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Brain Abscess in HHT — SCE Infectious Diseases MCQ

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HardCNS InfectionBrain Abscess in HHTSCE Infectious Diseases

A 48-year-old woman presents with a subacute brain abscess confirmed on MRI. She has chronic pulmonary arteriovenous malformations (PAVMs) associated with hereditary haemorrhagic telangiectasia (HHT). Why is she at increased risk of brain abscess?

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Correct answer: E — PAVMs create a right-to-left shunt bypassing the pulmonary capillary filter, allowing venous bacteraemia to seed the brain directly

Pulmonary arteriovenous malformations (PAVMs) in HHT create anatomical right-to-left shunts. Normally, the pulmonary capillary bed acts as a filter for particulate matter and bacteria in venous blood. When blood bypasses this filter through PAVMs, transient bacteraemia (e.g. from dental procedures, GI mucosal breaks) can seed the cerebral circulation directly, causing brain abscess. Antibiotic prophylaxis before dental procedures is recommended in HHT patients with PAVMs. Embolisation of PAVMs reduces the risk.

Reference: BTS 2023 – PAVM management; NICE CKS 2024 – Brain abscess