Neurosurgery notes/Paediatrics/Paediatric Vascular/Paediatric AVM

Paediatric AVM

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Paediatric Vascular

Pathophysiology

  • Possibly congenital vs De-Novo Post-Natal
  • Isolated/Sporadic > Syndromic
  • Syndromes associated with bAVMs:
    • HHT/Rendu-Osler-Weber (4-11%, Smaller bAVMs, Multiple bAVMs; Pulmonary AVMs contribute to Morbidity)
    • Cerebro-Facial AV Metameric Syndrome (Wyburn Mason)
    • RASA-1 Mutation

Presentation

  • Commonest cause of Haemorrhagic stroke (following peri-natal period) in Children
  • Haemorrhagic presentation more common in Children (vs Adults) – 65-80% (Hetts et al. 2012 J Neurint Surg; Dinca et al. 2012 J Neurosurg Pediatr)
  • Seizures (~ 8%)
  • Hydrocephalus (Very Rare presentation – Hydro-Venous dysfunction)

Differences between paediatric vs adult AVM

  • MORE common in Children:
    • Eloquent Location
    • Deep Lesions >>> Lobar Lesions
    • Deep Venous Drainage (more common in Children)
  • MORE common in Adults:
    • Chronic High Flow sequelae (Flow aneurysms, Venous ectasia, Venous occlusion/stenosis)

Risk Factors for Haemorrhage

  • Previous Haemorrhage (Highest Risk)
  • Deep Venous Drainage
  • Intra-Nidal/Flow-related Aneurysm
  • Venous Outflow Stenosis
  • Single Draining Vein
  • Periventricular location
  • Infratentorial / Deep location

Evaluation

  • Functional Status
  • Neuro-Anatomical Location / Eloquence
  • Arterial Inflow and Architecture
  • Nidus
  • Venous Outflow (Primary vs Secondary Draining) + Normal Veins
  • Spetzler-Martin Classification / Spetzler-Ponce
  • Lawton-Young Supplemental (Age, Bleed, Compactness of Nidus)

Estimating Rupture Risk

  • 2-4% Annual Risk;
    • Haemorrhage Neurological Morbidity (20-30%);
    • Haemorrhage Mortality (10-30%) (Ondra 1990, Brown 1988, Crawford 1986)
  • ARUBA (2.2% Annual Risk)
  • Stapf 2006 Columbia AVM Databank (1.3% in Un-Ruptured; 5.9% in previously ruptured)
  • Rupture Risk = 1 – (1-R)^n (Multiple assumptions e.g. Yearly rupture risk consistent, Risk in any year independent of other years)
  • Paediatric Patients (as with all vascular lesions) → Consider Lifetime Risk of Rupture (lower threshold to treat)

Treatment

  • Multimodality Treatment
    • Microsurgical Resection (+ Targeted Adjunctive Endovascular Therapy) - ~ 90% Obliteration with ~ 17% Morbidity (Gross 2015, J Neurosurg Pediatr)
    • Stereotactic Radiosurgery (SRS) – 71.3 – 88% Obliteration with ~ 1 – 2.2% Annual Haemorrhage Rate (Dinca 2012, Hanakita 2015)
    • Endovascular Therapy (Least likely to be successful except in highly selected cases)
  • Selection Bias
    • AVMs that are best treated with one modality are probably most likely to be ones amenable to another