bluuebunny/crossref_metadata_2025 huggingface dataset:
Case‐of‐the‐month: Painful thigh mass in a young woman: Diabetic muscle infarction
Authors: Barohn Richard J. , Kissel John T.
Published: January 2005

A 29‐year‐old female with type I diabetes mellitus developed pain, focal tenderness, and swelling in the posterior left thigh. Subsequent evaluation included a muscle biopsy, which revealed large confluent areas of necrosis and edema, compatible with a diagnosis of diabetic muscle infarction (DMI). Diabetic muscle infarction (DMI) is an unusual neuromuscular complication of diabetes mellitus. DMI begins with the acute onset of focal pain and swelling in the thigh. The anterior compartment (quadriceps muscle group) or posterior compartment (hamstring muscle group) are most frequently involved. The focal region of muscle damage can be noninvasively viewed by magnetic resonance imaging and radionuclide scans. Muscle biopsy demonstrates large confluent regions of muscle necrosis and edema. DMI needs to be differentiated from other processes that can cause leg pain in a diabetic patient.
A PCR‐based assay for the wild‐type dystrophin gene transferred into mdx mouse
Authors: Shrager Joseph B. , Naji Ali , Kelly Alan M. , Stedman Hansell H.
Published: January 2005

Myoblast transfer has emerged as a promising treatment for inherited myopathies such as Duchenne muscular dystrophy (DMD). Further development of the technique's therapeutic potential requires an experimental system in which issues of graft rejection can be clearly discriminated from those related to myoblast biology. Here we report the development and initial application of a quantitative assay for myogenic cells bearing a wild‐type dystrophin gene following transfer into the mdx mouse. The technique relies upon the ability of a mutagenizing polymerase chain reaction (PCR) primer to create a new restriction site in the amplification production of the wild‐type, but not the mdx dystrophin gene. The ratio of host to donor cells can be determined from muscle biopsies as small as 1 mg, regardless of donor H‐2 background. This simple technique should allow a number of basic questions related to myoblast and direct gene transfer to be addressed using the mdx mouse model. © 1992 John Wiley & Sons, Inc.
Abnormal distribution of desmin and vimentin in myofibers in adult onset myotubular myopathy
Authors: Misra Ajay K. , Menon Nirmala K. , Mishra Shri K.
Published: January 2005

We report, for the first time, muscle immunocytochemical studies in sporadic, adult onset myotubular myopathy (SAOMM), which show intramyofibrillar central, perinuclear desmin and vimentin. This pattern was absent in a normal control and in myofibers with increased internal nuclei associated with denervation and myotonic muscular dystrophy (MyD). These findings resemble those reported in 8‐ to 15‐week‐old human fetal myotubes and myofibers of infantile MM, implying a possible regression of intermediate filaments of adult myofibers to an early developmental phase in SAOMM. © 1992 John Wiley & Sons, Inc.
Turns‐amplitude analysis of the electromyographic recruitment pattern disregarding force measurement. II. Findings in patients with neuromuscular disorders
Authors: Liguori Rocco , Dahl Kristian , Fuglsang‐Frederiksen Anders , Trojaborg Werner
Published: January 2005

Turns‐amplitude analysis of the electromyographic recruitment pattern was performed on‐line in the brachial biceps muscle of 46 patients with neuromuscular disorders using the mean amplitude as an indicator of force. The parameters, peak‐ratio (PR) and number of time intervals (TI) from 0 to 1.5 ms, were increased in patients with myopathy. In patients with neurogenic involvement, the characteristic pattern was a decreased PR and a decreased incidence of TI between 0 and 1.5 ms. The results indicate that the two parameters supplement each other as some of the patients were identified only by one or the other. In patients with myopathy, the method had a higher diagnostic yield than the individual motor unit action potential analysis. The method is objective, fast, and reliable. © 1992 John Wiley & Sons, Inc.
Evidence for new isoform of fast myosin heavy chain in rat skeletal muscle
Authors: Sawchak Judith A. , Leung Betty , Shafiq Sayid A.
Published: January 2005

The purpose of this study was to investigate whether the previously demonstrated heterogeneity of myosin heavy chain (MHC) in type 2B fibers of the superficial portion of the lateral gastrocnemius (SLG) muscle of the rat may be due to presence of type 2D/X fibers. Immunohistochemical identification of MHC heterogeneity, histochemical identification of appendicular 2D/X muscle fibers, and immunoblotting of myosins were used. It was found that some,but not all, of the heterogeneity of rat SLG is correlated with the presence of type 2D/X fibers. Immunoblots with MHC from several muscles revealed the presence of at least two antigenically distinct isoforms of MHC with the same electrophoretic mobility as the “2B” band. These results show that a previously undetected type of MHC is expressed in rat skeletal muscle and raise the possibility that there may be as yet undetected MHC isoforms in human muscle which may be clinically important. © 1992 John Wiley & Sons, Inc.
The quadriceps strength of healthy elderly people remeasured after eight years
Authors: Greig Carolyn A. , Botella Jose , Young Archie
Published: January 2005

Isometric quadriceps strength was remeasured in 14 healthy survivors of a group of elderly people first studied 8 years previously. There were 4 men (median age 81 years, range 79 to 84) and 10 women (82 years, range 79 to 89). They were selected for their health, not their levels of physical activity. Nevertheless, they were active when first studied and, with 1 exception, had maintained or increased their levels of physical activity. Isometric quadriceps strength was well preserved; the median change in the strength of the stronger quadriceps was only −0.3% per annum (95% confidence interval = −1.4 to +0.8). © 1993 John Wiley & Sons, Inc.
“All‐or‐none” cytochrome C oxidase positivity in mitochondria in chronic progressive external ophthalmoplegia: An ultrastructural—cytochemical study
Authors: Matsuoka Taro , Goto Yu‐Ichi , Nonaka Ikuya
Published: January 2005

