Comparison of energy consumption in different clinical forms multiple sclerosis with normal subjects (cohort study).

BACKGROUND: Multiple sclerosis (MS) is one of the most common joint disorders that influence walking performance. OBJECTIVES: The objectives are to determine if energy consumption of three different clinical forms of MS differs from each other. Is there any difference between MS and normal subjects? Is there an association between the Physiological Cost Index (PCI) and the Expanded Disability States Scale (EDSS)? METHODS: MS subjects (EDSS>4) were separated in three groups based on the Ashworth and Ataxia scales, including ataxic (n=16), spastic (n=15) and ataxic-spastic (n=14). In addition, 13 age-and-gender-matched healthy subjects were used as the control group. A Heart Rate (HR) Polar Electro Finland was used to record the heart rate during resting and walking. The energy consumption was measured based on PCI. ANOVA, MANOVA, Post-hoc Tukey analysis and Pearson correlations were used for statistical analysis (P<0.05). RESULTS: There was a significant difference between the walking speeds of normal (76.05±5.70m/min) with ataxic (36.78±12.68m/min), spastic (34.45±16.32m/min) and ataxic-spastic (27.21±14.76m/min) groups (P<0.001). There were no significant differences between the resting HR and walking HR of four groups, and no significant difference between the PCI of ataxic, spastic and normal groups (P>0.1). The correlation between PCI and EDSS was 0.65 (P<0.001). CONCLUSION: The performance of the cardiovascular system in MS subjects was the same as normal subjects. Their energy consumption increased significantly due to a decrease in their walking speed. It seems that the weakness of muscles of the lower extremity and spasticity of knee extensors play a significant role in this regard.

A comparison of linear and nonlinear stability parameters in different clinical forms of multiple sclerosis.

BACKGROUND: Multiple sclerosis (MS) is one of the neurological diseases that affect the ability of subjects to stand and walk. The stability of MS subjects has been evaluated in various studies, mostly based on linear approach. Based on this approach it is controversial weather stability of MS subjects differ from normal or not. Therefore, the aim of this study was to evaluate stability in three groups of MS subjects (spastic, ataxic and ataxic-spastic) using both linear and non-linear approaches. METHOD: Seventeen healthy and 36 subjects with MS participated in this study. The MS group presenting with spastic, ataxic and ataxic-spastic (each group consisted of 12 subjects) participated in the study. The stability of the subjects was evaluated using Kistler force plate. The difference between stability of the subjects was evaluated using the Multi Analysis of Variance and significant value was set at P < 0.05. RESULT: There was a significant difference in the mean value of Approximate Entropy (ApEn) in anterior-posterior direction between normal (0.66 ± 0.13) and ataxic (0.85 ± 0.12) and ataxic-spastic (0.90 ± 0.12) subjects (P < 0.05) and no difference between normal and spastic groups (0.76 ± 0.13). The results of both linear and nonlinear approaches confirmed that both ataxic and ataxic-spastic subjects had more instability than normal subjects. Although, the mean values of stability parameters increased in spastic compared to normal, the difference was not statistically significant. CONCLUSION: Subjects with ataxic and ataxic-spastic MS disorder had difficulty in controlling their stability during quiet standing. The results of this study also confirmed that spasticity of muscles surrounding the hip and knee joints did not influence standing stability in patients with spastic MS.