Muscle ultrasonography: a diagnostic tool for amyotrophic lateral sclerosis.

Objective: In a prospective study we tested whether muscle ultrasonography can differentiate between amyotrophic lateral sclerosis (ALS) and mimics. Furthermore, we assessed the ability of ultrasonography to identify subclinical lower motor neuron involvement.

Methods: In 59 patients, suspected for adult onset motor neuron disease, ultrasound scans were made of 12 different muscle groups.

Fasciculations and their F-response revisited: high-density surface EMG in ALS and benign fasciculations.

Objective: To compare the prevalence of fasciculation potentials (FPs) with F-responses between patients with amyotrophic lateral sclerosis (ALS) and patients with benign fasciculations.

Methods: In seven patients with ALS and seven patients with benign fasciculations, high-density surface EMG was recorded for 15 min from the gastrocnemius muscle. Template matching was used to search for pairs of FPs with a repetition within 10-110 ms.

Enhanced physiological tremor deteriorates plantar flexor torque steadiness after bed rest.

This study evaluated the effectiveness of resistance training to preserve submaximal plantar flexor (PF) torque steadiness following 60 days of bed rest (BR). Twenty-two healthy male subjects underwent either BR only (CTR, n=8), or BR plus resistance training (RT, n=14). The magnitude of torque fluctuations during steady submaximal isometric PF contractions (20%, 40%, 60% and 80% of maximum) were assessed before and after BR.

Sensitivity and specificity of the 'Awaji' electrodiagnostic criteria for amyotrophic lateral sclerosis: retrospective comparison of the Awaji and revised El Escorial criteria for ALS.

The Awaji Commission recently proposed a modification of the electrodiagnostic criteria for ALS. We assessed whether the Awaji recommendations improve the sensitivity of the early diagnosis of ALS. In a retrospective study we reviewed clinical and neurophysiological data for 213 patients who visited our motor neuron disease outpatient clinic between October 2006 and December 2008.

The alpha-motoneuron pool as transmitter of rhythmicities in cortical motor drive.

Objective: Investigate the effectiveness and frequency dependence of central drive transmission via the alpha-motoneuron pool to the muscle.

Methods: We describe a model for the simulation of alpha-motoneuron firing and the EMG signal as response to central drive input. The transfer in the frequency domain is investigated.

Pulsed high-dose dexamethasone versus standard prednisolone treatment for chronic inflammatory demyelinating polyradiculoneuropathy (PREDICT study): a double-blind, randomised, controlled trial.

Background: Pulsed high-dose dexamethasone induced long-lasting remission in patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) in a pilot study. The PREDICT study aimed to compare remission rates in patients with CIDP treated with high-dose dexamethasone with rates in patients treated with standard oral prednisolone.

Methods: In eight neuromuscular centres in the Netherlands and one in the UK, patients aged 18 years or older who had newly diagnosed definite or probable CIDP were randomly assigned to a treatment regimen of either pulsed high-dose dexamethasone or standard oral prednisolone.

Prospective, blind study of the triple stimulation technique in the diagnosis of ALS.

Objective: To evaluate the diagnostic yield of magnetic cortical stimulation with the triple stimulation technique (TST) to identify upper motor neuron (UMN) involvement in patients suspected of having ALS.

Methods: Fifty-nine patients were recruited to undergo TST in addition to the standard work-up for suspected motor neuron disease. TST combines transcranial magnetic stimulation of the motor cortex with collision studies, which results in a higher sensitivity in detecting UMN involvement.

Prevalence and distribution of fasciculations in healthy adults: Effect of age, caffeine consumption and exercise.

Our objective was to determine the prevalence and distribution of fasciculations in healthy adults and to assess the effect of age, caffeine and exercise. Fasciculations were studied with ultrasonography in 58 healthy adults in various age categories. Questionnaires were used to determine effect of caffeine and regular exercise on the presence of fasciculations.

Muscle imaging: mapping responses to transcranial magnetic stimulation with high-density surface electromyography.