Teased single muscle fibers from 6 patients with chronic progressive external ophthalmoplegia (CPEO) showed a segmental defect in cytochrome c oxidase (COX) activity. On ultrastructural–cytochemical examination, the majority of mitochondria in COX‐positive segments were COX‐positive, whereas all mitochondria in COX‐negative segments were COX‐negative. This “all‐or‐none” COX positivity in mitochondria in CPEO with deleted mitochondrial DNA can be explained by the “threshold effect,” which induces the tissue‐specific involvement and clinical heterogeneity. © 1993 John Wiley & Sons, Inc.
Frequency of acoustic myography during isometric contraction of fresh and fatigued muscle and during dynamic contractions
Authors: Dalton Philip A. , Stokes Maria J.
Published: January 2005

The frequency of the acoustic myographic (AMG) signal was examined during fresh and fatigued isometric contractions of quadriceps and during dynamic contractions of biceps brachii (BB) in healthy subjects. Recordings were obtained from quadriceps over a range of forces between 10% and 100% maximal voluntary contraction prior to, and 15 minutes after, a fatiguing exercise. Recordings from BB were obtained over a range of submaximal forces (0–8.5 kg) during concentric and eccentric contractions. The mean power frequency (MPF) of the AMG signal was analyzed during each of these contractions by fast‐Fourier transform (FFT). The MPF was not significantly different (P > 0.05) during fresh and fatigued contractions of quadriceps and increased quadratically with force in both states (r = 0.81, fresh; r = 0.77, fatiqued). During concentric contractions of BB the MPF initially with force, but then decreased at the heavier loads (>5.5 kg). The MPF of eccentric contractions did not significantly (P > 0.05) alter with force. The AMG MPF was within a similar low frequency range for both muscles, during different types of contraction, and was unaltered with fatigue. © 1993 John Wiley & Sons, Inc.
Innervation patterns in the cat tibialis anterior six months after self‐reinnervation
Authors: Bodine‐Fowler Sue C. , Unguez Graciela A. , Roy Roland R. , Armstrong Alison N. , Edgerton V. Reggie
Published: January 2005

The spatial distribution of fibers belonging to a single motor unit was analyzed in 10 motor units from the tibialis anterior of the cat 6 months after denervation and self‐reinnervation of the anterior (superficial) compartment of the muscle. After self‐reinnervation, the distribution patterns of the fibers in the fast motor units were significantly different than control, whereas the fiber distribution in the slow unit was similar to control. Reinnervated fast units had a significant increase in the number of adjacencies among motor unit fibers, and there were often distinct “clusters or groups” of fibers distributed within the motor unit territory. Clustering or grouping of fibers was evident within the motor unit, even though fiber type grouping was not evident within the muscle. The differences in distribution patterns between control and reinnervated units may be related to variations in the branching pattern of axons during reinnervation compared to the process that occurs during development. © 1993 John Wiley & Sons, Inc.
AAEM case report #26: Seventh cranial neuropathy
Authors: Gilchrist James M.
Published: January 2005

AAEM CASE REPORT #26. A 25‐year‐old man with acute, bilateral facial palsies is presented. He had a lymphocytic meningitis, history of tick bites, and lived in an area endemic for Lyme disease, which was ultimately confirmed by serology. Electrodiagnostic investigation included facial motor nerve study, blink reflex and electromyography of facial muscles, which were indicative of a neurapraxic lesion on the right and an axonopathic lesion on the left. The clinical course was consistent with these findings as the right side fully recovered and the left remained plegic. The clinical features of Lyme associated facial neuritis are reviewed, as is the electrodiagnostic evaluation of facial palsy.
Motor unit estimation: Reproducibility of the spike‐triggered averaging technique in normal and ALS subjects
Authors: Bromberg Mark B.
Published: January 2005

Reproducibility of the spike‐triggered averaging technique of motor unit estimation (MUE) was assessed in biceps‐brachialis muscle in 10 normal subjects and 15 subjects with amyotrophic lateral sclerosis (ALS). MUE was calculated by dividing the compound muscle action potential by the mean amplitude of 15 surface motor unit potentials (S‐MUPs) of low recruitment threshold. Averaged MUE values in normal subjects were higher than in ALS subjects, with few values overlapping. Differences between test and retest MUE values were not significant for either subject group. The relative differences between test‐retest values were 45.3% for normal subjects and 32.6% for ALS subjects. Correlation coefficients between test and retest values were low (r = 0.07) for normal subjects when influential outlying points were removed, and higher (r = 0.65) for ALS subjects when individuals with MUE values within the normal range were removed. The higher correlation of testretest MUE values in ALS subjects compared to normal subjects may be due to a greater probability of resampling among the smaller number of motor units in ALS subjects. In summary, the reproducibility and technical aspects of the spike‐triggered averaging technique are similar to those reported for other MUE techniques. © 1993 John Wiley & Soncs, Inc.
Single channel properties of synaptic acetylcholine receptors in dystrophic fibers
Authors: Brennan Christine , Henderson Leslie P.
Published: January 2005

