bluuebunny/crossref_metadata_2025 huggingface dataset:
A myasthenia gravis plasma immunoglobulin reduces miniature endplate potentials at human endplates in vitro
Authors: Burges Judith , Wray Dennis W. , Pizzighella Sergio , Hall Zach , Vincent Angela
Published: January 2005

A particular myasthenia gravis (MG) plasma Ig has previously been shown to block a single α‐bungarotoxin (α‐BuTX) binding site on embryonic rat muscle acetylcholine receptor (AChR). We have investigated its effect on embryonic/denervated and adult human AChR both in extracts and in situ. Plasma Ig blocked 125I‐α‐BuTx binding by greater than 85% to the AChR extracted from denervated muscle, but only by 55% to AChR extracted from normal human muscle. Incubation of intact human muscle fibers with the plasma Ig reduced 125I‐α‐BuTx binding to the endplate AChRs by 63%, and substantially decreased the amplitude of miniature endplate potentials. We conclude that anti‐α‐BuTx site antibodies, when present, can be important in the pathophysiology of the disease.
Carpal tunnel syndrome : Which finger should be tested? An analysis of sensory conduction in digital branches of the median nerve
Authors: MacDonell Richard A. L. , Schwartz Martin S. , Swash Michael
Published: January 2005

Each digital branch of the median nerve was stimulated in turn in 34 women (55 hands) with carpal tunnel syndrome (CTS). The amplitude and conduction velocity of the sensory nerve action potential (SNAP) recorded at the wrist, and the threshold for patient perception of the electrical stimulus on the median innervated sides of each digit, were compared with the corresponding values in a group of asymptomatic, age‐matched women. Sensory conduction velocity of SNAP amplitude were abnormal in more than 80% of all digital nerves studied apart from those in the index finger. Stimulation of digital nerves in the index finger proved the least sensitive means of detecting the electrophysiological abnormality. We conclude that selective digital nerve stimulation is a sensitive technique in the diagnosis of CTS. If ring electrodes are preferred, our results suggest that the middle rather than the index finger should be used.
Neuralgic amyotrophy with involvement of cranial nerves IX, X, XI and XII
Authors: Pierre Philippe A. , Laterre Christian E. , Van Den Bergh Peter Y.
Published: January 2005

We report a patient who presented with involvement of multiple cranial nerves associated with otherwise typical neuralgic amyotrophy. This syndrome of unknown etiology is not limited to the brachial plexus. Simultaneous involvement of cranial nerves IX, X, XI, and XII is a unique presentation. The electrophysiological data indicate the presence of a multifocal neuropathy.
Myasthenia gravis presenting as weakness after magnesium administration
Authors: Bashuk Robert G. , Krendel David A.
Published: January 2005

We studied a patient with no prior history of neuromuscular disease who became virtually quadriplegic after parenteral magnesium administration for preeclampsia. The serum magnesium concentration was 3.0 mEq/L, which is usually well tolerated. The magnesium was stopped and she recovered over a few days. While she was weak, 2‐Hz repetitive stimulation revealed a decrement without significant facilitation at rapid rates or after exercise, suggesting postsynaptic neuromuscular blockade. After her strength returned, repetitive stimuation was normal, but single fiber EMG revealed increased jitter and blocking. Her acetylcholine receptor antibody level was markedly elevated. Although paralysis after magnesium administration has been described in patients with known myasthenia gravis, it has not previously been reported to be the initial or only manifestation of the disease. Patients who are unusually sensitive to the neuromuscular effects of magnesium should be suspected of having an underlying disorder of neuromuscular transmission.
Quantitative clinical electrophysiology in the evaluation of nerve injury and regeneration
Authors: Dorfman Leslie J.
Published: January 2005

Neuromuscular elecrophysiological techniques can provide clinically important information about the localization, severity, and pathophysiology of peripheral nerve injuries, and about the progress of reinnervation. The relevant variables for study are compound nerve and muscle action potentials, motor unit action potentials, and denervation potentials. Available methods do not permit meaningful quantitation of regeneration. Newer methods under development attempt to estimate the number of motor units in a muscle and the number of axons in a nerve.
Single fiber EMG evaluation in denervation and reinnervation
Authors: Wiechers David
Published: January 2005

SFEMG can be used o follow the course of reinnervation. The parameters of fiber density, mean jitter and percent blocking must each be followed and related to the type of injury to determine the stage of reinnervation. The few reported cases in the literature of SFEMG recordings followed over time after nerve compromise are reviewed and an additional case is presented by the author. Mean jitter values can return to normal approximately 1½ years postonset of reinnervation. Some individual recordings may remain abnormal permanently.
Schwartz–Jampel syndrome with dominant inheritance
Authors: Pascuzzi Robert M. , Gratianne Roberto , Azzarelli Biagio , Kincaid John C.
Published: January 2005

The Schwartz–Jampel syndrome (SJS) is a rare congenital multisystem disorder of unknown pathogenesis which is characterized by distinct faces, skeletal deformities, joint contractures, short stature, muscle hypertrophy, clinical myotonia, and continuous muscle fiber activity. The inheritance pattern of SJS has been assumed to be autosomal recessive. We report the occurrence of the classic SJS syndrome in both a father and son in a non‐consanguineous family, suggesting that SJS has the potential for a dominant pattern of inheritance.
Carpal tunnel syndrome: Correlations between pressure measurement and intraoperative electrophysiological nerve study
Authors: Luchetti Riccardo , Schoenhuber Rudolf , Alfarano Mauro , Deluca Stefano , De Cicco Giorgio , Landi Antonio
Published: January 2005

