bluuebunny/crossref_metadata_2025 huggingface dataset:
Improved techniques for measuring muscle fiber conduction velocity
Authors: Yaar Isreal , Niles Les
Published: January 2005

Cross‐correlation (CCT) and dip analysis (DAT) are accpeted techniques for estimating muscle fiber conduction velocity (MFCV). In the DAT, the product of the power spectrum of the conducted EMG times a cosine function of the MFCV is added to and inseparable from the noise power spectrum. The inclusion of the noise power is the weakness of the DAT. We propose and evaluate 2 new techniques that directly estimate the cosine function and, hence, the MFCV, avoiding the noise power: (1) The power‐modulating‐component (PMC), which equals the real part of the crosspower‐spectrum of the EMG signal divided by its magnitude; and (2) The power spectrum of the PMC (PMCP). We recorded intramuscular from 229 biceps in isometric maximum voluntary contraction. The EMG signals were analyzed by the 4 techniques, and the results were compared in pairwise design (sign‐tests and t tests) for quality and bias. The PMC surpassed the DAT (P < 0.00005); both the CCT and PMCP performed equally well and better than the DAT and the PMC (P < 0.00005). Also, the new techniques were superior with simulated EMG. In many cases only the PMCP worked. We conclude that the new techniques are valuable in supplementing the others, and most likely will enhance clinical use of MFCV estimations.
Localization of nerve depolarization with magnetic stimulation
Authors: Odderson Ib R. , Halar Eugen M.
Published: January 2005

The specific location on the magnetic stimulation (MS) coil that may correspond to the area of nerve depolarization has not been determined. In order to localize such and area, MS with 9‐cm and 5‐cm diameter coils was compared with conventional percutaneous electric stimulation (ES). On the 9‐cm coil the distribution of points of nerve depolarization corresponded to that quarter of the coil which was placed over and parallel to the median nerve, whereas on the 5‐cm coil, this area also extended outside the coil. The points of median nerve depolarization with MS were distributed over a distance of 7 cm on the stimulator head and was nearly identical for the 2 coil size at the wrist and elbow. Ulnar nerve costimulation was less frequent with the smaller coil at the wrist. A calculated reference point on the coil is suggested for more accurate NCV determinations.
Demyelinating polyneuropathy in eosinophilia–myalgia syndrome
Authors: Donofrio Peter D. , Stanton Constance , Miller Van S. , Oestreich Lisa , Lefkowitz David S. , Walker Francis O. , Ely E. Wesley
Published: January 2005

Eosinophilia–myalgia syndrome (EMS) is a newly recognized disorder, characterized by myalgia, weakness, scleroderma‐like changes, and eosinophilia. EMS is associated with lots of L‐tryptophan allegedly contaminated with byproducts of the manufacturing process. We describe 3 patients with EMS who presented with a severe demyelinating sensorimotor polyneuropathy. Electrodiagnostic studies revealed multifocal conduction block, slowing and temporal dispersion of motor responses, and prolonged or absent F‐responses. Despite plasmapheresis; corticosteroids; and, in 1 patient, cyclophosphamide, 2 patients died and the remaining patient experienced minimal recovery. Pathology revealed patchy perivascular infiltrates and fibrosis in the connective tissue of muscle and nerve. Autopsy of the central nervous system in 2 patients did not reveal changes unique to EMS. In addition to other organ involvement, EMS may manifest as a potentially fatal polyneuropathy, which initially appears to have prominent demyelinating features.
AAEM minimonograph #39: Digital filtering: Basic concepts and application to evoked potentials
Authors: MacCabee Paul J. , Hassan Nasser F.
Published: January 2005

Filtering of evoked potentials has been performed in clinical laboratories using both analog and digital methods. Analog methods introduce distortion caused by nonlinear phase shift which may be quite severe. Digital methods, while avoiding distortion caused by phase shift, reveal evoked potential components which may or may not correspond to distinct singular neuranatomic generators or homogeneous neuroanatomic systems. Thus, components identified with zero phase shift digital filters at restricted bandpass must be compared with components seen in open bandpass recordings. In some specific circumstances, high‐pass filtering of short‐latency somatosensory‐evoked potentials may distinguish slow asynchronous synaptic activity from fast and synchronous synaptic, lemniscal, or axonal activity. © 1992 John Wiley & Sons, Inc.
Treatment of hemifacial spasm with botulinum toxin
Authors: Yoshimura Don M. , Aminoff Michael J. , Tami Thomas A. , Scott Alan B.
Published: January 2005

The effectiveness of botulinum toxin injections in 11 patients with hemifacial spasm was investigated in a prospective placebo‐controlled blinded study. The patients were treated with four sets of injections to various facial muscles, selected by clinical evaluation. Three injections were with graded doses of toxin and one was with placebo. The order of injections was random and unknown to the patients. Results were scored both subjectively by patient assessment of symptoms and objectively by blinded review of videotapes made one month after each injection. Subjective improvement occurred after 79% of injections with botulinum toxin, regardless of dose of toxin. Only 1 patient improved after placebo. Objective improvement was seen after 84% of injections with botulinum toxin. No patient showed objective improvement after placebo injection. The most frequent side effect was facial weakness, seen after 97% of injections of botulinum toxin. Facial bruising (20%), diplopia (13%), ptosis (7%), and various other mild side effects were seen less frequently. Botulinum toxin appears to be an effective and safe method of therapy for hemifacial spasm. © 1992 John Wiley & Sons, Inc.
Impaired neuromuscular transmission during partial inhibition of acetycholinest‐erase: The of stimulus‐induced antiromic backfiring in the generation of the decrement–increment phenomenon
Authors: Besser Roland , Vogt Thomas , Gutmann Ludwig , Hopf Hanns C. , Wessler Ignaz
Published: January 2005

