摘要:

AbstractWe elicited motor evoked potentials (MEPs) using transcortical magnetic stimulation in 150 control subjects aged 14 to 85 years and 275 patients with a variety of diseases. There were no significant side effects.Cortex‐to‐target muscle latencies measured 20.2±1.6 ms (thenar),14.2 ± 1.7 ms(extensor digitorum communis), 9.4 ± 1.7 ms(biceps), and 27.2 ± 2.9 ms (tibialis anterior). Central motor delay between the cortex and the C‐7 and L‐5 measured 6.7 ± 1.2 ms and 13.1 ± 3.8 ms, respectively. Mean spinal cord motor conduction velocity measured 65.4 m/s. MEP amplitude expressed as a percentage of the maximum M wave was never less than 20% of the M wave. A value of less than 10% is considered abnormal. MEP latency increases linearly with age and central motor delay is longer in older subjects. Compound muscle action potentials and absolute MEP amplitudes decrease linearly with age.In multiple sclerosis (MS), MEP latency and central delay were often very prolonged. The MEP was more sensitive than the SEP in MS. In amyotrophic lateral sclerosis, MEP latencies were only modestly prolonged; the characteristic abnormality was reduced amplitude. When pseudobulbar features predominated MEPs were often absent. The MEP was of normal latency in Parkinson's disease, but age‐related amplitude was often increased. MEP latency and amplitude were normal in Huntington's disease. Abnormal MEPs persisted several months after stroke despite good functional recovery. The MEP could be used to advantage to demonstrate proximal conduction slowing and block in demyelinating neuropathies. In plexopathy, ability to elicit an MEP several days after onset of paresis was good evidence of neuronal continuity

ISSN:0148-639X    

DOI:10.1002/mus.880131102

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

年代:1990

数据来源: WILEY

摘要:

AbstractIn order to evaluate the mechanisms of weakness in muscles of patients with myasthenia gravis (MG), intercostal muscle biopsies were obtained from 9 normal subjects and 6 MG patients, and the compound muscle action potential (AP) and tension responses to nerve and muscle stimulation, and contracture responses on exposure to caffeine, were monitored in vitro. In normal muscle, on stimulation of the nerve or muscle at 30 to 100 Hz, the AP responses showed decrement in amplitude, one‐third of which was attributable to failure of neuromuscular transmission and two‐thirds to failure of muscle membrane excitation. On stimulation at 1 to 5 Hz, the AP responses showed very little decrement, while the contractile responses showed significant fade in tension, due to failure of E‐C coupling or contractility.In muscle from patients with generalized MG, stimulation of the nerve at all frequencies (1 to 100 Hz) caused much greater decrement in APs and fade in tension responses than in normal muscle, due mainly to failure of neuromuscular transmission. However, at 100 Hz, 40% of the decrement in APs was due to failure of muscle membrane excitation, and at 1 to 5 Hz, 40% of the fade in tension was due to failure of E‐C coupling or contractility, as in normal muscle. On direct stimulation the contraction and half‐relaxation times were slower and the tetanic tension was smaller than in normal muscle, especially in the MG patient with thymoma. Caffiene‐induced contractures were smaller in MG muscle than in normal muscle. These results indicate that while the weakness of MG muscle than in normal muscle. These results indicate that while the weakness of MG muscle is due mainly to failure of neuromuscular transmission, it is also partly due to reduced E‐C coupling or

ISSN:0148-639X    

DOI:10.1002/mus.880131103

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe sensitivity of monopolar and concentric electrodes for detecting fibrillation potentials (FP) has never been formally compared. We studied 35 muscles with FP, sampling 20 sites each with concentric and monopolar needles. The concentric needle identified 0.88 ± 3.44 (mean ± standard deviation) more sites with spontaneous activity. Although statistically significant (Wilcoxon signed rank test P<.03), this difference in sensitivity did not appreciably affect diagnostic interpretation. Subjects described the concentric needles as more painful. Needle insertions in 25 other muscles demonstrated that needle movement generated the majority of FP. We suggest that the increased tissue injury caused by concentric needles may account for both their increased sensitivity and discomfor

ISSN:0148-639X    

DOI:10.1002/mus.880131104

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

年代:1990

数据来源: WILEY

摘要:

AbstractA typical aspect of motoneuron plasticity is the sprouting which occurs during muscle reinnervation, resulting in a transitory multiple innervation of the muscle cells. In order to verify the effect of a decreased protection from free radical attack on the sprouting, the multiple innervation in the extensor digitorum longus muscle, following sciatic nerve crush and regeneration, was studied in vitamin E‐deficient rats. Thus, the innervated end‐plates and the end‐plates with multiple innervation were studied with histochemical and electrophysiological techniques. The percentage of innervated end‐plates was similar in both groups at 30 as well as at 60 days after nerve crush. Nevertheless, multiple innervation was found in a larger part of the muscle and it lasted longer in the deficient rats. This finding is discussed in relation to some of the major hypotheses of sprouting; it may be relevant in the treatment of some lesions of periphera

ISSN:0148-639X    

DOI:10.1002/mus.880131105

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

年代:1990

数据来源: WILEY

摘要:

AbstractWe studied 20 asymptomatic control subjects and 14 patients with clinically unequivocal cervical radiculopathy to compare the diagnostic value of thermography with that of electromyography. We measured the average skin temperature of designated regions over the neck, shoulder, and upper extremities. We then compared the temperature between corresponding regions of the two limbs, and between fingers innervated by different roots in the same hand. Thermography was abnormal in 6 patients (43%), whereas electromyography was abnormal in 10 (71%). Thermographic abnormalities were seen only in the hands and fingers, and the pattern did not follow the dermatome of the clinically involved cervical root. When compared to electromyography, thermography provided no additional diagnostic information. Thus, thermography does not have an established role in the evaluation of patients with cervical radiculopathy.

ISSN:0148-639X    

DOI:10.1002/mus.880131106

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

年代:1990

数据来源: WILEY

摘要:

AbstractThis study was designed to determine the effects of reduced neuromuscular activity on the expression of proteins associated with contractile and metabolic functions and the size of single muscle fibers in the cat soleus. Adult cats were spinalized (Sp) at T12‐T13 and maintained in a healthy condition for 6 months. Some of the cats were trained to weight‐support (Sp‐WS) for 30 minutes per day beginning one month posttransection. Cross‐sectional area (CSA), succinate dehydrogenase (SDH), alpha‐glycerophosphate dehydrogenase (GPD), and myofibrillar adenosine triphosphatase (ATPase) activities were determined in a population of single fibers identified in frozen serial cross‐sections. Each fiber was categorized as either light or dark based on its staining density for qualitative myosin ATPase, alkaline preincubation (pH 8.75). The Sp (45%) and Sp‐WS (31%) groups had significantly higher percentages of dark ATPase fibers than control (<1%). All dark ATPase fibers were shown to react positively for a fast myosin heavy chain monoclonal antibody, while some of these fibers showed a reaction to both fast and slow myosin heavy chain antibodies. Overall mean fiber CSA were significantly smaller (∼25%) than control in both Sp groups. In the Sp‐WS, but not the Sp cats, the dark fibers were larger than the light fibers (P<0.05), suggesting a preferential effect of postural training on the ATPase converted fibers. There were no significant differences among the three groups in any of the mean enzyme activities for either ATPase type fiber. However, there was a general tendency for the Sp cats to have elevated GPD and ATP activities per muscle; this appeared to be directly related to the percentage of fibers staining darkly for myosin ATPase. These data indicate that 6 months after spinalization some of the fibers of the slow muscle developed fast myosin staining patterns and oxidative and glycolytic enzyme profiles that are normally exhibited in fast fatigue‐resistant motor units. Periods of daily weight‐support appear to ameliorate some of these adaptations to spinalization. Further, the observation that SDH activities are maintained at control values in spinalized adult cats as well as in spinalized kittens (unpublished observations) suggest that, at least in the soleus, skeletal muscle fibers can maintain their oxidative potential even though there is a marked reduction in neuromuscular

ISSN:0148-639X    

DOI:10.1002/mus.880131107

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

年代:1990

数据来源: WILEY

摘要:

AbstractBeing the smallest functional units under neural control, motor units play an integral role in muscle physiology. However, at the present time, there does not exit any widely accepted technique for quantifying or estimating the number of motor units in a muscle. Specifically, the existing techniques are the increment‐counting technique, a technique based on spike‐triggered averaging, and a macro‐EMG based technique which vary in invasiveness from noninvasive to highly invasive, respectively. We discuss each of these techniques, along with their associated shortcomings, in d

ISSN:0148-639X    

DOI:10.1002/mus.880131108

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

年代:1990

数据来源: WILEY

摘要:

AbstractA previously reported family with amyloid polyneuropathy (FAP) was reinvestigated to determine the type of mutation in the transthyretin (prealbumin) molecule. Transthyretin was isolated from amyloid‐laden myocardium and serum, and tryptic peptides were resolved by high‐performance liquid chromatography. Amino acid sequencing of an anomalous peptide revealed an alanine‐for‐threonine substitution corresponding to position No. 60 of the transthyretin monomer. Detection of the FAP gene in asymptomatic carriers was accomplished by hybrid isoelectric focusing of transthyretin in the presence of dithiothreitol and high concentrations of urea, and by Southern blotting of Pvull‐digested leukocyte deoxyribonucleic acid. This type of FAP was found to be identical to the previously described Appalachian amyloid. Patients with FAP and their asymptomatic gene‐carrying offspring had significantly reduced levels of serum transthyretin and retinol‐bi

ISSN:0148-639X    

DOI:10.1002/mus.880131109

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

年代:1990

数据来源: WILEY

摘要:

AbstractTo assess the longitudinal dispersion of the stimulus induced by the magnetic coil, collision experiments were performed in seven normal ulnar nerves. A supramaximal electrical stimulus S1 was delivered at the wrist, and followed by a supramaximal stimulus S2 in the upper arm, which was either electrical (electrical collision studies), or magnetic (magnetic collision studies). The interstimulus interval was varied by 0.2 msec increments from the time of complete cancellation of the S2 evoked motor response onwards, to include the entire span of recovery of that compound motor action potential. Collision curves were obtained for both magnetic and electrical stimuli by plotting the amplitude of the motor response elicited by S2 as a function of the interstimulus interval. In all seven normal ulnar nerves, comparison of the collision curves showed that the S2 evoked motor response is restored significantly more slowly when magnetic stimulation is used. This finding is best explained by longitudinal dispersion of the stimulus induced by the magnetic coil relative to conventional electrical stimulation, the large fibers being stimulated further away from the coil than the small ones. This interpretation is confirmed by the findings obtained with the same method in two cases of ulnar neuropathy, and by comparison of different intensities of magnetic stimulation.

ISSN:0148-639X    

DOI:10.1002/mus.880131110

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

年代:1990

数据来源: WILEY

ISSN:0148-639X    

DOI:10.1002/mus.880131111

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

年代:1990

数据来源: WILEY