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Increase in hippocampal water diffusion and volume during experimental pneumococcal meningitis is aggravated by

Jon G Holler1, Christian T Brandt, Stephen L Leib

  • 1Department of Infectious Diseases, Copenhagen University Hospital Hvidovre, Kettegaard Alle 30, Hvidovre, Copenhagen 2650, Denmark. tiljon@hotmail.com.

BMC Infectious Diseases
|June 3, 2014
PubMed
Abstract

Insights

Bacterial meningitis in rats increases hippocampal apparent diffusion coefficient (ADC) and volume. Accompanying bacteremia significantly impacts these changes, highlighting its role in hippocampal alterations during infection.

Area of Science:

  • Neuroscience
  • Radiology
  • Infectious Diseases

Background:

  • Pneumococcal meningitis causes hippocampal apoptosis, leading to memory and learning deficits.
  • Understanding MRI-detectable changes in the hippocampus during meningitis is crucial for assessing neurofunctional outcomes.

Purpose of the Study:

  • To investigate changes in hippocampal apparent diffusion coefficient (ADC) and volume using MRI in experimental pneumococcal meningitis.
  • To determine the influence of bacteremia on hippocampal water distribution and volume.
  • To correlate MRI findings with the extent of hippocampal apoptosis.

Main Methods:

  • Experimental pneumococcal meningitis was induced in rats via intracisternal injection.
  • Four groups were studied: controls, meningitis, meningitis with early bacteremia, and meningitis with attenuated bacteremia.
  • MRI (T2 and diffusion-weighted) was used to measure hippocampal ADC and volume, correlated with cortical ADC, ventricular volume, and apoptosis.

Main Results:

  • Hippocampal ADC and volume were significantly increased in meningitis rats compared to controls.
  • Meningitis rats with early bacteremia showed significantly higher hippocampal ADC and volume than those with attenuated bacteremia.
  • Hippocampal ADC and ventricular volume were positively correlated, but neither correlated with apoptosis extent.

Conclusions:

  • Increased hippocampal volume and water diffusion in experimental meningitis are significantly associated with accompanying bacteremia.
  • Bacteremia, not apoptosis, appears to be a key factor influencing hippocampal changes observed via MRI in this model.

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