Representations of different body parts or muscles in the human primary motor cortex overlap extensively. At the effector level, most muscles are surrounded by and overlap with several neighbours as well. This hampers the assessment of excitability in individual muscles with transcranial magnetic stimulation (TMS), even if so-called "focal" stimulating coils are used.

Firing pattern of fasciculations in ALS: evidence for axonal and neuronal origin.

Background: In amyotrophic lateral sclerosis (ALS), the origin of fasciculations is disputed. We hypothesized that the discharge pattern of fasciculation potentials (FPs) would be different for FPs arising in the motor axon or in the spinal motor neuron.

Method: FPs were recorded by high-density surface EMG of the biceps brachii or vastus lateralis muscle for 15 minutes in 10 patients with ALS.

Interspike interval analysis in a patient with peripheral nerve hyperexcitability and potassium channel antibodies.

Neuromyotonia or Isaacs' syndrome is a rare peripheral nerve hyperexcitability disorder caused by antibodies against potassium channels of myelinated axons. We present the high-density surface electromyographic (EMG) recordings of a patient with fasciculations and cramps due to neuromyotonia. To characterize the time course of hyperexcitability, we analyzed the interspike intervals (ISIs) between fasciculation potentials, doublet, and multiplet discharges.

Fasciculation potentials in high-density surface EMG.

Fasciculation potentials (FPs) are observed in healthy individuals, but also in patients with neurogenic disorders. The exact site of origin and the clinical relevance in distinguishing, for example, amyotrophic lateral sclerosis (ALS) from other neurogenic diseases based on specific characteristics of the FPs is still a matter of debate and needs further exploration. This report describes the use of high-density surface EMG (HD-sEMG), with multiple electrodes in a compact grid to noninvasively record FPs.

Measuring the cortical silent period can increase diagnostic confidence for amyotrophic lateral sclerosis.

We evaluated a modified measurement of the cortical silent period (CSP) as a simple procedure to add further confidence in the diagnostic work-up for ALS. Thirty-seven consecutive patients with a suspicion of having ALS were included together with 25 healthy volunteers, and followed until a final diagnosis (ALS versus 'ALS mimic') was reached. Using a CSP cut-off value of 200 ms for males and 150 ms for females, the following test characteristics were obtained for ALS versus ALS mimics together with controls: sensitivity for excluding ALS 0.

Inter-operator agreement in decomposition of motor unit firings from high-density surface EMG.

High-density surface EMG can be used to obtain a spatially selective representation of several motor unit action potentials. Recently, a decomposition of the signal into the underlying motor neuron firing patterns has been described. The reliability of the algorithm has not yet been tested.

Expectancy induces dynamic modulation of corticospinal excitability.

Behavioral studies using motor preparation paradigms have revealed that increased expectancy of a response signal shortens reaction times (RTs). Neurophysiological data suggest that in such paradigms, not only RT but also neuronal activity in the motor structures involved is modulated by expectancy of behaviorally relevant events. Here, we directly tested whether expectancy of a response signal modulates excitability of the corticospinal system used in the subsequent movement.

Using two-dimensional spatial information in decomposition of surface EMG signals.

Recently, high-density surface EMG electrode grids and multi-channel amplifiers became available for non-invasive recording of human motor units (MUs). We present a way to decompose surface EMG signals into MU firing patterns, whereby we concentrate on the importance of two-dimensional spatial differences between the MU action potentials (MUAPs). Our method is exemplified with high-density EMG data from the vastus lateralis muscle of a single subject.

Multi-channel EMG of the M. triceps brachii in rats during treadmill locomotion.

Objectives: The study aims at a precise characterisation of intramuscularly varying recruitment patterns within the triceps brachii muscle (long and lateral head; proximal, medial, distal regions) in the time course of averaged step cycles during locomotion.

Methods: The triceps brachii muscle of 15 Hannover rats was investigated with a supramuscular 16-electrodes grid during treadmill locomotion. Multi-channel electromyogram (EMG) was recorded simultaneously with high-speed videography.