Changes in macro electromyography over time in patients with a history of polio: a comparison of 2 muscles.

OBJECTIVE

To investigate whether changes over time are different in a weight-bearing leg muscle than in a less heavily used arm muscle.

DESIGN

Prospective study.

SETTING

University hospital laboratory.

PARTICIPANTS

Twenty-three patients with a history of poliomyelitis.

INTERVENTION: Two investigations were performed 5 years apart, using macro electromyography and the patients' own assessments of symptoms in the tibial anterior and the biceps brachii muscles. Test-retest of macro electromyography was performed in controls and in patients with old polio.

MAIN OUTCOME MEASURES: Macro motor unit potential (MUP) and symptoms in the tibial anterior and biceps brachii over time.

RESULTS

The macro MUP amplitude increased by 24% (P<.05) in the tibial anterior but was unchanged in the biceps brachii muscle.

CONCLUSIONS

An increase in the macro MUP amplitude of the tibial anterior muscle, but not of the biceps brachii, most likely indicates a more pronounced ongoing denervation-reinnervation process over time in the tibial anterior. This difference could be activity dependent, but other factors cannot be excluded.