Motor unit action potential analysis of the paraspinal muscles. Paraspinal MUAP analysis is useful.
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Action Potentials↗
Biomedical subjects
Mark B Bromberg
Publications and source records attributed to Mark B Bromberg.
Corticosteroid use in the treatment of neuromuscular disorders: empirical and evidence-based data.
Corticosteroids have been used to treat neuromuscular disorders for many years. With few randomized, controlled trials, efficacy has been established primarily from empirical data. This has led to a range of treatment regimens varying in terms of initial dosing, dosing schedules, and taper rates. The goals of this review were to examine the literature for data concerning corticosteroid pharmacokinetics and for evidence-based treatment regimens in several prototypic neuromuscular disorders. The results provide a number of sound principles for corticosteroid use, but also indicate that corticosteroid regimens and patient management are largely based on empirical clinical experiences.
Adrenal Cortex Hormones↗
Comparison of conventional and decomposition-enhanced spike triggered averaging techniques.
OBJECTIVE: Spike triggered averaging (STA) is a technique to extract an estimate of a recurring motor unit potential from a complex electromyographic (EMG) signal. In conventional STA (C-STA), potentials related to the discharges of single intramuscular motor units are isolated and used to trigger an averager to obtain an individual surface-detected motor unit potential (S-MUP) from an EMG signal. In decomposition-enhanced STA (DE-STA), EMG signal decomposition algorithms determine discharges of a number of different motor units (4 to 10) that can be used to trigger an averager to obtain their corresponding S-MUPs. We tested the accuracy of extracting and averaging S-MUPs using DE-STA compared to C-STA for the same EMG signals. METHODS: We compared the intramuscular potentials used for triggering and the resultant averaged S-MUPs that were common in both techniques. RESULTS: We found no statistically significant differences in the metrics used to describe the triggering potentials and S-MUPs. CONCLUSIONS: We conclude that DE-STA is an accurate and efficient method to obtain a large number of intramuscular motor unit potentials and their corresponding S-MUP in proximal and distal muscles.
Action Potentials↗
Counting motor units in chronic motor neuropathies.
The degree of motor unit loss can not be accurately quantified in chronic motor neuropathies with routine electrodiagnostic testing or with pathologic examination. We used motor unit number estimation (MUNE), which is a unique electrophysiologic method that can estimate the number of surviving motor units innervating a muscle, to study axonal loss in spinal muscular atrophy (SMA) and Charcot-Marie-Tooth (CMT) neuropathies. MUNE is based on the ratio of the maximal compound muscle action potential (CMAP) to the average surface-recorded motor unit potential (S-MUP). The hypothenar muscle group was studied in infant and older subjects with SMA, and the hypothenar and biceps-brachialis muscle groups were studied in adult CMT1A and CMT2 subjects. The multiple point stimulation MUNE technique was used in SMA subjects and the spike triggered averaging MUNE technique was used in CMT subjects. In SMA, motor unit loss was profound in types 1 and 2 subjects and more moderate in type 3 subjects. In CMT, motor unit loss was prominent in distal muscles in both CMT1A and 2 subjects, and present in proximal muscles in CMT2 subjects. MUNE is efficient in assessing the degree of motor unit loss in chronic motor neuropathies. SMA is considered to be a proximal muscle disorder, but loss was marked in distal muscles in all SMA types. In CMT1A, the demyelinating form, motor unit loss was marked in distal muscles, consistent with the idea that axonal loss and not slow conduction velocity is the important pathologic condition. The pattern of proximal motor unit loss differed between CMT1A and 2, suggesting differences in underlying axonal pathology.
Action Potentials↗
Static magnetic field therapy for symptomatic diabetic neuropathy: a randomized, double-blind, placebo-controlled trial.
OBJECTIVE: To determine if constant wearing of multipolar, static magnetic (450G) shoe insoles can reduce neuropathic pain and quality of life (QOL) scores in symptomatic diabetic peripheral neuropathy (DPN). DESIGN: Randomized, placebo-control, parallel study. SETTING: Forty-eight centers in 27 states. PARTICIPANTS: Three hundred seventy-five subjects with DPN stage II or III were randomly assigned to wear constantly magnetized insoles for 4 months; the placebo group wore similar, unmagnetized device. INTERVENTION: Nerve conduction and/or quantified sensory testing were performed serially. MAIN OUTCOME MEASURES: Daily visual analog scale scores for numbness or tingling and burning and QOL issues were tabulated over 4 months. Secondary measures included nerve conduction changes, role of placebo, and safety issues. Analysis of variance (ANOVA), analysis of covariance (ANCOVA), and chi-square analysis were performed. RESULTS: There were statistically significant reductions during the third and fourth months in burning (mean change for magnet treatment, -12%; for sham, -3%; P<.05, ANCOVA), numbness and tingling (magnet, -10%; sham, +1%; P<.05, ANCOVA), and exercise-induced foot pain (magnet, -12%; sham, -4%; P<.05, ANCOVA). For a subset of patients with baseline severe pain, statistically significant reductions occurred from baseline through the fourth month in numbness and tingling (magnet, -32%; sham, -14%; P<.01, ANOVA) and foot pain (magnet, -41%; sham, -21%; P<.01, ANOVA). CONCLUSIONS: Static magnetic fields can penetrate up to 20mm and appear to target the ectopic firing nociceptors in the epidermis and dermis. Analgesic benefits were achieved over time.
