BackgroundConstipation has been recently recognized as a complication associated with motor and autonomic dysfunction in patients with motor neuron disease (MND), typified by amyotrophic lateral sclerosis (ALS). However, the long-term characteristics of constipation remain unclear in patients with MND. We longitudinally investigated the prevalence and risk factors of constipation in a consecutive cohort of patients with MND. MethodsData from Japanese patients with MND enrolled in a single-center registry from June 2017 to December 2021 were retrospectively investigated. The diagnosis of ALS was based on the updated Awaji criteria, and other MND subtypes were also included. The presence or absence of constipation symptoms was determined by referring to the Rome III criteria. The clinical backgrounds and symptoms of patients with and without constipation were compared. ResultsAmong 155 consecutive patients (female, 63; age, 66.5 ± 12.4 years), 30.3% had constipation at diagnosis and 52.9% after a median follow-up of 18 months. Univariate analysis showed that female sex, use of tracheostomy and invasive ventilation, and delivery of enteral nutrition were more frequent in the constipation group. The Revised Amyotrophic Lateral Sclerosis Functional Rating Scale score was significantly lower in the constipation group, especially for the sub-items related to physical motor function. Multivariate analysis showed that the use of enteral nutrition was an independent risk of constipation, with an odds ratio of 3.69 (95% CI, 1.49–9.17; p = 0.005). ConclusionConstipation had a high prevalence in patients with MND with impaired motor function. Controlling defecation is important in patients with MND, especially during enteral nutrition.