bluuebunny/crossref_metadata_2025 huggingface dataset:
Congenital myasthenic syndromes: I. Deficiency and short open‐time of the acetylcholine receptor
Authors: Engel Andrew G. , Nagel Alexandre , Walls Timothy J. , Harper C. Michel , Waisburg Hector A.
Published: January 2005

A 5.5‐year‐old girl had myasthenic symptoms since birth. Tests for antiacetylcholine receptor (AChR) antibodies were negative. To investigate the character of the neuromuscular transmission defect, an intercostal muscle specimen was obtained at age 27 months. Immune deposits were absent from the endplates. On electron microscopy, most postsynaptic regions appeared normal, but the density of AChR on the junctional folds was diffusely reduced. In vitro microelectrode studies revealed that the number of transmitter quanta released by nerve impulse was normal. The amplitude of miniature of endplate potentials and currents was abnormally low. A study of the kinetic properties of AChR by analysis of acetylcholine‐induced current noise demonstrated a significant decrease in mean channel open‐time; the mean channel conductance was normal. The safety margin of neuromuscular transmission in this disorder is likely to be compromised by the deficiency and abnormal kinetic properties of AChR. The findings are unique among those patients with congenital AChR deficiency described to date. © 1993 John Wiley & Sons, Inc.
A statistical approach to fiber diameter distribution in human sural nerve
Authors: Schellens Ronald L. L. A. , van Veen Benno K. , Gabreëls‐Festen Annexe A. W. M. , Notermans Servaas L. H. , van't Hof Martin A. , Stegeman Dick F.
Published: January 2005

Fifty‐one normal sural nerve biopsies were obtained from 800 diagnostic biopsies. The external diameter distribution of myelinated fibers was described using the sum of two beta probability density functions, describing the thin as well as the thick fiber group. A cross‐sectional study using these distribution functions showed increasing values of the peak of the larger fiber group, the diameter of the thickest fibers, and the separation between the smaller and the larger groups until the beginning of adult life. The transition from a uni‐ into a bimodal histogram occurred gradually between 7 and 13 months. Total transverse fascicular area increased with age, whereas fiber density decreased significantly with age. The number of fibers remained stable over age. The relative proportion of the numbers of fibers in both groups described by one of the beta distributions remained constant over age. This occurred despite a marked decrease in the number of small fibers with a diameter less than, e.g., 6.5 μm. The results indicated an outgrowth of especially the larger myelinated fibers with age. This process continues with decreasing intensity into adult life. © 1993 John Wiley & Sons, Inc.
The cortical silent period and amyotrophic lateral sclerosis
Authors: Prout Alister J. , Eisen Andrew A.
Published: January 2005

The cortical silent period (C‐SP) was elicited by transcranial magnetic stimulation in 25 normal subjects and 19 patients with amyotrophic lateral sclerosis (ALS). The inhibitory (S‐X) period was highly stimulus intensity (Sl)‐dependent (mean r2 = 0.89 for both normals and patients with ALS). The range of the C‐SP (difference between maximum and minimum S‐X intervals) was age‐dependent for normals (r2 = 0.701, P < 0.001) but not patients with ALS. Means, maximums and ranges for the C‐SP were not significantly different between normal and ALS groups and thresholds to cortical stimulation were also comparable. There was a significant, linear, relation between the maximum C‐SP and disease duration of ALS (P = 0.002). The maximum C‐SP was shorter early in the disease. It is hypothesized that the reduced inhibition early in the course of ALS might reflect glutamate‐induced corticomotoneuronal excitotoxicity. © 1994 John Wiley & Sons, Inc.
Postsurgical idiopathic brachial neuritis
Authors: Malamut Richard I. , Marques Wilson , England John D. , Sumner Austin J.
Published: January 2005

