The effects of gender and age on motor unit number estimation in a normal population.

Motor unit number estimation (MUNE), is a method developed to determine the numbers of motor axons to the best possible quantity. In this study, we aimed to test the MUNE in different age groups in the normal population. This study was done on healthy volunteers who had not neither peripheral nerve nor systemic/ metabolic disease, and had a normal neurological examination. All had normal median and ulnar nerve conduction velocities. One hundred and ten subjects including 58 males and 52 females at a mean age of 38.9 +/- 6.6 years were evaluated in 3 age groups. There were 36 volunteers in the age range of 15-30, 44 in the age range of 31-45, and 30 in the age range > or = 46 (46-83). Manual incremental method was performed for MUNE. Studies and recordings with a stimulation of 0.1 msec in all subjects were completed. Gender did not have an effect on the scores (p = 0.472). Motor units detected by MUNE showed a relative decrease with ageing; however this was not statistically significant.