Chapter 33 Stimulation at the foramen magnum level as a tool to separate cortical from spinal cord excitability changes

Abstract

Publisher Summary Motor cortical excitability changes, induced by several physiological or pathological conditions, have been investigated by various techniques. To know how the motor cortical excitability changes, the excitability of spinal cord levels should be evaluated. Responses to transcranial magnetic stimulation (TMS) reflect the excitability of the whole motor system, including intemeurons of the motor cortex. Responses to transcranial electrical stimulation (TES) reflect excitability of the whole motor system caudal to the cortex, those to brainstem stimulation (BST) excitability of pathways caudal to brainstem, H-reflex, and F-wave spinal cord excitability. The motor cortical excitability changes can be speculated by comparing size changes of the responses to TMS with those of some of the aforementioned responses. This chapter explains stimulation at the foramen magnum level, as a tool for this purpose. It first briefly describes this stimulation method, then presents several examples to evaluate cortical excitability changes, using TMS and BST, and finally compare the usefulness of various methods.