ISSN:0148-639X    

DOI:10.1002/mus.880131202

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

年代:1990

数据来源: WILEY

摘要:

AbstractThis study examined the latency relationship between mechanically and electrically elicited sensory nerve action potentials (SNAPs) and the somatosensory‐evoked potentials (SEPs) they produce. Brief air‐puff and electrical stimuli were applied to the tip of the index finger in separate trials and SNAPs from the median nerve at the wrist and SEPs from the scalp were recorded for each stimulus presentation. Air‐puff evoked SNAPs were polyphasic, usually consisting of 2 to 4 separate waves, unlike triphasic activity elicited by electrical stimulation. The SEPs produced by these 2 distinct forms of inputs, however, were similar in morphology. The latencies of the initial components of SNAPs and SEPs were longer for air‐puff stimulation. The conduction time, however, of the fastest afferent volleys from the wrist to cortex was not significantly different for air‐puff (20.52 ± 1.06 ms, mean ± SD) and electrical stimulation (20.17 ± 0.66 ms). It is therefore concluded that the latency delays for air‐puff evoked SNAPs and SEPs are due solely to a transduction time at the skin receptors and not due to differences in conduction velocities as suggested in the previ

ISSN:0148-639X    

DOI:10.1002/mus.880131203

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

年代:1990

数据来源: WILEY

摘要:

AbstractWe recorded isometric and isotonic twitches, in situ, from the cat soleus at various muscle lengths and temperatures. At a given temperature the duration of isometric twitches increased approximately 60% for each 10% increase in muscle length, which was primarily owing to decreases in the rate of relaxation. For the relaxation of isometric twitches recorded at different muscle lengths, the equivalent activation energies determined were the same (13.2 ± 0.3 kcal/M). The duration of isotonic twitch contractions increased only 20% for each 10% increase in muscle length. Even a small amount of shortening (3%) diminished the dependence of twitch duration on muscle length. In this case, twitch duration increased approximately 30% for every 10% increase in muscle length. Hence, even small changes in internal and/or external compliance (eg, changes in the tendon‐fiber continuity) can greatly influence twitch duration. Our findings are consistent with the hypotheses that in the cat soleus, Ca2+sequestration is primarily governed by a single energy dependent process and that the Ca2+sensitivity of the contractile apparatus increases with increasing sarcomere leng

ISSN:0148-639X    

DOI:10.1002/mus.880131204

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

年代:1990

数据来源: WILEY

摘要:

AbstractElectrodiagnostic studies were analyzed in patients with neuropathy associated with IgM monoclonal proteins, 7 with anti‐myelin associated glycoprotein reactivity (MAG) and 7 nonreactive to MAG. The findings were distinctly different in the two groups. The electrodiagnostic studies of all the MAG‐reactive patients had demyelinating features with slowing of conduction and prolonged distal latencies while only one of the MAG‐nonreactive patients had a demyelinating pattern. In fact, the MAG‐nonreactive patients were a heterogeneous group, both electrodiagnostically and clinically. This study supports the concept that MAG‐reactive polyneuropathy is demyelinating in type, and is caused by the activity of the IgM M‐protein directed at an antigen in the my

ISSN:0148-639X    

DOI:10.1002/mus.880131205

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe purpose of this investigation was to determine the effects of low extracellular calcium and calcium antagonists on skeletal muscle staircase and fatigue. Initial experiments revealed that, brief exposure (10 minutes) of single frog sartorius muscle to diltiazem, D‐600 (5 and 30 m̈M) and low calcium Ringer's solution (LCR, calcium replaced by magnesium and EGTA) had little effect on isometric twitches evoked every 30 seconds. However, when stimulated at 1 per second for 15 minutes, the calcium antagonists significantly decreased the magnitude and time course of the staircase, whereas LCR decreased only the time course. Each experimental condition significantly increased the rate of fatigue while diltiazem and D‐600 both increased the magnitude of fatigue. Following the stimulation period, caffeine (10 mM) elicited contractures from all muscles whereas high potassium (180 mM) elicited contractures from control muscles only. These results indicate that calcium channel antagonists depress the skeletal muscle staircase response. They also indicate that these compounds as well as LCR enhance the fatigue process. Extracellular calcium influx may therefore have some influence on skeletal muscle twitches during prolonged repetitive acti

ISSN:0148-639X    

DOI:10.1002/mus.880131206

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

年代:1990

数据来源: WILEY

摘要:

AbstractNormal results of CMCT to upper extremities do not correlate with height, age, or sex. In cases of peripheral conduction slowing, upper limits of CMCT must be adapted. Cervical root excitation can be carried out by electrical or magnetic stimulation. The F wave technique also produces reliable results. Electrical stimulation of lumbar roots produces the most reliable results when measuring CMCT to leg muscles. CMCT to the tibialis anterior correlates with height, but not with age or sex. The same is true for intraspinal motor conduction time. Contraction of the target muscle enlarges CMAP amplitudes after cervical and transcranial stimulation. However, a latency shortening is only seen after brain stimulation. This is thought to be at least partially due to spatial summation of D and I waves. Age affects peripheral nerve conduction and central nerve conduction in different ways.

ISSN:0148-639X    

DOI:10.1002/mus.880131207

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe spatial distribution of muscle fibers belonging to a motor unit was studied in the soleus (SOL) and tibialis anterior (TA) of adult cats to provide a detailed description of the spatial patterns which exist within the territory of a motor unit. Glycogen depletion of the motor unit was achieved through repetitive stimulation of either the intracellularly identified motoneuron or the functionally isolated motor axon. Muscle fibers belonging to the stimulated unit were identified in serial cross‐sections, and in the cross‐section which contained the most depleted fibers the centroid of each depleted fiber was determined. Subsequently, three spatial analyses, ie, a quadrat analysis, a point‐to nearest neighbor analysis and an interfiber distance analysis, were used to determine if motor unit fibers were distributed randomly throughout the territory of the unit. Motor unit fibers tended to be localized within the muscle cross‐section and were not evenly or homogenously distributed throughout the territory. In general, the analyses suggested that motor unit fibers may be arranged in clusters or subgroups of varying size. The data demonstrate three different quantitative analyses for studying the organization of muscle fibers of normal motor units, which can be used for objective assessment and diagnosis of neuromuscular d

ISSN:0148-639X    

DOI:10.1002/mus.880131208

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

年代:1990

数据来源: WILEY

摘要:

AbstractMotor unit spike counts in the biceps brachii muscle were evaluated using a monopolar needle electrode during maintenance of antigravity posture with the elbow flexed to 45° before and after maximal voluntary contraction (MVC). After MVC, the number of motor unit spikes/second needed to maintain this posture was about 50% less than prior to MVC. Surface rectified integrated EMG activity declined in parallel to the decline in spike counts. To determine whether different muscles were compensating for the reduction in spike counts, synergistic muscles were examined simultaneously. Similar reductions were noted. In one deafferented subject, EMG activity increased rather than decreased after MVC. Fatigue decreases the contraction–relaxation rate of muscle fibers, which lowers fusion frequency. Thus, lower rates of motor unit activiation can result in the maintenance of constant force. A feedback system from muscle to CNS likely senses this slowing and leads to the spike count reducti

ISSN:0148-639X    

DOI:10.1002/mus.880131209

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe Schwartz–Jampel syndrome (SJS) is a rare congenital multisystem disorder of unknown pathogenesis which is characterized by distinct faces, skeletal deformities, joint contractures, short stature, muscle hypertrophy, clinical myotonia, and continuous muscle fiber activity. The inheritance pattern of SJS has been assumed to be autosomal recessive. We report the occurrence of the classic SJS syndrome in both a father and son in a non‐consanguineous family, suggesting that SJS has the potential for a dominant pattern of inherita

ISSN:0148-639X    

DOI:10.1002/mus.880131210

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

年代:1990

数据来源: WILEY

摘要:

AbstractIn 19 carpal tunnel syndrome (CTS) patients and 4 control subjects a catheter was introduced into the carpal tunnel and slowly retracted in 5 mm steps. Pressure was measured with the continuous infusion technique. In the same group of patients and controls, median nerve antidromic sensory action potential (aSAP) was detected introperatively stimulating proximally (S1), in the center (S2), and distally (S3) to the carpal tunnel and recording from the third finger (R). Sensory conduction velocity (SCV) and aSAP amplitude were considered in S1‐S2, S2‐S3 and S3‐R segments. The intracarpal tunnel pressure was significantly higher in CTS patients than in controls, with the highest values located between 25 and 35 mm distal to the proximal border of the flexor retinaculum. SCV and aSAP amplitude were also decreased most often in the distal part (S2‐S3) of the carpal

ISSN:0148-639X    

DOI:10.1002/mus.880131211

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

年代:1990

数据来源: WILEY