bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrophysiologic studies of critically ill patients
Authors: Bolton Charles F.
Published: January 2005

Sepsis and critical illness occur as complications of illness, injury, or surgery in approximately 5% of patients in our critical care unit. Clinical evaluation of the nervous system is difficult in this clinical setting, and electrophysiologic studies are therefore quite valuable. Electroencephalography detects encephalopathy and electromyography (EMG) and nerve conduction studies detect neuromuscular disorders at early stages of their development. Thus, septic encephalopathy occurs in almost all patients and critically ill polyneuropathy in at least 50% of such patients. The polyneuropathy is a predominantly distal axonal degeneration of motor and sensory fibers. A catabolic myopathy is also present, but is difficult to detect electrophysiologically. No defect in neuromuscular transmission has so far been demonstrated. Both the encephalopathy and polyneuropathy may be quite severe, but with vigorous management of the sepsis and critical illness complete recovery may occur in the 40% of patients who survive.
Superoxide dismutases, Glutathione peroxidase, And catalase in neuromuscular Disease
Authors: Burr Ian M. , Asayama Kohtaro , Fenichel Gerald M.
Published: January 2005

Studies in experimental muscular dystrophy indicate a possible role for anomalous redox metabolism in the genesis of these disorders, prompting a retrospective review of changes in redox‐active enzymes in Duchenne muscular dystrophy (DMD). Both manganous and copper‐zinc superoxide dismutase (Mn and CuZn SOD) content and glutathione peroxidase and catalase activities were measured in muscle biopsy specimens taken from normal individuals and from patients with Duchenne muscular dystrophy and other neuromuscular diseases. Muscle from patients with Duchenne dystrophy differed from the norm in that both Mn SOD and CuZn SOD were decreased and glutathione peroxidase was increased. This profile differed from that in anterior horn cell diseases in that CuZn SOD was not decreased in these disorders and from polymyositis, where CuZn SOD was decreased without an increase in glutathione peroxidase. Thus, there appears to be disease‐specific changes in these enzymes in DMD. These data support the concept that changes in redox‐active enzymes may be associated with the genesis of DMD.
Aging rat neuromuscular junnctions: A morphometric study of cholinesterase‐stained whole mounts and ultrastructure
Authors: Cardasis Constance A. , LaFontaine Donna M.
Published: January 2005

Previous morphological studies of the adult rat soleus neuromuscular junction (NMJ) indicate that its ultrastructure changes with age, a consequence of a dynamic, ongoing remodeling of pre‐ and postsynaptic elements. With aging, the balance between axonal sprouting and withdrawal appears to shift in favor of denervation. Here we have examined the extent and direction of the remodeling process during the adult life of the rat (5–111 weeks) by quantificatation and morphometry of NMJ structure as seen in electron microscopic composites and in cholinesterase (ChE) stained whole mounts.

We have found that the net effect of axonal sprouting and withdrawal on the entire NMJ region varies with age: at 5–12 weeks there is rapid growth and maturation; at 12–48 weeks slower growth occurs, and at 48–82 weeks there is a gradual shift in direction to result in progressive loss of synaptic contact in individual NMJs; finally, at 82–111 weeks, there is loss of entire NMJs with some continued reinnervation at others. The diaphragm NMJ also exhibits continuous structural remodeling; however, between 82–111 weeks many changes in the ChE staining pattern appear abruptly.
Deficient function of the sarcoplasmic reticulum in patients susceptible to malignant hyperthermia
Authors: Condrescu Madalina , López José R. , Medina Pablo , Alamo Lorenzo
Published: January 2005

Calcium uptake and (Ca2+ + Mg2+)‐ATPase were measured in sarcoplasmic reticulum (SR) vesicles prepared from muscles of eight patients susceptible to malignant hyperthermia (MH) and eight control subjects. Intracellular resting free calcium level of some of the studied subjects was also determined. Both calcium uptake capacity and (Ca2+ + Mg2+)‐ATPase activity were significantly lower in SR prepared from MH‐susceptible patients than from normal subjects. Besides, in these MH‐susceptible patients myoplasmic free Ca2+ was increased. These results corroborate previous suggestions that abnormal function of the SR membrane was related to the MH syndrome.
Contractile and EMG studies of murine myotonia (mto) and muscular dystrophy (dy/dy)
Authors: Entrikin Richard K. , Abresch Richard T. , Sharman Robert B. , Larson Douglas B. , Levine Neil A.
Published: January 2005

This report focuses on the myotonic (mto) mouse, an autosomal recessive neuromuscular mutant first described in 1982. Studies in vivo confirmed the presence of hindlimb rigidity during walking and typical myotonic electromyographic (EMG) discharges that persisted after nerve transection and complete neuromuscular blockade. Studies of the contractility of mto muscles in vitro revealed reduced peak isometric tetanic tension and greatly prolonged relaxation times. Tubocurarine did not affect tension parameters, but did antagonize the delayed relaxation in vitro. On the basis of EMG studies alone this mutant can accurately be described as myotonic. Reduction of the contractile abnormalities by tubocurarine in vitro, however, poses further questions regarding the nature of the disorder. Although the more familiar dystrophic mouse (dy/dy) has been termed “myotonic” by some, the new mto mutant differs from it in all aspects examined.
Single fiber electromyography in chronic progressive external ophthalmoplegia
Authors: Krendel David A. , Sanders Donald B. , Massey Janice M.
Published: January 2005

