Radiologically Suspected Ventricular Infection in a Patient With Recent Self-Extraction of a Carious Tooth: A Case Report

A brain abscess is a potentially life-threatening intracranial infection that usually requires individualized management.The possible source of infection may remain unclear when microbiological confirmation is unavailable.A 48-year-old man developed headache, fever, chills, and agitation approximately two weeks after selfextraction of a carious tooth.However, an odontogenic source was not microbiologically confirmed, and the temporal association alone did not establish causality.He also reported a history of swimming in a public pool, although the timing and characteristics of this exposure were unclear.After receiving empirical antimicrobial therapy at a local hospital without substantial improvement, he presented to Beijing Tiantan Hospital with a six-day history of fever and headache.Contrast-enhanced brain magnetic resonance imaging (MRI) showed a right frontal lesion radiologically consistent with a brain abscess and abnormalities of the left lateral ventricle and ependyma suggestive of ventriculitis, with possible intraventricular empyema.The suspected ventriculitis and intraventricular empyema were based on imaging findings and were not microbiologically confirmed.Cerebrospinal fluid findings were suggestive of purulent intracranial infection, although blood and cerebrospinal fluid cultures were negative after prior antimicrobial exposure.The patient did not undergo abscess aspiration, ventricular drainage, or craniotomy.No abscess or ventricular specimen was obtained for microbiological examination.He received sequential antimicrobial therapy, including meropenem, vancomycin, linezolid, and ceftriaxone.The decision to avoid stereotactic aspiration or ventricular sampling was made after full discussion among attending physicians and senior clinicians within our department.The patient's clinical status improved rapidly after initiation of antimicrobial therapy.The team judged that the risks of invasive sampling outweighed the potential diagnostic benefits, and ventricular involvement was considered in this risk-benefit assessment since intraventricular extension increases procedural hazards.His fever, headache, agitation, cerebrospinal fluid inflammatory indices, and MRI abnormalities improved during follow-up.This case describes clinical and radiological improvement after non-surgical antimicrobial therapy in a patient with a small frontal brain abscess and MRI findings suggestive of ventricular infection.Neither the temporal association with tooth self-extraction nor the reported swimming exposure should be interpreted as evidence of causation.Management of brain abscess should remain individualized and guided by clinical, microbiological, and radiological findings.