The presence of unknown polio engagement confirmed by electromyography and muscle testing

Abstract

Objective: To evaluate the usefulness of electromyography at a polio clinic in identifying unperceived muscle denervation. Second, to compare people who perceived themselves as weak in 1 or both legs with those who did not.

Design: Cross-sectional study.

Subjects: The study included 542 persons with late effects of polio in Sweden. Mean age 58 at the first visit, 312 were female. Data used are from a clinical quality registry.

Methods: At the first visit patients answered sent-out questionnaires. They underwent an electromyography test, walk test, and muscle strength assessment.

Results: Electromyography identified signs of chronic neurogenic changes in lower limb muscles (n = 260) where the patient reported no previous involvement, comprising 239 of the participants. Significant differences in values shows that the group who did not perceive themselves as weak exhibited better performance, demonstrating greater speed, strength, and reduced reliance on wheelchairs.

Conclusion: Electromyography can identify signs of muscle denervation in association with weakness in people with late effects of polio who perceived themselves as healthy. This comparison suggests that those that do not perceive weakness may unknowingly overuse their muscles. These findings contribute to our understanding of the late effects of polio and importance of early detection and rehabilitation.

Fig. 1

Flowchart of the cohort

Fig. 2

Boxplots of the muscle index (measure of strength) of the aware group (left) and the unaware group. The unaware group is significantly stronger.