摘要:

AbstractA case study is reported regarding a 32‐year‐old man with classic clinical and electrophysiologic features of hereditary motor and sensory neuropathy, type I (HMSN I), a slowly progressive autosomal dominant condition marked by slow motor and sensory velocities and generalized segmental demyelination. Another clinically similar autosomal dominant neuropathy (HMSN II) is distinguished from HMSN I by nearly normal nerve conduction velocity. Acquired demyelinating neuropathy may occasionally resemble HMSN I clinically, but the former demonstrates electrophysiologic features not seen in the latter such as conduction block, dispersed compound muscle action potentials, and differential slowing of conduction velocity. Neuropathologic studies of HMSN I suggest that both neuronal and Schwann cell distrubances play a role in pathogene

ISSN:0148-639X    

DOI:10.1002/mus.880121102

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe cause of weakness was investigated in a patient with adynamia episodica hereditaria without myotonia. A pattern of exercise and rest produced episodes of hyperkalemic periodic paralysis. In addition, local muscle weakness was induced by forearm cooling. Investigations on isolated intercostal muscle demonstrated that a high potassium concentration in the bathing solution triggered a noninactivating membrane current causing depolarization of the muscle fibers. This current was carried by sodium as it could be inhibited by tetrodotoxin. The abnormal sodium conductance led to an increase of sodium within the fibers. This was demonstrated directly by intracellular recordings. Weakness induced by rest after exercise and cold‐induced weakness appeared to have different pathomechanisms. In the cold, the muscle fibers retained a normal resting potential, but their excitability was reduced and their mechanical threshold was increased. These findings also provide evidence that the mechanism of cold‐induced weakness in adynamia episodica is distinctly different from the cold‐induced weakness that occurs in paramyotonia cong

ISSN:0148-639X    

DOI:10.1002/mus.880121103

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe bulbocavernosus reflex (BCR) is a sacral segmental reflex which is suppressed throughout most of micturition. The BCR was evaluated by recording the associated EMG activity using a concentric needle electrode placed in the external urethral sphincter. The influence of the central nervous system (CNS) on the BCR was studied in 29 neurologically normal individuals and in 33 patients with upper motor neuron (UMN) lesions and voiding dysfunction. Ninety percent (26/29) of the neurologically normal patients did not have a BCR during most of micturition. By comparison, all the patients with an UMN lesion had a positive BCR beginning early during voiding. The finding of suprasegmental modulation of the BCR during voiding demonstrated by external urethral sphincter EMG was a more sensitive although slightly less specific sign of UMN bladder dysfunction than detrusor sphincter dyssynergia; uninhibited bladder contractions were neither sensitive nor specific for UMN lesions.

ISSN:0148-639X    

DOI:10.1002/mus.880121104

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

年代:1989

数据来源: WILEY

摘要:

AbstractTaurine reduces the excitability of striated muscle fibers by increasing the membrane conductance to chloride ions (GCI). This action was tested on rats made myotonic by drugs that blockGCIby different mechanisms. Experiments were made “in vivo” using electromyographic (EMG) recordings and “in vitro” with intracellular microelectrode recordings from extensor digitorum longus muscle fibers. Taurine did not antagonize the myotonic discharges produced in vivo by anthracene‐9‐carboxylic acid, nor did it restoreGCIlowered in vitro by this agent. However, when myotonia was chronically induced by 20,25 diazacholesterol, taurine given chronically in vivo or acutely in vitro antagonized the EMG myotonia as well as the reducedGCIand increased excitability of single fibers. We conclude that taurine acts directly on chloride channels to modify their kinetics. Our findings suggest that further clinical studies on the use of taurine in muscle disease involving abnormal excitability or chloride channel function wil

ISSN:0148-639X    

DOI:10.1002/mus.880121105

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

年代:1989

数据来源: WILEY

摘要:

AbstractElectrodiagnostic assessment of carpal tunnel syndrome (CTS) is hampered by the normal variability of conduction velocity, amplitude and duration of evoked responses, and hand temperature. Comparative testing of other nerves in the same hand may control for these variables and improve sensitivity for detection of mild focal entrapment. In consecutive cases referred for evaluation, antidromic sensory latencies were recorded from the thumb over 10 cm segments of the median and radial nerves, and the difference between these latencies was calculated. Median sensory antidromic conduction to digit III, ulnar sensory conduction, and median motor latency measurements were also made. Three hundred and thirty‐three upper limbs were studied in 262 patients. All tests were normal in 73 arms. Mild conduction slowing was identified in 86 median nerves. The median–radial latency difference was increased in 87% of these mild cases. The median–ulnar latency difference was diagnostic in 88%. Either median–radial or median–ulnar latency differences were abnormal in all confirmed cases. The routine median motor and sensory distal latency tests had sensitivities of 29% and 52%, respectively. Radial responses were elicited in 99% of the hands studied. The median–radial latency difference in digit I is a sensitive indicator of mild CTS that can be measured quickly with a minimum of

ISSN:0148-639X    

DOI:10.1002/mus.880121106

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

年代:1989

数据来源: WILEY

摘要:

AbstractCalcium (Ca2+) is mainly bound to anionic phospholipids and to sialic acid at the cell surface. We studied the ultrastructural localization of these Ca2+binding sites in normal human muscle fibers, using Polymyxin B as a marker for anionic phospholipids and the lectin Limulus Polyphemus as a probe for sialic acid. We found that anionic phospholipids have a patchy distribution along the muscle sarcolemma, with a preferential localization at the I band level and at the junction between the I and A band. Sialic acid has an uniform distribution along the muscle plasma membrane and basal lamina. Our observations suggest that the plasma membrane, basal lamina, and transverse tubular system play an important role in providing the negative charge of the human muscle cell surface and that these structures may be involved in the binding of calcium.

ISSN:0148-639X    

DOI:10.1002/mus.880121107

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

年代:1989

数据来源: WILEY

摘要:

AbstractElectrophysiological properties were monitored in detail in chronically constricted peripheral nerves by implanted, multicontact nerve cuff electrodes and correlated with morphometric histology in selected cases. The physiological and histological responses in nerve to a range of constricting cuffs of standard sizes were readily graded. The initial response to any significant constriction was a transient, focal conduction slowing or block at the constriction, followed by more protracted distal effects; the latter ranged from loss of excitability consistent with “dying‐back” degeneration to reductions in conduction velocity consistent with histologically observed atrophy. Smaller myelinated fibers tended to have similar but less pronounced changes than larger diameter fibers. Recordings from ventral and dorsal roots showed that distal degeneration was more pronounced in motor than in sensory fibers of similar caliber. Electronmicroscopical measurements showed that basal laminas were relatively preserved around even the most atrophic and demyelinated axons. Perimeter measurements of the basal lamina could be used to estimate the diameter of the original nerve

ISSN:0148-639X    

DOI:10.1002/mus.880121108

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe localization of the α subunit of the S‐100 protein (S‐100α) and β subunit (S‐100β) was studied in the peripheral nervous system of the rat. In peripheral nerves, S‐100α and S‐100β were found in the cytoplasm of Schwann cells. Axons were positively stained in part by S‐100α and almost totally by S‐100β. In the dorsal root ganglia, S‐100β was found in satellite cells and their processes and in some neurons. S‐100β was found in more of the large neurons, but almost all of the small neurons were negative for S‐100β. In the anterior horn cells, S‐100β staining was stronger than that of S‐100β. In Schwann cells, both S‐100β and S‐100β were present on the rough endoplasmic reticulum, free ribosomes, and nucleus, as seen by electron microscopy. The S‐100α and S‐100β in axons were

ISSN:0148-639X    

DOI:10.1002/mus.880121109

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

年代:1989

数据来源: WILEY

摘要:

AbstractTwo male patients from a single family with known PC and “potassium sensitivity” developed hypokalemic paralysis following generalized anesthesia. These patients confirm previous similar observations. It's significance and management are discus

ISSN:0148-639X    

DOI:10.1002/mus.880121110

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

年代:1989

数据来源: WILEY

摘要:

AbstractFatigue of tibialis anterior (TA) was induced by repetitive electrical stimulation. Using this test, patients with upper motor neuron muscle weakness owing to multiple sclerosis (MS) and injuries to the spinal cord showed greater fatigability of their TA muscles, suggesting that the muscle fiber population changed toward that typical of fatigable motor units. During repetitive stimulation, in addition to the decrement in tension there was an increase in half‐relaxation time of tetanic contractions at 40 Hz in both subjects and patients. The increase in half relaxation during repeated activity was greater in patients with MS and spinal cord injury than in healthy subjects, suggesting that the long‐term inactivity affected the efficiency of the Ca2+uptake mechanism of their muscle fibers. Thus long‐term inactivity of patients with upper motoneuron dysfunction leads to increased fatigability of their muscles and exaggerates the slowing of muscle relaxation after prolonged exe

ISSN:0148-639X    

DOI:10.1002/mus.880121111

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

年代:1989

数据来源: WILEY