Supplements to Clinical Neurophysiology

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Trauma to the external anal sphincter resulting in incontinence is a relatively common disorder. Methods to detect damage include pudendal nerve conduction studies and needle EMG. We have applied a quantitative EMG technique using decomposition-enhanced software to isolate motor unit potentials (MUPs) and their surface representation from an anal probe electrode in healthy nulliparous women. MUPs were readily isolated and metric values compared favorably with those recorded with different software.

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This study assessed the accuracy of three automatic motor unit analysis algorithms--multi-motor unit analysis, decomposition quantitative EMG, and EMGtools--on a set of real EMG signals whose true composition was determined by manual decomposition. All three algorithms correctly identified all the MUs in signals with up to 5 active MUs, and most of the MUs in signals with up to 10 active MUs. The algorithms accurately estimated MUAP amplitudes and firing rates, but they estimated duration less accurately because of baseline noise...

Quantitative EMG (QEMG) is a useful technique to diagnose subtle neuromuscular disorders. Automated QEMG techniques rely upon computer algorithms to extract motor unit action potentials (MUAPs). A number of different algorithms are available and we have compared the performance of three of them. We have also assessed a number of variables related to the operations performed by the algorithms, including marking of MUAP metrics, data acquisitions time, and effects of raising the high-pass filter. We have also assessed whether there are differences in MUAP metrics depending upon where the needle is placed in the muscle...

For clinicians to use quantitative electromyography (QEMG) to help determine the presence or absence of neuromuscular disease, they must manually interpret an exhaustive set of motor unit potential (MUP) or interference pattern statistics to formulate a clinically useful muscle characterization. A new method is presented for automatically categorizing a set of quantitative electromyographic (EMG) data as characteristic of data acquired from a muscle affected by a myopathic, normal or neuropathic disease process, based on discovering patterns of MUP feature values...

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We have used a technique to estimate the number of functioning motor units (MUNE) innervating a muscle in mice based on twitch tension. The MUNE technique was verified by modeling twitch tensions from isolated ventral root stimulation. Analysis by twitch tensions allowed us to identify motor unit fiber types. The MUNE technique was used to compare normal mice with transgenic superoxide dismutase-1 mutation (G94A) mice to assess the time course of motor unit loss with respect to fiber type. Motor unit loss was found to occur well in advance of behavioral changes and the degree of reinnervation is dependent upon motor unit fiber types...

MUNE provides valuable information when applied to animal models of motor neuron disease. It is potentially useful as a supplement to therapeutic trials on the SOD-1 transgenic mouse model and has been able to show increases in the functioning motor units in response to some stem cell transplantation. Even in models that have subtle or imperceptible phenotypes, MUNE can show reductions in motor unit compliment. Thus, it is a valuable addition to the armamentarium of investigative tools when studying models of motor unit loss...

Poliomyelitis is a monophasic illness affecting lower motor neurons and individuals may describe new problems years after the initial weakness. We have studied 38 people with the post-polio syndrome over a 15-year period assessing a number of neuromuscular measures, including motor unit number estimation (MUNE). Twenty-five individuals reported progressive weakness but there was no objective change in MUNE and other measures. There was an association with reported weakness and initial deficits. There was a slow decline in MUNE values over time in both groups...

We examined the relationship between the degree to which motor unit number estimates (MUNEs) decrease in association with the clinical features of patients with the infarction. Using a multiple-point stimulation technique, we obtained the MUNE of the hypothenar muscle group in 13 age-matched control subjects and 30 patients with cerebral infarction. In all patients, we obtained the Japan Stroke Scale (JSS) and head MR images. In 8 patients with acute cerebral infarction, admitted within 24 h after onset, we also obtained head MR angiograms and single-photon emission CT...

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We prospectively studied 64 patients with motor neuron disease (amyotrophic lateral sclerosis (ALS), familial ALS (fALS), progressive muscular atrophy (PMA) and primary lateral sclerosis (PLS)) using multiple point stimulation motor unit number estimation (MUNE), transcranial magnetic stimulation (TMS), proton magnetic resonance spectroscopic imaging (1H MRSI), diffusion tensor imaging (MRDTI), and clinical measures at baseline and every 3 months thereafter for 15 months. Substantial differences in MUNE were noted among the motor neuron disease subgroups (P = 0...

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Although statistical MUNE has many positive attributes, it is inappropriate for use in multicenter ALS clinical trials. No other commonly used technique for MUNE possesses all the attributes necessary to be a valid and useful outcome measure in ALS trials. However, MUNE as a theoretical outcome measure remains extremely attractive and new techniques must be sought so that it can reach its full potential as a valid and reproducible outcome measure in ALS clinical trials.

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