Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology
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To assess the modulation of acute provoked pain by repetitive transcranial magnetic stimulation (rTMS) of the motor cortex in patients with chronic neuropathic pain. ⋯ Previous studies have shown that rTMS delivered to various cortical targets by different protocols could modulate experimental pain, primarily in healthy subjects. The present results demonstrate the ability of motor cortex rTMS to interfere with the processing of acute provoked pain, even if there is an underlying chronic neuropathic pain.
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Transcranial direct current stimulation induces long-lasting changes in cortical excitability in humans depending on the current used. Further, transcutaneous spinal application of direct current (tsDCS) induces plastic changes in spinal conduction properties, tested by somatosensory evoked potentials. To verify this thesis on plastic changes in spinal circuitry, we investigated the effects of tsDCS on H-reflex size and post-activation depression. ⋯ Transcutaneous spinal DC stimulation might be a valuable new tool in modulating spinal motor pathways.
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To investigate changes in axonal persistent Na(+) currents in patients with neuropathic pain and the effects of mexiletine, an analogue of lidocaine, on axonal excitability properties. ⋯ Latent addition can be used for indirect in vivo monitoring of nodal Na(+) currents in large sensory fibers, and future studies using this approach in small fibers would provide new insights into the peripheral mechanism of neuropathic pain.
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Comparative Study
Effect of pain on the modulation in discharge rate of sternocleidomastoid motor units with force direction.
To compare the behavior of sternocleidomastoid motor units of patients with chronic neck pain and healthy controls. ⋯ These observations suggest that chronic neck pain affects the change in neural drive to muscles with force direction.
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Repetitive transcranial magnetic stimulation (rTMS) of the human motor cortex can produce long-lasting changes in the excitability of the motor cortex to single pulse transcranial magnetic stimulation (TMS). rTMS may increase or decrease motor cortical excitability depending critically on the characteristics of the stimulation protocol. However, it is still poorly defined which mechanisms and central motor circuits contribute to these rTMS induced long-lasting excitability changes. We have had the opportunity to perform a series of direct recordings of the corticospinal volley evoked by single pulse TMS from the epidural space of conscious patients with chronically implanted spinal electrodes before and after several protocols of rTMS that increase or decrease brain excitability. These recordings provided insight into the physiological basis of the effects of rTMS and the specific motor cortical circuits involved.