In 19 carpal tunnel syndrome (CTS) patients and 4 control subjects a catheter was introduced into the carpal tunnel and slowly retracted in 5 mm steps. Pressure was measured with the continuous infusion technique. In the same group of patients and controls, median nerve antidromic sensory action potential (aSAP) was detected introperatively stimulating proximally (S1), in the center (S2), and distally (S3) to the carpal tunnel and recording from the third finger (R). Sensory conduction velocity (SCV) and aSAP amplitude were considered in S1‐S2, S2‐S3 and S3‐R segments. The intracarpal tunnel pressure was significantly higher in CTS patients than in controls, with the highest values located between 25 and 35 mm distal to the proximal border of the flexor retinaculum. SCV and aSAP amplitude were also decreased most often in the distal part (S2‐S3) of the carpal tunnel.
On the shape of the normal turns‐amplitude cloud
Authors: Nandedkar Sanjeev D. , Sanders Donald B. , Stalberg Erik V.
Published: January 2005

Factors that affect the shape of the so‐called “normal cloud” of the turns and amplitude measurements of the electromyographic interference pattern are investigated. As the force of voluntary contraction increase from low to moderate levels, the number of turns in the signal increase faster than does the mean amplitude change between turns. This results in a cloud that is concave downward. At higher force levels, the pattern is reversed. The overall shape of the cloud thus depends on the maximum effort at which recordings are made, which is determined by the procedure of muscle activation.
Nerve‐muscle involvement in a large family with mitochondrial cytopathy: Electrophysiological studies
Authors: Torgbergsen Torberg , Stålberg Erik , Bless Janne K.
Published: January 2005

Thirteen patients with mitochondrial cytopathy were investigated. They represent different generations, ages, stages, and severities of the disease. All were assumed to have the same metabolic defect. The disease is a multisystem disorder with a metabolic defect located at complex 1 in the respiratory chain. Clinically, the disorder gives symptoms such as hearing loss, retinal pigmental degeneration, ataxia, cardiomyopathy, muscular fatiguability and neuropathy. The patients were investigated with nerve conduction studies, concentric needle EMG, SFEMG, and macro EMG examinations. Neurophysiologic studies revealed signs of myopathy in both the younger members and in those with slight muscular symptoms. In the more advanced stages, neuropathic changes of the axonal type were seen as well. Macro EMG was interpreted as indicating muscle fiber membrane abnormalities in the early stages. Single fiber EMG studies indicate that this metabolic defect does not distrub neuromuscular transmission.
Expression of superfast myosin in aneural regenerates of cat jaw muscle
Authors: Bssc Joseph F. Y. Hoh , Hughes Suzanne
Published: January 2005

We investigated whether innervation is necessary for the expression of superfast myosin in regenerating cat jaw‐closing muscle. Strips of jaw muscle were permitted to regenerate bilaterally in the beds of a fast limb muscle with innervation on one side being prevented surgically. Immunocytochemical analyses using anti‐myosin heavy chain antibodies were done at various times postoperatively, the latest being after 78 days. We found little difference between innervated and uninnervated regenerates up to 27 days postoperatively. All regenerating myotubes expressed fetal myosin. In addition, some myotubes stained for superfast or slow myosin, while others stained for both superfast and slow myosins. Subsequently, uninnervated myotubes became atrophic but continued to express fetal, slow, and superfast myosins while innervated myofibers suppressed fetal and slow myosin expression. These results are consistent with the notion that satellite cells of jaw‐closing muscles are committed to express superfast myosin during myogenesis, and that the expression of this program is independent of innervation.
External recording of twitch time course in cat ankle muscles
Authors: Eerbeek O. , Kernell D.
Published: January 2005

In chronic experiments concerning the activity‐dependent plasticity of muscle properties, a simple and noninvasive method was used for monitoring changes of twitch speed in conscious adult cats. The animals had been provided with implanted electrodes for nerve stimulation, and a hand‐held force transducer was pressed against the fully extended ankle joint while single test pulses were delivered to the common peroneal nerve. In the present report, this technique for the recording of ankle twitches is subjected to critical analysis and evaluation. The measurements were highly reproducible with respect to contraction time (time‐to‐peak) but less so for half‐relaxation time and twitch amplitude; other methods should be used for the long‐term monitoring of contractile force. The total force (torque) of the ankle twitch was mainly produced by tibialis anterior (about 45%), peroneus longus (PerL; 27%) and extensor digitorum longus (23%). The ankle twitch produced by PerL alone had about the same contraction time as that of all the muscles together. Among muscles that had become changed as a result of long‐term electrical stimulation there was, in general, a good correspondence between the contraction times from simple external recordings of ankle twitches and those separately measured for PerL under general anesthesia (force transducer then directly connected to PerL tendon).
Assessment of locomotor function in young boys with duchenne muscular dystrophy
Authors: Smith Robert A. , Newcombe Robert G. , Sibert Jo R. , Harper Peter S.
Published: January 2005

Thirty‐three young boys (mean age 3.42 years) with Duchenne muscular dystrophy (DMD) and 21 normal control boys (mean age 3.51 years) were studied prospectively to determine whether it is possible to objectively assess locomotor function in young boys with DMD so that they can be included in treatment trials. An initial reproducibility study using a hand‐held myometer demonstrated that this method was not useful. The Hammersmith Motor Ability Score demonstrated an increase in developmental abilities with age which was markedly different from normal. The locomotor quotient of the Griffiths' Scales demonstrated a deterioration of quotient scores and is a useful method of assessment that could be used in treatment trials involving young boys with DMD. Sample size planning for treatment trials is discussed.
A technique for needle localization in paraspinal muscles with cadaveric confirmation
Authors: Haig Andrew J. , Moffroid Mary , Henry Sharon , Haugh Larry , Pope Malcolm
Published: January 2005

Invasive electromyography (EMG) of the paraspinal muscles is useful in clinical and research settings. No technique for localization of the needle in specific fascicles has been validated. Recent descriptions of the segmented innervation of the multifidus imply that such a technique would add greatly to the EMG determination of root level of a radiculopathy. We have developed a technique for localization which relies on palpation of bony structures and needle insertion at certain angles and depths. The technique was evaluated by injecting latex dye in 199 locations in 13 cadavers. Dissection demonstrated that the technique was accurate in 91 of 112 injections into specific fascicles of the multifidus (originating from different spinous processes), 39 of 43 injections into the longissimus, and 35 of 44 injections into the iliocostalis. Certain types of errors would not have occurred with the aid of EMG in vivo. When these are added to the correct injections, accuracy improves 97%, 93%, and 82%, respectively. The technique described here should be useful for kinesiological studies, biopsies and injections, as well as for the EMG confirmation of a radiculopathy.
Comparison of stimulation and insulin effects on denervated mouse soleus muscles
Authors: Hofmann William W.
Published: January 2005

A comparison has been made between the responses of denervated mouse soleus muscles to direct electrical stimulation, as reported by earlier workers, and to incubation with supraphysiological concentrations of insulin. The parameters of interest were resting membrane potential (RMP), qualities of the active state, the amount of alpha bungarotoxin (BUTX) binding, and chemosensitivity, as measured by the strength of acetylcholine (ACh)‐induced contractures. In all aspects, the changes recorded after insulin, were in the same direction as with direct stimulation, however, owing to the time limitations of in vitro testing were smaller. It is suggested that the effects of electric shocks on denervated muscles are the result of activation of the insulin receptor, or some similar macromolecule, which appears to be sensitive to the membrane potential. The possible interrelations between acetylcholine and insulin receptors in neurotrophic control are discussed.
Glucocorticoids and immunosup pressants do not change the prevalence of necrosis and regeneration in mdx skeletal muscles
Authors: Weller Boaz , Massa Roberto , Karpati George , Carpenter Stirling
Published: January 2005

Therapeutic doses of methylprednisolone, azathioprine, cyclosporin A, and cyclophosphamide administered to mdx mice between 15 and 45 days of age failed to significantly influence the time course and prevalence of necrosis and regeneration or serum creatine kinase activity. This finding contrasts with previously reported findings of beneficial effects of glucocorticoids in Duchenne muscular dystrophy (DMD). This may indicate that, mechanisms upon which beneficial effects of glucocorticoids depend in DMD, do not operate (sufficiently) in mdx mice.
Dorsal nerve of the penis nerve conduction velocity: A new technique
Authors: Clawson David R. , Cardenas Diana D.
Published: January 2005

In the evaluation of a possible peripheral neuropathic process as the etiology of erectile dysfunction, studies of the dorsal nerve of the penis may be unique in that they allow examination of the most distal segment of pudendal nerve in isolation. This study describes a new technique using a simple traction device for elongation of the penis to determine the orthodromic nerve conduction of the dorsal nerve of the penis. With stimulation at the glans, and recording at the base of the penis, the value obtained in 20 normal subjects was 36.2 ± 3.2 m/s with an amplitude of 2.29 ± 1.08 mV.
Paradoxical lid elevation with sustained upgaze: A sign of lambert‐eaton syndrome
Authors: Breen Lenore A. , Gutmann Ludwig , Brick John F. , Riggs Jack R.
Published: January 2005

Myasthenia gravis and Lambert‐Eaton myasthenic syndrome are causes of acquired extraocular muscle weakness and ptosis. Exacerbation of ptosis after sustained upgaze is a clinically useful sign in the diagnosis of myasthenia gravis. A 54‐year‐old woman with established Lambert‐Eaton myasthenic syndrome exhibited transient improvement of her ptosis after sustained upgaze. We suggest that paradoxical lid elevation after sustained upgaze may be a clinically useful sign in distinguishing Lambert‐Eaton myasthenic syndrome from myasthenia gravis.
Invited review: Motor neuropathies, motor neuron disorders, and antiglycolipid antibodies
Authors: Md Alan Pestronk,
Published: January 2005

High titers of IgM anti‐GM1 antibodies are commonly found in the serum of patients with some lower motor neuron disorders and peripheral neuropathies. Enzyme‐linked immunosorbent assays (ELISA) are useful for the detection and quantitation of anti‐GM1 antibodies. Testing for serum anti‐GM1 activity is indicated in the diagnostic evaluation of lower motor neuron syndromes. The presence of high titers of anti‐GM1 antibodies mandates careful electrophysiologic testing for the motor conduction block that is found in multifocal motor neuropathy, a treatable disorder. Quantitation of anti‐GM1 antibodies may also be a useful guide in the treatment of multifocal motor neuropathy. Further study of antiglycolipid antibodies in motor neuron disorders and peripheral neuropathies may provide clues to the events that stimulate these antibodies and to the pathogenesis of such syndromes.
Estimate of motor conduction in human spinal cord: Slowed conduction in spinal cord injury
Authors: Chang Chein‐Wei , Lien I‐Nan
Published: January 2005

