Analysis of abnormal motor evoked potentials of the obese subjects induced by magnetic stimulation at T12 to L1

Abstract

Objective To study the abnormalities of motor evoked potentials(MEPs)obtained from obese subjects induced by magnetic stimulation at T12 to L1. Methods A total of 90 healthy subjects without any neuro-muscular system abnormalities were divided into 3 groups according to the body mass index(BMI).The control group consisted of 30 normal somatotype males(BMI 30)and weight-reduc-ing group(BMI>30)consisted of 30 obese somatotype males,respectively.The subjects in the control group and obese somatotype group maintain their usual lifestyle as before,while those in the weight-reducing group were reques-ted to lose weight by all means.MEPs were induced by using magnetic stimulation of 70%and 90%the output of the stimulator,respectively,at T12 to L1 and recorded from all the anbjcots at the time of admission to the study and one year later. Results At admission,the amplitude and conduction time of MEPs in obese somatotype group and weight-reducing group were significantly different from those in control group(P 0.05).One year later,the amplitude and conduction time of MEPs in obese somatotype group were significantly different from those in control group and weight-reducing group(P 0.05). Conclusion Supra-maximal magnetic stimulation should be used for recording the MEPs from the obese subjects,or false positive result would be obtained. Key words: Magnetic stimulation; Motor evoked potential; Obese subject