Neuromusuclar transmission was studied in the rat phrenic nerve–hemidiaphragm preparation with acetylcholinesterase (AChE) partially inactivated. Enzyme inhibition resulted in (1) increased single‐twitch tension of the diaphragm; (2) compound muscle action potential (CMAP) containing repetitive discharges; (3) stimulus‐induced antidromic backfiring (SIAB) seen in the phrenic nerve; and (4) repetitive nerve stimulation (RNS) eliciting a decrement—increment (D‐I) phenomenon (i.e., amplitude reduction maximal with the second CMAP). Using a high‐calcium and low‐magnesium solution, SIAB and the decrement of the second CMAP during RNS were intensified, whereas closely spaced trains and (+)‐tubocurarine (TC) abolished SIAB and simultaneously prevented the decrement of the second CMAP. Importantly, low concentrations of (+)‐TC prevented SIAB in the phrenic nerve, while the repetitive discharges of the CMAP and the increase in twitch tension remained unaffected. This observation suggests that preterminal nicotinic receptors stimulated by released acetylcholine induce SIAB, whereas postsynaptic events are less important in the generation of SIAB. SIAB, a presynaptic event, appears to be responsible for the transient impairment of the neuromuscular transmission, i.e., the D‐I phenomenon.
Dissociation of [H+] from fatigue in human muscle detected by high time resolution 31P‐NMR
Authors: Degroot Michael , Massie Barry M. , Boska Michael , Gober Joel , Miller Robert G. , Weiner Michael W.
Published: January 2005

Previous in vivo studies of skeletal muscle fatigue have demonstrated significant relationships between the decline of muscular force and changes in muscle metabolism. However, these studies performed measurements over relatively long time intervals or during steady state exercise, thereby obscuring rapid metabolic changes occurring at the onset of exercise and recovery. To overcome these limitations, fatigue of human calf musculature during sustained isometric foot plantar flexion was quantified continuously as the decline in maximal voluntary contraction force (MVC), while concentrations of phosphocreatine (PCr), inorganic phosphate (Pi), intracellular free hydrogen ion (H+), and monovalent phosphate (H2PO) were simultaneously measured at 2‐second intervals by 31P nuclear magnetic resonance. The first major finding was that [H+], which has been thought to be a mediator of muscle fatigue, actually declined during the first 10 seconds of exercise when force was declining and rose immediately postexercise, when force partially recovered. Second, the correlations of [H+], [H2PO] and Pi with MVC during the first minute of exercise were determined to be curvilinear and not linear as previously suggested. Furthermore, using either a linear or curvilinear regression model, [H2PO] and Pi demonstrated a closer correlation to MVC than [H+] during the first minute of exercise. Thus, these results reveal nuances in the relationships of MVC to metabolites previously undetected by low time‐resolution measurements. These findings suggest that during sustained isometric exercise, rising [H+] is not likely to be the sole mechanism of muscle fatigue and are consistent with the view that a rise of Pi or [H2PO4] is a major causation factor in force reduction. © 1993 John Wiley & Sons, Inc.
Electrophysiological changes in the acute “axonal” form of Guillain–Barre syndrome
Authors: Brown William F. , Feasby Thomas E. , Hahn Angelika F.
Published: January 2005

The acute “axonal” form of Guillain—Barre syndrome is characterized by rapid progression to severe widespread paralysis and respiratory dependence within 2–5 days of the onset of weakness with very poor and delayed recovery. In 3 cases studied within the first 7 days, the maximum thenar, hypothenar, tibialis anterior, and extensor digitorum bervis “M” potentials were either very reduced in size or absent in response to stimulation at the usual most distal sites of stimulation at the wrist, fibular head, and/or ankle. In the latter instances, advancing the site of stimulation closer to the motor point often evoked an M response. Furthermore, continued distal advance of the site of stimulation evoked progressively larger sized M potentials. Over succeeding days even these very distally evoked M potentials. Maximum conduction velocities in motor nerve fibers just prior to total loss of excitability were often very reduced. The pattern in these cases is most consistent with progressive loss of excitability and conduction in nerve fibers undergoing axonal degeneration, although coexisting primary demyelination in the terminal segment could not be excluded as the basis for the sometimes very slowed conduction velocities. © 1993 John Wiley & Sons, Inc.
Patterns of sensory nerve conduction abnormalities in demyelinating and axonal peripheral nerve disorders
Authors: Bromberg Mark B. , Albers James W.
Published: January 2005

