Is there a relationship between fatigue questionnaires and gait mechanics in persons with multiple sclerosis?

OBJECTIVE To evaluate reported fatigue levels and gait deficits in patients with multiple sclerosis (MS) to determine the relationships that may exist between fatigue in patients with MS and alterations in gait mechanics. DESIGN Cross-sectional. SETTING Biomechanics laboratory. PARTICIPANTS Subjects with MS (n=32) and age- and sex-matched controls (n=30). INTERVENTIONS None. MAIN OUTCOME MEASURES Fatigue Severity Scale (FSS), Modified Fatigue Index Scale (MFIS), and 36-Item Short Form Health Survey (SF-36) to assess fatigue and general health. Biomechanical gait analysis was performed to measure peak joint torques and powers in the sagittal plane at the ankle, knee, and hip. Correlations were performed between fatigue measures and degree of deficit within each patient with MS for each joint torque and power measure. RESULTS FSS score significantly correlated with deficits in ankle power generation at late stance and walking velocity. MFIS score significantly correlated with deficits in peak knee extensor torque and knee power absorption at early stance. SF-36 subscale scores correlated with several joint torque and power variables. CONCLUSIONS Subjective fatigue rating scale scores alone should not be used as an indicator of motor disability or disease progression as it affects walking performance of patients with MS.