MYCOTIC Brain Aneurysm

A mycotic brain aneurysm (also called a mycotic cerebral aneurysm) is an infected, balloon‑like dilation of a brain artery caused by a microorganism, most often bacteria from an infection elsewhere in the body such as infective endocarditis (infection of a heart valve). This weakens the arterial wall and can lead to rupture with brain hemorrhage, which is a life‑threatening emergency.​

Poor oral health can lead to a mycotic brain aneurysm because bacteria from an infection in the mouth can enter the bloodstream, travel to the brain, and weaken blood vessel walls, causing them to bulge and potentially rupture. Poor Dental hygiene and gum disease (periodontitis) are linked to an increased risk for this condition, which can be life-threatening. 

What it is

• “Mycotic” here means “infectious,” not necessarily fungal; most are due to bacteria, though fungi can occasionally be responsible.​

• The organism reaches the brain vessel wall (for example via septic emboli from an infected heart valve), causes inflammation and destruction of the wall layers, and a fragile aneurysm forms.​

How serious it is

• Intracranial (brain) mycotic aneurysms are rare but have a high risk of rupture, leading to subarachnoid or intracerebral hemorrhage, stroke, and death.​

• Reported mortality is much higher once rupture occurs compared with unruptured lesions, which is why early recognition and treatment are critical.​

Typical causes and risk factors

• Underlying infections include infective endocarditis, bloodstream infections, and in some cases infections in immunocompromised patients (HIV, cancer, diabetes, chemotherapy).​

• Risk is increased when infected material can embolize to brain arteries, especially from left‑sided heart valve infections.​

Symptoms and diagnosis

• Symptoms may include sudden severe headache, focal neurological deficits (weakness, speech or vision changes), seizures, or signs of stroke or brain bleed; some patients also have fever or signs of systemic infection.​

• Diagnosis relies on brain imaging and vascular studies (CT or MR angiography, or conventional cerebral angiography) along with work‑up to find the infection source (e.g., blood cultures, echocardiogram for endocarditis).​

Treatment

• Management usually combines prolonged intravenous antibiotics (or antifungals if indicated) to treat the underlying infection and either endovascular or surgical procedures to secure the aneurysm.​

• Endovascular techniques (such as coil or liquid embolization) are commonly used to occlude the diseased vessel segment; open surgery with clipping or bypass is considered when anatomy or infection extent makes endovascular therapy unsuitable.​

If this term came up in your own medical care or imaging report, urgent discussion with a neurologist and neurosurgeon (or neuro‑interventional specialist) is essential so they can explain your individual risk, imaging findings, and treatment plan.

Author

Paddy Kalish OD, JD and B.Arch Author and Blogger