The pattern of an abnormal median‐normal sural (AMNS) sensory response is associated with acute and chronic inflammatory demyelinating polyradiculoneuropathy (AIDP and CIDP) and considered unusual in other types of neuropathy, although specificity and sensitivity of this pattern have not been evaluated. We compared sensory responses (patterns and absolute values) in patients with AIDP, CIDP, diabetic polyneuropathy (DP), and motor neuron disease (MND). Using strict criteria, the AMNS pattern occurred more frequently in recent onset AIDP (39%) compared with CIDP (28%), DP (14%–23%), or MND (22%) patients. This pattern was found in 3% of control subjects. The extreme pattern of an absent median‐present sural response occurred only in AIDP and CIDP patients and in no other groups. Abnormalities of both nerves were more common in long‐standing polyneuropathies such as CIDP and DP compared with AIDP or MND. Median nerve amplitudes were reduced significantly in AIDP, CIDP, and DP patients compared with MND patients, whereas sural nerve amplitudes were significantly reduced only in DP and CIDP patients. These findings may reflect early distal nerve involvement particularly in AIDP patients which is highlighted by differences in median and sural nerve recording electrode placement. We conclude that, in the appropriate clinical setting, the AMNS pattern, an absent median‐present sural response pattern, or a reduced median amplitude compared with the sural amplitude supports a diagnosis of a primary demyelinating polyneuropathy. © 1993 John Wiley & Sons, Inc.
Sensory potentials evoked by magnetic stimulation of the cervical spine
Authors: Zwarts Machiel J.
Published: January 2005

Magnetic stimulation of cervical spinal roots was shown to elicit sensory potentials (MESP) which could easily be recorded at the fingers with ring electrodes. The latency of the MESP recorded at digit I was significantly shorter and the amplitude higher than of digits III and V. The latencies were largely independent of stimulus strength. In an attempt to localize the place of depolarization, the latencies of these potentials were compared with the N11 of the SEP (reflecting the arrival in the spinal cord) and with F‐wave latencies and motor evoked potentials (MEP) to abductor pollicis brevis. The MESP latencies showed a very constant difference with the N11, being 0.6 ms faster. The mean difference between F latency and MEP was 1.2 ms. It is concluded that the origin of these MESPs is very near the spinal foramina, possibly in the sensory ganglia. © 1993 John Wiley & Sons, Inc.
Anomalous origin of the sural nerve in a patient with tibial—common peroneal nerve anastamosis
Authors: Phillips Lawrence H. , Morgan Raymond F.
Published: January 2005

Recognition of anomalous innervation patterns may be important in dealing with peripheral nerve injuries. We describe a patient who suffered injury to the common peroneal nerve (CPN) at the knee when he laterally dislocated his knee. Intraoperative nerve conduction studies during surgical exploration revealed that nerve fibers from the tibial nerve crossed over to join the CPN immediately distal to a neuroma incontinuity. The sural nerve was also found to arise totally from the CPN. © 1993 John Wiley & Sons, Inc.
Deriving reference values in electrodiagnostic medicine
Authors: Campbell William W. , Robinson Lawrence R.
Published: January 2005

Traditional methods for determining nerve conduction reference values have usually involved studying a group of normal controls, and determining the mean ± 2 standard deviations (SD) for each parameter. Recent studies suggest other factors should be taken into account. Height has a greater effect on conduction velocity than age or temperature. The common assumption that conduction values follow a normal, bell‐shaped Gaussian distribution appears unwarranted. The curve for some conduction parameters is significantly skewed, making a mean ± 2 SD definition of normality inaccurate to a clinically important degree. In developing and using reference values one should consider height, age, and temperature, and calculate the mean ± 2 SD of the transformed data to remove the effects of skew. Reference values provide only a guide to the probability a given result came from a healthy or diseased individual; one should therefore seek multiple internally consistent abnormalities before diagnosing disease on the basis of electroneurography. © 1993 John Wiley & Sons, Inc.
Single fiber electromyography in myasthenia gravis during pregnancy
Authors: Massey Janice M. , Sanders Donald B.
Published: January 2005

We report the use of single fiber electromyography (SFEMG) to demonstrate changes in the physiologic abnormality of myasthenia gravis (MG) during pregnancy. A 23‐year‐old became pregnant 15 months after the onset of mild ocular weakness. On initial evaluation, SFEMG jitter measurements demonstrated a slight abnormality of neuromuscular transmission. There was no change in severity of clinical disease or jitter measurements until the third trimester, when she improved. Jitter measurements at that time were normal. Labor was normal and she delivered a normal male. Three days postpartum, myasthenic weakness recurred temporarily and jitter measurements showed worsening. At 16 days and 6 weeks postpartum, she had only minimal medial rectus weakness and jitter studies were normal. Three months postpartum, ocular symptoms recurred and jitter measurements were slightly abnormal. She continued to worsen, developing limb muscle and severe ocular muscle weakness at 4 months postpartum. She was treated with plasma exchange and thymectomy. Prednisone was added 2 months after thymectomy due to continued worsening and development of oropharyngeal weakness. Three years postpartum she was taking prednisone 10 mg every other day and had only slight weakness of neck flexors, and jitter studies were again normal. © 1993 John Wiley & Soncs, Inc.
Carnitine palmitoyl transferase deficiency in malignant hyperthermia
Authors: Vladutiu Georgirene D. , Hogan Kirk , Saponara Isora , Tassini Lawrence , Conroy Jeffrey
Published: January 2005

The activity of carnitine palmitoyl transferase, an enzyme that catalyzes the transport of long‐chain acylcarnitines into mitochondria, was quantitated in EB‐virus‐transformed lymphoblasts from 7 patients with susceptibility for malignant hyperthermia. Immunoreactive enzyme protein was also measured using an enzyme‐linked immunosorbent assay. Cell lines derived from patients with carnitine palmitoyl transferase deficiency of muscle and from normal individuals were used as positive and negative controls, respectively. One patient with malignant hyperthermia had a deficiency in the enzyme activity which was comparable with that of the known carnitine palmitoyl transferase deficient patients. This individuaľs lymphoblasts were also deficient in immunoreactive enzyme protein. All of the remaining patients with malignant hyperthermia were deficient only when the backward assay for carnitine palmitoyl transferase was used for quantitation. It is likely that a subset of individuals with a malignant hyperthermia phenotype have a primary deficiency of carnitine palmitoyl transferase and that others have a milder enzyme deficiency secondary to the primary defect in malignant hyperthermia. © 1993 John Wiley & Soncs, Inc.
Giant somatosensory evoked potentials in a patient with the anterior spinal artery syndrome
Authors: Triggs William J. , Beric Aleksandar
Published: January 2005

