unilateral involvement and then progress)
Magnetic resonance angiography (MRA) can be performed. Any of the above findings on MRA may preclude the need for conventional angiography.