T44. Abnormalities of motor axonal properties in amyotrophic lateral sclerosis

Abstract

Introduction To date, changes of axonal sodium and potassium currents have been reported in amyotrophic lateral sclerosis (ALS) (Bostock et al., 1995; Kanai et al., 2006), and the association to prognosis and characteristic symptoms such as fasciculations has been discussed. To confirm the previously reported changes, multiple axonal excitability properties were measured in patients with ALS, and compared with age-matched controls. Methods A total of 55 patients with sporadic ALS, who visited to Juntendo University Hospital from 2013 to 2017, were included in the study. Multiple excitability measurements were performed in the median nerve at the wrist using a computerized program (QTRAC with multiple excitability protocol, Institute of Neurology, London, UK). Results The age range of the patients was from 30 to 82 years old (median 62.7 years old), and there were 31 male and 24 female. As clinical phenotypes, 13 patients were bulber onset type, 31 were upper limbs onset type, 9 were lower limbs onset type, and 2 were multiple onset type. In ALS, there were extremely greater changes in depolarizing threshold electrotonus (P Conclusion This study suggested increased persistent sodium currents and reduced potassium currents in motor axons, as well as previous studies. Both of these changes lead to axonal hyperexcitability, and may contribute to the generation of fasciculations. Because neuronal hyperexcitibility is one of hypotheses of cause of neuronal death in ALS, these changes may also contribute motor neuronal death in ALS.