Intracortical facilitation of the muscle response after transcranial magnetic double stimulation

✍ Scribed by Kazuo Kaneko; Shinya Kawai; Yasunori Fuchigami; Gen Shiraishi; Takashi Ito

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 244 KB
• Volume: 19
• Category: Article
• ISSN: 0148-639X
• DOI: 10.1002/(sici)1097-4598(199608)19:8<1043::aid-mus13>3.0.co;2-y

✦ Synopsis

Transcranial magnetic double stimulation at interstimulus intervals between 10 and 30 ms has been shown to increase the amplitude of muscle res p o n s e ~. ~~~~' ~ An intracortical mechanism has been proposed to explain this increased muscle response after magnetic double stimulation. The aim of this study was to investigate the facilitation mechanism by simultaneous recording of compound muscle action potentials and evoked spinal cord potentials following transcranial magnetic double stimulation in humans.

Methods

Five male patients (21-35 years of age) with unilateral brachial plexus injuries were studied. Informed consent was obtained from all subjects. Studies were performed during the relaxed muscle condition while the patients were awake and under general anesthesia with volatile anesthetics.

Two Magstim 200 magnetic stimulators were connected to a Bistim system (Magstim, Whitland, UK), and magnetic double cortical stimulation was delivered a round 14cmdiameter coil. The center of the coil was held over the vertex and fixed during the procedure.1° The stimulus intensities of both the conditioning and test stimuli were set at 100% of output, and the interstimulus interval was set at 20 ms. Epidural electrodes (Unique Medical Co., Japan, UKG100-5PM) were inserted percutaneously ~