Neuromuscular transmission in dystrophic mice has been extensively studied through analysis of nerve‐evoked endplate potentials. In the present study, single channel ACh‐induced activity recorded from endplates of fast twitch muscle fibers from mdx and dy dystrophic mice, was compared with activity recorded from wild‐type fiber endplates to ascertain whether expression of these phenotypes leads to changes in ACh receptor properties and synaptic transmission. An 89 pS class of ACh‐induced events predominated in recordings from wild‐type and both strains of dystrophic mice. The mean open times for this class of events was well described by two exponential components, one with a voltage‐independent time constant of ∼ 0.3 ms and the other with a time constant of 2–5 ms which increased e‐fold with ∼ 120 mV of hyperpolarization. The expression of the mdx or the dy phenotype was not associated with significant differences in the conductance, distribution of open durations, or the voltage‐dependence of the mean open time for this class of ACh‐induced events. © 1993 John Wiley & Soncs, Inc.
Acute conduction block in vitro following exposure to antiganglioside sera
Authors: Arasaki Keisuke , Kusunoki Susumu , Kudo Norio , Kanazawa Ichiro
Published: January 2005

We studied the role of antiganglioside antibodies in the pathogenesis of autoimmune neuropathies using an in vitro preparation of a rat sciatic nerve. Human and rabbit sera with high titers of the antibodies were applied to a restricted segment of the sciatic nerve mounted in a recording chamber, and the compound nerve action potentials of the myelinated and unmyelinated fibers were observed. Myelinated fiber conduction became blocked at the segment within a few hours, whereas the unmyelinated fiber conduction remained unchanged. These results suggest that antiganglioside sera directly produce an acute conduction block only in myelinated nerve fibers and that this in vitro model is useful for studying the ionic mechanism by which the acute conduction block occurs. © 1993 John Wiley & Sons, Inc.
EMG power spectrum of respiratory and skeletal muscles during static contraction in healthy man
Authors: Badier Monique , Guillot Chantal , Lagier‐Tessonnier Françoise , Burnet Henry , Jammes Yves
Published: January 2005

Changes in EMG power spectrum during isometric voluntary contraction maintained until exhaustion in the range of 20–80% MVC were studied in three skeletal muscles (adductor pollicis or AP, vastus lateralis, and medialis) and two respiratory muscles (diaphragm and rectus abdominis). Quantitative EMG analysis consisted of computation of the median frequency (MF) of power spectra and also the continuous measurement of EMG power in two bands of high (EH) and low (EL) frequencies using bandpass filters. This allowed the calculation of the H/L ratio and its time constant of decay rate (TCHδ /L) throughout the sustained static contraction. The main results were: (1) highly significant, positive correlations between TCδH/L and the maximal MF changes and also the endurance time to fatigue; (2) EMG changes were determined early, within the first 10–20 s of contraction; and (3) EL always increased throughout the fatiguing isometric contraction, but EH changes markedly varied within the five muscle groups studied. These observations are discussed in terms of the differences in muscle fiber composition and also the variations in motor unit recruitment. © 1993 John Wiley & Sons, Inc.
Multifrequency characteristics of disposable and nondisposable EMG needle electrodes
Authors: Ackmann James J. , Lomas John N. , Hoffmann Raymond G. , Wertsch Jacqueline J.
Published: January 2005

The physical properties of recording electrodes coupled with the input characteristics of recording amplifiers can affect motor unit parameters. In recent years, there has been increased use of disposable needle electrodes; thus, a comparison of impedance characteristics with disposable types is of interest. Impedances at 10, 100, 1000, and 10,000 Hz of eight different electrode models including concentric and monopolar, both disposable and reusable, were measured. For all models of monopolar electrodes, no significant difference in impedance was found between disposable and nondisposable types. Intramodel variability was seen, however, with a twofold difference between minimum and maximum impedances for each model. For concentric electrodes, a moderate difference in impedance was found between disposable and nondisposable types, but less intramodel variability was seen; there was also more intermodel variability. To determine whether the measured impedances could affect recorded motor unit potentials, a theoretical analysis was conducted using typical waveforms along with circuit analysis techniques. Electrode impedances as high as 50 times nominal values caused no significant waveform distortion. © 1993 John Wiley & Sons, Inc.
Effects of chronic electrostimulation on rat soleus skinned fibers during hindlimb suspension
Authors: Furby Alain , Mounier Yvonne , Stevens Laurence , Leterme Damien , Falempin Maurice
Published: January 2005

In order to counteract the changes of the contractile properties of the rat soleus occurring during 10 days of hypokinesia‐hypodynamia, due to hindlimb suspension (HS), two different patterns of electrostimulation were applied to the tibial nerve. The contractile properties of single chemically skinned muscle fibers were investigated using the tension–pCa relationship characteristics, the similar or different calcium and strontium affinities, and by measuring the P/tmax kinetic parameters. Our results showed that a pattern similar to firing rates of motoneurons innervating slow twitch muscles inhibited the slow to fast fiber changes observed during HS, whereas a pattern similar to firing rates of motoneurons from fast twitch muscles seemed to favor these changes. Since neither pattern maintained the isometric contractile force developed by the soleus fibers, we concluded that the decrease in mechanical strains imposed on the muscle during unloading was the main factor for the development of atrophy, while the kinetic changes might be predominantly modulated by the nervous command.
Axonal form of Guillain–Barré syndrome: Evidence for macrophage‐associated demyelination
Authors: Berciano José , Coria Francisco , Montón Fernando , Calleja Jesús , Figols Javier , Lafarga Miguel
Published: January 2005

We report on the clinical, electrophysiological, and pathological findings in a patient with pure motor and axonal Guillain–Barré syndrome, who died 29 days after onset. There was marked reduction of compound motor action potential amplitudes and denervation potentials in the tibialis anterior muscle. Motor and sensory conduction velocities of median nerve were normal. Peroneal nerve was inexcitable at the ankle but its latency from knee to tibialis anterior was normal. F waves were absent or delayed. The major burden of pathological changes fell on ventral spinal roots. Fundamental lesions included segmental demyelination, axonal degeneration, widespread endoneurial lipid‐laden macrophage infiltrates, remyelination, and clusters of small regenerating fibers. These findings suggest that axonal damage in the axonal form of Guillain–Barré syndrome is secondary to demyelination.
Hereditary motor–sensory neuropathy and movement disorders
Authors: Cardoso Francisco E. C. , Jankovic Joseph
Published: January 2005

To explore the relationship between hereditary motor and sensory neuropathy (HMSN) and movement disorders, we examined 7 patients with HMSN referred to our Movement Disorders Clinic and surveyed members of the Charcot‐Marie‐Tooth association. The following movement disorders were observed in the index patients: postural tremor in 6, rest tremor in 3, and Parkinsonism and dystonia in 2. Tremor, present in 40% of the 201 patients who responded to the survey, was first noted at a mean age of 36 years, and mostly involved the hands. Family history of tremor was more frequent in the tremor group (P > 0.005), which also had a significantly worse writing score than the nontremor group (P > 0.001). The overlap in clinical features between HMSN‐associated tremor and essential tremor (ET), the high frequency of family history of tremor, and the lack of a relationship between the severity of tremor and of peripheral neuropathy suggest that the tremor in HMSN is pathogenically related to ET. © 1993 John Wiley & Sons, Inc.
Sympathetic skin response abnormalities in amyotrophic lateral sclerosis
Authors: Dettmers Christian , Fatepour David , Faust Harald , Jerusalem Felix
Published: January 2005

The sympathetic skin response (SSR) was evaluated in 25 patients with amyotrophic lateral sclerosis (ALS) to assess for involvement of the autonomic nervous system. Twenty‐two age‐matched normals and 6 patients with muscular dystrophy served as controls. The SSR was intact in all normal volunteers and all patients with muscular dystrophy. The mean SSR latency in the ALS patients was prolonged compared to that of normals (2.29 ± 0.28 versus 2.13 ± 0.16 s, P > 0.05). The SSR was absent in one or both legs of 10 ALS patients (40%). Absence or abnormal latency of SSR in patients with ALS without clinical findings of autonomic failure suggests involvement of the autonomic nervous system in addition to the motor system. © 1993 John Wiley & Sons, Inc.
Quantifying how location and dose of botulinum toxin injections affect muscle paralysis
Authors: Shaari Christopher M. , Sanders Ira
Published: January 2005

Despite the widespread use of botulinum toxin to treat muscle dystonias, no method exists to quantify muscle paralysis in either human or nonhuman models. In this study we examined how the location, dose, and volume of botulinum injection affects paralysis in the rat tibialis anterior muscle. Paralysis was quantified by electrically stimulating the nerve to the tibialis anterior and then staining sections of the muscle for glycogen. The areas of glycogen‐containing fibers represented regions of botulinum action. The results showed that the most important injection technique is to inject botulinum directly into the motor endplate region of a muscle. Injections only 0.5 cm from the motor endplate resulted in a 50% decrease in paralysis. Increases in dose increased paralysis, however, some of that increase was simply due to the increased volume of injection. Thus, delivering toxin in small volumes near the MEP band of a muscle should produce the most effectiveparalysis. © 1993 John Wiley & Sons, Inc.
An animal model of neuropathic pain: A review
Authors: Bennett Gary J.
Published: January 2005

Recent work has succeeded in producing models of painful peripheral neuropathies in laboratory animals. There is evidence that the animals experience both abnormal spontaneous pain and abnormal evoked pains (allodynia and hyperalgesia). Experimental analyses of these models have demonstrated potential pathophysiologic mechanisms in both the peripheral and central nervous systems; it is likely that the model neuropathic pain syndromes are due to several different mechanisms. One line of evidence suggests that these pain states gradually become centralized due to an excitotoxic effect on spinal cord dorsal horn inhibitory interneurons. The role of the sympathetic nervous system appears to vary, depending on the type of nerve injury and the temporal evolution of the syndrome. There is evidence indicating that theabnormality of cutaneous temperature regulation that often accompanies painful peripheral neuropathy is not necessarily due to the activity of sympathetic vasomotor efferents. © 1993 John Wiley & Sons, Inc.
Congenital myasthenic syndromes: II. Syndrome attributed to abnormal interaction of acetylcholine with its receptor
Authors: Uchitel Osvaldo , Engel Andrew G. , Walls Timothy J. , Nagel Alexandre , Atassi M. Zouhair , Bril Vera
Published: January 2005

