摘要:

AbstractWe studied 4 siblings (3 men and 1 woman), ages 22 to 43 years, with congenital ptosis, external ophthalmoplegia, proximal muscle weakness and fatigability unresponsive to acetylcholinesterase (AChE) inhibitors. Repetitive nerve stimulation showed a significant compound muscle action potential (CMAP) area decrement at 2 or 3 Hz. Nerve conduction studies and concentric needle electromyography were normal, and repetitive CMAPs to single nerve stimulation were not observed. Voluntary single fiber electromyography (SFEMG) showed increased jitter and blocking. Assessment of individual end‐plates using SFEMG with intramuscular axonal microstimulation showed no uniform relationship between jitter and the rate of stimulation, consistent with a postsynaptic defect of neuromuscular transmission. Edrophonium eliminated the decremental response to repetitive nerve stimulation, but caused no significant clinical improvement, suggesting an additional mechanism for weakness in these patient

ISSN:0148-639X    

DOI:10.1002/mus.880150302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractWe performed in vitro microelectrode studies in the anconeus muscle biopsy of a 6‐week‐old infant intoxicated withClostridium botulinumtoxin B. The most striking abnormalities were the severe reduction of the endplate potential (EPP) quantal content and the marked variability of EPP latencies. The increased variability was often limited to a “single quantum” component of the EPP. Neither the amplitudes nor the frequencies of spontaneous miniature endplate potentials (MEEPs) were decreased. However, there was a wide range of amplitudes and frequencies of MEPPs. This unique combination of electrophysiologic findings indicates a severe presynaptic failure of neuromuscular transmission, which appears to result from an impairment of the process of synaptic vesicle release taking place after the stimulus induced influx of calcium into the motor nerve te

ISSN:0148-639X    

DOI:10.1002/mus.880150303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThis study of quantitative electromyography examines the influence of sample size on motor unit action potential (MUAP) tolerance limits, intertrial variability, and diagnostic sensitivity. We recorded 20 randomly selected MUAPs from the biceps muscle twice in 21 normal subjects, and once in 10 patients with myopathy. The 95% tolerance limits for mean total duration in normal subjects progressively narrowed from 6.6 to 14.2 ms for 5 MUAPs to 7.4 to 13.0 ms for 20 MUAPs. The 95% tolerance limits for intertrial variability were ±22% for mean total duration of 20 MUAPs. Larger sample size had a greater effect on reducing intertrial variability than on narrowing 95% tolerance limits for amplitude and area. Quantitative EMG results for duration supported the presence of myopathy in 2 of 10 patients with analysis of 5 MUAPs, and 9 patients with analysis of 20 MUAPs. Although analysis of 5 potentials may be adequate for diagnosis occasionally, quantitative analysis of 20 MUAPs narrows tolerance limits, reduces intertrial variability, and improves diagnostic sensitivity

ISSN:0148-639X    

DOI:10.1002/mus.880150304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractEach of 10 rats inoculated with a synthetic peptide comprising residues 125–147 (without a disulfide bond) of human acetylcholine receptor (AChR) α‐subunit (Hα) had deposits of IgG and C3 (immune complexes) and showed morphological changes in the fine structure at the motor end‐plates 5 weeks after a single immunization. Antibody to the Hα peptides was elevated 1 week after immunization, but, antibody levels to solubilized human or rat AChR were very low in 8 of the 10 rats. These results suggest that the immune response to peptide Hα is the myasthenogenic site, which induces morphological change at the e

ISSN:0148-639X    

DOI:10.1002/mus.880150305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractPrevious clinical and neurophysiological studies of uremic neuropathy have focused almost exclusively on the function of large sensory and motor axons. The sensations of heat and cold depend on the function of unmyelinated afferents and small myelinated afferents, respectively, and these sensations can be quantified using a standardized psychophysical technique. Thermal thresholds were measured in 20 patients with end‐stage renal failure to determine the extent of small afferent fiber involvement and to compare this with the clinical and electrophysiological evidence of large fiber involvement. Whereas abnormalities of standard nerve conduction studies were found in 16 patients, abnormal thermal thresholds were found in only 6 patients. In the nerve conduction studies, the amplitudes of nerve potentials were reduced more than their conduction velocities, consistent with an axonopathy. This study found little evidence of significant dysfunction of small afferent fibers in end‐stage renal failure and, when such changes occurred, they did not correlate with the clinical evidence of polyneuropathy. The functional sparing of axons of small diameter is consistent with the relative sparing of these axons in pathological stud