By using motor evoked potential (MEP) created by transcranial electric stimulation over the motor cortex and F‐wave measurement from the peripheral nerve stimulation, it is possible to estimate the spinal cord motor conduction velocity (SCMCV) in the diseased state. Twenty‐four patients with spinal cord injury (SCI) between T1 and T11 neurological levels participated in this study. MEP in leg muscle was absent in all neurologically complete paraplegics. In 16 patients with neurologically incomplete SCI, MEP was obtained in 13 patients. The SCMCV estimated from C7 to T12 spinal levels was 32.1 (SD = 9.4) m/s. This was significantly slower than 63.3 (SD = 8.6) m/s in 40 normal controls. This noninvasive, indirect method is measurable, and can provide valuable electrophysiological data in the assessment of motor function in patients with SCI.
Canine X‐linked muscular dystrophy studied with in vivo phosphorus magnetic resonance spectroscopy
Authors: McCully Kevin , Giger Urs , Vet Met , Argov Zohar , Valentine Beth , Cooper Barry , Chance, Britton
Published: January 2005

Duchenne muscular dystrophy (DMD) is an X‐linked disease characterized by progressive muscle weakness and degeneration. Dystrophin is the product of the missing gene in this disorder. However, the cause of the dystrophic process is not understood. Transient muscle injury is normally seen after muscle exercise, and may be a necessary process in muscle growth and preservation. We, therefore, chose to evaluate the role of exercise in Duchenne dystrophy by studying the canine X‐linked animal model (CXMD). These dogs also lack dystrophin and have clinical signs similar to humans. Exercise was initiated by electrical stimulation, and muscle metabolism was monitored with phosphorus magnetic resonance spectroscopy (P‐MRS). Dogs with CXMD had abnormal muscle pathology and markedly elevated serum CK. The inorganic phosphate (Pi) to phosphocreatine (PCr) ratio was increased in CXMD dogs at rest compared with normal dogs (Pi/ (Pi+PCr) = 0.166 ± 0.054 for CXMD and 0.073 ± 0.017 for normals, mean ± SE). No changes in resting ATP, pH, phosphomonoesters (PME), and phosphodiesters (PDE) were seen. The mean Pi/(Pi+PCr) and pH values during stimulation were normal in the CXMD dogs. Two to three days after electrical stimulation, resting Pi/(Pi+PCr) ratios were significantly increased in the CXMD dogs (0.127 ± 0.029 compared with 0.172 ± 0.054, mean ± SD). Normal dogs showed no increase in Pi/(Pi+PCr) following stimulation. There was a 50‐fold greater increase in serum CK in CXMD compared with normal dogs following exercise. These results indicate greater muscle injury in CXMD muscle, and suggest that in the absence of dystrophin, exercise‐induced muscle injury may play a role in the dystrophic process.
Comparison of sensory nerve conduction in the palmar cutaneous branch and first digital branch of the median nerve: A new diagnostic method for carpal tunnel syndrome
Authors: Chang Chein‐Wei , Lien I‐Nan
Published: January 2005

Comparison of sensory nerve conductions in palmar cutaneous branch (PCB) and digit I nerves was applied in 50 patients suspected of having carpal tunnel syndrome (CTS) and 40 healthy persons. The abnormalities were defined as the differences in latencies and sensory nerve conduction velocities (SNCVs) of more than mean plus 2.5 SD of controls. Comparing these 2 sensory nerves, statistical differences were seen in 83.7% (36 of 43 patients) of their sensory latencies and 76.7% (33 of 43 patients) of their SNCVs. This excluded 7 patients who had unobtainable sensory nerve action potentials in digit I nerves. This method may serve as an adjunctive technique in the diagnosis of CTS. Its diagnostic sensitivity was high in comparison with other testing methods.
Myokymic discharges and enhanced facial nerve reflex responses after recovery from idiopathic facial palsy
Authors: Valls‐Sole Josep , Tolosa Eduard S. , Pujol Montserrat
Published: January 2005

A functional disorder of facial muscle activity commonly occurs in patients after recovery from Bell's palsy with axonal degeneration. The postparalytic facial dysfunction is probably related to the aberrant growing of regenerating axons. although other theories such as ephaptic transmission, spontaneous generation of impulses, and enhancement of motoneuron excitability should also be considered. In this work, we have carried out a comparative electrophysiological study of both sides of the face in 23 patients who had recovered from a unilateral Bell's palsy with axonal degeneration. At rest, spontaneous firing of motor units was observed in muscles of the previously paralyzed side. Direct motor responses to facial nerve stimulation were smaller in the muscles of the previously paralyzed side, but reflex responses obtained in the same muscles by stimulation of either the facial or trigeminal nerve were larger when compared with those of the contralateral side. These data indicate that patients with “postparalytic facial dysfunction” may have an increased background muscle activity, as well as an enhanced recruitment of facial motoneurons to reflex activation in the side of the previous paralysis. These findings are compatible with an enhanced level of motoneuron excitability in the facial nucleus.
Possible model for generation of P9 far‐field potentials
Authors: Hashimoto Shuji , Kawamura Junichiro , Segawa Yoshiaki , Yamamoto Toru , Nakamura Michikazu
Published: January 2005

