摘要:

AbstractFiltering of evoked potentials has been performed in clinical laboratories using both analog and digital methods. Analog methods introduce distortion caused by nonlinear phase shift which may be quite severe. Digital methods, while avoiding distortion caused by phase shift, reveal evoked potential components which may or may not correspond to distinct singular neuranatomic generators or homogeneous neuroanatomic systems. Thus, components identified with zero phase shift digital filters at restricted bandpass must be compared with components seen in open bandpass recordings. In some specific circumstances, high‐pass filtering of short‐latency somatosensory‐evoked potentials may distinguish slow asynchronous synaptic activity from fast and synchronous synaptic, lemniscal, or axonal activity. © 1992 John Wiley&Son

ISSN:0148-639X    

DOI:10.1002/mus.880150802

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

年代:1992

数据来源: WILEY

摘要:

AbstractFluorescence‐labeled dextrans were evaluated as markers for endocytosis in skeletal muscle. Fluorescein isothiocyanate (FITC)‐labeled dextrans (average molecular weight 3900 to 71200) showed a higher uptake in denervated than in innervated muscle both in vitro and in vivo. The in vitro uptake of FITC‐dextran (35.600) increased linearly with time at 37°C, and was almost completely inhibited by low temperature (4°C). The uptake was not a pure bulk uptake, because a saturable component was evident from the concentration dependence and from competition experiments with unlabeled dextran. The uptake of FITC‐labeled or rhodamine B isothiocyanate (RITC)‐labeled dextrans in denervated muscle occurred mainly in small segments of the fibers centered around the denervated endplate region. However, not all denervated fibers showed such segments. Periodic acid Schiff's base staining for carbohydrates stained dextrans in denervated muscle fibers. Some staining, probably of lysosomes, was also observed in denervated muscle not exposed to dextran. © 1992 John Wil

ISSN:0148-639X    

DOI:10.1002/mus.880150803

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

年代:1992

数据来源: WILEY

摘要:

AbstractStimulation of lumbosacral nerve roots using a monopolar needle electrode was compared with magnetic stimulation using a 7‐cm diameter surface coil. Compound muscle action potentials were recorded from the tibialis anterior (TA) and flexor hallucis brevis (FHB) muscles. Although the mean latency of CMAPs did not differ using the two techniques, amplitudes were considerably larger using a needle. Mean amplitudes were 66% (TA) and 64% (FHB) of the direct M response obtained by distal, supramaximal stimulation compared with mean values using maximal magnetic coil stimulation of 36% (TA) and 25% (FHB). Minimum F‐wave latencies from FHB were used to estimate the site of nerve root stimulation using both techniques. Although there was a large amount of variability in the data from individual subjects, the results suggested that, on the average, both forms of stimulation act proximal to the intervertebral foramen. We conclude that a needle electrode is a more suitable technique for stimulating lumbosacral nerve roots. © 1992 John Wiley&Sons,

ISSN:0148-639X    

DOI:10.1002/mus.880150804

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

年代:1992

数据来源: WILEY

摘要:

AbstractA patient with sensorimotor mononeuritis multiplex had a type II cryoglobulin with an IgM kappa M‐protein that appeared to contain monoclonal anti‐MAG antibodies of the same isotype. A sural nerve biopsy demonstrated necrotizing arteritis and features of both axonal degeneration and demyelination. IgM kappa and C3 deposits were present on the myelin sheath of some residual nerve fibers. The findings suggest that the anti‐MAG antibodies contributed to the myelin damage, while cryoprecipitates may have caused the vasculitis and axonal degeneration. © 1992 John Wiley&Son

ISSN:0148-639X    

DOI:10.1002/mus.880150805

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

年代:1992

数据来源: WILEY

摘要:

AbstractWe report cases of 2 patients with pure motor Guillain‐‐Barré syndrome of explosive onset who required mechanical ventilation for more than 2 months. Their electrophysiologic findings and poor clinical recoveries suggested severe axonal degeneration involving the motor nerves. Enzymelinked immunosorbent assay and thin‐layer chromatogram‐immunostaining showed the sera of both patients had high IgG antibody titer against GD1aganglioside. Their titers decreased with the clinical course of the illness. GD1aas well as GM1, appears to be the target pathogenic antigen in motor axon disorders. Elevated IgG anti‐GD1aantibody titer may prove useful for predicting severe GBS. © 1992 John Wile

ISSN:0148-639X    

DOI:10.1002/mus.880150806

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

年代:1992

数据来源: WILEY

摘要:

AbstractA Japanese family is described in which 6 persons showed familial amyloid polyneuropathy (FAP). Mean ages of onset were 38 for 4 males and 54 for 2 females. Three of the 6 became emaciated and died after 4 to 10 years. In 5, muscular weakness and autonomic dysfunction were the initial symptoms followed by sensory disturbances. Amyloidotic cardiomyopathy was present in 3 of the subjects. Amyloid deposits showed an immunohistological relation to transthyretin (TTR). Analysis of 1 patient's TTR gene revealed a single base change (A→G) that led to amino acid substitution (Glu42→Gly). This base change produced a new restriction site for endonuclease Cfr13 l in exon 2. Polymorphic analysis of the length of the Cfr13 l‐restriction fragment confirmed the base change, and made it possible to detect the mutant TTR Gly42 gene in the FAP subjects. Amino acid sequencing analysis showed a variant of TTR Gly42 in 1 patient's serum. © 1992 John Wiley&Son

ISSN:0148-639X    

DOI:10.1002/mus.880150807

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

年代:1992

数据来源: WILEY

摘要:

AbstractWe studied F‐wave minimum latency, persistence, and chronodispersion in the median and ulnar nerves of 70 controls and 75 patients with various polyneuropathies. Prolonged minimum latency was the most frequent F‐wave abnormality in all groups of patients with polyneuropathy. The finding of decreased persistence or absence of F‐responses was comparable in sensitivity to prolonged minimum latency in Guillain–Barré syndrome (GBS) and chronic inflammatory demyelinating polyneuropathy (CIDP), whereas chronodispersion had a comparable sensitivity only in CIDP. Decreased persistence of obtained F‐responses, and the absence of F‐responses in nerves with low compound muscle action potential amplitudes, were nonspecific findings. F‐wave studies often provide useful additional information in the evaluation of patients suspected of having a polyneuropathy. In patients with axonal polyneuropathies, we found that F‐wave studies are significantly more sensitive than standard motor conduction studies in identifying physiological abnormalities of motor axons. Furthermore, in a patient with an acquired polyneuropathy, the finding of markedly prolonged minimum latency, or the absence of F‐responses in nerves with normal CMAP amplitude, is highly specific for the presence of demyelination. © 1992 J

ISSN:0148-639X    

DOI:10.1002/mus.880150808

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe sympathomimetic agent, clenbuterol, induces a muscle‐specific hypertrophy in both normal and catabolic muscle. Drug‐induced hypertrophy is not generally associated with an increase in DNA content, thus the role of satellite cells in the response of soleus muscles from weanling rats is questioned. Following simultaneous sciatic section and administration of clenbuterol, responses are similar in innervated and denervated muscles after 4 days. Increased protein accretion in treated muscles is associated with evidence of satellite cell activation, but with little evidence of division. It is speculated that satellite cell production of growth factors may play an important role in the hypertrophic action of clenbuterol, and the clinical implications of the findings are discussed. © 1992 John Wiley&Sons,

ISSN:0148-639X    

DOI:10.1002/mus.880150809

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

年代:1992

数据来源: WILEY

摘要:

AbstractThere has been recent interest in measuring sympathetic sudomotor function by autonomic surface potential analysis. The purpose of the present study was to assess factors affecting the reproducibility of the test. We determined the within‐day and between‐day reproducibility in 24 healthy vclunteers. We used an increasing rather than a constant electrical stimulus to minimize habituation. The amplitudes were still highly variable (an average within‐day coefficient of variation in the soles of 35%). Habituation did not, however, affect the latencies of the responses, which were much more reproducible (an average within‐day coefficient of variation in the soles of 8%). Studies of between‐day reproducibility revealed that the mean amplitudes were lower on day 2 vs. day 1 (0.706 ± 0.10 vs. 0.85 ± 0.10 mV in the soles, P<0.01) but the mean latencies were similar on the different testing days (2.09 ±.04 seconds for the soles on day 1 vs. 2.16 ±.05 seconds on day 2). We also assessed the sensitivity of surface potential analysis and report the results of testing 35 patients with far advanced autonomic neuropathy. © 1992 John W

ISSN:0148-639X    

DOI:10.1002/mus.880150810

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe effects of phenytoin treatment were evaluated in 2 myotonic horses with hyperkalemic periodic paralysis (HPP). Phenytoin treatment abolished the clinical signs of muscle fasciculations following oral potassium challenge and decreased or abolished repetitive firing and myotonic discharges found on electromyographic examination. In both horses, an abnormally low threshold for calcium‐induced calcium release was measured in heavy sarcoplasmic reticulum fractions from skeletal muscle, and this threshold increased with phenytoin treatment. Results suggest phenytoin is useful in modifying disordered ion regulation in the sarcolemma and sarcoplasmic reticulum of skeletal muscle in equine hyperkalemic periodic paralysis. © 1992 John Wiley&Sons, I

ISSN:0148-639X    

DOI:10.1002/mus.880150811

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

年代:1992

数据来源: WILEY