Idiopathic brachial neuritis (IBN) is a well‐recognized clinical syndrome characterized by brachial pain followed by a patchy amyotrophy of muscles in the shoulder girdle and arm innervated by individual branches of the brachial plexus. Postsurgical IBN has not been widely recognized since Parsonage and Turner's original description in which 10% of patients had antecedent surgery. We present 6 patients who 1–13 days postoperatively developed signs and symptoms which met the clinical and electrophysiologic criteria for IBN. Postsurgical neuralgic amyotrophy is an under‐recognized clinical entity which in most cases is ascribed to brachial plexus stretch injuries occurring during anesthesia. Early recognition of this condition may prevent unnecessary surgical exploration and allow for a more accurate prediction of functional recovery. © 1994 John Wiley & Sons, Inc.
Single‐fiber electromyography in neuromuscular disorders: Correlation of muscle histochemistry, single‐fiber electromyography, and clinical findings
Authors: Bertorini Tulio E. , Stalberg Erik , Yuson Carlo P. , Engel W. King
Published: January 2005

We performed single‐fiber electromyography (SFEMG) and correlated the results with muscle‐biopsy histochemistry in 56 patients with various neuromuscular diseases. Increased muscle‐fiber density, delineated by SFEMG, was most prominent in diseases of ordinary denervation, namely motor neuron disorders and peripheral neuropathies, and it correlated with histochemical fiber type grouping. Both phenomena reflect denervation followed by reinnervation. In patients with central core disease and rod disease, fiber density was not increased despite massive type I fiber predominance. The normal distribution of type I fiber subtypes in those patients indicated that their fiber predominance was not due to sprouting and reinnervation, but probably to paucity of the type II fibers. In type I fiber hypotrophy with central nuclei, fiber density was increased, perhaps attributable to the small diameter and consequent denser packing of the type I fibers. Fiber density was slightly increased in the majority of patients with acidmaltase deficiency, limb‐girdle dystrophy, and polymyositis, in nearly half with mitochondrial myopathy, and in 1 older Duchenne dystrophy patient. In these myopathic disorders, myogenous deinnervation (followed by reinnervation) is one possible explanation. Normal fiber density was present in all patients with muscle phosphorylase deficiency, myotonia congenita, and in the hypokalemic periodic paralysis patients under age 40. © 1994 John Wiley & Sons, Inc.
Outliers, a way to detect abnormality in quantitative EMG
Authors: Stålberg Erik , Bischoff Christian , Falck Björn
Published: January 2005

In visual analysis of motor unit potentials it is common to decide abnormality by a few motor unit potentials with definitely abnormal amplitude, duration, and shape. The aim of the present investigation was to define limits of normal values and to compare the diagnostic yield of assessing definitely abnormal values outliers, with conventional mean values of MUP parameters. MUPs were extracted and measured with a new decomposition method. Reference values were obtained for three commonly studied muscles. Patients with various types of neuropathies and myopathies were studied in the same way with measurement of outliers and mean values. It was found that outliers were as sensitive as mean values in neuropathies and better in myopathies. Often an increased number of outliers could already be detected after only a few MUPs had been obtained. It would not have been necessary to obtain all 20 MUPs in these patients. The conclusion is that the outlier method is as sensitive as mean values. Because the number of MUPs required may be reduced, the investigation takes a shorter time and is less painful for the patient. If the degree of abnormality is to be quantified, calculation of mean values is still necessary. The combination of outliers and mean values may be the optimal way to detect and express abnormality. © 1994 John Wiley & Sons, Inc.
Absent F‐waves early in a of transverse myelitis
Authors: Syme Jackie A. , Kelly John J.
Published: January 2005

