What are the symptoms of an arteriovenous malformation (AVM)?

Symptoms of Arteriovenous Malformations (AVMs)

The most common presenting symptom of brain AVMs is intracranial hemorrhage, occurring in 50-60% of all cases, followed by seizures (20-25%) and headaches (15%). 1, 2

Primary Clinical Presentations

Hemorrhagic Presentation (Most Common)

• Intracranial hemorrhage is the initial symptom in approximately half of all AVM patients, representing the most frequent mode of discovery 2, 3
• In pediatric populations, more than 75% of symptomatic AVMs present with hemorrhage 4, 2
• Hemorrhage carries significant consequences: mortality ranges from 10-30% for first hemorrhage, with 10-20% of survivors experiencing permanent neurological disability 1, 2
• The risk of recurrent hemorrhage is substantially elevated in the first year after initial bleeding, ranging from 6% to 32.9% depending on the study 4, 2

Seizure Presentation

• Seizures occur as the presenting symptom in 20-25% of adult AVM cases 2
• Seizures are more common in adults than children as an initial presentation 2
• Some evidence suggests patients presenting with seizures may be at slightly higher risk for subsequent hemorrhage, though this finding is inconsistent 4

Headache Presentation

• Headaches are the presenting symptom in approximately 15% of AVM cases 2
• These headaches can be chronic or acute in nature 5

Focal Neurological Deficits

• Focal neurological deficits can occur without obvious hemorrhage, resulting from mass effect or vascular steal phenomenon 4, 5
• Deficits may be fixed or progressive over time 5

Age-Specific Presentations

Neonatal and Infant Presentations

• Symptomatic neonates often present with unexplained high-output cardiac failure, and these patients tend to have worse outcomes 4
• Infants may develop hydrocephalus, particularly with posterior fossa lesions causing vein of Galen aneurysmal dilatation and aqueductal compression 4

Pediatric Presentations

• Children predominantly present with hemorrhage (>75% of symptomatic cases) rather than other symptoms 4, 2
• The remaining pediatric cases present with seizures, headaches, or focal deficits 4

Adult Presentations

• Adults show more varied presentations: hemorrhage (50-60%), seizures (20-25%), headaches (15%), or focal deficits 2
• AVMs can remain clinically silent for decades before becoming symptomatic 2

Less Common Presentations

Intracranial Hypertension

• Isolated intracranial hypertension mimicking pseudotumor cerebri can occur occasionally 4

Incidental Discovery

• Incidental AVMs are being diagnosed with increasing frequency due to widespread use of noninvasive neuroimaging 3
• These asymptomatic lesions are discovered during imaging performed for unrelated reasons 3

Associated Genetic Conditions

Hereditary Hemorrhagic Telangiectasia (HHT)

• Approximately 70-90% of pulmonary AVMs are associated with HHT, an autosomal dominant disorder 1
• Multiple AVMs should prompt consideration of hereditary hemorrhagic telangiectasia 4

Familial AVMs

• Familial AVMs have been described in families without specific genetic vascular conditions 4
• Multiple AVMs in the same individual are relatively common 4

Clinical Pitfalls and Important Considerations

• The absence of symptoms does not eliminate hemorrhage risk: unruptured AVMs carry a 2-4% annual hemorrhage risk 4
• Prior hemorrhage is the strongest predictor of future bleeding, making it a critical historical feature 4, 2
• Small AVM size paradoxically may be associated with higher hemorrhage risk, contrary to intuitive expectations 4, 2
• Comprehensive evaluation requires both detailed clinical examination and radiological clarification with MRI and arteriography after symptom presentation 4
• The lifetime risk of hemorrhage can be approximated by the formula: Lifetime risk (%) = 105 - patient's age in years 4, 2