摘要:

AbstractElectrodiagnostic evaluation of patiets with suspected polyneuropathy is useful for detecting and documenting peripheral abnormalities, identifying the predominant pathophysiology, and determining the prognosis for certain disorders. The electrodiagnostic classification of polyneuropathy is associated with morphologic correlates and is based upon determining involvement of sensory and motor fibers and distinguishing between predominantly axon loss and demyelinating lesions. Accurate electrodiagnostic classification leads to a more focused and expedient identification of the etiology of polyneuropathy in clinical situations.

ISSN:0148-639X    

DOI:10.1002/mus.880131002

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

年代:1990

数据来源: WILEY

摘要:

AbstractA potentially fatal condition, yet preventable, malignant hyperthermia (MH) lacks a satisfactory noninvasive diagnostic test. Studying the effects of intravenous dantrolene (3 mg/kg) on electrically stimulated skeletal muscle, we found that this approach does not conclusively distinguish between normal humans and those susceptible to malignant hyperthermia but nonetheless yielded important information about the action of dantrolene in man and in MH. Supramaximal single‐and multiple‐pulse stimulation of the common peroneal nerve produced stable torque responses of the dorsiflexor muscles (monitored in vivo), which dantrolene suppressed. With the multiple‐pulse stimulation (5–6 pulses) this torque suppression was significantly less in MH‐susceptible subjects than in control subjects. This distinction, also observed in MH swine, confirms this animal as a good model for human MH. That dantrolene's effect in MH can be more completely reversed with high frequency stimulation is intriguing; presumably, excitation‐contraction coupling differs in MH and no

ISSN:0148-639X    

DOI:10.1002/mus.880131003

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

年代:1990

数据来源: WILEY

摘要:

AbstractThere is currently considerable interest in using disposable concentric needle (CN) electrodes for clinical electromyography (EMG). To determine how these electrodes compare with reusable CN electrodes, we have compared signals recorded by these two electrode types from the same muscle in normal subjects. We also made similar recordings with two groups of reusable electrodes. There was no difference in the features of motor unit action potentials (MUAPs) recorded by the two groups of reusable electrodes. Disposable electrodes performed satisfactorily in conventional EMG examination. However, compared to reusable electrodes, the disposable electrodes recorded MUAPs with smaller amplitude and area but with the same area: amplitude ratio and MUAP duration. The physical and electrical properties of the CNE groups were also investigated. Disposable electrodes had lower electrical resistance and greater capacitance than reusable electrodes when measurements were made in saline. Photomicrographs showed that the disposable electrodes had smaller recording surfaces and that the central wire was frequently eccentric in the cannula. The differences in electrical recording characteristics could be due to differences in the size of the recording surface, eccentric placement of the central wire in the cannula or differences in the metal used for the central wire. We conclude that electrical and physical testing may not predict the recording characteristics of needle electrodes. Electrophysiologic testing is necessary to determine how EMG signals recorded by new types of electrodes compare with those recorded by currently used electrodes.

ISSN:0148-639X    

DOI:10.1002/mus.880131004

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

年代:1990

数据来源: WILEY

摘要:

AbstractTwo children about to undergo corrective surgery were required to be investigated for malignant hyperthermia (MH). These investigations arose out of concern by the anesthetist who had obtained a history of unexplained pyrexial reactions to anaesthetic in other members of the family. Because over the years we have encountered several children with multiple congenital abnormalities who have been found to be susceptible to MH, we stressed the advizability of biopsying not only the patient but also the patient's parents. Positive responses for MH were obtained in the patients and in one of the parents on each occasion. The hypothesis of intrauterine MH with its pharmacogenetic propensity for heat production is considered as a possible etiological factor which may cause abnormalities of a congenital nature.

ISSN:0148-639X    

DOI:10.1002/mus.880131005

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

年代:1990

数据来源: WILEY

摘要:

AbstractA patient is described with “orthostatic” tremor. Electromyography revealed tremor bursts of 15 Hz in the lower extremities while standing and with isometric activation of the muscles, but the bursts disappeared with isotonic activation of muscles. Similar tremor was recorded in the arms with isometric, but not isotonic activation. Review of previously reported cases confirms these findings. The clinical and electrophysiologic features of this tremor distinguish it from other recognized forms of tre

ISSN:0148-639X    

DOI:10.1002/mus.880131006

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

年代:1990

数据来源: WILEY

摘要:

AbstractTwenty‐four adult albino rats were injected with tetanus toxin into the right gastrocnemius muscle and then subjected to sustained dorsiflexion of the right ankle joint for 2 to 14 days. Histologic examinations of the soleus after this procedure showed myopathic changes, characterized by variations in fiber diameters, myonecrosis with opaque fibers, interstitial fibrosis, and small groups of regenerated fibers. Electron microscopy revealed derangement of T‐tubules immediately adjacent to the sarcolemma in the early degenerative stage. The size and wet weight of soleus increased compared to that of the control side between 2 and 5 days post‐tetanus. Serum GOT, LDH, and creatine kinase (CK) levels were elevated especially in the early degenerative stages. Peri‐ and endomysial fibrosis developed gradually from about 3 days post‐tetanus. Pathomechanisms inducing these changes were

ISSN:0148-639X    

DOI:10.1002/mus.880131007

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

年代:1990

数据来源: WILEY

摘要:

AbstractWhen the force of muscle contraction is increased, the amplitude of the EMG envelope (ENAMP) increases. The ENAMP is usually assessed subjectively and its value in EMG analysis has been established. In this article we describe a method to make automatic measurements of the ENAMP. This method was tested on recordings of the EMG interference pattern (IP) from the biceps muscle of normal subjects. Normal values of this feature in the biceps muscle are described. There was a good concordance between the ENAMP measurements made by subjectve assessment and by automatic analysis and the ENAMP values correlated strongly with a previously described feature of the IP called the upper centile amplitude. We infer that ENAMP is a robust feature of the IP that reflects the amplitude of the largest MUAP in the IP.

ISSN:0148-639X    

DOI:10.1002/mus.880131008

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

年代:1990

数据来源: WILEY

摘要:

AbstractMuscle myotube cultures were obtained from normal and Duchenne muscular dystrophy (DMD) biopsies by using an explant technique. The currentvoltage (I/V) curve of the whole sodium (Na+) current (INa) in normal myotubes was similar to that obtained from DMD myotubes. However, the inactivation curve of the whole INawas different in normal myotubes when compared to that obtained from DMD myotubes. Addition of 10−4tetrodotoxin (TTX, a fast INablocker) decreased the whole INain both preparations. The inorganic calcium (Ca2+) blocker manganese (Mn2+) completely blocked the remaining TTX‐resistant INaof normal myotubes and decreased this current in DMD myotubes leaving behind a TTX‐ and Mn2+‐insensitive INathat was insensitive to the Ca2+blocker desmetoxyverapamil ((–)D888). The slow inward barium current (IBa) of both normal and DMD myotubes was blocked by Mn2+and (–)D888. However the kinetics of the slow channel in normal myotubes was different from that of DMD myotubes. This study demonstrates the presence of a TTX‐ and Mn2+‐insensitive INain DMD myotubes. This channel may contribute to the increase of intracellular Na+([Na]i) in DMD and allow Ca2+to enter the cells through the Na+Ca2+exchanger, thus contributing t

ISSN:0148-639X    

DOI:10.1002/mus.880131009

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

年代:1990

数据来源: WILEY

摘要:

AbstractWe present electrodiagnostic data on 30 patients with inclusion body myosistis (IBM) in order to better delineate its electrophysiological features. Comprehensive electromyography (EMG) and nerve conduction studies (NCS) were performed in all cases. Twelve patients had single fiber electromyography (SFEMG). EMG showed abundant short‐small motor unit potentials (MUP) with fibrillations and positive sharp waves in 56.6% of patients, and a mixed pattern of large and small MUP in 36.7%. In 6.7%, only “neurogenic” features were seen. NCS were slow in 33.3%. SFEMG revealed a mildly abnormal jitter and a slightly increased fiber density. IBM demonstrates a heterogeneous EMG profile. A pattern of large and small MUP is highly suggestive of IBM but is seen in only about one third of

ISSN:0148-639X    

DOI:10.1002/mus.880131010

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

年代:1990

数据来源: WILEY

摘要:

AbstractA muscle biopsy from a patient with hypothyroid myopathy showed striking central changes. “Cores” were seen in most type 1 fibers with oxidative enzyme prepartions. Electron microscopy of these areas revealed Z disc streaming, myofilament disruption, and absent mitochondria. The myopathy rapidly improved with thyroxine treatment. This biopsy is of interest, as numerous “cores” have not previously been reported in hypothyroid m

ISSN:0148-639X    

DOI:10.1002/mus.880131011

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

年代:1990

数据来源: WILEY