What are the clinical manifestations and management of neonatal Arteriovenous Malformations (AVMs)?

Clinical Manifestations and Management of Neonatal Arteriovenous Malformations (AVMs)

Neonatal arteriovenous malformations most commonly present with high-output cardiac failure due to significant arteriovenous shunting relative to cardiac output, and require prompt multidisciplinary management to prevent mortality. 1

Clinical Manifestations

Primary Presentations

• High-output cardiac failure: The most distinctive presentation in neonates and infants due to the large degree of arteriovenous shunting relative to cardiac output 1, 2
• Hemorrhage: Pediatric AVMs have an 80-85% hemorrhage rate as initial presentation, significantly higher than in adults 1
• Hydrocephalus: Particularly when posterior fossa lesions result in aneurysmal dilatation of the vein of Galen and aqueductal compression 1

Secondary Presentations

• Seizures: Less common initial presentation in neonates but may occur with supratentorial AVMs 1
• Headache: More common in older children than neonates 1
• Neurological deficits: May be subtle in neonates unless motor pathways or brainstem are involved 1

Diagnostic Evaluation

Initial Assessment

• Cardiac evaluation: Assess for signs of high-output failure including tachycardia, hepatomegaly, and pulmonary edema 2
• Neurological examination: May reveal focal deficits depending on AVM location 1

Imaging Studies

• Doppler ultrasound: First-line imaging examination for initial assessment 3
• MR angiography or CT angiography: For detailed anatomic evaluation 3
• Cerebral angiography: Essential for proper classification and treatment planning 3

Management Approaches

Acute Management

• Cardiac support: Management of high-output cardiac failure with diuretics, inotropes, and ventilatory support as needed 2
• Hemorrhage management: For AVMs presenting with hemorrhage, urgent insertion of ventricular drainage catheters may be necessary for hydrocephalus 1
• Intracranial pressure monitoring: Via ventricular catheters in intensive care settings 1

Definitive Treatment Options

Treatment decisions should be based on the high lifetime risk of hemorrhage (25% mortality rate with hemorrhagic events) and the potential for cardiac complications. 1

• Surgical resection: Gold standard for accessible pediatric AVMs 4

  • Higher morbidity (18%) and mortality (11%) rates than adult series 1
  • Risk of recurrence in pediatric patients even after complete resection 1

• Endovascular embolization:

  • Used as adjunctive therapy to reduce blood loss during surgery 4
  • Can be used to decrease AVM volume before radiosurgery 4
  • When used as primary treatment, carries 28% morbidity and 16% mortality 1

• Radiosurgery:

  • Alternative approach for inaccessible AVMs 4
  • 30% rate of permanent neurological deficits reported 1

Special Considerations

• Location challenges: Pediatric AVMs are more commonly found in eloquent locations such as the basal ganglia and thalamus, complicating treatment 1
• Ventriculoperitoneal shunting: May be required for chronic hydrocephalus after ventricular blood is cleared 1
• Seizure management: AVM obliteration may reduce seizure incidence; 83% of patients become seizure-free after surgical resection 1
• Recurrence risk: Pediatric AVMs may express higher astrocytic vascular endothelial growth factor than adult AVMs, potentially explaining their ability to recur after treatment 1

Treatment Decision Algorithm

1. Assess clinical stability:

   • If cardiac failure present: Stabilize cardiac function before definitive treatment 2
   • If hemorrhage present: Address acute bleeding and manage intracranial pressure 1

2. Evaluate AVM characteristics:

   • Location (eloquent vs. non-eloquent brain)
   • Size and vascular architecture
   • Presence of high-risk features (deep venous drainage, associated aneurysms)

3. Select treatment approach:

   • For accessible AVMs: Surgical resection, potentially with pre-operative embolization 4
   • For deep/eloquent AVMs: Consider radiosurgery or multimodality approach 4
   • For extensive AVMs with cardiac failure: Staged embolization to reduce shunt volume 3, 2

4. Long-term follow-up:

   • Monitor for recurrence with serial imaging 1
   • Assess cardiac function normalization 2, 5
   • Evaluate developmental outcomes and neurological function

Prognosis

• Neonates with symptomatic AVMs tend to fare worse than those presenting later in childhood 1
• Mortality rate of 25% is associated with hemorrhagic events from pediatric AVMs 1
• Long-term outcomes are influenced by location, size, treatment modality, and presence of complications 4