What you may notice
A report may describe an aneurysm (an artery-wall bulge), an AVM (an abnormal tangle connecting arteries and veins), or a fistula (an abnormal direct connection). Some are found incidentally; others are investigated after headache, seizures, bleeding, pulse-like ear noise or eye symptoms. The terms describe different problems.
An artery-wall bulge
What could cause it?
Normal vessel variants and other abnormalities can resemble these findings, so the actual images and specialist interpretation matter. An unruptured aneurysm is not the same as a brain haemorrhage. MRI, CT angiography or catheter angiography may clarify the anatomy when clinically needed; not every finding requires an invasive test.
When to contact a doctor
Arrange a neurovascular specialist review of a new report and bring the images, not just the written conclusion. Sudden severe headache, weakness, speech or vision change, a seizure or collapse needs emergency care: call 108. A painful red bulging eye or new double vision also warrants urgent assessment.
How interventional radiology may help
Neurointervention can use coils, flow-diverting devices or embolic materials for selected abnormalities. Monitoring, medicines for associated symptoms, surgery or focused radiation may be appropriate alternatives or partners. The benefit of preventing bleeding or relieving a fistula must be weighed against treatment risk; finding an abnormal vessel does not automatically mean it should be treated.
Further reading: detailed assessment and treatment options
Patient information sources
References are in English.
Educational information, not a diagnosis. The causes listed are examples, not a complete list. Tests and treatment depend on your individual assessment.