Common Conditions Associated with Arteriovenous Malformations (AVMs)
AVMs are most commonly associated with hereditary hemorrhagic telangiectasia (HHT), with approximately 70-90% of pulmonary AVMs occurring in patients with this autosomal dominant disorder. 1
Primary Associated Genetic Conditions
Hereditary Hemorrhagic Telangiectasia (HHT)
- HHT should be considered in any patient presenting with multiple AVMs of the nervous system, as this represents the most significant genetic association 2
- Familial AVMs have also been described in families without a specific genetic condition that features vascular lesions 2
- AVMs have been inconsistently described as features of various other genetic conditions, though specific syndromes are not well-characterized in the guidelines 2
Genetic Mutations
- Recent evidence suggests that somatic and germline mutations contribute to AVM pathophysiology, particularly in peripheral AVMs 3
- TNF-α-238 AG genotype and ApoE ε2 carrier status are independent risk factors for hemorrhage in patients with AVMs 2
Associated Vascular Abnormalities
Aneurysms
- The occurrence of an aneurysm and an AVM in the same individual is more common in children than in adults 2
- Presence of intranidal aneurysms or feeding artery aneurysms increases the risk of hemorrhage 2
- Multiple aneurysms can coexist with AVMs and represent important risk factors for bleeding 2
Other Vascular Malformations
- In pediatric series, 42.6% of children with intracranial hemorrhage had some type of vascular anomaly including arterial aneurysm, cavernous malformation, AVM, or arteriovenous fistula 2
- Venous angiomas, capillary telangiectasias, and cavernous malformations can coexist with AVMs 2
- Multiple AVMs in the same individual are relatively common 2
Clinical Presentations and Associated Symptoms
Hemorrhage (Most Common)
- More than 50% of AVMs present with intracranial hemorrhage, which can be intracerebral, subarachnoid, or intraventricular 2
- In children, more than three-fourths of symptomatic AVMs present with hemorrhage 2
- The annual hemorrhage risk is 2-4% with mortality from first hemorrhage between 10-30% 2
Seizures
- Seizures occur in approximately 20-25% of AVM cases and may be focal or generalized 2
- After microsurgical obliteration, 83% of patients who initially presented with seizures were seizure-free at 2 years, with 48% discontinuing anticonvulsant therapy 2
Headaches
- Headaches occur in approximately 15% of AVM patients 2
- Occasionally, patients present with isolated intracranial hypertension that mimics pseudotumor cerebri 2
Focal Neurological Deficits
- Focal neurological deficits occur in fewer than 5% of cases 2
- These deficits are not due to obvious hemorrhage and may result from mass effect or altered perfusion 2
Age-Specific Associations
Neonates and Infants
- Symptomatic neonates often present with unexplained high-output cardiac failure, and these patients tend to fare much worse than those presenting later 2
- Some infants develop hydrocephalus, particularly when a posterior fossa lesion results in aneurysmal dilatation of the vein of Galen and aqueductal compression 2
- Large head due to hydrocephalus and seizures are common presentations in children younger than 2 years 2
Children and Young Adults
- An estimated 20% of cerebral AVMs are diagnosed during infancy and childhood 2, 4
- AVMs are typically diagnosed before the patient reaches age 40 years 2
Secondary Causes of Pulmonary AVMs
For extracranial (pulmonary) AVMs specifically:
Important Clinical Pitfalls
- Pregnancy may be associated with rapid growth of pulmonary AVMs due to hormonal changes, requiring heightened surveillance 1
- Severe vasospasm from AVM-related hemorrhage is distinctly uncommon, unlike aneurysmal subarachnoid hemorrhage 2
- Vascular malformation-related steal phenomena causing focal neurological deficit by altering perfusion are distinctly uncommon 2