We studied a previously healthy 25‐year‐old woman with the anterior spinal artery syndrome, a rare thoracocervical myelopathy with multiple potential etiologies. Quantitative and clinical sensory examination showed dissociated loss of pin‐prick and temperature discrimination below the level of the lesion, with normal light touch, vibratory, and position sense. Magnetic resonance imaging was consistent with cervical spinal cord infarction. Median SEPs showed normal Erb's potential with absent spinal N—13 and normal scalp N—20 latency. Tibial SEPs showed normal lumbosacral responses and normal scalp P—30 latency. Both median and tibial nerve stimulation produced cortical responses of unusually large amplitude (median 38 m̈V, tibial 17 m̈V). We hypothesize that large SEP amplitudes in this patient resulted from loss of anterolateral inhibitory influences on the dorsal column–medial lemniscal system. © 1993 John Wiley & Soncs, Inc.
Muscle fiber conduction velocity changes with length
Authors: Trontelj Jože V.
Published: January 2005

While recording activity from individual muscle fibers by single fiber EMG (SFEMG), stimulated either through their axons or directly, the length of the recorded muscle fiber was changed—stretched or made shorter—by manipulating the recording needle or by passive joint movements. This resulted in significant changes of latency corresponding to an increase in propagation velocity on shortening of the muscle fiber and to a slowing of its lengthening. The maximum increase in velocity was estimated to 33% and slowing to about 22%. These lengthdependent changes of muscle fiber propagation velocity are suggested to contribute to the supernormal phase of propagation velocity recovery function and to be responsible for an important part of the myogenic, interdischarge interval‐dependent, jitter. © 1993 John Wiley & Soncs, Inc.
Potassium channels from normal and denervated mouse skeletal muscle fibers
Authors: Escobar Ariel L. M. , Schinder Alejandro F. , Biali Fabian I. , Siri Leonardo C. Nicola , Uchitel Osvaldo D.
Published: January 2005

The properties of singles K+ channels in normal and denervated muscles were compared using the “patch‐clamp” technique. Single channels were recorded from vesicles obtained by stretching bundles of normal and denervated extensor digitorium longus (EDL) muscles. The most frequently observed channel in normal muscles was a high conductance (266 pS) Ca++ activated K+ channel. Although channel density, as estimated by patch recording, showed a significant decrease in denervated muscles, no differences were found in conductance and gating properties. Another voltage‐dependent K+ channel (81 pS) was only recorded from normal muscles, but never from denervated ones. In addition, a 35 pS conductance was recorded from both normal and denervated fibers. This channel displayed neither voltage dependence nor sensitivity to tetraethylammonium (TEA). In contrast, another TEA‐insensitive (16 pS) channel was recorded only from denervated muscles. We conclude that denervation induces significant changes in the distribution and expression of K+ channels in mammalian skeletal muscles. © 1993 John Wiley & Sons, Inc.
Lambert–Eaton myasthenic syndrome with prominent postexercise exhaustion
Authors: Gutmann Ludwig , Weidman David , Gutierrez Alvaro
Published: January 2005

A 66‐year‐old man with Lambert–Eaton myasthenic syndrome, polyneuropathy, and small cell lung cancer, developed profound muscle weakness with a prolonged period of ventilatory dependency. Electrophysiological studies demonstrated very small compound muscle action potentials in response to supramaximal nerve stimulation, limited tetanic and postexercise facilitation, and prolonged prominent postexercise exhaustion (40–60% of baseline value) persisting up to 20 minutes. It is hypothesized that these changes may reflect both a severe defect in acetylcholine release and decreased availability of releasible acetylcholine from the terminal axon.
Quantitative EMG analysis and longitudinal nerve conduction studies in a Refsum's disease patient
Authors: Kuntzer Thierry , Ochsner François , Schmid Florence , Regli Franco
Published: January 2005

A patient with anosmia and night blindness had repeated clinical and electrophysiological examinations during a 21‐year period. Within the first 11 years, he experienced two subacute episodes of numbness with weakness and ataxia. Over the 10 ensuing years, no additional functional disability appeared. We looked retrospectively for a correlation between repeated manual muscle scoring and different nerve conduction parameters. Further studies were done in order to estimate reinnervation in proximal and distal muscles and to assess autonomic functions. A direct relationship was found between the magnitude of muscle weakness and the amplitude of compound muscle action potentials, whereas nerve conduction velocities were inhomogeneously reduced but almost unchanged over time. Parasympathetic tests were normal but sympathetic skin responses were absent. As estimated by macro‐EMG and turns‐amplitude analysis the compensatory reinnervation was very high. We conclude that, in Refsum's disease, recurrent segmental demyelination of a significant portion of the motor units can occur in parallel with exacerbations of weakness, and that a considerable degree of progressive motor and sudoromotor axonal loss can be found although there is an apparent long‐term clinical stabilization of the neuropathy. © 1993 John Wiley & Sons, Inc.
Increased spike‐frequency adaptation and tea sensitivity in dorsal root fibers after sciatic nerve injury
Authors: Utzschneider David A. , Bhisitkhul Robert B. , Kocsis Jeffery D.
Published: January 2005

Excitability of rat dorsal root axons were studied 3 weeks after injuryto the sciatic nerve. Whole nerve recordings were obtained from injured andcontrol nerves in a sucrose gap chamber. Constant current depolarization pulses (30–200 ms) applied approximately 50% above the stimulus strength required for maximal amplitude compound action potentials (CAPs) evoked burst of action potentials in the dorsal root which displayed spike adaptation. The depolarization‐induced burst response of the dorsal roots was greatly reduced after crush or transection of the sciatic nerve. However, application of the potassium channel blocker, tetraethylammonium (TEA), restored the burst discharge in injured dorsal root axons. Brief tetanic stimulation of the dorsal root also induced an afterhyperpolarization (AHP) that was twice as large in the transection group as compared to the control group, and which was blocked by TEA. There were no changes seen in the amplitude of the compound action potential, frequency‐following characteristics, refractory properties, or 4‐AP sensitivity in the dorsal roots after peripheral nerve injury. These results suggest that there is enhanced spike adaptation that occurs at the same time as an increase in the sensitivity to the potassium channel blocker, TEA, in axon regions proximal to the site of nerve injury and have implications for the pathophysiology of nerve injury. © 1993 John Wiley & Sons, Inc.
Muscle pain: Animal and human experimental and clinical studies
Authors: Marchettini Paolo
Published: January 2005

The search for the identification of the sensory apparatus encoding muscle pain sensation in humans is recounted. Basic neurophysiologic animal studies, leading to a description of slowly conducting afferent from muscle and definition of high threshold polymodal muscle nociceptors, and pioneer psychophysic human studies together with recent microneurographic experiments in humans are described. The phenomena of muscle pain broad localization and distant referral are discussed, and clinical implications are extrapolated to interpret muscle pain as a localizing sign of mononeuropathy or radiculopathy. The identification of human muscle nociceptors has defined the scientific standard to test emerging clinical descriptions having muscle pain as a symptom. © 1993 John Wiley & Sons, Inc.
Causalgia—reflex sympathetic dystrophy—sympathetically maintained pain: Myth and reality
Authors: Dotson Rose M.
Published: January 2005

Causalgia, reflex sympathetic dystrophy, and sympathetically maintained pain (SMP) are a complex group of disorders, with symptoms of spontaneous/stimulus‐induced pain and vasomotor, sudomotor or skeletomotor dysfunction of the involved area. Sympatholysis has been recommended for diagnosis/classification and treatment of these patients. Lack of adequate placebo control makes the physiologic response to this intervention unclear. Sensitization of wide dynamic range (WDR) neurons in the central nociceptive pathway has been proposed as a key element in pathophysiologic mechanisms of these disorders. Low threshold mechanoreceptors and nociceptors have been implicated as the primary afferents transmitting signals to or maintaining sensitization of WDR neurons in SMP. Vasomotor disturbances may result from antidromic vasodilatation, vasoparafytic dilatation, normal somatosympathetic reflexes, and denervation supersensitivity. There is conflicting information regarding the use of phentolamine and clonidine in these pain syndromes. Treatment of these patients remains a challenge given the many potential underlying mechanisms. © 1993 John Wiley & Sons, Inc.
CMAP dispersion, amplitude decay, and area decay in a normal population
Authors: Taylor Peter Kenneth
Published: January 2005

The aim of this investigation was to define the boundaries of compound motor action potential (CMAP) dispersion, amplitude decay, and area decay in a control population and determine their dependence on external variables such as age and interelectrode distance. Measurements were made from median, ulnar, and common peroneal motor nerves of 110 normal subjects of ages 15–90 years. Significant differences between nerves were found in mean values of each parameter. Dispersion and amplitude decay increased with the square of age in all three nerves, while area decay increased with age in the median nerve. Dispersion was the main cause of amplitude decay. Use of regression equations to predict dispersion and amplitude decay in each nerve significantly tightened confidence limits and should therefore increase the accuracy of these parameters in detecting demyelinating pathology in peripheral nerve. © 1993 John Wiley & Sons, Inc.
β‐Adrenergic potentiation of E–C coupling increases force in rat skeletal muscle
Authors: Cairns Simeon P. , Dulhunty Angela F.
Published: January 2005

We examined the mechanism(s) which allow terbutaline, a β2‐adrenergic agonist, to increase isometric force in bundles of normal and denervated rat soleus fibers. Terbutaline (10 μmol/L) potentiated tetanic contractions during exposure to 1 mmol/L ouabain, 10 μmol/L nifedipine, or 0.5 mmol/L iodoacetate. Terbutafine induced equivalent increases in submaximal potassium (K+) contracture and tetanic force: these effects were mimicked by 2 mmol/L dibutyrl‐cyclic AMP. Therefore, terbutaline increased force by a cyclic AMP‐dependent mechanism other than enhancement of sodium‐pump activity, dihydropyridine sensitive Ca2+ currents, glycolysis, or action potentials. Pretreatment with 1 mmol/L caffeine induced submaximal potentiation of peak tetanic force but prevented further potentiation by terbutaline. This suggested that terbutaline did not influence the myofilaments, but acted on the sarcoplasmic reticulum (SR) to increase the myoplasmic Ca2+ concentration and hence force production. We speculate that force is potentiated following β‐adrenoceptor activation by a cyclic AMP‐dependent phosphorylation of Ca2+ release channels to facilitate SR calcium release during tetanic stimulation. © 1993 John Wiley & Sons, Inc.
Hereditary motor and sensory neuropathy type I: Clinical and neurographical features of the 17p duplication subtype
Authors: Hoogendijk Jessica E. , de Visser Marianne , Bolhuis Pieter A. , Hart Augustinus A. M. , de Visser Bram W. Ongerboer
Published: January 2005

Forty‐four affected individuals, aged 8–68 years (mean 34 years), from six families with hereditary motor and sensory neuropathy type I (HMSN) I, Charcot–Marie–Tooth disease type (1) were investigated to determine the clinical and electroneurographical characteristics of the HMSN I subtype that is defined by the presence of a DNA duplication on chromosome 17p. Motor nerve conduction velocity (MNCV) and, to a lesser extent, compound muscle action potential amplitude, were inversely related to clinical severity. Neither clinical severity nor MNCV were significantly related to age. These results suggest that the primary pathological process is not, or only slightly active after childhood. © 1994 John Wiley & Sons, Inc.
Congenital myopathies
Authors: Bodensteiner John B.
Published: January 2005

Several dozen congenital myopathies are defined by clinical and morphological criteria. The application of the current generation of scientific techniques including immunohistochemistry and molecular genetics has resulted in the expansion of our knowledge and understanding of the well‐established conditions including central core myopathy and centronuclear/myotubular myopathy and allowed greater understanding of the interrelationships of some of the less common or less wellestablished conditions. In the near future molecular genetics may allow the identification of the specific gene defect in many of these diseases. This article reviews the major congenital myopathies and presents some of the information gained by application of new technology to these conditions. © 1994 John Wiley & Sons, Inc.
The familial occurrence of carpal tunnel syndrome
Authors: Radecki Patrick
Published: January 2005

Epidemiological studies of the carpal tunnel syndrome have generally overlooked the possibility of a familial occurrence. A prospective study was undertaken to determine the prevalence and significance of a positive family history of carpal tunnel syndrome. Seventy‐ive of 253 women and 40 of 168 men with a confirmed carpal tunnel syndrome had at least one relative with symptoms of, or surgery for, carpal tunnel syndrome. A positive family history was predictive of a median abnormality or prior surgery at the carpal tunnel (chi‐square = 20.484, P < 0.001). The 84 patients with a prior carpal tunnel surgery, likely the most well informed historically, had a positive family history of 39.3% versus 13.3% in the 279 patients without median latency slowing. The familial occurrence appears crucial in the epidemiological study of carpal tunnel syndrome, and may be important in the selection of normal subjects for electrodiagnostic standards. © 1994 John Wiley & Sons, Inc.
AAEM minimonograph #43: Neuromuscular problems in the performing arts
Authors: Lederman Richard J.
Published: January 2005

Over the past 10–15 years, there has been increasing interest in the health problems of performing artists. In this review, I will discuss the major playing‐related disorders seen in instrumental musicians. Among the 672 instrumentalists evaluated, the major diagnoses identified included musculoskeletal disorders in 64%, peripheral nerve problems in 22.5%. and focal dystonia in 7%. Sixty percent of instrumentalists were female although males predominate in the group with focal dystonia. The average age of those evaluated was 32 years. Among musculoskeletal disorders overuse syndrome is the most common. Frequent peripheral nerve disorders include thoracic outlet syndrome, carpal tunnel syndrome, and ulnar neuropathy. A characteristic distribution of symptoms and signs is identified for each instrument group. Electrodiagnostic studies are an important part of the evaluation of these disorders. With carefully designed treatment, the majority of instrumental musicians can be returned to full and pain‐free playing activities. The success rate is highest in some entrapment neuropathies but remains low in focal dystonia. © 1994 John Wiley & Sons, Inc.
Osteomalacic myopathy
Authors: Russell James A.
Published: January 2005

A 45‐year‐old woman reported the development of thigh pain followed within a year by proximal muscle weakness. Clinical findings included short stature, prominent kyphoscoliosis, proximal weakness, and brisk reflexes. Recognition of an increased level of serum alkaline phosphatase and hypophosphatemia led to the diagnosis of osteomalacia. Identification of iron deficiency anemia and hypocholesterolemia implicated previously unrecognized gluten‐sensitive enteropathy with associated vitamin D malabsorption as the cause of the osteomalacia. Adherence to a gluten‐free diet and treatment with vitamin D2 resulted in weight gain, resolution of pain, and improvement in strength within 3 months. Painful proximal weakness and hyperreflexia may be the initial and primary manifestations of osteomalacia, a readily treatable cause of muscle and bone disease. © 1994 John Wiley & Sons, Inc.
Pathogenesis of axonal Guillain–Barré syndrome: Hypothesis
Authors: Yuki Nobuhiro
Published: January 2005

Pathologic studies of acute motor axonal neuropathy show strong evidence of the presence of primary axonal Guillain–Barré syndrome (GBS). The pathogenesis of axonaf GBS is speculated to be as follows: (1) Infection by an organism induces the high production of a crossreactive antibody between an infectious agent and the motor nerve axon in patients with a particular immunogenetic background. (2) The antineural antibody binds to the motor nerve terminals, thereby inhibiting motoneuron excitability and causing muscular weakness. (3) Binding of the antineural antibody, or subsequent functional impairment of the motoneurons, causes the motor axon to degenerate from the terminals. (4) In severe cases, extensive axonal loss and central chromatolysis of the motoneurons occur. These inhibit recovery and lead to a poor functional prognosis. © 1994 John Wiley & Sons, Inc.
Muscle histopathology in myotonic dystrophy in relation to age and muscular weakness
Authors: Tohgi Hideo , Kawamorita Atsushi , Utsugisawa Kimiaki , Yamagata Munehisa , Sano Mitsuhiko
Published: January 2005