A 21‐year‐old woman had myasthenic symptoms since birth that responded poorly to anticholinesterase therapy. Tests for acetylcholine receptor (AChR) antibodies were negative. An intercostal muscle specimen was obtained to investigate the character of the neuromuscular transmission defect. There were no immune deposits at the endplates. The quantal content of the endplate potential was normal. Miniature endplate potentials and currents were very small, but the number of AChR per endplate was normal. On electron microscopy, the synaptic vesicles were of normal size, the junctional folds were intact, and the density and distribution of AChR on the folds was normal. The kinetic properties of AChR were studied by analysis of acetylcholine (ACh)‐induced current noise. The mean single channel conductance was normal. The noise power spectrum was abnormal, containing two components of different time course. This could result from an abnormal interaction of ACh with AChR, or from two populations of AChR at the endplate. The second possibility is unlikely because if two populations of AChR were present at the endplate, then both would have to have low conductance to explain the small miniature endplate current, but the average conductance of the channels that did open was normal. © 1993 John Wiley & Sons, Inc.
F tacheodispersion: Quantitative analysis of motor fiber conduction velocities in patients with polyneuropathy
Authors: Chroni Elisabeth , Panayiotopoulos Chrysostomos P.
Published: January 2005

The distribution of motor fiber conduction velocities (FCVs) of the ulnar and peroneal nerves in patients with polyneuropathy was estimated using F tacheodispersion, a technique based on F wave latencies. Twenty‐three ulnar and 23 peroneal nerves were studied. Three groups of nerves were identified according to conventional, M response, and F wave measurements: those with all parameters normal (group 1), those with abnormal F wave parameters only (group 2), and those with all parameters abnormal (group 3). Application of F tacheodispersion to nerves in group 1 revealed a shift of the distribution of FCVs toward the lower normal values in 6 of 7 nerves. In group 2, a significant proportion of FCVs were below the lower normal limits despite normal maximum conduction velocity estimated by the M response. In group 3, all nerve fibers were abnormally slow. The results indicate that application of F tacheodispersion in clinical practice will increase sensitivity of nerve conduction studies and enable quantitative estimation of conduction in a motor nerve fiber population. © 1993 John Wiley & Sons, Inc.
Effect of the inhibitory phenomenon following magnetic stimulation of cortex on brainstem motor neuron excitability and on the cortical control of brainstem reflexes
Authors: Leis A. Arturo , Kofler Markus , Stokic Dobrivoje S. , Grubwieser Gert J. , Delapassebme J. Scott
Published: January 2005

We studied the effect of the inhibitory phenomenon following transcranial magnetic stimulation (TMS) on brainstem motor neuron excitability and on the cortical control of brainstem reflexes in 5 normal subjects. The R1 component of the blink reflex assessed excitability of the facial nucleus during the period of post‐TMS inhibition (experiment 1). TMS effect on the cortical control of brainstem reflexes was assessed by delivery of a stimulus that was less than or equal to the threshold for the R1 with the subject relaxed, yet elicited a potentiated reflex during maneuvers requiring cortical input (i.e., voluntary eye‐closure and anticipation, experiment 2). In experiment 1, a suprathreshold electric stimulus applied during post‐TMS inhibition elicited an R1 response that was preserved in amplitude (mean 476 ± 44 μV; 123%) compared to control responses not preceded by TMS (mean 386 ± 31 μV). Conversely, in experiment 2, when the R1 was dependent on cortical drive, the mean R1 amplitude during post‐TMS inhibition was only 15% (P < 0.01) and 8% (P < 0.01) of control values obtained during eye‐closure and anticipation, respectively. These findings imply that the inhibition following TMS originates rostral to the facial nucleus, at a cortical level. © 1993 John Wiley & Sons, Inc.
The effects of hyperthyroidism on muscular dystrophy in the mdx mouse: Greater dystrophy in cardiac and soleus muscle
Authors: Anderson J. E. , Liu L. , Kardami E.
Published: January 2005

Muscle damage and repair were studied in mdx mice treated with triiodothyronine (T3) for 14 days. Hindlimb and cardiac muscles were examined for the severity of dystrophy, the degree of muscle centronucleation, and fiber size. In control and mdx mice, cardiac hypertrophy and skeletal muscle atrophy were present after T3 treatment. Both cardiac and soleus (but not fast‐twitch) muscles had larger, more frequent dystrophic lesions in T3‐treated mdx mice, and mdx soleus had an increased area of new myotubes after T3. Skeletal myogenesis in mdx mice may have been delayed by excess T3, possibly related to the general reduction in staining for basic fibroblast growth factor in hyperthyroid mice. These are the first observations of a metabolic perturbation which worsens mdx dystrophy and possibly repair in a musclespecific manner, and are likely related to T3‐induced changes in myosin heavy chain expression, and to increased mechanical strain on dystrophin‐deficient muscles. © 1994 John Wiley & Sons, Inc.
Long lasting excitability changes in human peripheral nerve
Authors: Potts Frisso , Young Robert R. , Shefner Jeremy M.
Published: January 2005

When pairs of equal but submaximal electrical stimuli are delivered to a peripheral nerve, the second stimulus does not always excite the same number of fibers as the first. The number of fibers responding to the second stimulus depends on the interstimulus interval; the refractory period, a well‐defined period of hypoexcitability, is followed by longer lasting and less well‐characterized periods of hyper‐ and hypoexcitability. These cycles last at least 200 ms after the initial stimulus. We have carefully studied these cycles of excitability in human peripheral nerve in 12 normal subjects. The magnitude of excitability changes were found to be much greater in motor fibers than in mixed nerve; under some conditions, the motor response was reduced by more than 80% at interstimulus intervals of 40 ms, while the mixed nerve response never varied by more than 20%. In addition, the amplitude of the excitability changes varied as a function of the stimulus strength, so that stimuli that were near threshold or evoked near maximal responses were associated with smaller excitability changes than stimuli evoking midrange responses. Given that the excitability fluctuations are of large magnitude and occur at interresponse intervals easily achieved during physiological firing, it is suggested that they may be important modifiers of firing rate under experimental or physiological conditions. © 1994 John Wiley & Sons, Inc.
Inability of insulin to maintain normal nerve function during high‐frequency stimulation in diabetic rat tail nerves
Authors: Andersen H. , Nielsen J. F. , Nielsen V. Kamp
Published: January 2005

