Moyamoya Disease
This 6-year-old boy with bilateral vertebral artery beading, left MCA and ACA occlusion, multiple territory infarcts, family history of stroke in siblings, and seizures most likely has moyamoya disease and requires urgent catheter angiography for definitive diagnosis followed by surgical revascularization.
Diagnosis
The clinical presentation is virtually diagnostic of moyamoya disease 1:
- Bilateral arterial involvement (beaded vertebral arteries) with anterior circulation occlusions (left MCA and ACA)
- Multiple territory infarcts (MCA and PCA territories) indicating progressive arteriopathy
- Strong family history (stroke in siblings) - familial incidence in first-degree relatives is 6-12% 1
- Age 6 years - peak pediatric presentation occurs in the first decade 2
- Seizures - common presenting feature in pediatric moyamoya
The "beaded appearance" of vessels represents the characteristic stenosis and collateral vessel formation that defines this arteriopathy 1, 2.
Diagnostic Workup Required
- Catheter angiography of all 6 vessels (bilateral ICAs, VAs, and ECAs) - gold standard for diagnosis and Suzuki staging
- MRI with diffusion-weighted imaging to assess acute and chronic infarcts
- MRA can supplement but cannot replace catheter angiography for definitive diagnosis
- Cerebral perfusion studies (SPECT or PET with acetazolamide challenge) to assess hemodynamic compromise
The diagnosis requires demonstration of: (1) stenosis at the distal ICA bifurcation and proximal ACA/MCA, (2) dilated basal collateral vessels ("puff of smoke"), and (3) bilateral abnormalities 2.
Management Strategy
Acute Phase
Medical stabilization 2:
- Maintain euvolemia and avoid hypotension
- Prevent hyperventilation (causes vasoconstriction and can precipitate stroke)
- Control fever aggressively
- Minimize anxiety and crying (triggers ischemic events)
- Manage seizures with appropriate antiseizure medications
Aspirin therapy may be considered acutely, though evidence is limited 2.
Definitive Treatment
Surgical revascularization is the treatment of choice 1, 2:
- Medical therapy alone fails in approximately 40% of pediatric moyamoya patients 1
- Without treatment, >66% have symptomatic progression within 5 years resulting in permanent deficits or death 1
- Surgery reduces symptomatic progression from >66% to <4% 1
- Neurological status at time of treatment is the most important predictor of long-term outcome 1, 2
Surgical options 2:
- Indirect revascularization (pial synangiosis, encephaloduroarteriosynangiosis) - preferred in young children due to small vessel size
- Direct bypass (STA-MCA anastomosis) - technically challenging in children
- Combined procedures - increasingly used with good results
Surgical outcomes 2:
- 96% probability of remaining stroke-free over 5 years post-surgery
- 4% perioperative stroke risk per hemisphere
- 87% derive symptomatic benefit from revascularization
Critical Pitfalls to Avoid
Do NOT use anticoagulation - contraindicated in moyamoya due to hemorrhage risk and difficulty maintaining therapeutic levels in children 2
Do NOT delay surgery - progressive arteriopathy continues, and baseline neurological status determines outcome 1, 2
Avoid hyperventilation during anesthesia/procedures - precipitates ischemic events 2
Screen siblings - given family history, first-degree relatives warrant vascular screening with MRA 1
Follow-up
- Periodic clinical and radiographic monitoring for disease progression 2
- 27% with unilateral disease develop bilateral involvement 2
- Younger patients more likely to have disease progression 2
- Reoperation rates range 1.8-18% for refractory disease 2
Alternative Consideration
While pediatric fibromuscular dysplasia can present with beaded arteries and stroke 3, 4, 5, the bilateral involvement, family history, and characteristic anterior circulation pattern strongly favor moyamoya disease over FMD. FMD typically shows "string-of-beads" in renal or carotid arteries and is exceedingly rare intracranially in children 4.