Terminal Innervation Ratio in Neuromuscular Disease

Abstract

The terminal innervation ratio (TIR) of 48 randomized biopsy specimens was measured by three examiners, two having no clinical or histological information on the patients. Analysis of variance and correlation coefficient between examiners demonstrated the reliability of the method. A control group of 31 biopsy specimens was compared to a previous control study of 12 biopsy specimens and to the measurement of the TIR in 13 healthy young adult volunteers. No significant differences were found. The normal mean value of TIR in biceps, palmaris longus, flexor carpi radialis, vastus medialis, and tibialis anterior was 1.11 ±0.05 SD (range 1.01 to 1.20). There was no significant difference in mean TIR between these muscles and no variation with age.