Study of Motor-evoked Potentials Using Transcranial Magnetic Stimulation in Young Healthy Indian Adults

• Main Authors: Shalesh Rohatgi, Prajwal Rao
• Format: Article
• Language: English
• Published: Wolters Kluwer Medknow Publications 2018-01-01
• Series: Medical Journal of Dr. D.Y. Patil Vidyapeeth
• Subjects: Motor-evoked responses; normal values; transcranial magnetic stimulation; young healthy Indian
• Online Access: http://www.mjdrdypv.org/article.asp?issn=2589-8302;year=2018;volume=11;issue=1;spage=53;epage=56;aulast=Rohatgi
• ISSN: 2589-8302; 2589-8310

Aim and Objective: Motor-evoked responses using transcranial magnetic stimulation (TMS) have been studied in India in various diseases. However, no normative data are available for young healthy Indian adults. The aim was to generate normative data for young healthy Indian adults in our laboratory so that it can be used as normative data for comparison in various disorders. Materials and Methods: Motor-evoked responses using TMS in 15 young healthy Indian adults (mean age 32.8 years, mean height 166 cm) was studied using circular flat coil capable of delivering 1.5 tesla magnetic energy. Various parameters such as cortical threshold (CT), cortical latency (CL), central conduction time (CCT), root latency (RL), and amplitude of motor-evoked potentials (MEP) were studied. Results: The mean CT was 830 standard deviation (SD) 45 mv (55%) for abductor pollicis brevis (APB), 930 SD 65 mv (62%) for biceps brachii, and 1260 SD 52 mv (84%) for extensor digitorum brevis (EDB). The mean CL was 21.2 SD 1.14 ms for APB, 11.5 SD 0.1 ms for biceps, and 37.6 SD 0.75 ms for EDB. The mean RL was 14.7 SD 0.96 ms in APB, 6.12 SD 0.78 ms in biceps, and 21.33 SD 1.30 ms in EDB. The mean CCT was 6.53 SD 1.02 ms in APB, 5.6 SD 1.1 ms in biceps, and 16.7 SD 0.92 ms in EDB. The mean MEP amplitude was 4.20 SD 2.14 mv in APB, 3.21 SD 1.37 mv in biceps, and 1.10 SD 0.38 mv in EDB. The mean normal value of MEP/MAP ratio for APB was 0.29 SD 0.09, for EDB 0.12 SD 0.03. Conclusion: Various studies have been done using TMS to study motor-evoked responses. However, there has been a slight difference in values among them due to the type of coil used, energy delivered, and interobserver difference. Every electrophysiology laboratory should have its own value to act as a baseline for comparison with that in disorders of nervous system. No data for normal values in Indian population is available.