Fatigue in motor neuron diseases.

Motor neuron diseases as amyotrophic lateral sclerosis and post-polio syndrome are characterized by prominent muscular weakness and severe motor disability. The prevalence of fatigue in motor neuron diseases is remarkably high, and may contribute significantly to patients' disability and a poor quality of life. Despite its high prevalence, fatigue is an understudied clinical problem in motor neuron diseases and is often overlooked. The present review will attempt to explain the pathogenic mechanisms of muscle fatigue in amyotrophic lateral sclerosis and post-polio syndrome, to cover the various methods of quantification of fatigue that measure both subjective and physiological components, and to summarize the evidence regarding therapeutic interventions that can be used in order to minimize this symptom.