ISSN:0148-639X    

DOI:10.1002/mus.880150306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractClass II MHC antigen expression has been investigated in muscle tissue and cultured cells from normal human skeletal muscle by light and electron immunocytochemistry. In muscle tissue, these antigens were detected in satellite cells, interstitial cells, and blood vessels. In cultures, muscle cells were stained with a pan‐reactive anti‐HLA class II antibody and with isotypes specific for DP, DQ, and DR. The staining was present on mononucleated cells and persisted on myotubes; it was stronger for DR and DQ isotypes than for DP. At the subcellular level, staining was located not only at the cell surface, but also next to the endoplasmic reticulum and in the cytosol. Thus, myosatellite cells and aneurally cultured cells from human normal skeletal muscle express class II MHC antigens. Moreoever, the myotube staining and the presence of gold particles inside the cells suggested synthesis of these antigens after myoblast fus

ISSN:0148-639X    

DOI:10.1002/mus.880150307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractSkeletal muscle vibrates laterally during voluntary and evoked muscle contractions. We hypothesized that the vibration amplitude from evoked muscle twitches is directly related to evoked twitch force from fatiguing muscle. To test the hypothesis, vibrations produced by evoked muscle twitches were recorded during short (5‐second) rest periods as the muscle was intermittently exercised with voluntary contractions. Trials were performed at 30%, 50%, and 70% of maximal coluntary contraction. Evoked muscle twitches eliminated the problems of motivation and tremor that complicatye sound and vibration measurements during voluntary contractions. Results from the first dorsal interosseus hand muscle in 11 normal adult volunteers from the first dorsal interosseus hand muscle in 11 normal adult volunteers revealed that the vibration amplitude is highly correlated (r2= 0.93, at 70% MVC,r2= 0.97, at 50% MVC;r2= 0.85, at 30% MVC) with force. Both potentiation and reduction of force with exercise were accompanied by parallel changes in vibration amplitude, as measured with an accelerometer. Compound muscle action potentials did not increase with exercise‐induced twitch potentiation, and did not correlate as highly with force during fati

ISSN:0148-639X    

DOI:10.1002/mus.880150308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractTo evaluate the regenerative capacity of mdx skeletal muscle, changes in contractile properties of the fast‐twitch extensor digitorum longus (EDL) of normal and mdx mice were studied at 7 and 16 weeks of age, following denervation and devascularization (DD) at 4 weeks of age. At 7 weeks, DD EDL of both strains showed significantly decreased isometric twitch and tetanus tensions compared with their non‐DD controls. By 16 weeks, normal operated muscle exhibited a recovery of 57% and 58% of absolute tetanus and twitch tensions while the mdx EDL recovered remarkably to 96% and 99% of 7‐week values. At 7 weeks, the DD EDL of both strains exhibited significantly slower time‐to‐peak (TTP) and one‐half relaxation time (1/2RT). By 16 weeks, TTP and 1/2RT of the mdx DD EDL no longer differed from non‐DD controls, but the normal EDL showed slowed TTP. No differences were found in the maximum velocity of shortening (Vo) or in posttetanic potentiation (PTP). Following DD, there was an increase in resistance to fatigue in both strains at 7 weeks. This resistance persisted at 16 weeks in the normal mouse, but the operated mdx EDL returned to normal. It would appear that following a denervation/devascularization insult, the mdx EDL is able to recover contractile characteristics to a remarkably larger extent th

ISSN:0148-639X    

DOI:10.1002/mus.880150309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractA modified sensory “inching” method for the electrodiagnosis of carpal tunnel syndrome (CTS) Is described. The median nerve as stimulated at the cubital portion, with 8 channel recording electrodes placed along the nerve across the carpal tunnel. In most of the CTS cases, there was a conductive abnormality from 3 to 4.5 cm distal to the proximal ending of the flexor retinaculum. Subjects'; values, obtained by subtracting the theoretical latency from the measured latency, which were more than 0.6 ms, could not be improved by conservative therapy. As we could determine from subtle change at the short span of nerve condcution, below the electrodes from the proximal to the affected site of the carpal tunnel, this method provides high sensitivity and specificity for the diagnosis of

ISSN:0148-639X    

DOI:10.1002/mus.880150310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractWe studied membrane ultrastructural localization of anionic phospholipids (AP) and sialic acid (SA) calcium binding sites in muscle biopsies from Duchenne muscular dystrophy (DMD) and 3 Becker's muscular dystrophy (BMD) patients using polymyxin B (PXB) and limulus polyphemus (LP) as cytochemical markers. We found that AP calcium binding sites are lacking at muscle cell surface in all DMD muscle tissues, in both intact and degenerating muscle fibers. In BMD, AP have an unusual distribution along plasma membrane. Sialic acid calcium binding sites have the same localization along plasma membrane and basal lamina in DMD, BMD, and control muscles. The absence or alterations of structures involved in calcium binding in DMD and BMD may alter membrane calcium permeability, leading to abnormal Ca2+influx into cells causing muscle necrosis.

ISSN:0148-639X    

DOI:10.1002/mus.880150311

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY