Electrodiagnosis of vitamin E-deficient and denervated skeletal muscle of rabbits

¹ Department of Pharmacology and Therapeutics and Department of Anatomy, Graduate School and Stritch School of Medicine, Loyola University, Chicago, Illinois

Nutritional muscular dystrophy was produced in rabbits maintained on a vitamin E-deficient diet. Electrodiagnostic data collected from the anterior tibial muscles of these animals were compared with data from control animals on the same diet supplemented with vitamin E, and animals on the control diet which had unilateral surgical denervation of one anterior tibial muscle. Strength-duration curves of muscles developing dystrophy demonstrated a pronounced upward trend and were complex, containing two segments with a discontinuity at their juncture. This upward trend and the discontinuity of the strength-duration curves suggest the presence of denervation, for these are characteristically found in muscle denervated by partial or complete section of the motor nerve. Chronaxie, repetitive stimulation and galvanic tetanus ratio values of dystrophic muscle in the late stages were found to be comparable to the observations of the same criteria in the early stages of denervated muscle. No change in threshold of vitamin E-deficient muscle to faradic stimulation was found. In denervated muscle, response to faradic stimulation persisted, though with increased threshold at the end of a 60-day observation period.