# Mycotic cerebral aneurysm secondary to Streptococcus parasanguinis infective endocarditis: a case report

## TL;DR

This case report describes a rare instance of a cerebral aneurysm caused by Streptococcus parasanguinis infective endocarditis in a 70-year-old man.

## Contribution

The novelty lies in highlighting the rare association between S. parasanguinis and cerebral mycotic aneurysms.

## Key findings

- S. parasanguinis can lead to mycotic cerebral aneurysms as a complication of infective endocarditis.
- A multidisciplinary approach is essential for managing such complex cases involving both neurological and cardiac interventions.

## Abstract

The pathogenesis of infective endocarditis can cause a range of extracardiac complications. Delayed diagnosis may result in catastrophic embolic sequelae. Streptococcus parasanguinis is a pathogen that insidiously causes infective endocarditis and has rarely been associated with intracerebral mycotic aneurysms in contemporary medical literature.

The objective of this cae report is to describe the presentation, investigation, and management of a peculiar case of S. parasanguinis-associated infective endocarditis causing a mycotic cerebral aneurysm.

We report our experience in treating a 70-year-old New Zealand European male patient who presented with a left parietal lobe hemorrhage. He was subsequently found to have a mycotic cerebral aneurysm. The patient had underlying S. parasanguinis infective endocarditis. This patient was treated neurosurgically for the mycotic aneurysm with subsequent surgical valve replacement. We discuss relevant considerations of treating these pathologies. We discuss the clinical features, cardioradiology and neuroradiology of this obscure but important disease process.

S. parasanguinis, a viridans group Streptococcus, is an important cause of infective endocarditis but is rarely associated with cerebral mycotic aneurysms. It often causes a subacute form of infective endocarditis, which can hinder initial diagnostic clarity. When embolic phenomena cause the formation of an intracerebral aneurysm, the specific neuroradiological findings of intracerebral mycotic aneurysms should raise the clinician’s suspicion of underlying infective endocarditis. Infective endocarditis becomes significantly more common as people age. Thus, the holistic and objective clinician must maintain a broad differential and investigate widely until a definitive etiology is elucidated. Early recognition is key to favorable outcomes. Management of similar cases requires a multidisciplinary approach with both physicians and surgeons working to identify pathology and provide treatment in a logical sequence.