The distribution of P9 far‐field somatosensory evoked potentials, after ulation of the median nerve with a knee reference, was examined to mine the mechanism of the generation of P9 potentials. In addition to tive potentials (P9s), we found a negative potential (N9) recorded from the chest ipsilateral to the stimulation. The simulation of the distribution of these P9/N9 potentials by an electrical circuit diagram suggested the validity of this model for generation of the P9s.
Single fiber macro versus concentric trigger macro EMG: A comparison of methods
Authors: Nix Wilfred A. , Scherer Andreas
Published: January 2005

The values obtained from two different macro EMG methods were compared, and found to be different. Normally, macro electromyography (EMG) is performed with a modified single fiber (SF) needle using the SF potential as a trigger; a new method recommends a modified concentric needle and triggers on the concentric EMG signal. The concentric macro EMG has a 40% to 50% smaller amplitude and area values than data obtained with a SF macro EMG needle. The different values are the result of variant spatial relationships of the respective needles to the motor unit under stud, and may be due to a recruitment‐dependent bias resulting from different trigger properties of the two methods. The concentric macro EMG needle can be used to estimate motor unit size, to scan the unit, and to investigate its different concentric EMG signals.
Guidelines in electrodiagnostic medicine
Authors:   American Association Of Electrodiagnostic Medicine
Published: January 2005

The American Association of Electrodiagnostic Medicine (AAEM) is committed to the development of sound and clinically relevant guidelines through review of literature, expert opinion and consensus. In 1979, with the assistance of its Professional Practice Committee and association leaders, the association published its initial guidelines, Guidelines in Electrodiagnostic Medicine, covering the practice of electrodiagnostic medicine. The committee is charged with ongoing revision of the document, as needed, and the current version includes standards of practice in clinical electromyography, risks in electrodiagnostic medicine, basic equipment requirements, and the role of paramedical support. In 1988, Educational Guidelines for Electrodiagnostic Training Programs (Appendix A) was prepared by the AAEM Training Program Committee and added to aid training program directors in establishing new training programs or in reviewing the current status of the educational aspects of existing programs. In 1986, the AAEM charged its Quality Assurance Committee with the responsibility for the development of guidelines pertinent to electrodiagnostic medical consultations. The impetus for the charge was the requests received from members of the AAEM and other interested parties for educational material on indications for and conduct of electrodiagnostic medical consultations. As a result of the committee's efforts, Suggested Guidelines for Electrodiagnostic Medical Consultations (Appendix D), was published in 1989 and additional sections added subsequently. The current document includes (1) general indications for an electrodiagnostic medical consultation for patients with suspected myopathies, neuromuscular junction disorders, polyneuropathies, mononeuropathies, plexopathies, radiculopathies, neuronopathies and central nervous system disorders, (2) specific indications for patients with suspected lumbosacral or cervical radiculopathies, (3) general principles of electrodiagnostic studies, including techniques and diagnostic categories, and (4) an overview of electrodiagnostic studies for patients with suspected carpal tunnel syndrome, idiopathic polyneuritis, amyotrophic lateral sclerosis and myasthenia gravis.
In vitro microelectrode study of neuromuscular transmission in a case of botulism
Authors: Maselli Ricardo A. , Burnett Margaret E. , Tonsgard James H.
Published: January 2005

We performed in vitro microelectrode studies in the anconeus muscle biopsy of a 6‐week‐old infant intoxicated with Clostridium botulinum toxin B. The most striking abnormalities were the severe reduction of the endplate potential (EPP) quantal content and the marked variability of EPP latencies. The increased variability was often limited to a “single quantum” component of the EPP. Neither the amplitudes nor the frequencies of spontaneous miniature endplate potentials (MEEPs) were decreased. However, there was a wide range of amplitudes and frequencies of MEPPs. This unique combination of electrophysiologic findings indicates a severe presynaptic failure of neuromuscular transmission, which appears to result from an impairment of the process of synaptic vesicle release taking place after the stimulus induced influx of calcium into the motor nerve terminals.
Quantitative motor unit analysis: The effect of sample size
Authors: Engstrom John W. , Olney Richard K.
Published: January 2005

This study of quantitative electromyography examines the influence of sample size on motor unit action potential (MUAP) tolerance limits, intertrial variability, and diagnostic sensitivity. We recorded 20 randomly selected MUAPs from the biceps muscle twice in 21 normal subjects, and once in 10 patients with myopathy. The 95% tolerance limits for mean total duration in normal subjects progressively narrowed from 6.6 to 14.2 ms for 5 MUAPs to 7.4 to 13.0 ms for 20 MUAPs. The 95% tolerance limits for intertrial variability were ±22% for mean total duration of 20 MUAPs. Larger sample size had a greater effect on reducing intertrial variability than on narrowing 95% tolerance limits for amplitude and area. Quantitative EMG results for duration supported the presence of myopathy in 2 of 10 patients with analysis of 5 MUAPs, and 9 patients with analysis of 20 MUAPs. Although analysis of 5 potentials may be adequate for diagnosis occasionally, quantitative analysis of 20 MUAPs narrows tolerance limits, reduces intertrial variability, and improves diagnostic sensitivity.
Contractility Of mdx skeletal muscle after denervation and devascularization
Authors: Mechalchuk Cheri L. , Bressler Bernard H.
Published: January 2005

To evaluate the regenerative capacity of mdx skeletal muscle, changes in contractile properties of the fast‐twitch extensor digitorum longus (EDL) of normal and mdx mice were studied at 7 and 16 weeks of age, following denervation and devascularization (DD) at 4 weeks of age. At 7 weeks, DD EDL of both strains showed significantly decreased isometric twitch and tetanus tensions compared with their non‐DD controls. By 16 weeks, normal operated muscle exhibited a recovery of 57% and 58% of absolute tetanus and twitch tensions while the mdx EDL recovered remarkably to 96% and 99% of 7‐week values. At 7 weeks, the DD EDL of both strains exhibited significantly slower time‐to‐peak (TTP) and one‐half relaxation time (1/2RT). By 16 weeks, TTP and 1/2RT of the mdx DD EDL no longer differed from non‐DD controls, but the normal EDL showed slowed TTP. No differences were found in the maximum velocity of shortening (Vo) or in posttetanic potentiation (PTP). Following DD, there was an increase in resistance to fatigue in both strains at 7 weeks. This resistance persisted at 16 weeks in the normal mouse, but the operated mdx EDL returned to normal. It would appear that following a denervation/devascularization insult, the mdx EDL is able to recover contractile characteristics to a remarkably larger extent than normal EDL.
Eye movement disorder: An early expression of the myotonic dystrophy gene?
Authors: ter Bruggen Jan P. , Tijssen Cees C. , Brunner Han G. , van Oost Bernard A. , Bastiaensen Louis A. K.
Published: January 2005

Eye movement recording (EMR) has been performed in 5 asymptomatic myotonic dystrophy (MyD) gene carriers, 7 mildly affected MyD patients, and 23 age‐ and sex‐matched healthy controls. The purpose of the study was to evaluate whether eye movement abnormalities are an early expression of the MyD gene, and to determine the value of this procedure for detection of otherwise asymptomatic gene carriers. EMR did not reveal any abnormalities in the asymptomatic group, but in the mildly affected group showed significantly (P < 0.01) decreased maximum velocities of the saccades, compared with controls. The results indicate that EMR may aid in the detection of mildly affected MyD patients. However, true presymptomatic diagnosis with EMR has not yet proven possible.
Repression of the embryonic myosin heavy chain phenotype in regenerating chicken slow muscle is dependent on innervation
Authors: Gao Lizhu , Kennedy John M.
Published: January 2005

Ventricular‐like and fast myosin heavy chains (VL‐MHC and FMHC) are transiently expressed during slow skeletal muscle development. The influence of innervation on repression of these MHC isoforms is investigated over an 84‐day time course in: (1) normal anterior latissimus dorsi (N‐ALD) muscles, (2) regenerating ALD (R‐ALD) muscles, (3) denervated ALD (D‐ALD) muscles, and (4) regenerating and denervated ALD (RD‐ALD) muscles. Western blotting demonstrates that the VL‐MHC is expressed in R‐, D‐, and RD‐ALD muscles, but not in N‐ALD muscles. Expression of the VL‐MHC is transient in R‐ALD musles. In contrast, VL‐MHC expression persists in RD‐ALD muscles, and appears with time in D‐ALD muscles. FMHC was not detected in N‐ALD muscles by Western blotting. Two FMHCs are seen in R‐ALD and RD‐ALD muscles, and in 13‐day emryonic ALD muscles. The slower migrating FMHC (FMHCA) comigrates with developmentally regulated FMHCs in fast pectoralis muscle, while the faster migrating FMHC (FMHCB) comigrates with the faster migrating FMHC in embryonic ALD muscle (13 days in ovo). FMHCB decreases in amount over the time course in R‐ALD muscles, while FMHCA persists. In contrast, substantial levels of both FMHCs persist in RD‐ALD muscles, and appear with time in D‐ALD muscles. The cellular distribution of MHCs is followed by immunocytochemistry. Regenerating cells expressing VL‐MHC and FMHC are replaced by a mature population in R‐ALD muscles. Some of the mature myofibers in R‐ALD muscles express FMHC, but not VL‐MHC. In RD‐ALD and D‐ALD muscles, both regenerating and mature muscle cells are seen which express VL‐MHC and FMHC. Our results indicate that innervation is required for the repression of VL‐MHC and FMHCB during regneration of slow muscle.
Evaluation of phrenic nerve and pulmonary function in hereditary motor and sensory neuropathy, type I
Authors: Carter Gregory T. , Kilmer David D. , Bonekat H. William , Lieberman James S. , Fowler William M.
Published: January 2005

Phrenic nerve and diaphragmatic dysfunction has been assumed to be the cause of respiratory failure in hereditary motor and sensory neuropathy, type 1 (HMSN I). In order to determine the relationship between phrenic nerve and pulmonary function in this disease, 25 patients underwent a 4‐step evaluation process consisting of: (1) bilateral phrenic nerve conduction study; (2) median, peroneal, and tibial motor conduction studies; (3) measurement of forced vital capacity (FVC) and maximal inspiratory and expiratory pressures (MIP, MEP); and (4) pulmonary‐focused history and physical. Phrenic nerve motor latency was abnormally prolonged in 22 of the 23 (96%) subjects when a response was obtained. All had slowed velocity or absent peripheral motor conduction responses. Vital capacity was abnormally reduced in 6 of the 25 (24%) subjects. Eight (32%) had an abnormally reduced MIP, while 19 (76%) had an abnormally reduced MEP. Only 2 (8%) subjects had clinical evidence of pulmonary dysfunction. None of the depenent variables (FVC, MIP, MEP, peripheral nerve conduction, or clinical examination) correlated with phrenic nerve latencies. Although phrenic nerve latencies are markedly prolonged in HMSN I, these values are not useful in predicting respiratory dysfunction.
Blink reflex measurement of effects of trichloroethylene exposure on the trigeminal nerve
Authors: Feldman Robert G. , Niles Clyde , Proctor Susan P. , Jabre Joseph
Published: January 2005