We studied histopathological changes in the biceps brachii muscle in relation to age and the degree of muscle weakness in 64 patients (aged 11–59 years) with myotonic dystrophy. The proportion of type 1 fibers was unaltered in the adolescent patients compared with control values, but increased with age. The average diameters of all the fiber types were smaller than control values in the adolescents, suggesting immature development; however, there was an increase in diameter with age that was associated with an increase of hypertrophic type 2 fibers. At all ages, type 1 fibers were smaller than type 2 ones. Small angular fibers and small group atrophy consisted mainly of type 1 fibers, their incidences decreasing with age. The severity of muscular weakness was related to the predominance of type 1 fibers, the reduction in the number of hypertrophic type 2 fibers, and the accumulation of adipose cells, but not to the presence of small angular fibers or to small group atrophy. © 1994 John Wiley & Sons, Inc.
Fetus‐like dystrophin expression and other cytoskeletal protein abnormalities in centronuclear myopathies
Authors: Mora Marina , Morandi Lucia , Merlini Luciano , Vita Giuseppe , Baradello Alice , Barresi Rita , Di Blasi Claudia , Blasevich Flavia , Gebbia Marinella , Daniel Sergio , Cornelio Ferdinando
Published: January 2005

We have investigated supposed maturational arrest of muscle in ceatronuclear myopathies (CNMs) by characterizing the expression of dystrophin, other cytoskeletal proteins, and fetal myosin in the muscle fibers of 9 CNM patients (4 sporadic, 3 familial, 2 adult sporadic). Dystrophin and β‐spectrin localized intracytoplasmically in centrally nucleated fibers. Talin and vinculin were normally expressed. Desmin was radially organized in several fibers in all patients. Scattered vimentin positive fibers were found in 3 cases. Six myotonic dystrophy cases and 4 inflammatory myopathy cases with regenerating fibers were also studied: dystrophin and the membrane cytoskeletal proteins were normally expressed in the former; and dystrophin, spectrin, and vinculin were reduced in the latter. Intracytoplasmic dystrophin is further evidence of maturational arrest in CNMs. Spectrin and dystrophin codistnbute in these pathological conditions as in normal muscle. We conclude that the altered cytoskeletal network found in CNMs likely plays a pathogenetic role in these conditions. © 1994 John Wiley & Sons, Inc.
Assessment of motor pathways to masticatory muscles: An examination technique using electrical and magnetic stimulation
Authors: Türk Ülkü , Rösler Kai M. , Mathis Johannes , Müllbacher Wolf , Hess Christian W.
Published: January 2005

To study motor pathways to masticatory muscles, a new recording technique using surface electrodes was developed. The recording electrode was mounted on a spatula and inserted enorally into the pterygomandibular plica over the belly of m. masseter. Using this technique, mean latencies/amplitudes of the compound action potentials (CMAPs) in 18 healthy subjects were 1.2 ms/4.9 mV after electrical stimulation of the trigeminal nerve below the zygomatic arch, and 5.5 ms/1.1 mV after magnetic stimulation of the cortex. In 15 patients with unilateral lesions of the facial nerve, masticatory CMAPs had virtually symmetrical configuration, latency, and amplitude, excluding a major contribution of volume conducted activity from other cranial muscles. The technique was evaluated in patients after surgical treatment for trigeminal neuralgia. Patients with with retrogasserian thermocoagulation and central demyelinating lesions were consistently identified. © 1994 John Wiley & Sons, Inc.
Sixth annual stuart reiner memorial lecture: Embryonic development of nerve and muscle
Authors: Sohal G. S.
Published: January 2005

This article provides a basic scheme of sequential anatomic and some physiologic events occurring during the course of embryonic development of motor neurons and muscles, leading to the establishment of mature nerve‐muscle relationships. Motor neurons and muscles begin their development independently and during embryogenesis they become dependent on each other for further development and survival. Aspects of development which occur independently and those requiring mutual interactions are identified. The development of motor neurons is discussed with respect to their production, projection, neuromuscular transmission, myelination, sprouting, survival, and death. The development of muscles is discussed with respect to the origin, differentiation, and muscle fiber types. Discussion on the development of neuromascular junction includes differentiation of presynaptic nerve terrninal, postsynaptic components, and elimination of multiple axons.© 1995 John Wiley &Sons, Inc.
CMAP variability as a function of electrode site and size
Authors: Van Dijk J. Gert , van der Kamp W. , Tjon‐A‐Tsien Aimee
Published: January 2005

