bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of electrophysiologic tests to measure disease progression in ALS therapeutic trials
Authors: Kelly John J. , Thibodeau Linda , Andres Patricia L. , Finison Lorenz J.
Published: January 2005

A battery of electrophysiologic tests was developed to assess the relative degree of lower and upper motor neuron (spasticity) deficit in a group of ALS patients enrolled in a therapeutic trial. Test results were correlated with strength in the tibialis anterior muscle as determined by measurement of maximum voluntary isometric contraction (MVIC), using strain gauge tensiometers, and were also correlated with a clinical spasticity rating scale. Patients were tested every 6 to 8 weeks over more than 1 year. Compound muscle action potential amplitude (CMAPa) from tibialis anterior correlated best with MVIC and also showed a strong linear correlation with time, as did MVIC. Other tests correlated poorly with MVIC on the average, although individual patients did show high correlations. In those patients where correlation between CMAPa and MVIC was low, MVIC did not show a high linear correlation with time and was also highly variable. This study suggests that the addition of CMAPa should be considered in ALS therapeutic trials if MVIC is not available. In addition, CMAPa can be useful in study samples where MVIC deterioration is not linear over time or is highly variable.
Immunocytochemical study of dystrophin at the myotendinous junction
Authors: Samitt Craig E. , Bonilla Eduardo
Published: January 2005

Dystrophin is the protein whose deficiency results in Duchenne muscular dystrophy. The protein has homologies with a number of cytoskeletal proteins, is localized at the muscle sarcolemma and it may provide stability to the muscle plasma membrane. Using immunocytochemical techniques, we have studied dystrophin localization at the myotendinous junction, a region of membrane complexity that requires more stability because it is subjected to great mechanical stress during the transmission of contractile force to the tendon. The results showed subsarcolemmal deposits of dystrophin at the junctional folds of the myotendon as well as membrane‐associated dystrophin at extrajunctional sarcolemma. The findings suggest that dystrophin may be one of the components linking terminal actin filaments to the subplasmalemmal surface of the junctional folds of the myotendon.
Muscle biopsy in AIDS and ARC: Analysis of 50 patients
Authors: Gabbai Alberto A. , Schmidt Beny , Castelo Adauto , Oliveira Acary S. B. , Lima Jose G. C.
Published: January 2005

We report a large spectrum of histological muscle abnormalities in 50 homosexual men with AIDS and ARC. We encountered moth‐eaten fibers in 76%, angulated fibers in 76%, type groupings in 62%, type 2 fiber atrophy in 58%, mononuclear endomysial and/or perivascular in filtrates in 36%, necrosis and phagocytosis in 30%, and target fibers in 6%. Two patients showed vasculitis and two others showed perifascicular atrophy. On the whole, 96% of the biopsies showed substantial abnormalities. Muscle involvement in AIDS seems more common than previously suspected.
Effects of intermittent high frequency electrical stimulation on denervated EDL muscle of rabbit
Authors: Nix Wilfred A.
Published: January 2005

This study was performed to determine whether electrical stimulation can retard denervation‐induced changes. The denervated extensor digitorum longus of the rabbit, a fast‐twitch muscle, was stimulated at a rate mimicking its motoneuron firing pattern. The 100‐Hz stimulation given intermittently ubjected the muscle to a low mean total daily frequency of 1.6 Hz. Four weeks of stimulation resulted in no effect upon the denervated stimulated muscle. This stimulation protocol, therefore, is unable to substitute for the lost neuronal influence of the nerve. The muscle contralateral to the stimulated side showed physiological changes making it unsuitable to serve as a control.
Early myelin lesions in experimental allergic neuritis
Authors: Rosen Janet L. , Brown Mark J. , Hickey William F. , Rostami Abdolmohammad
Published: January 2005

We examined the evolution of demyelination in spinal roots of Lewis rats immunized with whole nerve and complete Freund' adjuvant. Roots were morphologically normal until 11 days after immunization, when we found endoneurial edema and myelin vesiculation in the absence of mononuclear cell contacts. Macrophage‐associated myelin stripping was not detected until day 12. Macrophage infiltrations were extensive by day 14, but lymphocytes were sparse. These observations indicate that in experimental allergic neuritis, myelin injury may occur before macrophage‐mediated demyelination, and provide support for an early role of serum factors in the development of this disorder.
Forearm ulnar‐to‐median nerve anastomosis of sensory axons
Authors: Hopf Hanns C.
Published: January 2005

A 22‐year‐old man showed electrophysiological evidence of an ulnar‐to‐median nerve communication involving only sensory fibers. The nerve action potentials evoked by stimulation of the middle finger (ulnar side) and the ring finger (radial side) digital nerves were propagated with the median nerve at the wrist and the ulner nerve at the elbow. He was the only subject among 30 studied with this abnormality.
Clinical and electromyographic studies of postpoliomyelitis muscular atrophy
Authors: Ravits John , Hallett Mark , Baker Michael , Nilsson Jan , Dalakas Marinos
Published: January 2005

