Focal Lesion in Upper Part of Brachial Plexus can be Detected by Magnetic Cervical Motor Root Stimulation

Central and Peripheral Motor Conduction Studies by Single-Pulse Magnetic Stimulation

Single-pulse magnetic stimulation is the simplest type of transcranial magnetic stimulation (TMS). Muscle action potentials induced by applying TMS over the primary motor cortex are recorded with surface electromyography electrodes, and they are called motor-evoked potentials (MEPs). The amplitude and latency of MEPs are used for various analyses in clinical practice and research. The most commonly used parameter is the central motor conduction time (CMCT), which is measured using motor cortical and spinal nerve stimulation. In addition, stimulation at the foramen magnum or the conus medullaris can be combined with conventional CMCT measurements to evaluate various conduction parameters in the corticospinal tract more precisely, including the cortical-brainstem conduction time, brainstem-root conduction time, cortical-conus motor conduction time, and cauda equina conduction time. The cortical silent period is also a useful parameter for evaluating cortical excitability. Single-pulse magnetic stimulation is further used to analyze not only the central nervous system but also the peripheral nervous system, such as for detecting lesions in the proximal parts of peripheral nerves. In this review article we introduce four types of single-pulse magnetic stimulation-of the motor cortex, spinal nerve, foramen magnum, and conus medullaris-that are useful for the diagnosis, elucidation of pathophysiology, and evaluation of clinical conditions and therapeutic effects. Single-pulse magnetic stimulation is a clinically useful technique that all neurologists should learn.

Non-invasive electrical and magnetic stimulation of the brain, spinal cord, roots and peripheral nerves: Basic principles and procedures for routine clinical and research application. An updated report from an I.F.C.N. Committee

These guidelines provide an up-date of previous IFCN report on “Non-invasive electrical and magnetic stimulation of the brain, spinal cord and roots: basic principles and procedures for routine clinical application” (Rossini et al., 1994). A new Committee, composed of international experts, some of whom were in the panel of the 1994 “Report”, was selected to produce a current state-of-the-art review of non-invasive stimulation both for clinical application and research in neuroscience.

Since 1994, the international scientific community has seen a rapid increase in non-invasive brain stimulation in studying cognition, brain–behavior relationship and pathophysiology of various neurologic and psychiatric disorders. New paradigms of stimulation and new techniques have been developed. Furthermore, a large number of studies and clinical trials have demonstrated potential therapeutic applications of non-invasive brain stimulation, especially for TMS. Recent guidelines can be found in the literature covering specific aspects of non-invasive brain stimulation, such as safety (Rossi et al., 2009), methodology (Groppa et al., 2012) and therapeutic applications (Lefaucheur et al., 2014).

This up-dated review covers theoretical, physiological and practical aspects of non-invasive stimulation of brain, spinal cord, nerve roots and peripheral nerves in the light of more updated knowledge, and include some recent extensions and developments.

Motor cortical excitability in peritoneal dialysis: a single-pulse TMS study

The aim of this paper is to investigate cortical excitability in patients with end-stage renal disease receiving peritoneal dialysis (PD) without any symptoms suggestive of uremic encephalopathy. We performed transcranial magnetic stimulation for 52 PD patients and 28 normal subjects. We compared the active motor threshold (AMT), resting motor threshold (RMT), root latency, central motor conduction time (CMCT), and cortical silent period (CSP) in PD patients to those in normal subjects. AMT, RMT, CMCT, and CSP were not significantly different between PD patients and normal subjects. However, root latency was significantly prolonged in PD patients compared to normal subjects. The root latency correlated linearly with HbA1c or duration of PD in the patients. The results suggest that the corticospinal tract and the cortical and spinal excitabilities are preserved but the peripheral nerves are disturbed in PD patients. The severity of peripheral neuropathy corresponds to the severity of DM and the duration of PD. We uncovered no evidence suggestive of any subclinical abnormality of the motor cortical excitability in PD patients.