Trichloroethylene (TCE) exposure is known to have specific toxic effects on cranial nerves, the trigeminal nerve (V) in particular. The electrophysiological measurement of the blink reflex (BR) can quantify changes in the Vth and VIIth cranial nernve reflex arc. Prior study looked at the their drinking water. This study evaluated the use of the electrophysiologic blink reflex as an indicator of neurotoxic effects of TCE in occupationally exposed workers. The BR was tested in individual cases with documented histories of exposure to known chemical neurotoxins including TCE (n = 18). When compared with the nonexposed laboratory control values (n = 30), the subjects with a significant history TCE exposure demonstrated the most prolonged latencies (≥ 3.0 SD above the nonexposed group mean) in the R1 component of the blink reflex measurement. The electrophysiological study of te blink reflex has application in assesing TCE exposure and in documenting the neurotoxic effects of that exposure on trigeminal nerve functions in humans.
Guillain–Barré syndrome in children: Clinical course, electrodiagnosis, and prognosis
Authors: Bradshaw Deborah Young , Jones H. Royden
Published: January 2005

The electrodiagnostic features of acute childhood Guillain‐Barré syndrome (GBS) have not been distinguished from those in the adult. We report nerve conduction and electromyographic data from 23 children. Sixty‐one percent (14 of 23) fulfilled strict electrodiagnostic criteria for a demyelinating neuropathy, and the remainder demonstrated demyelination in at least one nerve. Reduced compound muscle action potential (CMAP) amplitude was the most common finding overall. Children <10 years old demonstrated significantly greater slowing of motor CV than children >10 years old. Electrodiagnostic criteria associated with poor outcome (low mean CMAP and fibrillation potentials) in previous studies, primarily of adult patients, occurred in 39% (9 of 23 children). All patients on whom follow‐up data were obtained recovered without residual disability. We conclude that electrodiagnostic prognostic indicators identified in general series of GBS may not apply to children.
Phrenic nerve conduction studies
Authors: Swenson Michale R. , Rubenstein Robert S.
Published: January 2005

To refine in the technique of phrenic nerve conduction, we first studied electrode positioning and sources of chest wall artifact. Diaphragmatic compound motor action potentials (DCMAPs) were mapped at close intervals over 4 hemithoraces of two subjects, finding optimum recording sites which were then used to quantitate artifacts due to EKG, chest wall EMG, and configurational thoracic changes of respiration. Based on these findings, 20 normal subjects were studied, showing ease of application and good side‐to‐side agreement for DCMAP laterncies; but, in contrast to prior reports, right‐to left correlation for amplitude and waveform was poor, making the unaffected side an unreliable standard in unilateral partial phrenic nerve lesions.
Spinal fusion in duchenne muscular dystrophy: A multidisciplinary approach
Authors: Shapiro Frederic , Sethna Navil , Colan Steven , Wohl Mary Ellen , Specht Linda
Published: January 2005

We studied 27 Duchenne muscular dystophy patients having spinal fusion for scoliosis. One patient died intraoperatively of cardiac arrest; all others have done well with no instances of malignant hyperthermia, postoperative ventilatory system dependence, pneumothorax, persisting infection, neurologic damage, nonunion, or pain. The anesthetic management included primarily intravenous general anesthetics with minimal myocardial depressant effects, avoiding succinylcholine and inhalation agents. Preoperative cardiac studies aided anesthetic management intra‐operatively. There was analmost universal sinus tachycardia. Holter monitoring defined 4 fo 16 with ventricular premature beats, 4 of 16 with atrial premature beats, and no ventricular tachycardia or atrial flutter or fibrillation. Echocardiogram demonstrated mitral prolapse in 2 of 22, frequent abnormal systolic performance with abnormal shortening fraction < 28% in 7 of 16, and reduced rate‐corrected velocity of fiber shortening in 9 of 15. Afterload was elevated in 7 of 15. The mean forced vital capacity (FVC) preoperatively was 45.3 ± 15.9% with continuing diminution to 28.7 ± 14.9% at 3.3 ± 2.2 years after surgery. The main benefit of surgical stabilization is the relative ease and comfort of wheelchair seating compared with those nonoperated patients who develop progressive deformity. We have not seen lasting improvement or stabilization in FVC following surgery as decreasing function is related primarily to muscle weakness.
Neuromuscular transmission as a function of motor unit size in patients with prior polimyelitis
Authors: Maselli Ricardo A. , Cashman Neil R. , Wollman Robert L. , Salazar‐Grueso Edgar F. , Roos Raymond
Published: January 2005

We studied neuromuscular transmission in 16 patients with prior poliomyelitis by measuring single fiber electromyographic (SFEMG) jitter. This was compared with 3 indirect methods of assessing reinnervation: SFEMG fiber density, macro EMG, and the presence of fibre type grouping on muscle biopsy. In patients with acute poliomyelitis before the age of 10, there was a positive correlation between the extent of neuromuscular transmission impairment, demonstrated by increased SFEMG jitter, and the enlargement of the motor unit, as indicated by increased fiber density, increased macro EMG signals, and fiber type grouping on muscle biopsy. However, there was no correlation between any of these parameters and the presence or absence of new symptoms of weakness. These findings suggest that impaired neuromuscular transmission is most common in patients with prior poliomyelitis whose motor units have been maximally enlarged by axonal sprouting, but is independent of the presence or absence of new symptoms of weakness.
Beneficial effects of training on developing dystrophic muscle
Authors: Elder Geoffrey C. B.
Published: January 2005

The objective of this study was to determine whether increased contractile activity is beneficial or detrimental to developing dystrophic muscle. Hamsters (20‐days‐old) were gradually introdued to running at a speed of 14m/min at 10% grade for 2 (T2) or 4 (T4) h/d for 4 weeks, 5 d/wk. Histological and fiber type properties were determined in the soleus (SOL), plantaris (PL), and extensor digitorum longus and contractile properties in SOL and PL from 5 animals/group, including 5 controls. Experimental animals had normal body and muscle mass. Training for 2 h/d had little effect on SOL contractile properties, whereas 4 h/d resulted in significant increases in force, percentage of type I fibers, and type I hypertrophy. Force also increased in PL. Muscle necrosis was reduced in SOL (T2 and T4) and unchanged in PL. In conclusion, endurance training generally had a beneficial or, at least, no detrimental effect on developing dystrophic muscles.
Needle electromyography of the diaphragm
Authors: Bolton Charles F. , Grand'maison Francois , Parkes Anthony , Shkrum Michael
Published: January 2005

A method is described for performing needle electromyography of the diaphram which is safe and causes little discomfort. It provides valuable information concerning neuropathies and myopathies which may affect the diaphragm, and complements information derived form phrenic nerve conduction studies. Firing patterns of motor unit potentials during spontaneous respiration identify upper motor neurone disorders causing respiratory insufficiency.
Cutaneous reflexes in Parkinson's disease
Authors: Fuhr Peter , Zeffiro Thomas , Hallett Mark
Published: January 2005

The physiology of rigidity in Parkinson's disease (PD) can be investigated by the study of reflexes. Cutaneous reflexes (CR) were measured in 10 patients with PD and in 10 age‐ and sex‐matched normal volunteers. EMG activity was recorded from the first dorsal interosseous muscle with surface electrodes, rectified and averaged. The index finger was stimulated with an intensity four times the sensory threshold. The subjects abducted the index finger with 20% of maximal force. While the latencies of the different reflex components and the amplitudes of the excitatory peaks were not different in the two groups, the first inhibitory components was less pronounced in patients with PD as compared with normals. This effect is partially reversed with dopaminergic drug treatment. The results are compatible with the loss of an inhibitory spinal mechanism elicited by cutaneous afferents, and can be a partial explanation for increased tone in PD.
Quantitation of axon loss and conduction block in acute radial nerve palsies
Authors: Watson Bradley V. , Brown William F.
Published: January 2005

Eleven acute radial nerve palsies were examined between 3 days and 14 weeks following the onset of the neuropathy. Our objective was to quantify the relative extent of axon loss and conduction block in radial motor fibers supplying the extensor and abductor pollicis longus (EPL/APL) muscles. In 10 of 11 cases, conduction block exceeded axon loss. Maximum motor and sensory conduction velocities were normal distal to the spiral groove, suggesting that the larger myelinated fibers were not selectively involved in this acute neuropathy. The localization of the conduction block and slowing was, in every case, across the spiral groove. This method provides a relatively simple way of assessing the approximate contributions of axon loss and conduction block, and fits well with the early and usually complete clinical recovery in these cases.
Myotrophic effects of an anabolic steroid in rabbit limb muscles
Authors: Salmons Stanley
Published: January 2005

There has been no reliable evidence that the actions of anabolic steroids extend to limb muscles. In this study, female rabbits were treated with anabolic steroid (nandrolone decanoate) or arachis oil placebo for 4 weeks or 12 weeks. After 12 weeks, tibialis anterior muscles of treated animals showed highly significant increases in wet weight (38%), twitch tension (66%), maximum isometric tetanic tension (48%), maximum cross‐sectional area (27%), and specific tension (17%). Fiber type composition showed a significant trend toward a less oxidative metabolic character. The experiments provided clear physiological and morphological evidence of a steroid‐induced hypertrophy that was not attributable to fluid retention or changes in body weight. Of the muscles examined, the myotrophic effect was confined to the tibialis anterior muscle; extensor digitorum longus, plantaris, and soleus muscles showed no significant response. The work establishes an experimental model for the response of limb muscles to anabolic compounds.
The influence of the stimulus on normal sural nerve conduction velocity: A study of the latency of activation
Authors: Krarup Christian , Horowitz Steven H. , Dahl Kristian
Published: January 2005

Conduction along the sural nerve was studied in 64 normal subjects using near‐nerve electrodes. Conduction velocities over the same nerve segments were calculated: (1) from the latency recorded from a site of stimulation to a site of recording (1R‐method); and (2) from the difference in latency between 2 recording sites, the site of stimulation being situated elsewhere along the nerve (2R‐method). Consistently faster velocities were seen with the 2R‐method and could best be explained by a fixed delay of about 0.15 ms at the stimulus site (latency of activation, utilization time). This delay was markedly prolonged when a ramp rather than a rectangular stimulus was applied, though fast fibers were excited with both types of stimuli. The delay is thought to be dependent on the relationship between the density of current at the stimulus site and the threshold of responding fibers. © 1992 John Wiley & Sons, Inc.