Abstract
In a case with the Eaton-Lambert syndrome (ELS), two unusual observations were made: (1) the reversible electromyographic findings and (2) histochemical abnormalities. The first needle electromyogram study in the weak muscles showed a significant decrease in mean duration of motor unit potentials (MUP) and increased polyphasic acitivity. With guanidine hydrochloride treatment these abnormalities were normalized. Decreased duration of MUPs is most likely secondary to functional loss of muscle fiber due to the basic defect of ELS. The histochemical study revealed type II fiber atrophy and type grouping in one fascicle. We believe that type II fiber atrophy is secondary to a form of disuse.

This publication has 5 references indexed in Scilit: