Analysis of the causes of micturition and defecation dysfunction in motor neuron disease patients

Objective To investigate the clinical features and causes of micturition and defecation dysfunction in motor neuron disease (MND) patients. Methods The micturition and defecation function was evaluated by a questionnaire covering storage and voiding of urine and feces respectively in 50 MND patients. The clinical features and external anal sphincter electromyography (EAS-EMG) were analyzed to explore the causes of micturition and defecation dysfunction in MND patients. Results Micturition and defecation dysfunction was detected in 9 of 50 (18.0%) MND patients. The main types of micturition and defecation dysfunction were constipation (4/9), urinary frequency, urgency with or without incontinence, fecal urgency (4/9), powerlessness for micturition and defecation (2/9), hesitancy for micturition (1/9). EAS-EMG was normal in 9 MND patients accompanied with micturition and defecation dysfunction. Conclusions MND patients accompanied with micturition and defecation dysfunction were not very rare. Constipation, urgency and powerlessness were the main types of micturition and defecation dysfunction and they were not related to the function of external anal sphincter. Gastrointestinal dysfunction from abnormal autonomic nerve involvement, muscle weakness and the resulted reduced activity, severe upper motor neuron damage and respiratory muscle weakness may be the main causes of micturition and defecation dysfunction in MND patients. Key words: Motor neuron disease; Amyotrophic lateral sclerosis; Constipation; Urination disorders; Anal canal; Electromyography