Muscle & Nerve. Supplement

The major clinical impact of single-fiber electromyography has been from its role in confirming, or excluding, the diagnosis of myasthenia gravis (MG). Jitter measurements also have a clinical role in demonstrating changes in disease severity in patients with MG and Lambert-Eaton myasthenic syndrome, in demonstrating subtle changes in motor unit architecture and physiology in patients with nerve and muscle diseases, and in demonstrating the remote effects of locally injected botulinum toxin. In addition to these clinical roles, the ability to identify the activity from single muscle fibers makes it possible to mark the discharges of single motor units...

The development of single-fiber electromyography is described. This method, introduced in 1963, was met with doubts, and there were strong arguments that subunits, 10-30 synchronized muscle fibers, were in fact being recorded. The dispute ended in 1971, and single-fiber electromyography is now generally accepted.

No abstract text is available yet for this article.

No abstract text is available yet for this article.

No abstract text is available yet for this article.

The recognition of uncommon pediatric motor unit disorders or unusual clinical presentations of common illnesses, such as Guillain-Barré syndrome (GBS), have increased the need for electromyography (EMG) in childhood critical care units. There are two different clinical sets, one appropriate to newborns and infants and the other to older children. Some illnesses that present as an acute floppy infant are not found in the differential diagnosis of motor unit disorders in the older child or adult. These include spinal muscular atrophy, postvaccine poliomyelitis, intrauterine GBS, infantile botulism, and severe myopathies, such as myotonia dystrophy, and some glycogen storage diseases...

The aim of this study was to describe the outcome of patients with critical illness polyneuropathy (CIP). Twenty-six patients with CIP were studied to determine the clinical and electrophysiological profile 13-24 months after the onset of CIP. Seven patients refused to participate in the study; 6 patients died within the 1st year. Eleven of the 13 survivors showed clinical evidence of polyneuropathy. Five of these patients also had mononeuropathies, including peroneal and ulnar nerves. The quality of life was markedly impaired in all patients...

The X-linked form of Charcot-Marie-Tooth disease has been associated with mutations in the connexin 32 (Cx 32) gene, which encodes a gap junction protein. The majority of identified mutations are missense, but a few nonsense mutations or frame-shifting microdeletions have been encountered. Functional assessments of the mutated gap junction protein have demonstrated altered or simple losses of function. Mutations segregate with a typical clinical phenotype, which is the result of an age-related, progressive neuropathy...

Local events in the milieu of injured peripheral nerve trunks may have an important influence on the likelihood of regenerative success or the development of neuropathic pain. Injury-related changes in the microcirculation of this milieu have provided some evidence that axonal endbulbs, structures that form at the proximal end of transected axons, dump peptides and other molecules into the injury milieu where they may exert local actions, including those on microvessels. During a later phase of nerve repair, macrophage influx and pancellular proliferative events appear to develop in a coordinated fashion...

Transcranial magnetic stimulation (TMS) is a safe, noninvasive, and painless way to stimulate the human motor cortex in behaving human subjects. When it is applied as a single-pulse, measurements such as central conduction time, motor threshold, silent-period duration, recruitment curve, and mapping of muscle representation can be determined. Paired-pulse TMS is a useful way to examine cortical excitability. Single and paired-pulse TMS have been applied to study plasticity following amputation and cortical excitability in patients with dystonia...

Recent studies support the long-standing hypothesis that continuous arm movements consist of overlapping, discrete submovements. However, the cortical activation associated with these submovements is unclear. We tested the hypothesis that electroencephalography (EEG) activity would more strongly correspond to the particular combinations of muscle electrical activity, the independent components (ICs) of surface electromyography (EMG), than the surface EMG from individual muscles alone. We examined data recorded from two normal subjects performing sustained submaximal contractions or continual, unpaced repetitive movements of the arm...

Recent advances in clinical neurophysiology have made it possible to non-invasively stimulate single motor axons and determine the physiological characteristics of the associated motor units. Some motor units lend themselves to longitudinal studies of their electrical and contractile characteristics. The former include the conduction velocities of their motor axons and the sizes and shapes of their motor unit action potentials and the latter such contractile characteristics of the motor unit as their contractile speeds, twitch and tetanic tensions, and resistance to fatigue...

We recorded the late electromyographic (EMG) responses to predictable and unpredictable stretches of the wrist flexor and extensor muscles during ballistic movement or isometric contractions. We simultaneously recorded the accompanying cerebral responses. Our findings suggest that the late EMG responses are influenced by suprasegmental (cerebral) phasic mechanisms that seem to have a dual functional role, being involved in the control of limb stiffness and in a servomechanism to return the displaced limb to its intended position...

No abstract text is available yet for this article.

No abstract text is available yet for this article.

Based on a review of the literature and the clinical research and experience of the authors and reviewers, the American Association of Electrodiagnostic Medicine proposes 17 criteria which should be used to construct and evaluate diagnostic and/or therapeutic outcome studies for patients with symptoms and signs of neuromuscular diseases. Neuromuscular diseases are defined as diseases that cause pathology and/or dysfunction of the sensory, motor, and/or autonomic nerve fibers and/or muscles.

No abstract text is available yet for this article.

No abstract text is available yet for this article.

No abstract text is available yet for this article.

No abstract text is available yet for this article.