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<23),while the obese somatotype group(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),when the magnetic stimula- tion of 70%the stimulator output was employed.but all the indexes were not difierent when 90%the stimulator uot- put were adopted(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),but all the indexes were not different within 3 groups when 90%the stimulator output was adopted(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.