Fatigue in Multiple Sclerosis: Assessing Pontine Involvement Using Proton MR Spectroscopic Imaging
Wan Hazlin Zaini1, Fabrizio Giuliani2, Christian Beaulieu1
1Department of Biomedical Engineering, University of Alberta, Edmonton, Alberta, Canada.
Plos One
|February 20, 2016
Summary
Investigating fatigue in multiple sclerosis (MS), this study found higher creatine (tCr) in the pons of patients with severe fatigue. This suggests potential gliosis or creatine imbalance in the ascending reticular activating system (ARAS).
Area of Science:
- Neuroimaging
- Neurochemistry
- Neurology
Background:
- The mechanisms of fatigue in multiple sclerosis (MS) are not fully understood.
- The ascending reticular activating system (ARAS), located in the pontine brainstem, is a potential contributor to MS-related fatigue.
Purpose of the Study:
- To investigate the role of the ARAS in MS fatigue.
- To examine brain metabolite concentrations in the pons of MS patients with varying fatigue levels.
Main Methods:
- Magnetic resonance spectroscopic imaging (MRSI) at 1.5T was used.
- Seventeen female relapsing-remitting MS patients and 15 controls were recruited.
- N-acetylaspartate (NAA) and total creatine (tCr) were measured in the rostral pons using MRSI, with fatigue assessed by the Fatigue Severity Scale (FSS).
Main Results:
- MS patients with high fatigue (FSS ≥ 36) exhibited lower NAA/tCr ratios in the tegmental pons compared to controls.
- These changes were primarily driven by increased tCr concentration, not decreased NAA.
- The observed alterations were localized to white matter regions within the pons.
Conclusions:
- The elevated tCr in the pons of MS patients with fatigue may indicate gliosis.
- An imbalanced creatine and phosphocreatine ratio could also explain the findings.
- These metabolite changes in the ARAS may contribute to the pathophysiology of fatigue in MS.
