The objective of this study was to elucidate the mechanism of transcranial magnetic stimulation (TMS) with maximum voluntary muscle contraction (MVC) (used to facilitate motor neuron function), the effects of magnetic stimulation at the foramen magnum level with MVC were tested by recording motor evoked potentials (MEPs) and the maximum muscle force. In addition, changes in regional cerebral blood flow (rCBF) due to TMS to the motor cortex during MVC were assessed using near infrared spectroscopy (NIRS). Three MEPs in the first dorsal interosseus (FDI) muscle elicited by TMS to the motor cortex or foramen magnum stimulation were recorded before and then at 15 minutes intervals for 1 hour after 4 MVCs (while subjects maximally pinched a strain-gauge transducer for 2 seconds). Five healthy volunteers received TMS to the left motor cortex while maximally grasping a hand dynamometer for 2 seconds 3 times at 10-second intervals and then repeated TMS with MVC 4 times within 1 hour. Oxy-hemoglobin (Hb) and deoxy-Hb levels were recorded at 24 scalp sites using NIRS while subjects grasped a hand dynamometer with MVC for 5 seconds before and after TMS with MVC. Foramen magnum stimulation with MVC significantly decreased MEP amplitudes after TMS with MVC for 1 hour. Oxy-Hb concentration of the left M1, subtracting the right M1, tended to increase after TMS with MVC. The present results suggest that TMS during MVC induces increased cortical motor neuron excitability. However, further studies are needed to elucidate the mechanism of how TMS with MVC might modulate cortical neuron excitability.
Effect of Combination Therapy of Low-Frequency Repetitive Transcranial Magnetic Stimulation and Intensive Occupational Therapy on Poststroke Patients with Upper Limb Paralysis
