[Fatigue and functional system involvement in multiple sclerosis]

Fatigue is a frequent complaint in multiple sclerosis (MS) patients. Its pathogenesis is unknown and the question of whether or not there is a specific type of fatigue in MS is controversial. The aim of this work was to determine the link between fatigue in MS and physical and psychological involvement. We studied 50 patients diagnosed of MS category la by Poser's criteria. They were examined using the Kurtzke and Hamilton scales for depression and anxiety. We also applied an original scale for assessing the spontaneity, clinical characteristics, severity and frequency of fatigue. Asthenia, a tendency to feel tired and a worsening of other symptoms were identified as clinical traits. Using statistical tests for non parametric distribution of data (Spearman's R and Kruskal-Wallis's H coefficients), we found a positive correlation between the characteristics of and severity of fatigue and functional system involvement, anxiety and depression. Thirty-one (62%) patients suffered fatigue, 22 of them spontaneously. Fatigue was the main symptom in 3. and was proportional to pyramidal involvement (r = 0.41; p < 0.01) and intelligence quotient (r = 0.30; p < 0.03). Depression and anxiety were not related to fatigue (p > 0.05). Patients in the progressive phase of disease had higher fatigue scores than did patients who were stable or in remission. Disease duration was not proportional to fatigue. Our results point to a high rate of fatigue in MS patients. The severity of fatigue is proportional to pyramidal involvement and mental decline and is linked to phases of disease progression.