The site of the recording electrode influences the amplitude of the compound muscle action potential (CMAP) and its variation over a length of nerve. The effects of large electrodes on this source of intra‐individual variability were assessed. Right median nerves of 20 healthy subjects were studied, and recordings made at three sites (at 1‐cm intervals) using five electrode sizes (0.01, 1, 2, 4, and 10 cm2). Site‐induced variability was defined as the standard deviation (SDi) and coefficient of variation (CVi) of the measurements of the three sites. Site induced variability of all parameters (latency, duration, amplitude, area, MNCV, and the percentile changes of duration, amplitude, and area over the forearm) decreased significantly with electrode size. Decreases were most pronounced for amplitude and area: CVi fell from 29% and 30% (0.01‐cm2 electrode) to 10% and 8% (10 cm2). It is argued that large electrodes record activity of more motor units than small electrodes, and that their measurement fields overlap to a greater extent. The use of large electrodes is recommended in order to reduce site‐induced CMAP variability.© 1995 John Wiley &Sons, Inc.
Monopolar needle evaluation of paraspinal musculature in the cervical, thoracic, and lumbar regions and the effects of aging
Authors: Travlos Andrew , St Trueman Sandra , Eisen Andrew
Published: January 2005

Motor unit characteristics (Phases, turns, amplitude, duration, and area) were measured using a monopolar needle and narrowed bandpass (500 Hz to 10 kHz) in cervical, thoracic, and lumbar paraspinal muscles in 66 subjects (36 women and 30 men) aged 22‐81 years (mean age 45.7 years). Cervical motor units were of lower amplitude and area than thoracic and lumbar motor units (P = 0.0001), respectively. The durations of lumbar motor units were longer and larger than cervical and thoracic motor units (P = 0.0004). Analysis of covariance of the measured characteristics against age showed no significance in the cervical and thoracic regions. In lumbar paraspinal motor units, phases and turns increased significantly with age (P = 0.044 and P = 0.016, respectively). The increase was < 1.0 phase over 30 years. Motor unit amplitude increased with aging (P = 0.055) showing an increase of 360 μV over a 30‐year time period. It is appropriate to assess the number of phases and turns, as well as the duration of the motor units in the cervical and thoracic (but not lumbar) spines in addition to seeking evidence of spontaneous, single fiber discharges.© 1995 John Wiley &Sons, Inc.
Late motor involvement in cases presenting as “chronic sensory demyelinating polyneuropathy”
Authors: Berger Alan R. , Herskovitz Steven , Kaplan Jerry
Published: January 2005

Chronic inflammatory demyelinating polyneuropathy (CIDP) is usually characterized by prominent motor deficits. A pure sensory presentation, labeled chronic sensory demyelinating neuropathy (CSDN), has been reported, but it is unclear if this neuropathy is a distinct clinical and immunologic entity or merely the sensory presentation of the more usual sensorimotor CIDP. We describe 5 patients with what initially appeared to be CSDN; 3 subsequently developed substantial weakness coincident with the electrophysiologic appearance of multifocal motor conduction block. These cases indicate that, in some cases, CSDN may be a transitional clinical stage of CIDP in which the more usual sensorimotor deficits develop later. Immune‐based therapy, including intravenous immunoglobulin, was found to be effective in both the pure sensory and sensorimotor types. © 1995 John Wiley & Sons, Inc.
Issues & opinion. Sporadic ALS and chromosome 22: Evidence for a possible neurofilament gene defect
Authors: Meyer Michael A. , Potter Nicholas T.
Published: January 2005

ALS is associated with the P2 blood group phenotype. Molecular evidence now shows the gene encoding this antigen to be on the long arm of human chromosome 22 near the newly discovered gene for heavy neurofilament (NF‐H). Since an ALS‐type condition can be generated in transgenic mice expressing the human NF‐H gene, and since the gene for the CNTF‐related cytokine leukemia inhibitory factor (LIF) is located adjacent to this gene, it is hypothesized that a defect on the chromosome 22 band region q12 is involved in the pathogenesis of sporadic ALS. © 1995 John Wiley & Sons, Inc.
Issues & opinion. Neurofilaments, free radicals, excitotoxins, and amyotrophic lateral sclerosis
Authors: Al‐Chalabi Ammar , Powell John F. , Leigh P. Nigel
Published: January 2005

There is increasing evidence implicating abnormalities of neurofilament function in the pathogenesis of amyotrophic lateral sclerosis (ALS). The observation that the P2 blood protein phenotype is overrepresented in patients with ALS is potentially important, but needs confirmation. It should be shown that this segregation is selective for ALS. If it is, the implications outlined in Meyer's hypothesis will need to be explored, bearing in mind that much of the evidence implicating excitotoins, free redicals, and neurofilaments in familial and sporadic ALS is still circumstantial. Thus the identification of candidate genes, the pursuit of large segregation studies, and identification of specific point mutations, remain key goals in ALS research. © 1995 John Wiley & Sons, Inc.
AAEM minimonograph #16: Instrumentation and measurement in electrodiagnostic medicine–part I
Authors: Gitter Andrew J. , Stolov Walter C
Published: January 2005

Technical and instrumentation factors play an important role in obtaining reliable information during electrodiagnostic studies. With contemporary electrodiagnostic equipment, neurophysiologic potentials are detected using a variety of electrodes and undergo differential amplification, filtering, conversion to digital form, and finally, analysis and display. Understanding the signal processing principles, limitations, and sources of errors that can occur during this multistep process can improve the technical quality of studies, minimize preventable errors, and improve clinical interpretation. Part I of this minimonograph reviews the basic principles of action potential generation and overviews electrodiagnostic instrumentation. The concept of waveform frequency content is related to the role of filters in suppressing noise while preserving waveform latency, amplitude, and morphology. The electrical characteristics of various surface and needle electrodes influence instrument design and the nature of the potentials recorded. This is especially important in understanding the differences in motor unit characteristics obtained from monopolar and concentric needle electrodes. © 1995 John Wiley & Sons, Inc.