We have reviewed the electromyographic (EMG) studies of 17 patients with chronic progressive external ophthalmoplegia (CPEO). In 13 of 17 patients, conventional concentric needle EMG demonstrated a “myopathic” pattern, usually predominating in the shoulder muscles. Single‐fiber EMG showed increased jitter and/or blocking in at least one muscle in 13 of 16 patients. Jitter was increased in the frontalis muscle in 10 of 13 patients and in an arm muscle in 5 of 12. When both muscles were tested, jitter was greater in the frontalis muscle in 5 patients and in the arm muscle in 2. These observations demonstrate that it may be difficult to distinguish myasthenia gravis from CPEO by EMG. The frequency with which abnormal jitter is found in CPEO suggests that, in addition to a mild generalized myopathy, a primary defect in neuromuscular transmission may be present.
Bilateral anterior interosseous nerve syndromes associated with cytomegalovirus infection
Authors: Dunne John W. , Prentice David A. , Stewart‐Wynne Edward G.
Published: January 2005

The occurrence of bilateral brachial mononeuropathies presenting as anterior interosseous nerve syndromes in association with cytomegalovirus mononucleosis in an otherwise healthy adult is reported, a relationship not previously described.
Somatosensory evoked response evaluation of cervical spondylytic myelopathy
Authors: Perlik Stuart J. , Fisher Morris A.
Published: January 2005

There were 13 patients with cervical spondylytic myelopathy (CSM) evaluated. All had extradural defects with distortion of the cervical cord and partial or complete obstruction of myelographic dye. Posterior tibial scalp (SSEPs) were absent or delayed in all 13, whereas median SSEPs were abnormal in 9. Median SSEP abnormalities were limited to those with cord lesions at C5‐C6 or above. There were eight patients with associated radiculopathies confirmed by electromyography. No meaningful differences in SSEPs were noted between those with or without root injury. Surgery confirmed the level of cord injury in 10

CSM is common with a high morbidity. The results indicate SSEPs using leg stimulation can be a sensitive indicator of cord injury in these patients and that the more commonly used arm stimulation is of value primarily for localizing the level of the myelopathy.
Electrophysiologic follow‐up in whipple's disease
Authors: Martínez A. Cruz , González P. , Garza E. , Bescansa E. , Anciones B.
Published: January 2005

Neurologic and electrophysiologic findings in a 57‐year‐old man with Whipple's disease are reported. The patient had severe proximal weakness and weight loss of more than 20 kg. Conventional electromyography and nerve conduction studies suggested mild neuropathy in distal segments of lower limbs and myopathy in proximal muscles. Automatic analysis of the electromyogram in proximal muscles was consistent with myopathy. Conduction velocity of muscle fibers in situ showed low propagation velocity of the impulse. Weakness, weight loss, and all the electrophysiologic parameters improved after treatment, including a compression of the peroneal nerve at the knee, perhaps related to weight loss (slimmer's paralysis).
Detection of muscle injury in humans with 31‐P magnetic resonance spectroscopy
Authors: McCully Kevin K. , Argov Zohar , Boden Barry P. , Brown Richard L. , Bank William J. , Chance Britton
Published: January 2005

Strenuous exercise can result in muscle injury that may persist for 2 weeks. Our purpose was to determine if muscle injury can be detected with 31‐P magnetic resonance spectroscopy. Normal subjects performed repeated lengthening contractions with either arms or legs designed to result in mild muscle injury. One hour after the arm exercise, there was a significant increase in the inorganic phosphate to phosphocreatine ratio (Pi/PCr), with the maximum increase in Pi/PCr occurring 1 day postexercise (0.12 ± 0.01 to 0.21 ± 0.05). Pi/PCr remained elevated for 3–10 days. Similar results were seen following the leg exercise protocol. ATP/(Pi+PCr) decreased in all the arm exercised subjects. Exercise protocols that did not contain lengthening contractions did not result in changes of Pi/PCr or ATP/(Pi+PCr). Patients with various neuromuscular diseases with evidence of muscle damage (elevated CK, muscle soreness, and histopathological findings) also showed increased Pi/PCr at rest. We conclude that elevated Pi/PCr at rest can reflect nonspecific muscle damage in normal and diseased subjects.
F/M ratios in polyneuropathy and spastic hyperreflexia
Authors: Fisher Morris A.
Published: January 2005

The ratios of F to M amplitudes were determined by dividing the mean amplitude of 15 F‐waves (mF AMP) by the maximum evoked motor response amplitude recording from the abductor pollicis brevis and calf muscles. Data were compared from age‐matched control subjects and patients with polyneuropathies or spastic hyperreflexia. In comparison to normals, mF AMP/M—but not mF AMP—values were increased at statistically significant levels in all patient groups. M amplitudes were decreased (versus normal, P < 0.005) in the patients with either peripheral or central lesions. In these patients, the normal significant correlation between mF AMP and M amplitudes may be disrupted, whereas the data suggest that increased mF AMP ratios in neuropathies are related to their duration. These results indicate that mF AMP/M ratios can be increased not only with increased central excitability but also in peripheral neuropathies. Although mechanisms may differ, the data are consistent with a similar physiological response to peripheral and central injury and emphasize that M amplitudes may be decreased with central lesions.
Sympathetic skin response in diabetic peripheral neuropathy
Authors: Niakan Enayat , Harati Yadollah
Published: January 2005

There were 72 diabetic patients with clinical evidence of sensorimotor peripheral neuropathy investigated to determine the sensitivity of the sympathetic skin response test (SSR) for detection of sudomotor dysfunction and its correlation with other autonomic function tests, autonomic symptoms, and degree of peripheral neuropathy. Nerve conduction velocities (NCV) were abnormal in all patients, SSR was absent in 60 of 72 patients (83%), Valsalva test was abnormal in 32 of 67 patients (48%) who had the test, and 6 of 72 (9%) had orthostatic hypotension. Statistically significant correlation was found between the Valsalva test abnormality, the degree of peripheral neuropathy, and the SSR in our patients. All patients with orthostatic hypotension had an absent SSR and an abnormal Valsalva test. Most patients had one or more autonomic signs or symptoms. Orthostatic dizziness only correlated with SSR, however. These results suggest that subdomotor activity detected by sympathetic skin response is a valuable test for investigation of dysautonomia in diabetic peripheral neuropathy.
Single fiber EMG in juvenile idiopathic scoliosis
Authors: Trontelj Jož V. , Fernandez José M.
Published: January 2005

A single fiber EMG (SFEMG) study was performed in 51 patients with idiopathic juvenile scoliosis of moderate degree (mean 23.8° of Cobb), aged 7–18 years (mean 13.2 years). The findings in the extensor digitorum communis muscle (EDC) include a moderate but significant increase in fiber density (mean 2.02, ± 0.21, P < 0.001), a mild but significant (P < 0.001) neuromuscular transmission abnormality (7.6% of fibers showed increased jitter and 4.5% intermittent blocking), and a moderately prolonged mean interspike interval (mean 0.98 msec, ±0.20, P < 0.005) in EDC. Five of the patients had normal fiber density, 9 had a normal jitter study, and further 7 had a normal mean interspike interval. However only one had all the parameters normal. The paraspinal and intercostal muscles at the apex of the scoliotic curvature examined in some of the patients showed similar abnormalities. The study thus suggests the existence of a subclinical systemic neuromuscular disorder in nearly all of our patients with idiopathic scoliosis, which might have a pathogenetic significance.
A model of the differing change in motor and sensory action potentials over distance
Authors: Kincaid John C. , Minnick Katherine A. , Pappas Steven
Published: January 2005

Clinically recorded motor and sensory nerve responses show different degrees of change in response size over distance along a nerve. We describe a computer model to investigate possible causes of this phenomenon. Effects of the range of conduction velocity in a nerve and the size of the constituent action potentials forming the recorded response are evaluated. We conclude that the broader duration of the motor unit potential is the predominant factor in accounting for motor nerve responses showing less change over distance than sensory responses. The contributions of temporal dispersion and phase cancellation are also discussed.
α‐Glucosidase isoenzymes in normal and acid maltase‐deficient human skeletal muscles
Authors: Usuki Fusako , Ishiura Shoichi , Nonaka Ikuya , Sugita Hideo
Published: January 2005

One acid α‐glucosidase and two neutral α‐glucosidases were separated from human skeletal muscle by DEAE‐cellulose column chromatography. The appearance of the two human neutral α‐glucosidase isoenzymes was found to be age dependent. We called them “fetal” and “adult” neutral α‐glucosidases. The biochemical properties of the fetal and adult types of neutral α‐glucosidase appeared to be similar to those previously reported for neutral α‐glucosidases AB and C, respectively. The neutral α‐glucosidase activity in the column eluate of the infantile acid maltase deficiency (AMD; 5‐month‐old) muscle was completely of the adult type, whereas 18% of the total neutral α‐glucosidase activity in age‐matched control muscle was of the fetal type. In contrast, the eluate of the late‐onset AMD (32‐year‐old) muscle contained both the adult and fetal neutral α‐glucosidases, 68 and 32%, respectively.
Motor unit estimates in the biceps‐brachialis in amyotrophic lateral sclerosis
Authors: Strong Michael J. , Brown William F. , Hudson Arthur J. , Snow Robert
Published: January 2005

A newly developed technique for estimating the number of motor units in the biceps‐brachialis muscles and for studying the innervation patterns of motor units in the same muscles has been applied to the study of 17 patients with amyotrophic lateral sclerosis (ALS). Although severe motor unit losses were seen in many ALS cases, in most there were clear indications of increases in innervation densities, linked potentials, and blocking. This technique provides a powerful new tool for quantitatively assessing the extent of motor unit losses and the accompanying changes in innervation patterns in ALS.
Halothane‐caffeine contracture testing in neuromuscular diseases
Authors: Heiman‐Patterson Terry D. , Rosenberg Henry , Fletcher Jeffrey E. , Tahmaoush Albert J.
Published: January 2005

The association of malignant hyperthermia (MH) with neuromuscular disorders has been recognized since 1970. These disorders include central core disease, Duchenne muscular dystrophy, myotonia congenita, myotonic dystrophy, nonspecific myopathies, and King–Denborough syndrome. In order to assess the anesthetic risk of MH in the neuromuscular population, we performed halothane and caffeine contracture testing for MH susceptibility on biopsied muscle removed from 25 consecutive neuromuscular patients during diagnostic evaluation. Positive contracture tests were found in 7 to 18 patients with myopathic disorders and 3 to 7 patients with neurogenic disorders. Two of our patients had anesthetic events suggesting MH. These findings suggest that myopathic and neuropathic disorders share pathogenic mechanisms with MH, resulting in positive contracture tests and possibly leading to clinical events during anesthesia. Although there is controversy regarding the interpretation of a positive contracture test, contracture testing remains the most widely accepted test for MH susceptibility. Thus, a variety of neuromuscular disorders may be associated with MH susceptibility, and caution should be exercised during anesthesia in this group of patients.
Slow sodium channel inactivation in mammalian muscle: A possible role in regulating excitability
Authors: Ruff R. L. , Simoncini L. , Stüuhmer W.
Published: January 2005

Sodium currents were recorded in rat fast and slow twitch muscle fibers. Changes in the membrane potential around the resting potential produced slow changes in the sodium current amplitude due to alterations of the slow inactivation process that was increased by steady depolarization and removed by prolonged hyperpolarization. In contrast, classical fast inactivation was not operative around the resting potential, and depolarizations of greater than 20 mV were required to close half of the channels by fast inactivation. Because slow inactivation is operative around the resting potential of mammalian muscle fibers, it may partially explain why small depolarizations, such as those that occur in some patients with periodic paralysis, can reduce excitability.
Stimulus artifact compensation using biphasic stimulation
Authors: Nilsson Jan , Ravits John , Hallett Mark
Published: January 2005

The feasibility of using biphasic stimulation as a method of reducing stimulus artifact was explored in several different circumstances. Sensory and muscle evoked potentials were compared using monophasic and biphasic constant‐current stimuli. The monophasic stimulus was a negative rectangular pulse with a duration of 0.1–0.2 msec. The biphasic stimulus was a negative rectangular pulse of 0.1–0.2 msec duration followed, after a variable delay, by a positive rectangular pulse of the same duration and variable amplitude. When the conducting distances were long, stimulus artifact did not disturb either monophasically or biphasically evoked potentials. When the conducting distances were short, stimulus artifact occurred with monophasic stimulation but could be diminished readily using biphasic stimulation. The method can be accomplished easily using standard instruments with dual stimulators.
Noncoordinate expression of M band proteins in slow and fast embryonic chick muscles
Authors: Grove Barbara Kay , Thornell Lars‐Eric
Published: January 2005

The expression of the myosin‐associated M band proteins myomesin and M protein in differentiating muscle fibers in the anterior latissimus dorsi (ALD) and posterior latissimus dorsi (PLD) muscles during embryonic chicken development was examined by immunocytochemistry using monoclonal antibodies. Early in the embryonic development of both muscles, both myomesin and M protein are expressed in primary and secondary myotubes. However, beginning at 10 days in ovo, M protein is gradually suppressed first in primary, then in secondary, presumptive slow‐tonic type 3 fibers. M protein is transiently suppressed in presumptive fast‐twitch type 2 fibers derived from primary myotubes but continuously expressed in those derived from secondary myotubes. Thus, initially all myotubes have a common intrinsic M band composition with respect to myomesin and M protein, whereas at later stages the expression of M protein is fiber‐type specific. Intrafusal spindle fibers, which are segregated from extrafusal fibers around 14 days in ovo, have a heterogeneous M band composition atypical of extrafusal fibers.
Molecular genetics in muscular dystrophy research: Revolutionary progress
Authors: Stedman Hansell , Sarkar Satyapriya
Published: January 2005

The contribution of “reverse genetic” strategies to neuromuscular disease research is evident in the progression of breakthroughs that have recently culminated in the cloning of the Duchenne muscular dystrophy (DMD) cDNA. The resultant improvements in our understanding of the genetic basis of Becker muscular dystrophy (BMD) and DMD serve as models for similar investigation of other heritable disorders. These genetic advances have outpaced concurrent work on the molecular pathogenesis of the dystrophic process, with the curious result that inferences about the DMD protein's amino acid sequence have preceded any information about its function or intracellular localization. In recognition that this foundation sets the stage for the rapid elucidation of the disease's pathogenesis, we review the experimental basis of such advances, with reference to relevant progress in basic myology, pathology, and molecular biology. We conclude with a view towards the ultimate clinical implications of these experimental break‐throughs.
Effects of glucocorticoids on motor units in cat hindlimb muscles
Authors: Robinson Andrew J. , Clamann H. Peter
Published: January 2005

The purpose of this study was to examine the effects of glucocorticoid treatment on the contractile, electrical and fatigue properties of isolated motor units of identified type. Although it is known that glucocorticoid administration induces atrophy and weakness most strongly in fast, pale muscles and to a lesser extent in red muscle, the relationship between steroid effects and motor unit type is not known. Properties of medial gastrocnemious (MG) and soleus (SOL) motor units were studied in normal cats and in cats treated with triamcinolone acetonide (3–4 mg/kg body weight for 10–16 days). Glucocorticoid treatment produced weakness preferentially in fast‐twitch motor units. This suggests that catabolic steroids cause a reduction in the amount of contractile protein and hence contractile strength of motor units in inverse proportion to their relative activity or degree of use.
Reversible proximal conduction block underlies rapid recovery in Guillain‐Barré syndrome
Authors: Berger Alan R. , Logigian Eric L. , Shahani Bhagwan T.
Published: January 2005

Three patients with Guillain‐Barré syndrome underwent electrophysiological examination prior to and during a period of rapid clinical recovery. In each case, improved strength of the abductor digiti minimi coincided with electrophysiologic evidence of a marked reversal of proximal conduction block. In contrast, the degree of distal conduction block remained relatively unchanged after stimulation at the wrist, elbow, axilla, and Erb's point. These findings indicate that rapid motor recovery, early in the course of Guillain‐Barré syndrome, can result from reversal of proximal conduction block and explains the often noted dissociation between clinical improvement and conventional distal nerve conduction studies.
Fatigue‐related changes in neuromuscular excitability of rat hindlimb muscles
Authors: Enoka Roger M. , Rankin Lucinda L. , Joyner Michael J. , Stuart Douglas G.
Published: January 2005

Brief repetitive trains of supramaximal nerve stimulation produce intermittent muscle activation and, in time, a progressive decline in force (i.e., neuromuscular fatigue) and depression of the electromyogram (EMG). These changes may include within‐train reductions in EMG due to a failure of neuromuscular propagation.13The aim of the present study was to investigate changes in EMG during a 360‐second stimulus regimen designed to fatigue soleus and extensor digitorum longus muscles of anesthetized rats by activating the muscle with repetitive trains of 40 Hz stimuli. Measurements included peak force for each tetanus, variation of the within‐train EMG (coefficient of variation for area), and magnitude of the first EMG waveform (area) of each train. Fatigue was characterized as the relative decline in force over the course of the test. The responses of the test muscles were categorized, based on an absolute scale of fatigability, into five groups: potentiated, nonfatigable, low fatigability, intermediate fatigability, and high fatigability. Fatigable muscles (low, intermediate, and high fatigability groups) demonstrated a decreased EMG magnitude and an increased EMG‐area variation with repetitive activation. This increased variation, however, was nonmonotonically related to fatigability such that the leastandmost fatigable muscles had the smallest within‐train EMG variation. We suggest that these data can be explained by considering the EMG (compound muscle action potential) as a stochastic process that represents a composite of single‐fiber events (axonal to sarcolemmal transmission) with variable probabillities.
Prediction by 31P‐NMR of the irreversibility of ischemic injury in rat skeletal muscle after ligation of the femoral artery
Authors: Authier B. , Rossi A. , Albrand J. P. , Decorps M.
Published: January 2005

Rat leg muscles, rendered ischaemic 1 hour previously by ligation of the femoral artery, were submitted to 20 minutes exercise by electrical stimulation of the sciatic nerve. 31P‐NMR spectroscopy was used to monitor the changes in high‐energy phosphate content of the muscles before, during, and after exercise. Fifteen of the 35 studied muscles evolved toward total necrosis, whereas the others showed signs of recovery over a 2–5‐hour postexercise period. Those muscles which did not subsequently recover contained significantly more inorganic phosphate (Pi) at rest (before exercise) than those which recovered. It is suggested that under acute ischaemic conditions the Pi level at rest is correlated with the extent of blood flow restriction and can be used to predict the severity of the ischemia.
Myosin heavy chain composition of muscle fibers in spinal muscular atrophy
Authors: Biral Donatella , Scarpini Elio , Angelini Corrado , Salviati Giovanni , Margreth Alfredo
Published: January 2005

Muscle biopsies from 20 cases of spinal muscular atrophy (SMA), mostly diagnosed as Werdnig–Hoffmann (W–H) disease, were examined for myosin heavy chain (HC) composition. The fetal, fast, and slow heavy chains were characterized in the isolated muscle myosin, and in myosin of single, chemically skinned fibers, by electrophoresis in SDS‐6% polyacrylamide gels and by immunoblot techniques, using specific antibodies directed to each main type of myosin HC. The fiber distribution of myosin HC isozymes was further investigated on muscle cryostat sections by an indirect immunofluorescent technique. Fetal myosin HC was found to be expressed in a subpopulation of severely atrophic fibers, alone or together with the slow form of myosin HC. Triangulated fibers of intermediate size contained fetal and fast myosin or fast myosin alone. The hypertrophic fibers were characterized by the predominant expression of slow myosin HC; but in some of these fibers, also low amounts of HC fetal were found to be expressed. These findings are discussed in relation to developmental transitions of myosin heavy chains in human muscle.
Recording sound from human skeletal muscle: Technical and physiological aspects
Authors: Bolton Charles F. , Parkes Anthony , Thompson Terry R. , Clark Michael R. , Sterne Chris J.
Published: January 2005

In order to examine technical factors that influence muscle sound recording, single twitches of muscle were utilized since their waveforms were likely to be reproducible. We observed that satisfactory recordings could be made with either Archer air interface, or Hewlett‐Packard direct contact sensor, microphones. Firm contact and stability between the microphone and the skin surface were particularly important. Frequencies below 20 Hz, the lower limit of the human auditory range, must be recorded, since they account for at least 90% of the power of the muscle sound wave. The chief frequencies were below 4 Hz.

The sound wave produced by a maximal twitch of human thenar muscle induced by median nerve stimulation at the wrist is maximal in amplitude over the center and recedes to near zero at the margins of the muscle. It is preceded by the muscle compound action potential and is followed by the force curve, recorded with a strain gauge attached to the thumb. The sound resembles force in total time course, and it increases with increasing strengths of nerve stimulation. However, it differs in its latency, phase relationships, and response to nerve stimulation at different frequencies. Some of the features of muscle sound suggest it relates to both the active contractile and the parallel elastic components of muscle during a twitch contraction, but not the series elastic component.
Fibrillatory activity and other membrane changes in partially denervated muscles
Authors: Arancio Ottavio , Cangiano Alberto , De Grandis Domenico
Published: January 2005

Rat soleus muscles were partially or totally denervated by sectioning the radicular nerve L5 or the radicular nerves L3 through L6, respectively. Three days after these procedures, fibrillation potentials were not observed in the case of partial denervation, whereas they were clearly detectable after total denervation. At later times, spontaneous spike activity also developed in the partially denervated muscles. The difference in time of onset of fibrillation between partially and totally denervated muscles was confirmed by a more gradual increase in the number of acetylcholine receptors and a greater sensitivity to tetrodotoxin of the former muscles. These differences between partially and totally denervated muscles are interpreted on the basis of the different amounts of nerve breakdown products generated in the two situations.
The in vitro determination of susceptibility to malignant hyperthermia
Authors: Iaizzo Paul A , Lehmann‐Horn Frank
Published: January 2005

To evaluate the reliability of the in vitro contracture test for susceptibility to malignant hyperthermia, we studied muscles from normal pigs and those susceptible to malignant hyperthermia. We performed the contracture test with various muscles from the same animal. Trapezius and intercostal muscles gave similar results, whereas the extensor digiti II muscle had lower sensitivities to both caffeine and halothane. Thus, the muscle chosen to determine susceptibility to malignant hyperthermia is important. In several animals, a false negative diagnosis would have resulted if only the distal muscle had been studied, and this was true even if weak contractures (<200 mg) were considered significant. In addition, we compared the response to caffeine or halothane of cut and intact muscle fibers. Although the cut fibers were depolarized, the sensitivity to these drugs was unchanged. Hence, results of the in vitro contracture test are independent of the resting membrane potential.
Handcuff neuropathy revisited
Authors: Scott Thomas F. , Yager John G. , Gross John A.
Published: January 2005

Peripheral nerve injury due to handcuff placement has been reported in the past, always involving the superficial radial nerve, and sometimes involving other peripheral nerves at the wrist. We present two unusual cases in which the ulnar nerves were affected, but the radial nerves were normal or only minimally affected. This serves to emphasize a broader clinical spectrum of handcuff injury. Significant disability may result. These cases also involve alcohol intoxication, which may predispose patients to this type of injury because of overly aggressive application of restraints motivated by the patients' bellicose behavior.
Duchenne muscular dystrophy: A study of wrist and hand function
Authors: Wagner Marilyn B. , Vignos Paul J. , Carlozzi Chris
Published: January 2005

The wrist and hands of 18 Duchenne muscular dystrophy (DMD) patients were assessed for abnormalities. The subjects were divided into three groups by age. Flexion and ulnar deviation contractures of the wrist began in the youngest age group, 8–14 years. Other abnormalities, present in all age groups, included extrinsic and Intrinsic digital muscle shortness, boutonniere and swan neck deformities, and hyperextension of the digital interphalangeal joints. Pain found with passive proximal interphalangeal joint flexion has not been reported previously. This study supports the importance of early assessment of the wrist and hand in DMD and suggests intervention techniques to possibly retard the deforming process.
Abnormalities of the fast sodium current in myotonic dystrophy, recessive generalized myotonia, and adynamia episodica
Authors: Rüudel Reinhardt , Ruppersberg Johann Peter , Spittelmeister Wolfgang
Published: January 2005

Myoballs, i.e., spherical muscle cell regenerates, were cultured from the biopsied muscles of three patients with myotonic dystrophy, three patients with recessive generalized myotonia, and a patient with adynamia episodica. The membrane of these myoballs was voltage‐clamped in the whole‐cell mode for the recording of sodium currents (at 11, 24, and 37°C). The voltage dependence of the steady‐state activation and inactivation curves showed only minor abnormalities in all cases. The time constants of activation (τm) and inactivation (τh), when studied at the three temperatures, showed a characteristic pattern of abnormalities. In myotonic dystrophy, both τm and τh were larger than control; in recessive generalized myotonia and adynamia episodica both τm and τh were smaller than control. In the latter diseases, these time constants also showed a smaller than normal decrease with membrane depolarization. The changes seen for recessive generalized myotonia and adynamia episodica would favour the occurence of myotonia, the opposite results for myotonic dystrophy would oppose myotonia.
Therapeutic strategies in promoting peripheral nerve regeneration
Authors: Horowitz Steven H.
Published: January 2005

Currently, regeneration chambers, adrenocorticotropic hormone (ACTH) and related peptides, and gangliosides appear to be the most promising therapies in the promotion of peripheral nerve regeneration, growth, and repair. Regeneration chambers enhance rat sciatic nerve regeneration in vivo after transection by providing a structurally organized and protected preformed space within which nerve fibers are exposed to macromolecular compounds which direct and enhance nerve growth. ACTH and related peptides, independent of their corticotropic activities, increase the availability of structural proteins to the axon terminal in rats subjected to nerve crush injuries and demonstrate inotropic effects in adrenalectomized and/or hypophysectomized rats. Exogenously administered gangliosides promote neuronal sprouting, regeneration, and reinnervation in experimental situations and have undergone clinical testing in acute and chronic peripheral nerve disorders. At the current dosage levels and schedules, the clinical results of ganglioside therapy have been mixed. The success of the experimental studies supports further clinical testing of these therapies in peripheral nerve disorders.
Electromyographic evaluation of an accessory hand muscle
Authors: McManis Philip G. , Daube Jasper R.
Published: January 2005

Accessory hand muscles consistent with extensor digitorum brevis manus muscles were noted in a young women. Well‐defined compound muscle action potentials were elicited in these muscles with stimulation of the radial nerve. Needle electromyography showed poor recruitment and large motor unit potentials with frequent cramp discharges only in the anomalous muscles. Therefore, the extensor digitorum brevis manus is innervated by the posterior interosseous nerve, and symptoms may be due to chronic denervation and cramping.
Single‐fiber EMG study of the flexor carpi radialis H reflex
Authors: Jabre Joe F. , Stålberg Erik V.
Published: January 2005

Late responses were studied in the flexor carpi radialis muscle by surface‐recording and single‐fiber electromyography. By single‐fiber studies we were able to distinguish 2 distinct components. One was an H reflex obtained without a preceding M response and with a stimulus response jitter of about 100 μsec; its latency was shortened and jitter decreased with the Jendrassik maneuver. The other was an F wave always preceded by an M response and with a stimulus response jitter of under 50 μsec; its jitter and latency are unaffected by the Jendrassik maneuver. At the single‐fiber level it was possible to determine the rate of occurrence of individual H reflexes and F responses for a given number of surface‐applied stimuli. The H reflex had a very high rate of occurrence (up to 97%), whereas the F wave occurred very infrequently (less than 2% of the time). Using the H reflex rate of occurrence in conjunction with the maximal surface H/M amplitude ratios allowed us to determine the proportion of alpha motor neurons which participate in the H‐reflex generation. The study of H‐reflex jitter gives an estimate of the central synaptic jitter and effectiveness of the spatial and temporal summation of type 1a fiber inputs on the motor neurons.
AAEE minimonograph #33: Electrodiagnostic approach to defects of neuromuscular transmission
Authors: Keesey John C.
Published: January 2005

Clinical testing for neuromuscular dysfunction is supported by an extensive amount of excellent basic information about normal and abnormal subcellular physiology and ultrastructure. This information provides an essential frame of reference for describing the rationale of single‐fiber electromyography (SFEMG). SFEMG in turn helps to explain the more conventional clinical testing of neuromuscular function by repetitive nerve stimulation (RNS). Electrical findings in myasthenia gravis, Lambert–Eaton myasthenic syndrome, and botulinum intoxication are discussed from the subcellular level via the cellular level (SFEMG) to the integrated responses of whole muscle (RNS) as a rational means of understanding the technique of clinical repetitive nerve stimulation.
Coexpression of myosin isoforms in muscle of patients with neurogenic disease
Authors: Sawchak Judith A. , Lewis Simeon , Shafiq Saiyid A.
Published: January 2005

Three well‐characterized antimyosin heavy chain monoclonal antibodies (McAbs) were used as immunocytochemical reagents to study myosin iso‐form expression in relationship to adenosine triphosphatase (ATPase) defined fiber types in human muscle. The biopsy specimens were from patients with neurogenic muscle disease whose muscle exhibited fiber type grouping and group atrophy. The use of McAbs revealed heretofore unrecognized coexpression of multiple myosin isoforms in selected fibers in the pathologic samples which was not apparent with ATPase reactions and not present in normal muscle. The fibers containing multiple myosin isoforms were probably undergoing neurally directed fiber type transformation. Furthermore, a small population of fibers in neurogenic specimens expressed a “prenatal” myosin signifying the presence of regenerating fibers. We also demonstrated immunocytochemical evidence of the persistence of adult slow myosin in denervated mature human skeletal muscle despite the reputed necessity of innervation for maintenance of expression of this myosin isoform proffered by others.
Localization and characterization of dystrophin in muscle biopsy specimens from Duchenne muscular dystrophy and various neuromuscular disorders
Authors: Uchino Makoto , Araki Shukuro , Miike Teruhisa , Teramoto Hitoo , Nakamura Tetsuji , Yasutake Toshiaki
Published: January 2005

Dystrophin, surmised to be the causative protein of Duchenne muscular dystrophy (DMD) was studied for its intracellular localization and characterization by immunostaining and Western blotting using antidystrophin antibodies. In normal controls and in patients with various neuromuscular diseases other than DMD and Becker's muscular dystrophy (BMD), dystrophin was detected homogeneously on the entire surface membrane of the muscle fibers, whereas it was absent in DMD patients and partially observed in BMD cases. The density of dystrophin was low in BMD and female DMD patients. In mouse skeletal and cardiac muscles, too, dystrophin localized in the muscle surface membrane, and its presence in the brain was also suggested. However, dystrophin was not detected in mdx mice. These data suggest that myofiber necrosis in DMD patients and mdx mice is likely to be the result of plasma membrane instability.
Paramyotonia congenita or hyperkalemic periodic paralysis? Clinical and electrophysiological features of each entity in one family
Authors: de Silva Shari M. , Kuncl Ralph W. , Griffin John W. , Cornblath David R. , Chavoustie Steven
Published: January 2005

The nosological distinction between paramyotonia congenita (PC) and hyperkalemic periodic paralysis (HPP) continues to generate debate. Recently, electrophysiological signs thought to be specific for each entity have been described and have been used to bolster the argument that the two disorders are distinct. We report a particularly instructive family wherein individual members had clinical features of either PC or HPP and electrophysiological features of both. We suggest that PC and HPP represent part of the spectrum of a single genetic disorder. Evoked response testing, with exercise and cold provocation, may be useful in determining the physiologic pattern that predominates in any one individual.
Neurofibromatous neuropathy
Authors: Thomas P. K. , King R. H. M. , Chiang T. R. , Scaravilli F. , Sharma A. K. , Downie A. W.
Published: January 2005

Three cases of chronic distal sensorimotor neuropathy are described in patients with neurofibromatosis. One had type 2 or central neurofibromatosis with a chromosome 22 deletion; the precise form of the disease was not established in the other two. A striking clinical feature was a diffuse nodular enlargement of the peripheral nerves. Nerve biopsies from all three cases demonstrated the presence of neurofibromatous pathology. Neurofibromatous neuropathy constitutes a rare manifestation of neurofibromatosis, related to diffuse neurofibromatous changes in the peripheral nerves.
Steroid‐responsive electromyographic abnormalities in polymyalgia rheumatica
Authors: Bromberg Mark B. , Donofrio Peter D. , Segal Barbara M.
Published: January 2005

Prior to definitive diagnosis, electrodiagnostic studies are often requested in patients with polymyalgia rheumatica to evaluate complaints of muscle aching, tenderness, and weakness. These studies are generally normal, although rare reports of electromyographic abnormalities in polymyalgia rheumatica exist. Two patients with polymyalgia rheumatica and electro diagnostic findings consistent with diffuse denervation are described. Following steroid treatment, both patients experienced impressive clinical and electromyographic improvement. To explain this improvement, we hypothesize a steroid‐responsive microvascular arteritis resulting in ischemic damage to axons of motor nerve terminal branches.
Electromyographic and morphological functional compensation in late poliomyelitis
Authors: Einarsson Gisli , Grimby Gunnar , Stålberg Erik
Published: January 2005

Patients with prior poliomyelitis may experience muscle function deterioration decades after onset of disease. The present study is aimed at describing electromyographic and morphometric evidence of muscular compensation and of on‐going muscular instability. Ten subjects 42–62 years of age with onset of polio 25–52 years earlier were studied with macro EMG, single‐fiber EMG (SFEMG), muscle strength measurement, and morphometrical analysis of muscle biopsies from the vastus lateralis muscle. SFEMG revealed increased fiber density (FD) and large macro‐MUP potentials indicating pronounced reinnervation as compensation to loss of motor neurons. From electrophysiological data of motor unit size, morphometric measures of fiber size, and muscle strength data, the minimal degree of motor neuron loss was estimated to be greater than 70%.
Toward more rational nerve conduction interpreations: The effect of height
Authors: Rivener Micheael H. , Swift Thomas R. , Crout Barbara O. , Rhodes Karen P.
Published: January 2005

One hundred four normal subjects ranging in age from 17 to 77 years and in height from 115 to 203 cm underwent nerve conduction studies of sural, peroneal, tibial, and median nerves. Foot temperature was measured in each patient. A strong inverse correlation was found between height and sural (r = −0.7104), peroneal (r = −0.6842), and tibial (r = −0.5044) conduction velocities. These correlations were significant at the P< 0.001 level. Median conduction velocity was not correlated with height. Height was correlated with the distal latencies of all nerves studied (sural r = 0.6518), peroneal r = 0.4583, tibial r = 0.7217, median (r = 0.5440). These correlations were significant at the P < 0.001 level. Age was inversely correlated with both tibial (r = −0.4071) and median (r = −0.3464) nerve conduction velocities but not with sural and peroneal conductions. There were no correlations between distal latencies and age. If the variation in conduction velocity accounted for by the linear relationship with height was removed, then age would be inversely correlated to all conduction velocity measurements with the exception of the sural. Temperature is inversely correlated with the sural (r = −0.2233), peroneal (r = −0.2102), and tibial (r = −0.2710) distal latencies. In all instances, the effects of age and temperature were minor determinants when compared with the effects of height. Diagnostic conclusions made from nerve conduction data without correcting for height may be invalid in patients taller and shorter than normal. We believe that using normal values for nerve conductions that do not take height into account can no longer be considered an acceptable standard of practice.
Muscle fatigue unrelated to phosphocreatine and pH: An “in vivo” 31‐P NMR spectroscopy study
Authors: Le Rumeur Elisabeth , Le Moyec Laurence , Toulouse Pierre , Le Bars René , de Certaines Jacques D.
Published: January 2005

Metabolic events were followed by 31‐P NMR spectroscopy during mechanical exhaustion of directly stimulated rat gastrocnemius. During mechanical fatigue, phosphocreatine (PCr) and pH first declined but although stimulation continued high values were recovered without mechanical recovery. Total recovery was only observed after cessation of stimulation. Partial mechanical recovery was elicited by lowering stimulation rhythm; it was accompanied by decrease in PCr to a steady–state level without pH alteration. When exhaustive exercise was induced immediately after nonexhaustive exercise, failure of mechanical function occurred without decrease in pH. Major findings were: first, during exhaustive stimulations, the greater the muscle fatigue, and the higher the PCr level at the end of stimulation. Secondly, PCr and force levels did not depend on preceding levels of PCr and pH. Thirdly, acidosis was observed transiently during the first minutes of the first exercise period. These findings strongly suggested that electrical events and/or excitation–contraction (EC) coupling play a crucial role in this type of fatigue.