The effect of insulin on the response to long‐term high‐frequency stimulation (HFS = 143 Hz for 20 min) was studied in mixed tail nerves of acute streptozotocin‐induced diabetic rats. In consecutive tests, untreated diabetic rats showed a significant decrease in nerve conduction velocity (NCV) and peak‐to‐peak amplitude (P‐Pamp) and the depression of the P‐Pamp during HFS was augmented. In contrast, NCV and P‐Pamp in the insulin‐treated rats were unchanged from the prediabetic state, but the depression of the P‐Pamp during HFS reached the same degree as in untreated rats. This implies that although insulin treatment of acute experimental diabetes is able to preserve a normal NCV and P‐Pamp in the resting state, it is unable to preserve normal nerve function under stress produced by HFS. Monitoring of the axon membrane functional capacity may have clinical implications in the control of peripheral neuropathies. © 1994 John Wiley & Sons, Inc.
Do GM1 antibodies induce demyelination?
Authors: Lange Dale J. , Trojaborg Werner
Published: January 2005

We review clinical, neurophysiological, immunological, and experimental data concerning multifocal motor neuropathy (MMN), a newly recognized disorder that mimics MND. It is separated from MND by the presence of multifocal conduction block (CB) demonstrated electrophysiologically, and in some instances by the association of high liters of GM1 antibodies. The possible immunopathogenetic effect of GM1 antibodies is discussed. However, 70% of patients with MMNCB do not have elevated titers of GM1 antibodies, but may respond nevertheless to immunosuppressive treatment. Thus, so far unrecognized antibodies may react against some other epitopes in the paranodal region than those attacked by GM1 antibodies to cause CB. © 1994 John Wiley & Sons, Inc.
Transcranial magnetic stimulation in patients with cervical spondylotic myelopathy: Clinical and radiological correlations
Authors: Tavy Dénes L. J. , Wagner G. Louis , Keunen Ruud W. M. , Wattendorff A. Rolf , Hekster Ruben E. M. , Franssen Hessel
Published: January 2005

Motor evoked potentials (MEPs) were studied in 28 patients with cervical spondylotic myelopathy. MEPs after cortical stimulation were abnormal in 27 patients, the responses in the leg muscles being affected the most often. Clinically asymptomatic motor lesions were detected in 7 patients (25%). The central motor conduction time (CMCT) for the abductor digiti minimi muscles correlated significantly with the clinical disability, whereas the radiological findings did not correlate with the clinical and neurophysiological parameters. In 9 patients MEPs were also recorded in the biceps muscles. The 7 patients with an abnormal CMCT for the biceps muscles had the most severe stenosis at the C‐4–C‐5 level or higher. The 2 patients with normal MEPs of the biceps muscles both had a stenosis at the C‐5–C‐6 level. The results of this study suggest that MEPs are useful for detecting spinal cord dysfunction and for localizing the level of the lesion. Some recommendations regarding the possible use of MEPs in the clinical evaluation of patients with cervical spondylotic myelopathy are given. © 1994 John Wiley & Sons, Inc.
Pseudoneurogenic thoracic outlet syndrome
Authors: Simpson David M.
Published: January 2005

A 61‐year‐old man developed progressive weakness, numbness, and exercise‐induced vascular symptoms in the left hand. There was left thenar wasting. The presence of a supraclavicular bruit and vascular studies indicated left subclavian artery stenosis, but electrophysiological studies demonstrated no evidence for brachial plexopathy. Subsequent neuroimaging studies revealed multifocal right cerebral infarction. Focal atrophy and weakness from a cerebral lesion can simulate a brachial plexus lesion. © 1994 John Wiley & Sons, Inc.
Median nerve sensory responses evoked by tactile stimulation of the finger proximal and distal phalanx in normal subjects
Authors: Caruso Giuseppe , Nolano Maria , Lullo Francesco , Crisci Claudio , Nilsson Jan Bsee , Massini Riccardo
Published: January 2005

We compared the characteristics of near‐nerve recorded sensory potentials elicited in response to electrical stimulation of digital nerves versus tactile stimulation of the digital skin in 17 healthy subjects with a mean age of 26 years. We also calculated the density of Meissner's corpuscles in the distal and proximal phalanx of digit III of 6 males who had suffered a violent death, but were free from diseases of the peripheral nerve system. Responses to tactile stimulation had a longer latency and lower amplitude than responses to electrical stimulation. Unlike electrically elicited responses, responses to tactile stimulation, which consisted of six or seven main spike components plus several minor components, were similar in recordings from the wrist and elbow. However, with proximal stimulation the electrically evoked responses were more compact and had a higher amplitude and area, whereas the tactile evoked potential became significantly reduced in maximum amplitude and cumulative area. The differences in sensory conduction between distal and proximal could reflect activation of a larger number of nerve fibers when electrical stimuli are used and a smaller amount of mechanoreceptors when tactile stimuli are used. © 1994 John Wiley & Sons, Inc.
Retrograde effects of digital nerve severance on somatosensory evoked potentials in man
Authors: Chu Nai‐Shin
Published: January 2005

