Noninvasive Brain Stimulation Training to Help Recover Brain-related Symptoms

Introduction TMS is a non-invasive neuronal stimulation of surface areas of the brain that since its introduction in 1985 has been frequently used in neurology as a diagnostic and research tool. TMS uses magnetic fields to induce electrical currents that cross the nervous tissue depolarizing neurons, and reproduced motions generated are recorded as electromyograph potentials. TMS is able to explore the functionality of the cortical-spinal system, measure cortical excitability, mapcortical features, and evaluate brain modulators.

Repetitive transcranial magnetic stimulation (rTMS) is frequently used in the experimental field for cortical function scans and modulation of the intrinsic cortical plasticity. In particular, high frequency rTMS has facilitating effects on cortico-spinal excitability and the low-frequency one is usually inhibitory. rTMS is a method of extreme interest for the possible therapeutic role in conditions of altered cerebral excitability, both psychiatric (schizophrenia, posttraumatic stress disorder, obsessive-compulsive disorder, major depression) and neurological (epilepsy , stroke, degenerative diseases). At experimental level, the actual stimulation is compared with an inactive stimulus called sham, which acts as a control condition.

Direct Transcranial Electric Stimulation (tDCS) requires the application of weak electrical currents directly to the head for several minutes. These currents generate an electric field modulating neural activity based on the application mode. tDCS alters the rate of discharge of neurons. In fact, cathodic polarization applied to the motor cortex can induce a robust reduction in cortical excitability, while anodic polarization increases the excitability of the motor cortex. The short-term effects of tDCS are probably due to a change in neural membrane polarization. Similarly to rTMS, these changes last even after the end of stimulation for periods ranging from minutes to hours. Thus, tDCS can modify performance in many cognitive tasks.

Non-invasive cerebral stimulation have demonstrated a potential for the treatment of neurological disorders such as chronic pain, Parkinson's disease, neglect, aphasia, memory, motor deficiency and epilepsy. In general, non-invasive brain stimulation techniques have shown to induce changes in cortical plasticity that may last even beyond the end of the stimulation period. Considering this potential, there is an increasing interest in the application of these techniques in the therapeutic field.

In our study, we suggest evaluating any variations in the muscular tone of the lower limbs as a result of high frequency repetitive transcranial magnetic stimulation (rTMS) in patients with multiple sclerosis with relapsing-remitting pattern without evidence of medullary demyelination areas. rTMS allows modulation of intracortical excitability and can therefore modify the control of spinal excitability.