Cerebral abscess

Case contributed by Royal Melbourne Hospital

Presentation

Recent (days to a couple of weeks) of cognitive decline and behavioural change.

Patient Data

Age: 80 years
Gender: Male
CT

CT demonstrates a hypodense frontotemportal lesion with ill-defined margins and patchy contrast enhancement, most notable in the leptomeninges of the Sylvian fissure and floor of the middle cranial fossa. 

MRI

MRI confirmed these findings. The peripheral contrast enhancement around the lesion is irregular (sometimes referred to as furry). The degree of vasogenic oedema is less than one would expect for a cerebral abscess, which may be due to partial treatment and relatively chronic time-course. 

MRS demonstrates a very high lactate peak. 

Most convincing is the very pronounced restricted diffusion (DWI and ADC). 

Features are consistent with an abscess, likely secondary to pachy / leptomeningitis which in turn was secondary to direct ascent of infection from the neck - probably from a thrombosed and infected emissary vein. 

This patient had been treated over the preceding weeks for a left sided parapharyngeal abscess, before presenting with altered mentation. They went on to have a craniotomy and evacuation of the cerebral abscess. 

Microbiology

Specimen Type : Pus

Description   : Left Frontal Cerebral Abscess

GRAM STAIN

  • Leucocytes : +++
  • Gram positive bacilli : +++
  • Gram negative coccobacilli : +++
  • Gram negative bacilli : +

CULTURE

  1. Prevotella Sp : +++
  2. Propionibacterium acnes : +++

Case Discussion

Historically direct extension from adjacent infections was the most common source. More recently haematological spread has become the most common aetiology. 

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Case information

rID: 13746
Case created: 12th May 2011
Last edited: 29th Jun 2017
Inclusion in quiz mode: Included

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