The Motor Cortex Mapping Using Transcranial Magnetic Stimulation by Large and Angled Figure of Eight Coil in Normal Subjects

J Korean Assoc EMG Electrodiagn Med 2010;12(1):14-18.
Published online June 1, 2010.

Abstract

Objective: To investigate the characteristics of the motor cortex mapping using large and angled figure of eight stimulator in normal subjects. Methods: Twenty-four subjects without history of neurological diseases were recruited. The motor cortex mapping for abductor pollicis brevis muscle was performed with large(diameter: 80 mm) and angled(120°) figure of eight stimulator. Results: The optimum stimulation point were found at coordination(5.83, 0.67), (-5.50, 0.54). Excitation threshold was 75.83% of the maximum stimulus for right motor cortex and 76.25% for the left. Average latency was 20.36 msec for the right and 20.35 msec for the left, and average amplitude was 367 μV for the right and 451 μV for the left, respectively. Ipsilateral motor evoked potential was not found in any subjects. Conclusion : We conclude that transcranial magnetic stimulation using this large and angled figure of eight coil is useful for motor cortex mapping.

Key Words: Figure of eight coil, Motor cortex, Brain mapping, Motor evoked potential, Magnetic stimulation