General
- Idiopathic, Chronic, Progressive Occlusive Arteriopathy
- Classically:
- Terminal ICA, proximal ACA & MCA (Bilateral)
- Ischaemia → Development of Basal Arterial Collaterals (Lenticulo-Striate, Thalamo-Perforating)
- +/- Involvement of Posterior Circulation (PCA, BA)
- ~6% of Strokes in Children
- Idiopathic (No risk Factors) = Moya Moya Disease
- Underlying Risk Factor/Syndrome = Moya Moya Syndrome
Clinical features
- Symptoms at initial evaluation in a series of 143 patients over 17 years
- Symptom totals are greater than patient numbers because some patients had multiple symptoms at initial evaluation.
Symptom | No. Patients | Percentage of Patients |
Stroke | 97 | 67.8% |
Transient ischemic attacks (including drop attacks) | 62 | 43.4% |
Seizures | 9 | 6.3% |
Headache | 9 | 6.3% |
Choreiform movements | 6 | 4.2% |
Incidental (asymptomatic) | 6 | 4.2% |
Intraventricular or intracerebral bleeding | 4 | 2.8% |
Pathophysiology
- Idiopathic (progressive smooth muscle hyperplasia + intimal thrombosis; NO arteriosclerotic or inflammatory changes)
- Genetic Factors:
- ACTA2
- Asian Ancestry (RNF213)
- TIMP-2 (MMP Inhibitor)
- Familial Incidence (6-12%)
- Increased Factors (HIF-1α, FGF, TGF-β)
- ? primary
- ? secondary to ischemia
Natural History
- Untreated / Medical Management (Aspirin) in SYMPTOMATIC Patients
- Reference: Kurokawa T, Tomita S, Ueda K, Narazaki O, Hanai T, Hasuo K, Matsushima T, Kitamura K (1985) Prognosis of occlusive disease of the circle of Willis (moyamoya disease) in children. Pediatr Neurol 1:274–277
- 65% Symptomatic Progression
- 37% major Neurological Morbidity / Impairment
- 3% Mortality
- ASYMPTOMATIC Patients
- Difficult in patients with Incidental
- Stroke risk of 3%
- Evidence that 50% may get Clinical/Radiological progression ≤ 5 years
- Patients with MMS or OTHER AETIOLOGIES (e.g., Vasculitis, Sickle Cell)
- Decision making difficult
- Limited to Case reports/Case series
- MDT experience in High-Volume centers is crucial
- Untreated / Medical Management (Aspirin) in SYMPTOMATIC Patients:
- Reference: Kurokawa T, Tomita S, Ueda K, Narazaki O, Hanai T, Hasuo K, Matsushima T, Kitamura K (1985) Prognosis of occlusive disease of the circle of Willis (moyamoya disease) in children. Pediatr Neurol 1:274–277
- 65% Symptomatic Progression
- 37% major Neurological Morbidity / Impairment
- 3% Mortality
Management
Key Factors in Achieving Excellent Results
- Patient selection
- Biology at work!
- In children, "Hungry Brain" is key!
- Our primary role as Moyamoya Surgeons!
- "To facilitate in the safest way, what the body wants to do by itself when the brain is hungry"
- Perform the safest, fastest surgery with the least amount of risk
- Recognition of the critical role of Peri-Operative management
Most Important of all = PERI-OPERATIVE MANAGEMENT
- “It is the Anaesthetic and Peri-Operative Course that is the Greatest Morbidity to Fragile Patients”
- Role of Aspirin Peri-Operatively
- Peri-Operative Hydration (100-150% maintenance with isotonic IV fluids)
- Avoid:
- Hypotension
- Pain
- Hypocarbia (Hyperventilation with Vasoconstriction)
- Hyperthermia
- Haemodilution (Sickle Cell Patients ensure adequate Exchange Transfusion and HbS level)
- Utilisation of intra-operative EEG monitoring
- Avoid diuretics
- Anaesthesia – Balance Flow-Metabolism (CBF vs CMR02)
Surgical Revascularisation – Aims
- Utilize an alternative source to augment cerebral blood flow and reduce the risk of stroke.
- Does NOT reverse underlying occlusive arteriopathy.
- External carotid artery (ECA) is classically spared in Moyamoya and commonly used (Adjacent Tissue Source).
- Multiple ECA sources utilized include:
- Dura, MMA (EDS)
- Muscle (EMS)
- Galea / Pericranium (EGPS)
- Multiple Burr-Holes
- STA (Direct STA – MCA vs EDAS / EDAMS)
- Pial Synangiosis
- Distal tissue sources
- Omental Cranial Transposition.
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