Changes in motor nerve excitability in acute phase Guillain-Barré syndrome.

Background: The most common subtypes of Guillain-Barré syndrome (GBS) are acute inflammatory demyelinating polyneuropathy (AIDP) and acute motor axonal neuropathy (AMAN). In the first days after the onset of weakness, standard nerve conduction studies (NCS) may not distinguish GBS subtypes. Reduced nerve excitability may be an early symptom of nerve dysfunction, which can be determined with the compound muscle action potential (CMAP) scan.

Motor nerve excitability after childhood Guillain-Barré syndrome.

Residual motor nerve dysfunction after pediatric Guillain-Barré syndrome (GBS) was determined in an observational cross-sectional cohort study in patients who previously developed GBS during childhood (<18 years). Ulnar motor nerve dysfunction was defined by compound motor action potential (CMAP) scan in patients after a follow up of at least 1 year compared with age-matched healthy controls, in relation to clinical course and outcome. A total of 37 persons previously diagnosed with GBS in childhood were included with a mean age at current examination of 20.

Electrically evoked multiplet discharges are associated with more marked clinical deterioration in motor neuron disease.

Introduction: The aim of this study was to determine whether electrically evoked multiplet discharges (MDs) are related to severity of clinical deterioration in motor neuron disease (MND).

Methods: Stimulated high-density surface electromyographic (HDsEMG) recordings were performed in thenar muscles. Data were collected from 31 MND patients.

Residual fatigue in Guillain-Barre syndrome is related to axonal loss.

Objective: To determine the occurrence of residual loss of peripheral nerve axons by motor unit number estimation (MUNE) and conventional nerve conduction studies (NCS) in patients with and without severe fatigue.

Methods: Thirty-nine patients at a median of 8 years (range 1-23 years) after diagnosis of Guillain-Barré syndrome were neurologically examined and divided in 2 subgroups based on the presence of severe fatigue (defined as a fatigue severity score ≥5). All patients were investigated with standard NCS and MUNE.

Limb motor nerve dysfunction in Miller Fisher syndrome.

Typical Miller Fisher syndrome (MFS) lacks limb muscle weakness, but some patients may unpredictably progress to severe Guillain-Barré syndrome. The compound muscle action potential (CMAP) scan is a recently developed non-invasive, painless, and reproducible method for detecting early changes in motor nerve excitability. This technique was used to monitor subclinical limb motor nerve dysfunction during disease course in typical MFS.

The CMAP scan as a tool to monitor disease progression in ALS and PMA.

Amyotrophic lateral sclerosis (ALS) and progressive muscular atrophy (PMA) are characterized by a loss of motor units (MUs), reinnervation and, eventually, muscle fibre loss. These three aspects are all reflected in the compound muscle action potential scan (CMAP scan, a high-detail stimulus response curve), which visualizes large MU potentials as 'steps'. We explored changes in the CMAP scan over time, combined the information on steps and CMAP amplitude into a CMAP scan-based progression score (CSPS), and correlated this score with motor unit number estimates (MUNE).

Multiplet discharges after electrical stimulation: new evidence for distal excitability changes in motor neuron disease.

We hypothesized that action potentials evoked by distal stimulation might trigger ectopic activity (multiplet discharges, MDs). By studying MDs, we investigated the involvement of the axonal part of the peripheral motor neuron in amyotrophic lateral sclerosis (ALS) and progressive muscular atrophy (PMA). We performed stimulated high-density surface EMG recordings of the thenar muscles in 10 ALS/PMA patients, five recordings per patient over a three-month period.

Optimal stimulation settings for CMAP scan registrations.

Background: The CMAP (Compound Muscle Action Potential) scan is a non-invasive electrodiagnostic tool, which provides a quick and visual assessment of motor unit potentials as electrophysiological components that together constitute the CMAP. The CMAP scan records the electrical activity of the muscle (CMAP) in response to transcutaneous stimulation of the motor nerve with gradual changes in stimulus intensity. Large MUs, including those that result from collateral reinnervation, appear in the CMAP scan as so-called steps, i.

Guillain-Barré syndrome subtypes related to Campylobacter infection.

Background: In Guillain-Barré syndrome (GBS), the diversity in electrophysiological subtypes is unexplained but may be determined by geographical factors and preceding infections. Acute motor axonal neuropathy (AMAN) is a frequent GBS variant in Japan and one study proposed that in Japan, Campylobacter jejuni infections exclusively elicit AMAN. In The Netherlands C jejuni is the predominant type of preceding infection yet AMAN is rare.

Reproducibility of the CMAP scan.

Introduction: The CMAP scan is a surface EMG method based on the successive activation of motor units. It provides information about reinnervation processes, the number of functional motor units and nerve excitability. The CMAP scan has potential value as a follow-up tool in monitoring disease progression, recovery or aging of the peripheral nerves.

Motor unit tracking with high-density surface EMG.

Following (tracking) individual motor units over time can provide important new insights, both into the relationships among various motor unit (MU) morphological and functional properties and into how these properties are influenced by neuromuscular disorders or interventions. The present study aimed to determine whether high-density surface EMG (HD-sEMG) recordings, which use an array of surface electrodes over a muscle, can increase the yield of MU tracking studies in terms of the number of MUs that can be tracked. For that purpose, four HD-sEMG recording sessions were performed on the thenar muscles of ten healthy subjects.

The electrophysiological muscle scan.

This study aims to assess the potential of the electrophysiological muscle scan or stimulus-response curve as a diagnostic instrument. If stimulus intensity is gradually increased from subthreshold to supramaximal values, all motor units in a muscle are successively activated. Thus, by plotting response size versus stimulus intensity, an impression (scan) of the entire muscle can be obtained.