Eleven patients with progressive weakness following polio (postpoliomyelitis muscular atrophy syndrome) were compared electromyographically with nine patients who had stable strength following polio. Abnormalities included (1) abnormal motor unit characteristics in many muscles indicating widespread loss of motor neurons and reinnervation in muscles, including many not clinically affected by the polio; (2) prevalent spontaneous denervation potentials; and (3) abnormalsingle‐fiber electromyographic jitter. These electromyographic abnormalities were similar in progressive and stable postpoliomyelitis patients even when muscles were separated by strength, stability, age and duration of the postpoliomyelitis state. Postpoliomyelitis muscular atrophy appears to be the clinically apparent end of the spectrum of abnormalities existing in all postpoliomyelitis patients.
Aberrant reinnervation
Authors: Sumner Austin J.
Published: January 2005

Although great empasis is placed on providing a satisfactory conduit for regeneration of peripheral axons after nerve repair, the quality of functional restoration is influenced as much by the quality as the quantity of axonal regeneration. Misdirected regeneration is so commonly encountered that motor axons appear to enter and regenerate to muscles in an almost random manner. Thus, when there are several choices, as usually is the case with more proximal nerve or plexus repairs, misdirected reinnervation accounts in many incidences for a poor quality of functional restoration. The regenerative capacities of type I and type II motor axons appear to differ. Proprioceptors and other sensory axons have been shown to reinnervate inappropriate end organs. Consequently, deranged central reflex modulation and disturbed orderly recruitment of motor units according to the size principle also contributes to this problem. Central re‐education or adaptation to misdirected regeneration does not occur to any appreciable extent.
Surgical repair of peripheral nerve injury
Authors: Kline David G.
Published: January 2005

Magnification, useof fine interfascicular grafts for repair, and development of intraoperative electrophysiologic measurements of function have had a substantial impact on this field in the last 10 to 20 years. Basic surgical principles established during and since World War II remain the foundation for surgical repair of peripheral nerve injury but have been complemented nicely by these more recent advances. Selection of patients for surgery, as well as the timing of such, has been reviewed with emphasis on the differences between suspected transections and lesions in continuity, as well as comments on serious peripheral enterpments and tumors affecting nerve. The importance of not only preoperative electromyographic studies but also the intraoperative use of stimulation and stimulation and recording of nerve action potentials (NAPs) for lesions in continuity has been stressed. Operative techniques such as neurolysis, NAP recordings, suture, split repair, and interfascicular graft repair have been reviewed and some commentary on results provided. There has been a gradual evolution of centers in this country and abroad for care of the more serious surgical nerve problems. It is anticipated that in the future, such centers will be able to provide improved data concerning results with civilian nerve injuries.
Recording and physical characteristics of disposable concentric needle EMG electrodes
Authors: Nandedkar Sanjeev D. , Tedman Brian , Sanders Donald B.
Published: January 2005

There 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.
A comparison of magnetic and electrical stimulation of peripheral nerves
Authors: Olney Richard K. , So Yuen T. , Goodin Douglas S. , Aminoff Michael J.
Published: January 2005

We compared magnetic stimulation using different coil designs (2 rounded coils and a butterfly‐prototype coil) with electrical stimulation of the median and ulnar nerves in 5 normal subjects. Using magnetic stimulation we were able to record technically satisfactory maximal sensory and motor responses only with butterfly coil. Submaximal electrical stimuli preferentially activated sensory rather than motor axons, but submaximal magnetic stimuli did not. The onset latency, amplitude, are and duration of responses elicited electrically or magnetically with the butterfly coil during routine sensory and motor nerve conduction studies were similar, and motor and sensory conduction velocities were comparable when studied over long segments of nerve. However, the motor conduction velocities with magnetic and electrical stimulation differed by as much as 18 m/sec in the across‐elbow segment of ulnar nerve. Thus, recent developments in magnetic stimulator design have improved the focality of the stimulus, but the present butterfly coil design cannot replace electrical stimulation for the detection of focal changes in nerve conduction velocity at common entrapment sites, such as in the across‐elbow segment of the ulnar nerve.
Central motor conduction: Method and normal results
Authors: Claus Detlef
Published: January 2005

Normal 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.
Diaphragmatic fatigue produced by constant or modulated electric currents
Authors: Jammes Yves , Collett Peter , Lenoir Patrick , Lama Abdelkalek , Berthelin Francis , Roussos Charis
Published: January 2005

In anesthetized rabbits the efficiency of phrenic nerve stimulation with trains of electric current was studied either when ventilation was effected entirely by bilateral nerve stimulation (electrophrenic ventilation) or during unilateral nerve stimulation when animals were ventilated with a pump and open chest. Trains of rectangular electric pulses (RPT) with constant amplitude and frequency or sine waves, both the amplitude and frequency of which were modulated and controlled by a computer (MSWT), were used with each animal. MSWT closely reproduced the physiological shape of transdiaphragmatic pressure waves. Diaphragm fatigue, as determined from the decrease in the maximal relaxation rate of twitches, occurred after 20 minutes of bilateral or unilateral nerve stimulation with RPT, but only after 60 min (unilateral stimulation) or 98 min (bilateral stimualtion) with MSWT. These data show the importance of the motor signal pattern in long‐lasting nerve stimulation.
Dystrophin: Localization and presumed function
Authors: Miyatake Masahiko , Teruhisa Miike , Zhao Ji‐En , Yoshioka Kowashi , Uchino Makoto , Usuku Gentaro
Published: January 2005

