One of the refreshing aspects of taking care of children is that, generally, they don’t have a mile long list of medications or an extensive known past medical history, unlike their adult counterparts.  Unfortunately, this generality can lead us to become complacent and be caught off guard when a child presents with concerning symptoms or has unusual medical problems. We have previously discussed several “adult” illness that occur in children (ex, Pulmonary Embolism, Cholelithiasis, Nephrolithiasis) and one of those surprising entities is Stroke (CVA). While children may have an AVM that leads to hemorrhagic stroke, one important condition that may be on their PMHx list and can lead to CVA in moyamoya.  Let’s take a moment to review moyamoya so we can remain vigilant!

Moyamoya: Basics

• Moyamoya is a Japanese term that means “something hazy, like puff of smoke drifting in the air.” [Singhi, 2012]
  • Refers to the angiographic appearance of the abnormal collaterals that develop.

• Cerebrovascular arteriopathy that leads to progressive stenosis and eventual occlusion.
  • It is not inflammatory and not due to atherosclerosis.
  • Stenosis is due to progressive intimal thickening and thrombosis formation.
  • Affects internal carotid, middle cerebral artery, and anterior cerebral artery [Singhi, 2012; Kim, 2010]
  • Can also affect posterior cerebral artery [Lee, 2015; Lee, 2014]

• Rare cerebrovascular occlusive disease, but incidence varies between ethnic groups. [Smith, 2009]
• Occurs in all ethnic groups.
• Bimodal distribution: [Singhi, 2012]
  • One peak in childhood – usually before 10 years of age.
  • Second peak occurs during 4th decade of life.

• Unknown cause
  • Likely combination of environmental and genetic factors
  • One large study found only 12% of cases to be familial. [Kim, 2010]

Moyamoya: What’s in a Name?

“Moyamoya,” “moyamoya syndrome,” “moyamoya disease” may be confused.

• Moyamoya – generic term for the angiographic findings
• Moyamoya Disease – bilateral, angiographic findings without associated clinical cause (i.e., idiopathic)
• Moyamoya Syndrome – unilateral moyamoya or moyamoya found in association with systemic disorders that are known to be associated with moyamoya. [Singhi, 2012; Smith, 2012]
  • Genetic Disorders:
    • Down’s Syndrome
    • Neurofibromatosis type 1
    • Tuberous sclerosis
    • Marfan Syndrome
    • Alagille Syndrome
  • Hematologic Disorders:
    • Sickle cell disease and other hemoglobinopathies
    • Fanconi’s anemia
  • Hyperthryoidism
  • Congenital Heart Disease
  • Tubercular meningitis
  • Previous cranial therapeutic radiation

Moyamoya: Presentation

• There are 4 main types of moyamoya based on clinical manifestations:
  • Infarct Type
    • Motor deficits (in one study, ~95% of cases) [Singhi, 2012]
    • Hemiparesis (44%) [Singhi, 2012]
    • Sensory symptoms
    • Some patients will present with ischemic symptoms precipitated by crying, coughing, blowing, or hyperventilation (which leads to hypocapnia and vasoconstriction) [Smith, 2009]
  • Transient Ischemic Attacks (TIAs) Type
    • Repeated TIAs is a presentation that needs to be respected.
  • Hemorrhagic Type
    • Hemorrhage is rare in children, but does occur. More common in adults. [Singhi, 2012]
  • Epileptic Type
    • May be initial presentation or recurrent in patient with known Moyamoya
    • Seizures on presentation rates vary: ~34% in [Singhi, 2012]; 19% in [Kim, 2010]
    • Surgery shown to help reduce recurrent seizure activity (97% seizure free)  [Kim, 2010]

• Other commonly encountered symptoms:
  • Headaches (33%) [Kim, 2010]
    • Surgery does not as greatly affect headache recurrence (26% still w/ headaches, and 16% developed new headaches) [Kim, 2010; Seol, 2005]
  • Fever
    • 30% presented with fevers [Singhi, 2012]
    • Unclear association, but fever can lead to carotid artery constriction.

Moyamoya: Evaluation

• Gold standard for evaluation is Intra-arterial cerebral angiography. [Singhi, 2012]
  • Better able to fully image the blood vessels.
  • Helps with correlation of Stage of Disease.
    • Stages progress from Stage 1 to Stage 6
    • Staging based on progressive stenosis and eventual occlusion of internal carotid artery (ICA) along with development of moyamoya collaterals at base of brain and development of external carotid artery (ECA) collateral vessels.
• MRI/MRA has been found reliable and often used for screening for disease and monitoring, but surgery often based on intra-arterial angiography. [Singhi, 2012; Smith, 2012]

Moyamoya: Management

• There is no effective pharmacotherapy to treat moyamoya. [Singhi, 2012]
• Therapies aimed at underlying syndromes, if present, for Moyamoya Syndrome. [Smith, 2012]
• Surgical revascularization to augment collateral circulation can be helpful.
  • Various techniques debated amongst neurosurgeons.
  • Typically reserved for patients with progressive ischemic symptoms or those with evidence of inadequate cerebral perfusion. [Singhi, 2012; Smith, 2012]

• Prognosis is highly variable.
  • May have slow progression with intermittent events.
  • May have rapid neurologic deterioration.
  • Early diagnosis and active intervention before irreversible changes occur can lead to favorable outcomes. [Bao, 2014]
  • Sadly, even in the absence of CVA, there is still often a lower quality of life observed in the patient’s with Moyamoya. [Ball, 2016]

Moral of the Morsel:

• Not every child has “no significant past medical history.” Some children have rather complex medical histories.
• “Adult” medical problems can occur in children.
• A child with a history of possible TIAs should not be dismissed… consider Moyamoya!
• A child with Moyamoya may present with progression of disease… be aware of the increased risk for further ischemic disease.

References