Use of transcranial magnetic stimulation in the treatment of selected movement disorders

Abstract

Transcranial magnetic stimulation (TMS) is a valuable technique for assessing the underlying neurophysiology associated with various neuropathologies, and is a unique tool for establishing potential neural mechanisms responsible for disease progression. Recently, repetitive TMS (rTMS) has been advanced as a potential therapeutic technique to treat selected neurologic disorders. In healthy individuals, rTMS can induce changes in cortical excitability. Therefore, targeting specific cortical areas affected by movement disorders theoretically may alter symptomology. This review discusses the evidence for the efficacy of rTMS in Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, and multiple sclerosis. It is hoped that gaining a more thorough understanding of the timing and parameters of rTMS in individuals with neurodegenerative disorders may advance both clinical care and research into the most effective uses of this technology.

Insight Into the Effects of Clinical Repetitive Transcranial Magnetic Stimulation on the Brain From Positron Emission Tomography and Magnetic Resonance Imaging Studies: A Narrative Review

“…RMT is measured while the muscle is at rest, and it is defined as the minimal intensity of a single pulse of TMS required to elicit an MEP with a peak-to-peak amplitude ≥50 μV in at least 5 out of 10 consecutive trials ( Boroojerdi et al, 2001 ). AMT is obtained the same way but during an isometric contraction of 5–20% of the maximal voluntary contraction, and where the peak-to-peak MEP amplitude needs to be ≥200 μV in at least 5 out of 10 consecutive trials ( Berardelli et al, 2008 ; Boyd et al, 2014 ; Auriat et al, 2015 ).…”

Noninvasive brain stimulation as a rehabilitation tool for cognitive impairment.

“…The methods have focused on the motor system because TMS to the hand area of the motor cortex can evoke motor responses as quantifiable neurophysiological readouts. The measures, therefore, can be used as clinical tools to probe the pathophysiology of brain injury/disease and effectiveness of treatment on brain and/or behavioral outcome measures (e.g., diagnostic biomarkers; Brown et al, 2014). TMS also can be applied as a train of repetitive pulses to a brain region at a given intensity and frequency to induce plastic changes in the brain that outlast the stimulation period, and this can be used to assess the capability for plasticity (Hallett, 2007).…”

Transcranial Magnetic Stimulation as a Potential Biomarker in Multiple Sclerosis: A Systematic Review with Recommendations for Future Research

“…Nevertheless, several prospective modalities are under continuing evaluation and validation, including magnetic resonance imaging (MRI) [28, 29], optical coherence tomography (OCT) [30], corticospinal fluid (CSF) parameters [31], and neurofilament light chain (NfL) analyses [32]. Alternatively, some work has argued that TMS may be ideally suited as a surrogate marker for MS [33–35]. TMS has the potential to be less expensive, time consuming, and invasive than other methodologies used in the clinical approach to MS, lending support to its clinical use [36].…”

“…TMS has the potential to be less expensive, time consuming, and invasive than other methodologies used in the clinical approach to MS, lending support to its clinical use [36]. Furthermore, TMS has the unique ability to map and interrogate, in real time, characteristics of the CNS such as corticomotor latency, intracortical excitability, and transcallosal inhibition, which can be examined in relation to observable behaviour and clinical signs [24, 33–35, 37]. However, some TMS measures can be unreliable both between individuals and across time [38, 39]; their utility is highly dependent on factors related to the research participant, disease etiology, and laboratory environment [34, 40]; and stringent controls and rigorous reporting are required to glean valid physiological and clinical information from TMS findings [40].…”

“…Finally, few works have combined TMS and clinical assessments of MS [8, 41–43]. Overall, it is challenging to determine the clinical utility of TMS in its application to MS [33, 34, 44].…”