To determine if retrograde conduction changes might occur long after injury of the most distal peripheral nerves, short‐latency somatosensory evoked potentials (SEPs) to median or ulnar nerve stimulation at the wrist were studied in 10 subjects who had sustained traumatic digit amputation 4 months to 15 years previously. SEPs were recorded from Erb's point (N9), the cervical region (N13), and the contralateral scalp hand area (N20). While N9 latency was slightly delayed or not affected, the amplitude was either markedly reduced or undetectable. For N13 and N20 components, latency prolongation and amplitude reduction were mild to moderate, but the central conduction time (N13–N20) remained normal. The present data indicate that even the most distal nerve injury may have profound long‐term retrograde effects on parental nerve function which are presumed mainly due to an axonopathy. © 1994 John Wiley & Sons, Inc.
Focal lipoatrophy
Authors: Jablecki Charles K.
Published: January 2005

Focal atrophy of a limb is usually caused by loss of muscle due to nerve or muscle disease. However, focal atrophy of subcutaneous tissues, an uncommon but well described entity, can mimic neuromuscular disease by producing a similar appearance of the limb. The clinical sign of thinness of the subcutaneous tissues (the “pinch‐an‐inch” test) suggests lipoatrophy as the cause of limb asymmetry. © 1994 John Wiley & Sons, Inc.
The effects of altered metabolism (hypothyroidism) on muscle repair in the mdx dystrophic mouse
Authors: McIntosh L. M. , Pernitsky A. N. , Anderson Judy E.
Published: January 2005

After dystrophic damage, the limb muscles of the mdx mouse recover very effectively compared to muscles in Duchenne muscular dystrophy (DMD) patients. Since thyroid hormone is required for muscle development and integrity, we examined whether a deficiency of the hormone, induced by 0.05% propylthiouracil (PTU) in drinking water over 8 weeks, would be deleterious to the myogenesis and muscle repair in control and mdx mice. Measured metabolic and growth parameters confirmed hypothyroidism in PTU‐treated mice. Histological and morphometric techniques were used to study myogenesis and the repair of the tibialis anterior muscle (TA) after crush injury in mdx mice and their nondystrophic controls (C57B1/10ScSn). After 8 weeks, PTU‐treated TA from mdx mice had larger crush sites and lower myotube density than TA in untreated mdx mice. In unoperated mdx TA, there was a larger proportionate area of active dystrophy and smaller fiber diameter in PTU‐treated than in untreated mdx TA, which suggested that PTU increased the activity of dystrophy as well. In contrast, in control TA neither the regeneration of myotubes or fiber diameter were affected significantly by PTU. Therefore, these results suggest that mdx muscle regeneration is more affected by hypothyroidism than normal muscle repair. This may be due to the larger pool of muscle precursors in mdx than control muscle, and a possible impairment of precursor cell proliferation or fusion during myotube formation. © 1994 John Wiley & Sons, Inc.
Focal myopathy induced by chronic intramuscular heroin injection
Authors: Louis Elan D. , Bodner Russ A. , Challenor Yasoma B. , Brust John C. M.
Published: January 2005

A patient developed focal fibrotic myopathy after manry Years of intramuscular heroin use. While such changes have been associated with chronic intramuscular injections of pentazocine and a similar myopathy resulting from chronic intramuscular heroin has not been convincingly described. © 1994 John & Sons, Inc.
Sodium channels accumulate at the tips of injured axons
Authors: England John D. , Gamboni Fabia , Ferguson Michele A. , Levinson S. Rock
Published: January 2005

The axolemmal distribution of voltage‐gated sodium channels largely determines the regions of axonal electrical excitability. Using a wellcharacterized anti–sodium channel antibody, we examined peripheral nerve fibers focally injured by exposure to the neurotoxic agent, potassium tellurite (K2TeO3). Immunocytochemical and radioimmunoassay data showed a focal accumulation of sodium channels within the tips of injured axons. The major increase in sodium channel concentration occurred between 7 and 11 days after toxin exposure; however, immunocytochemically, excess sodium channels persisted in several axonal endings for a much longer time. The accumulation of sodium channels at injured axonal tips may be responsible, in part, for ectopic axonal excitability and the resulting abnormal sensory phenomena (especially pain and paresthesias) which frequently complicate peripheral nerve injury in humans. © 1994 John Wiley & Sons, Inc.
Paramyotonia congenita: Abnormal short exercise test, and improvement after mexiletine therapy
Authors: Jackson Carlayne E. , Barohn Richard J. , Ptacek Louis J.
Published: January 2005

The diagnosis of paramyotonia congenita (PC) can be aided by demonstrating a decrease in compound motor action potential amplitude after exercise and a decrement on repetitive stimulation, following cold exposure. We report a patient with PC who presented with complaints of cold‐induced hand and jaw stiffening, in the absence of any episodes of weakness. Treatment with mexiletine led to resolution of the abnormalities exhibited during a short exercise test and repetitive stimulation following ice bath immersion. Molecular genetic analysis revealed a missense mutation (cytosine to thymidine) on chromosome 17 in the alpha‐subunit of the skeletal muscle sodium channel gene that results in the replacement of threonine with methionine. This case demonstrates that, despite the absence of weakness, the short exercise test following cold exposure can be used to confirm the diagnosis of PC in patients without episodic weakness. Furthermore, improvement of the electrophysiologic abnormalities with mexiletine was documented, corresponding with clinical improvement. © 1994 John Wiley & Sons, Inc.
Botulinum toxin converts muscle acetylcholine receptors from adult to embryonic type
Authors: Költgen Dirk , Ceballos‐Baumann Andres O. , Franke Christian
Published: January 2005

