MS is a chronic disease of the central nervous system (which includes the brain and spinal cord) characterized by abnormal sensation, tremors, slurred speech, difficulty walking and moving, pain and sometimes blindness. Fatigue affects up to 87 percent of patients with MS and is a major reason why many MS sufferers remain unemployed, according to the article. Although the biological causes of fatigue are unknown, some scientists believe the widespread axonal (nerve fiber) damage associated with MS may also be the root cause of the fatigue reported by patients with MS.
Maria Carmela Tartaglia, B.Sc., M.D., of Montreal Neurological Institute and Hospital, Quebec, and colleagues examined the relationship between nerve fiber damage in the brains of patients with MS and fatigue. Based on their responses to a questionnaire on fatigue, patients were divided into two fatigue groups: low-fatigue (n=26), and high-fatigue (n=34). Using magnetic resonance spectroscopy, the researchers measured the N-acetylaspartate/creatine ratio (NAA/Cr, the ratio between these two naturally occurring brain chemicals is an indicator of proper nerve functioning, and a higher NAA/Cr ratio indicates better nerve functioning) in the brains of patients with MS.
The researchers found that the NAA/Cr ratio was significantly lower in the brains of patients in the high-fatigue group, indicating more nerve fiber damage and poorer nerve functioning.
"Our observations, combined with those of others, suggest that widespread axonal dysfunction is associated with fatigue in MS," the authors write. "It may be hypothesized that diffuse white matter [brain] disease translates into an incr
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