Adult↗
Assessment of axonal loss in Charcot-Marie-Tooth neuropathies.
Sensory loss and weakness in Charcot-Marie-Tooth (CMT) neuropathy is due to axonal loss. However, the pattern and degree of axonal loss cannot be accurately determined from routine electrodiagnostic or strength testing due to collateral reinnervation. We sought to quantify axonal loss in two upper extremity muscles in CMT1A and CMT2 subjects using the electrophysiologic endpoint measure of motor unit number estimation (MUNE). Hypothenar and biceps-brachialis muscle groups were studied in 9 CMT1A, 9 CMT2, and 10 control subjects. The spike-triggered averaging (STA) technique was used to collect surface motor unit potentials for MUNE calculations, and a needle electrode was used to collect corresponding intramuscular data. Maximal voluntary hypothenar and handgrip strength was measured quantitatively, while biceps-brachialis strength was measured qualitatively. Compared to normal subjects, CMT1A and CMT2 subjects had significantly lower MUNE values in hypothenar muscles. Biceps-brachialis MUNE values were reduced in CMT2 but not in CMT1A subjects. In support of proximal axonal loss in CMT2 subjects, surface motor unit and intramuscular potential amplitudes were higher in biceps-brachialis muscles compared to controls. Correlations between quantitative strength and MUNE were significant for hypothenar but not for grip muscle groups. Axonal loss is demonstrated in distal muscles in CMT1A and CMT2 supporting a length-dependent axonopathy. Despite clinical findings of normal or near-normal strength and small reductions in compound muscle action potential (CMAP) amplitude, MUNE values were significantly lower in CMT2 subjects in proximal muscles, consistent with more diffuse denervation. These data indicate that subclinical axonal loss is present that cannot be appreciated using clinical examination or routine electrodiagnostic techniques.
Action Potentials↗
A survey of clinicians' practice in the symptomatic treatment of ALS.
UNLABELLED: Symptomatic management is the mainstay of ALS patient care, but there are few controlled trials of drugs and interventions for common symptoms. METHODS: We queried ALS clinic neurologists to determine drugs and interventions of choice and neurologists' perceived efficacy for 14 symptoms. RESULTS: The results are tabulations of the physicians' four most frequent choices for each symptom, the physicians' perception of efficacy, the average doses and average daily costs. A wide range of drugs and interventions were nominated for management of ALS symptoms. Consensus on treatment was rare for individual symptoms, and efficacy for any symptom was judged moderate at best. A few drugs were recommended for multiple symptoms. Comparisons of perceived efficacy compared to drug costs are informative. DISCUSSION: The results of the survey emphasize the challenges of symptom management in ALS. These data aid clinical management and guide rational choices for randomized controlled trials.
Amyotrophic Lateral Sclerosis↗
Comparison of instruments addressing quality of life in patients with ALS and their caregivers.
Most quality of life (QoL) instruments for ALS focus on function. An open instrument, the Schedule for the Evaluation of Individual Quality of Life-Direct Weight (SEIQoL-DW) that asks subjects to nominate and rate QoL areas important at the time of evaluation, was given to patients and caregiver spouses. Patients also completed function-based instruments. Correlations were poor between SEIQoL-DW and function-based instruments. SEIQoL-DW scores were worse for caregivers than for patients, probably explained by shifts in patient expectations with disease progression.
Activities of Daily Living↗
Motor unit number estimation in infants and children with spinal muscular atrophy.
Spinal muscular atrophy (SMA) is a disease of lower motor neurons. Motor unit number estimation (MUNE) is an electrophysiologic method to estimate the number of motor neurons innervating a muscle group. We applied the multiple point stimulation technique to the ulnar nerve--hypothenar muscle group to study lower motor neuron loss in 14 SMA subjects, including those presymptomatic, and varying from newborn through 45 years of age. Preliminary data support the value of MUNE to help understand the time course of motor neuron loss in SMA.
Action Potentials↗
Motor unit number estimation: con.
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Amyotrophic Lateral Sclerosis↗
Diagnostic criteria and outcome measurement of amyotrophic lateral sclerosis.
ALS is a most challenging disease. Accurate diagnostic criteria are well along in refinement, and experience with patients who are at the limits of the criteria should be presented to increase our comfort with the limits of ALS or motor neuron disease. As our understanding of the pathophysiology is further refined, there will be new drugs to test. It will be important to have sensitive clinical and electrophysiologic measures available to detect changes in the rate of progression. When effective drugs are identified, they will, in addition to helping patients, lend support to proposed mechanisms. Charcot would be impressed with our advances in the ability to detect and follow upper and lower motor neuron loss, but would urge us to press on in our clinical endeavors.
Amyotrophic Lateral Sclerosis↗