To assess the postsynaptic consequences of botulinum toxin injection into muscle we characterized the nicotinic acetylcholine receptor (nAChR) with the patch clamp technique, using adult mouse muscle after destruction of the nerve ending and after treatment with botulinum toxin (BoTX). In both, embryonic channels with a conductance of 30 and 34 pS could be identified, whereas on adult control muscle nAChR channels had a conductance of 48 pS. The mean open times were 1.2 ms for the channels in control, 2.5 ms in denervated, and 2.4 ms in BoTX‐treated muscle. The dose–response curves of the maximal acetylcholine‐elicited currents showed a Km of 60 μmol/L for denervated, 70 μmol/L for BoTX‐treated, and 100 μmol/L for control muscle. Destruction of the nerve ending and inhibition of acetylcholine release by BoTX has the same effect as far as the increase of sensitivity of the muscle to acetylcholine is concerned. In contrast to single‐fiber EMG findings in patients treated for focal dystonia no distant changes could be found in the control muscle of the BoTX‐treated animals. © 1994 John Wiley & Sons, Inc.
Statistical errors and their effect on electrodiagnostic medicine
Authors: Rivner Michael H.
Published: January 2005

Failure to demonstrate abnormalities on diagnostic tests in patients felt certain to have a disease is all too common, especially when symptoms are mild to moderate. One strategy used in such cases is to perform multiple tests hoping that one will confirm the clinical suspicion. An example of this strategy is found in carpal tunnel syndrome where multiple tests are often used to confirm the diagnosis. Unfortunately, this approach is often erroneous. Since no diagnostic test can perfectly discriminate between normal and abnormal, critical values are set at levels where most subjects are correctly classified. Using this methodology, approximately 2.5% of patients who are normal will be mistakenly called abnormal. This type I error, is additive when additional independent tests are performed. Since no two tests for a single condition are completely independent, the total error is less than the sum of the individual errors for each test. Even after accounting for interdependency, the total error of combined tests may be unacceptably high. If a single, highly discriminating, test is not available and multiple tests are used, abnormalities in more than a single test are needed to distinguish between normals and abnormals. © 1994 John Wiley & Sons, Inc.
Diagnostic tests: A statistical review
Authors: Schulzer Michael
Published: January 2005

Common measures of the accuracy of diagnostic tests are reviewed. It is shown that the actual performance (predictive value) of these tests depends not only on their sensitivity and specificity, but also on the prevalence of the disease in the population tested (Bayes' theorem). The effect of an inaccurate “gold standard” on the calibration of a new diagnostic test is discussed. Receiver operating characteristic (ROC) curves are introduced as a tool for selecting an optimal cutpoint for a test, and for comparing different tests. Schemes are given for combining tests to improve their accuracy. When multiple continuous measurements are available, methods of discriminant analysis (and logistic regression) are shown to provide measurement combinations with improved accuracy. Examples and key references are provided. © 1994 John Wiley & Sons, Inc.
Postexercise phosphocreatine resynthesis is slowed in multiple sclerosis
Authors: Kent‐Braun Jane A. , Sharma Khema R. , Miller Robert G. , Weiner Michael W.
Published: January 2005

To determine whether skeletal muscle oxidative metabolism is impaired in multiple sclerosis (MS), 31 phosphorus magnetic resonance spectroscopy was used to measure the rate of intramuscular phosphocreatine (PCr) resynthesis following exercise in MS and controls. Thirteen MS patients underwent intermittent isometric tetanic contractions of the dorsiflexor muscles elicited by stimulation of the peroneal nerve. Eight healthy control subjects performed voluntary isometric exercise of the same muscles. During exercise, there were no differences between groups in the fall of either PCr or pH. However, the half‐time (T‐1/2) of PCr recovery following exercise was significantly longer in MS (2.3 ± 0.3 min) compared to controls (1.2 ± 0.1 min, P < 0.02). These data provide evidence of slowed PCr resynthesis following exercise in MS, which indicates impaired oxidative capacity in the skeletal muscle of this group. This finding suggests that intramuscular changes consistent with deconditioning may be important in the altered muscle function of persons with MS. © 1994 John Wiley & Sons, Inc.
Electrical myotonia of rabbit skeletal muscles by HMG‐CoA reductase inhibitors
Authors: Sonoda Yoshito , Gotow Tsukasa , Kuriyama Masaru , Nakahara Keiichi , Arimura Kimiyoshi , Osame Mitsuhiro
Published: January 2005

HMG‐CoA reductase (HCR) inhibitors are effective cholesterol‐lowering agents in the treatment of hypercholesterolemia. Using intracellular microelectrodes, we studied the pathomechanism of myotonia experimentally induced in rabbits by HCR inhibitors, simvastatin, and pravastatin. The external intercostal muscle of rabbits showed some electrophysiologic characteristics of myotonia including repetitive firing after administration of simvastatin (50 mg/kg per day, for 4 weeks). The relative chloride conductance, though reduced in both, was more affected in simvastatin‐administered muscles. In normal muscles perfused with a solution containing the inhibitors, both simvastatin and pravastatin produced membrane hyperexcitability with repetitive firing similar to that seen in simvastatin‐administered rabbits. The minimum concentrations required to cause repetitive firing was 0.3 mg/L for simvastatin and 30 mg/L for pravastatin. These results indicate that HCR inhibitors induce some characteristics of myotonia by blocking the chloride channel in the muscle membrane. © 1994 John Wiley & Sons, Inc.