To determine the localization and functional significance of dystrophin, we studied various tissues from almost the entire body of control and mdxmice, and control rats, using polyclonal antibodies against dystrophin. We observed a dystrophin reaction in synaptic regions such as neuromuscular junctions, the equatorial region of intrafusal muscle fibers, the outer plexiform layer of the retina, the myoepithelial cell layer of salivary and sweat glands, tactile nerve endings, and neurons in the brain. These dystrophinpositive regions reportedly contain actin filaments as a common characteristic, which is compatible with the dystrophin cDNA sequence. Dystrophin was absent in these regions in mdx mice. These results suggest that dystrophin plays an important physiological and/or structural role in cell motility as a trigger for propagating contractile force in, for example, the conduction system, with some relationship between actin filaments.
Invited review: Myoblast transfer: A possible therapy for inherited myopathies?
Authors: Partridge Terence A.
Published: January 2005

A potential therapeutic strategy for genetic diseases is to alter the genetic constitution of the affected tissues by means of grafts of normal precursor or stem cells. Over several years, evidence has accumulated to suggest that primary diseases of skeletal muscle, such as Duchenne muscular dystrophy, may be susceptible to this approach. This review makes a critical examination of such background evidence, and also of more recent data directly addressing the concept of therapy by means of grafts of normal myogenic cells. It is concluded that the data establish the principle that such grafts effect an alteration of the genetic constitution and phenotype of skeletal muscle and, therefore, might be used to alleviate recessively inherited myopathies. Several obstacles to the therapeutic application of this method to human disease are also identified; these seem to be problems of a technical nature rather than of basic principle, and none appears insuperable.
Expression of heat shock protein epitopes in tubular aggregates
Authors: Martin Joanne E. , Mather Kanti , Swash Michael , Gray Alan B.
Published: January 2005

Tubular aggregates may be found in a variety of conditions and have been associated with a wide range of chemical and ischemic insults. We report clinical and histological features in a case of myopathy with tubular aggregates. The structure of these tubular aggregates was examined using antibodies to cytoskeletal proteins and heat shock proteins. Epitopes of the 72 kD heat shock protein were expressed in the areas of abnormality in this case and in a case of hypokalemic periodic paralysis with tubular aggregates. Heat shock proteins have a role in the modulation of the tertiary structure of proteins and may be involved in the pathogenesis of tubular aggregates and other microtubular abnormalities in muscle.
AAEM case report #22: Polymyositis
Authors: Robinson Lawrence R.
Published: January 2005

Polymyositis usually presents with progressive proximal muscle weakness, increased serum levels of muscle enzymes, inflammatory changes on muscle biopsy, and characteristic electromyographic (EMG) abnormalities. Motor unit action potential (MUAP) changes of configuration, duration, and amplitude are the most frequently observed EMG abnormality. Fibrillation potentials are commonly seen and tend to reflect active disease, diminishing after successful medical management or disease regression. Other muscle diseases can present with similar electromyographic abnormalities, thereby necessitating muscle biopsy for definitive diagnosis.
CO2 laser‐induced pain‐related somatosensory evoked potentials in peripheral neuropathies: Correlation between electrophysiological and histopathological findings
Authors: Kakigi Ryusuke , Shibasaki Hiroshi , Tanaka Kaoru , Ikeda Teruaki , Oda Ken‐Ichiro , Endo Chiyoko , Ikeda Akio , Neshige Ryuji , Kuroda Yasuo , Miyata Kiyonori , Yi Shigehiro , Ikegawa Shinichi , Araki Shukuro
Published: January 2005

Pain‐related somatosensory evoked potentials (pain SEPs) following co2 laser stimulation as well as conventional electrically stimulated SEPs (electric SEPs) were examined in 10 patients with peripheral neuropathies in whom the histopathological examination of the sural nerve was done. Results of pain SEPs showed a positive relationship with clinical impairment of pain sensation and densities of small myelinated fibers of the sural nerve. In contrast, results of electric SEPs showed a positive relationship with clinical impairment of deep and tactile sensations and with densities of large myelinated fibers of the sural nerve. Therefore, pain SEPs are considered to be generated by ascending signals mediated through nociceptive receptors and Aδ fibers. The pain SEP is only one noninvasive and objective method currently available to investigate a physiological condition of the sensory pathway responsible for pain sense, and is especially useful when combined with the conventional electric SEPs.
Ultrasound imaging of the quadriceps muscle in elderly athletes and untrained men
Authors: Sipila Sarianna , Suominen Harri
Published: January 2005

Ultrasound (US) technique was applied to measure the thickness, crosssectional area (CSA), and internal structure of the quadriceps muscle ih 70‐to 80‐year‐old endurance and power athletes and untrained men. Isometric knee extension strength was higher in the power athletes than in the other groups. The mean values for thickness and CSA did not differ between the athletes and the untrained men. The intensity of the intramuscula echo was, however, lower and the echo reflected from the connective tissue septa and bone was higher in the athletes than in the untrained men. Both the CSA and internal structure of the muscle group correlated signifjaayntly with muscle strength and number of training kilometers per year. The resuits suggest that long‐term training maintains the muscle architecture and counteracts the age‐related replacement of contractile tissue by other tissues such as fat.
Immobilization‐induced changes in motor unit force and fatigability in the cat
Authors: Robinson Grant A. , Enoka Roger M. , Stuart Douglas G.
Published: January 2005

The purpose of this study was to examine the effects of 3 weeks of immobilization on the mechanical properties of motor units in a cat hindlimb muscle. The muscle, tibialis posterior, was immobilized in a shortened position. Motor units were classified as type FF, F(int), FR, or S. Force, axonal conduction velocity, fatigability, and proportions of motor unit types were compared in control and immobilized muscles. All properties exhibited some change after immobilization, including slower axonal conduction velocities, greater twitch forces, slower twitch contraction times, and greater tetanic forces. In addition, most motor units were less fatigable after immobilization. The number of motor units that could not be included in one of the four classification categories increased significantly after immobilization; these units exhibited normal axon conductivity but failed to produce measurable force or associated EMG. Short‐term immobilization induced a variety of physiological adaptations in neuromuscular processes that varied with motor unit type.
Carnitine in muscle, serum, and urine of nonprofessional athletes: Effects of physical exercise, training, and L‐carnitine administration
Authors: Arenas J. , Ricoy J. R. , Encinas A. R. , Pola P. , D'Iddio S. , Zeviani M. , DiDonato Stefano , Corsi M.
Published: January 2005

Efficient utilization of fatty acids to sustain prolonged physical efforts is thought to be dependent on the carnitine shuttle of muscle. A study has been carried out in 24 athletes (13 long‐distance runners and 11 sprinters). These subjects received placebo or L‐carnitine (1 g/orally b.i.d.) during a 6‐month period of training. In endurance athletes, training induced lowering of total and free muscle carnitine. Increase of esterified muscle carnitine was also observed. Post‐exertional overflow of acetylcarnitine and long chain acylcarnitine, as well as reduction of the free fraction was also noticed in the blood. Fasting plasma carnitine levels, however, were not affected in carnitine‐treated atheletes at rest. These changes were likely related with the significantly increased urinary excretion of esterified and total carnitine which occurred after physical exercise. In the sprinters only, a decrease in free and total carnitine of muscle was detected after training. Both these potentially unfavourable effects were prevented by oral administration of L‐carnitine. Our data suggest that training in endurance athletes, and to a lesser extent, in sprinters, is associated with a decrease in free and total carnitine of muscle, due to an increased overflow of short‐chain carnitine esters in urine.
Type 2 fiber predominance in lambert–eaton myasthenic syndrome
Authors: Squier Marian , Chalk Colin , Hilton‐Jones David , Mills Kerry R. , Newsom‐Davis John
Published: January 2005

Serial muscle biopsies in a noncarcinomatous case of Lambert–Eaton myasthenic syndrome (LEMS) have shown progressive atrophy and loss of type 1 fibers, resulting in overwhelming type 2 predominance. A similar abnormality was found in a single biopsy from a second case of LEMS without associated carcinoma. Review of the literature suggests that type 2 fiber predominance has been observed in at least one other biopsied case. Interference with transmitter release caused by anti–voltage‐gated calcium channel antibodies may deprive type 1 muscle fibers of the low frequency discharge necessary to maintain their metabolic properties.
Acute peripheral arterial occlusion: Electrophysiologic study of 32 cases
Authors: Lachance Daniel H. , Daube Jasper R.
Published: January 2005

Thirty patients with 32 acute peripheral arterial occlusions underwent nerve conduction and electromyographic studies at a mean of 12.4 months after the vascular occlusion. Compound action potentials showed greater reduction than conduction velocity (26% to 75% vs 8% to 13% lower than normal). All changes were more prominent in the legs than arms, including fibrillation potentials (64% vs 28%). Short motor unit potentials were seen in extent of abnormality vareid with location of occlusion. Signs of nerve damage were significantly decreased in patients who had early revascularization. The electrophysiologic findigns suggested exonal destruction rather than demyelination.
Distant effects of locally injected botulinum toxin: A double‐blind study of single fiber EMG changes
Authors: Lange Dale J. , Rubin Michael , Greene Paul E. , Kang Un J. , Moskowitz Carol B. , Brin Mitchell F. , Lovelace Robert E. , Fahn Stanley
Published: January 2005

We used single fiber electromyography (SFEMG) to study 42 patients who had enroleld in a double‐blind, placebo‐controlled trial undertaken to assess the efficacy of botulinum toxin (BTX) injection of neck muscles to treat torticollis. SFEMG in a limb muscle was performed before treatment, 2, and 12 weeks after injection of placebo or BTX. Before treatment, the mean jitter was 26.8 μsec in patients who were to receive BTX, and 25.7 μsec in the placebo group. Two weeks after injection, mean jitter in the group receiving BTX was 43.6 μsec. In the placebo group, it was 26.5 μsec (P = <.05). Twelve weeks after injection, mean jitter in the BTX group was 35.5; for the placebo group it was 24.5. Fiber density did not change in any patient during the study. There were no remote clinical effects of BTX. Injection of BTX into muscles affected with focal dystonia is a promising and safe treatment, but there are subclinical effects on uninjected muscles.
Large amplitude sensory action potentials in myelopathy: An observation
Authors: Pullman Seth L. , Rubin Michael
Published: January 2005

Subjects with at least one sensory action potential (SAP) amplitude greater than 2 SD above the age‐matched mean during standard nerve conduction tests were evaluated for evidence of spinal cord disease. From a total of 153 subjects, 16 had at least one large amplitude SAP and 12 of 16 (75%) had a documented myelopathy. While a mechanism has yet to be determined, this observation suggests that SAP amplitudes greater than 2 SD above normal may be correlated with clinical evidence of injury to the central nervous system.
AAEM minimonograph #14: The influence of temperature in clinical neurophysiology
Authors: Denys Eric H.
Published: January 2005

AAEM MINIMONOGRAPH #14Temperature affects biologic and neurophysiologic processes and is, therefore, always well controlled in in vitro experiments. Its role is equally important in the clinical laboratory but has often been neglected. Lower temperatures cause slower nerve conduction velocities (NCVs), and increased amplitudes of muscle and nerve potentials. Fibrillations may disappear, and muscle contraction will be slower and weaker. Neuromuscular transmission improves. Somatosensory evoked potentials (SEPs) are similarly vulnerable in the peripheral segments, or with changes in central temperature. As a result, abnormalities are artificially created or existing defects are not detected, resulting in false or missed diagnoses. Control of temperature, albeit somewhat time consuming, will result in greater diagnostic accuracy.
Use of a catchlike property of human skeletal muscle to reduce fatigue
Authors: Binder‐Macleod Stuart A. , Barker Charles B.
Published: January 2005

This study compared the force output produced by variable frequency, short‐duration trains (VFTs) of electrical pulses with the forces produced by constant frequency, short‐duration trains (CFTs). Human quadriceps femoris muscle was stimulated with a 300‐msec train of pulses once every second for 180 seconds. Each subject (n = 12) participated in 4 randomly assigned experimental sessions. During 3 sessions, a CFT of 80, 40 or 20 pps was used. During a fourth session, a VFT, which consisted of all 3 of the above frequencies, was used. The force at 100 msec, average force of each contraction and peak force were calculated for every 30th contraction. By the 90th contraction, the force at 100 msec and the average force were significantly greater for the VFT than for each CFT. Thus, the VFT, by using a catchlike property, may provide significant advantages over any CFT when using electrical stimulation for functional electrical stimulation.
Far‐field potentials in muscle
Authors: Dumitru Daniel , King John C.
Published: January 2005

Far‐field potentials have been predicted by computer simulations as well as demonstrated in both animals and humans with respect to the peripheral and central nervous systems. Computer simulations have also predicted far‐field potentials originating at the termination of muscle tissue. This investigation demonstrates the occurrence of 2 far‐field potentials in the human biceps muscle resulting from action potential termination at the musculotendonous junctions. A monophasic potential is produced at both the muscle's origin and insertion, and the polarity is entirely dependent upon the recording montage. Sequential stimulation of the biceps muscle at 2.5‐cm increments resulted in the 2 far‐field potentials and their respective latencies changing proportional to the distance between the stimulus site and the 2 musculotendonous junctions. Various stimulation and recording montages are used to investigate the properties of these far‐field potentials. The leading/trailing dipole model is utilized to explain the production and polarity of far‐field potentials generated by muscle tissue.
Axonal damage in Guillain‐Barré syndrome
Authors: Van Der Meché Frans G. A. , Meulstee Jan , Kleyweg Ruud P.
Published: January 2005

In Guillain‐Barré syndrome patients, severe axonal degeneration occasionally occurs, often resulting in permanent functional deficit. In order to assess the development of axonal degeneration, we followed a consecutive series of 42 patients longitudinally using clinical and neurophysiological methods. Eight patients were considered to have severe axonal degeneration: in these patients denervation potentials were eventually found and at least 1 nerve proved inexcitable, and clinical recovery was slow and incomplete. Five of these 8 patients initially showed a pronounced generalized conduction block, the physiological hallmark of demyelination, before signs of axonal degeneration developed. In the remaining three patients, the first evaluation revealed low amplitudes with only modest conduction block; this is consistent with predominantly distal demyelination, but might, alternatively, be explained by primary axonal degeneration. Caution is necessary in using distal CMAP parameters for prognostic purposes, because the distal CMAP may be relatively spared in the early phase of the disease despite severe axonal degeneration later.
Autonomic function in hereditary motor and sensory neuropathy (charcot‐marie‐tooth disease)
Authors: Ingall Timothy J. , McLeod James G.
Published: January 2005

Autonomic tests of heart rate and blood pressure control using both invasive and noninvasive techniques were performed on 11 patients with hereditary motor and sensory neuropathy (HMSN) types 1, and 4 patients with HMSN type 2. The results were compared with those of 76 control subjects. No significant difference was found between the patient and control groups. Impairment of sweating on the extremities was found in patients with HMSN types 1 and 2, consistent with distal degeneration of sympathetic fibers in peripheral nerves, but there were no abnormalities of cardiovascular reflex control mechanisms.
Stimulated single‐fiber electromyography in lambert‐eaton myasthenic syndrome
Authors: Chaudhry Vinay , Watson Danny F. , Bird Shawn J. , Cornblath David R.
Published: January 2005

The Lambert‐Eaton myasthenic syndrome (LEMS) is an autoimmune disorder of neuromuscular transmission. Electrodiagnosis is confirmed by an increase in compound muscle action potential amplitude during high‐frequency repetitive nerve stimulation or following brief exercise. We describe the results of stimulated single‐fiber electromyography in 4 patients with disorders of neuromuscular transmission: LEMS (2), LEMS/myasthenia gravis (MG) overlap (1), and MG (1). Stimulated SFEMG was performed in the extensor digitorum communis muscle with axonal intramuscular suprathreshold stimulation at low and high rates. In all 4 patients, a rate dependence of jitter was found. In LEMS and LEMS/MG, jitter and blocking improved with high stimulation rates, as compared with the opposite effect in MG. We conclude that stimulated SFEMG is a valuable technique in the diagnosis of LEMS.
Class II MHC antigens in normal human skeletal muscle
Authors: Cifuentes‐Diaz Carmen , Delaporte Christine , Dautréaux Brigitte , Charron Dominique , Fardeau Michel
Published: January 2005

Class II MHC antigen expression has been investigated in muscle tissue and cultured cells from normal human skeletal muscle by light and electron immunocytochemistry. In muscle tissue, these antigens were detected in satellite cells, interstitial cells, and blood vessels. In cultures, muscle cells were stained with a pan‐reactive anti‐HLA class II antibody and with isotypes specific for DP, DQ, and DR. The staining was present on mononucleated cells and persisted on myotubes; it was stronger for DR and DQ isotypes than for DP. At the subcellular level, staining was located not only at the cell surface, but also next to the endoplasmic reticulum and in the cytosol. Thus, myosatellite cells and aneurally cultured cells from human normal skeletal muscle express class II MHC antigens. Moreoever, the myotube staining and the presence of gold particles inside the cells suggested synthesis of these antigens after myoblast fusion.
Muscle fatigue measured with evoked muscle vibrations
Authors: Barry Daniel T. , Hill Timothy , Im Dukjin
Published: January 2005

Skeletal muscle vibrates laterally during voluntary and evoked muscle contractions. We hypothesized that the vibration amplitude from evoked muscle twitches is directly related to evoked twitch force from fatiguing muscle. To test the hypothesis, vibrations produced by evoked muscle twitches were recorded during short (5‐second) rest periods as the muscle was intermittently exercised with voluntary contractions. Trials were performed at 30%, 50%, and 70% of maximal coluntary contraction. Evoked muscle twitches eliminated the problems of motivation and tremor that complicatye sound and vibration measurements during voluntary contractions. Results from the first dorsal interosseus hand muscle in 11 normal adult volunteers from the first dorsal interosseus hand muscle in 11 normal adult volunteers revealed that the vibration amplitude is highly correlated (r2 = 0.93, at 70% MVC, r2 = 0.97, at 50% MVC; r2 = 0.85, at 30% MVC) with force. Both potentiation and reduction of force with exercise were accompanied by parallel changes in vibration amplitude, as measured with an accelerometer. Compound muscle action potentials did not increase with exercise‐induced twitch potentiation, and did not correlate as highly with force during fatigue.
Muscle energy metabolism in female DMD/BMD carriers: A 31P‐MR spectroscopy study
Authors: Barbiroli Bruno , Funicello Rosanna , Ferlini Alessandra , Montagna Pasquale , Zaniol Paolo
Published: January 2005

31P nuclear magnetic resonance spectroscopy (31P‐MRS) was used to investigate the energy metabolism of the gastrocnemius muscle in 16 DMD/BMD female carriers. No significant difference was found with the controls in the resting muscle, while all carriers showed a decreased ability to perform work, and a higher Pi/PCr ratio for comparable relative levels of steady‐state work. The rate of postexercise recovery of PCr/Pi ratio was lower in all carriers. The decreased rate of PCr/Pi recovery appears to be mainly due to a decreased rate of Pi recovery. Our findings show abnormal muscle energy metabolism in DMD/BMD female carriers.
X‐linked recessive Charcot–Marie‐Tooth neuropathy: Clinical and genetic study
Authors: Ionasescu Victor V. , Trofatter James , Haines Jonathan L. , Summers Anne M. , Ionasescu Rebecca , Searby Charles
Published: January 2005

We describe three families with X‐linked recessive Charcot–Marie–Tooth (CMT) neuropathies. The disease phenotype in family 1 was characterized by infantile onset, weakness of lower legs, areflexia, pes cavus, and mental retardation (2 of 5 patients). The disease phenotype in families 2 and 3 was characterized by late onset, distal weakness, and normal intelligence. Hereditary spastic paraparesis was also present in the CMT patients of family 2. Thirty X‐linked DNA markers were used for linkage studies. A maximum lod score of +3.48 was obtained by multipoint linkage analysis for the DXS16 locus mapped at Xp22.2 in family 1. In families 2 and 3, there was suggestion of linkage of Xq26 markers; the peak mutlipoint lod score for these 2 CMT families was 1.81, at DXS144. These results were suggestive of heterogeneity. The joint analysis including both regions (Xp22.2 and Xq26) provided evidence against homogeneity (χ2 = 9.12, P < 0.005).
Dantrolene sodium and fatigue of long duration
Authors: Moussavi Robabe S. , Lehman Steven L. , Miller Robert G.
Published: January 2005

A long‐lasting imparment of muscular force generation follows fatiguing exercise (fatigue of long duration), the physiological basis of which is not well understood. To investigate the role of reduced calcium release in longlasting fatigue, we examined the effects of dantrolene sodium, which selectively decreases calcium release from the sarcoplasmic reticulum. The drug impaired muscle function in a pattern identical to that of long‐lasting fatigue. The results are consistent with either indeependent effects of dantrolene and exercise at the same site in the excitation–contraction coupling chain, or independent actions at separate serial sites.
Adverse effect of verapamil in myasthenia gravis
Authors: Swash Michael , Ingram David A.
Published: January 2005

Verapamil, a class IV anti‐arrhythmic drug that blocks voltage‐dependent calcium channels in cardiac and smooth muscle, also has effects on presynaptic and postsynaptic voltage‐dependent calcium channels at the neuromuscular junction. In a postoperative patient with pre‐existent myasthenia gravis, oral verapamil caused a marked exacerbation in myasthenic weakness.
Jitter of the stimulated motor axon
Authors: Trontelj Jože V. , Stålberg Erik , Mihelin Marjan , Khuraibet Adnan
Published: January 2005

Electrical microstimulation of motor axons in conjunction with single fiber EMG (SFEMG) is increasingly used to measure the jitter of the motor endplates. This study examines the jitter of the stimulation site on the axon when stimulus strength is at threshold. In the absence of spurious blocking, this was found to be 5 µs on the average. With intermittent blocking, however, a mean additional jitter of 40 µs was obtained. The latter is considered to result from changing propagation velocity in the muscle fiber due to irregularity of activation rate. In clinical jitter studies, inadvertent threshold stimulation can result in significant error when associated with intermittent blocking.
Modulation of soleus H reflex by lateral tilting in man
Authors: Aiello I. , Rosati G. , Sau G. F. , Cacciotto R. , Lentinu M. E. , Tidore B. , Traccis S.
Published: January 2005

Static vestibular infuences on extensor tone of the lower limbs in man were studied by analyzing the changes in right soleus H‐reflex (RSHR) area in relation to lateral titings. Eight normal asult volunteers were tested in an experimental situation designed to minimize all afferent inputs, except the vestibular ones. Each subject was seated on a chair which could be tited laterally from the vertical to both sieds. Lateral titings were applied at a random order from the vertical (0° control position) to 4°, 8°, 12°, 16°, and 20°, of both sides (test positions). The results showed inhibtion in SHR area of the leg ipsilateral to the titing and facilitation of the contralateral SHR. These data indicate that, in man as in the decerebrate cat, tonic labyrinth reflexes act asymmetrically and that, in static condition, the vestibular syseral perturbation of upright position.
Localization of protein kinase C in human skeletal muscle
Authors: Nakano Satoshi , Shimohama Shun , Saitoh Tsunao , Akiguchi Ichiro , Kimura Jun
Published: January 2005

The immunolocalization of protein kinase C (PKC) isozymes α, βI, and βII, was investigated in human skeletal muscle. All three isozymes were present on the muscle fiber surface membrane and within the muscle fibers. The α‐isozyme was most clearly delineated on the surface membrane of the muscle fiber and on small blood vessels in the connective tissue. The axons of myelinated intramuscular nerves stained intensely for the βI isozyme, whereas the endoneurial connective tissue reacted more strongly for the α‐ and βII‐isozymes. PKC isozymes may regulate intracellular signal transduction in human skeletal muscle, as in the other tissues. but their exact role in muscle remains unknown.
Human myoblast transplantation: Preliminary results of 4 cases
Authors: Huard J. , Bouchard J. P. , Roy R. , Malouin F. , Dansereau G. , Labrecque C. , Albert N. , Richards C. L. , Lemieux B. , Tremblay J. P.
Published: January 2005

Myoblasts from immunocompatible donors have been transplanted into the muscles (tibialis anterior, biceps brachii, and/or extensor carpi radialis longus) of 4 Duchenne patients in the advanced stages of the disease. Although no immunosuppressive treatment was used, none of the patients showed any clinical signs of rejection such as fever, redness, and inflammation. One patient transiently produced antibodies against the donor myoblasts as determined by cytofluorometric analysis. This patient and 2 others were shown to form antibodies against their donor's myotubes. Muscle biopsies of the injected tibialis anterior of 4 patients revealed that 80%, 75%, 25% and 0% of the muscle fibers, respectively, showed some degree of dystrophin immunostaining, The contralateral noninjectd muscles of the latter 3 patients did not contain any dystrophin positive fibers, while that of the first patient showed dystrophin expression in 16% of the fibers examined. Myoblasts were also injected into the extensor carpi radialis longus or the biceps brachii of these patients. A few months subsequent to injection, one patient was shown to have a 143% increase of strength during static wrist extension. This result must be interpreted with caution because a double‐blind strength‐measuring protocol was not used. Furthermore, we have noted that this change slowly decayed over time. The strength of 2 other patients was increased less remarkably (41% and 51%), while the strength of the fourth patient was unchanged.
Eosinophilia–myalgia syndrome: Myopathic electrodiagnostic characteristics
Authors: Tanhehco Justina L. , Wiechers David O. , Golbus Joseph , Neely Sarah E.
Published: January 2005

Eosinophilia–myalgia syndrome (EMS) is disorder characterized by generalized muscle pain and eosinophilia. The etiology of this syndrome appears to be related to the ingestion of L‐tryptophan. Most studies to date describe an associated peripheral neuropathy or combined myopathy and peripheral neuropathy. This report presents 2 EMS patients with myopathy, confirmed by muscle biopsy in 1 case and electrophysiology in both cases. No clinical evidence of neuropathy was found. Both routine and single fiber electromyography failed to demonstrate abnormalities, suggesting neuropathy. Electrodiagnostic abnormalities paralleled the clinical course. After 10 months, both patients continued to have symptoms of muscle cramping and reduced endurance, with mild electromyographic abnormalities, perhaps reflecting changes in their motor unit.
Median–ulnar nerve communications and anomalous innervation of the intrinsic hand muscles: An electrophysiological study
Authors: Amoiridis Georgios
Published: January 2005

One hundred (100) left arms were examined for median‐to‐ulnar or ulnar‐to‐median nerve anastomoses using surface electrodes. Muscles innervated by the anastomosis were determined using a concentric needle electrode. We found a motor median‐to‐ulnar nerve anastomosis in the forearm in 32% of the cases (Martin–Gruber anastomosis, MGA). No case of motor ulnar‐to‐median nerve anastomosis in the forearm could be found. The MGA mainly innervated muscles, which are normally supplied by the ulnar nerve. The high incidence of MGA in this study shows that all clinically relevant motor median‐to‐ular nerve communications in the forearm can be detected using surface electrodes in routine examinations. Stimulus spread must be looked for and eliminated by the methods described.
Neuromuscular causes of prolonged ventilator dependency
Authors: Spitzer A. Robert , Giancarlo Thomas , Maher Leo , Awerbuch Gavin , Bowles Alvin
Published: January 2005

We prospectively evaluated 21 patients with prolonged ventilator dependency, to determine the frequency of unsuspected neuromuscular disease as a cause of this condition, and to determine the types of such diseases. Assessment was performed with routine and specialized electrophyiologic procedures. None of the patients had known prior neuromuscular disease, and none of had ongoing medical problems that could account for their continued ventilator dependency. Sixty‐two precent were found to have a neuromuscular disease severe enough to account for the ventilator dependency. Most of the remaining cases had a contributory neuromuscular disease. In addition to critical illness polyneuropathy, several other significant categories were identified. Myopathic EMG changes were found in 50% of the subgroup assessed by quantitative EMG. We conclude that neuromuscular disease is the most important factor in prolonged ventilator dependency, and that disease other than critical illness polyneuropathy represent an important cause of this syndrome.
Modeling fiber type grouping by a binary markov random field
Authors: Venema Henk W.
Published: January 2005

A new approach to the quantification of fiber type grouping is presented, in which the distribution of histochemical type in a muscle corss section is regarded as a realization of a binary Markov random field (BMRF). Methods for the estimation of the parameters of this model are discussed. The first order BMRF, which is used in this article, contains 2 parameters: α and β. The parameter β is of prime importance, as it is an interaction parameter which governs the degree of type grouping. The value of this parameter is estimated for 9 muscle biopsies. The interpretation of the results is discussed.
Dominantly inherited malignant hyperthermia (MH) in the King–Denborough Syndrome
Authors: Isaacs Hyam , Badenhorst Margaret E.
Published: January 2005

A 14‐year‐old boy, an only child, with the phenotypical dysmorphic features of the King–Denborough Syndrome developed a severe hyperthermic episode during anesthesia which responded to the administration of sodium dantrolene. As adequate metabolic studies were not available at the time of the crisis he was referred for confirmation of the malignant hyperthermia (MH) status. Muscle tension studies confirmed the presence of MH. The patient's mother and father were subsequently tested and the mother was found to be MH positive, the father MH negative.