A 29‐year‐old female presented with acute onset of interscapular pain, followed by weakness of both legs and both hands, and a thoracic sensory level. F‐waves in her legs and arms were absent initially, but other conduction studies were normal. An initial spine MRI was normal but a second study 10 days later revealed an enlarged spinal cord with areas of enhancement. Repeat neurophysiologic studies showed return of F‐waves in the legs and absent compound muscle action potential (CMAP) in the hands with early denervation on needle examination. An acute intraxial lesion needs to be included in the differential diagnosis of absent F‐waves. © 1994 John Wiley & Sons, Inc.
H reflex studies in cerebral palsy patients undergoing partial dorsal rhizotomy
Authors: Logigian Eric L. , Wolinsky Joel S. , Soriano Sulpicio G. , Madsen Joseph R. , Scott R. Michael
Published: January 2005

H reflex studies were performed in ten spastic children with cerebral palsy who underwent partial dorsal rhizotomy (PDR). Under anesthesia prior to PDR, H reflex amplitude evoked by percutaneous peripheral nerve stimulation gradually declined in all patients and became unobtainable in five. Motor responses could still be evoked by apparent dorsal root stimulation in these five, but since it was shown that they were M responses and not reflexes, PDR was performed randomly. In the other five patients, in whom H reflexes were still evokable, dorsal root stimulation evoked motor responses which were true reflex responses, and PDR was performed “selectively.” Compared to preoperative values, postoperative Hmax/Mmax ratios declined, but no more so in selective than in random PDR. We conclude that current intraoperative methods for selection of “abnormal” dorsal rootlets for section may be invalid and may have no bearing on successful outcome, since spasticity improves even with random PDR. © 1994 John & Sons, Inc.
Association between muscle architecture and quadriceps femoris H‐reflex
Authors: Garland S. Jayne , Gerilovsky Lubomir , Enoka Roger M.
Published: January 2005

The purpose of the present study was to establish the relationship between muscle architecture and H‐reflex recordings in quadriceps femoris muscle. H‐reflexes were elicited in human quadriceps femoris muscle over a broad area of skin to document the shape and amplitude of the H‐potentials. This, in combination with recording monopolar and bipolar H‐potentials, was performed to determine the location and method for measuring maximum‐amplitude H‐reflexes. The influence of neural and peripheral factors on the H‐potential during passive length changes was studied by comparing the amplitude of H‐potentials to motor unit action potentials. Monopolar recordings of the H‐potential were found to be preferable to bipolar recordings because of the reproducibility of shape and easier distinction between the M‐ and H‐potentials. The location for recording maximum H‐potentials was in the distal one third of the quadriceps femoris muscle, over the border between vastus lateralis and rectus femoris. The inferred relationship between H‐potential amplitude and reflex excitability must be made with caution in quadriceps femoris muscle because the amplitude of both the motor unit potential and H‐potential change as a function of muscle length. © 1994 John Wiley & Sons, Inc.
Satellite cell activity is required for hypertrophy of overloaded adult rat muscle
Authors: Rosenblatt J. David , Yong David , Parry David J.
Published: January 2005

Hypertrophy of extensor digitorum longus muscle, overloaded by the removal of the synergist tibialis anterior (TA) muscle, in growing rats is inhibited if endogenous satellite cells are sterilized by exposure to irradiation. However, normal muscle growth is not eliminated, only diminished. To test whether irradiated, overloaded muscle can hypertrophy in the absence of normal growth‐related stimuli, experiments were conducted on mature rats. TA muscle ablation caused hypertrophy of EDL muscle, characterized by a significant increase in muscle mass and the size of type IIx and type IIb fibers, and a proportional increase the number of myonuclei. When ablation was preceded by irradiation hypertrophy did not occur. The results indicate that satellite cell activation, division, and fusion is necessary for compensatory hypertrophy of fully mature muscle, and may be important to the understanding of the limits of recovery of inherited muscle myopathies treated by myogenic cell implantation. © 1994 John Wiley & Sons, Inc.
Ophthalmoplegia, demyelinating neuropathy, leukoencephalopathy, myopathy, and gastrointestinal dysfunction with multiple deletions of mitochondrial DNA: A mitochondrial multisystem disorder in search of a name
Authors: Uncini Antonino , Servidei S. , Silvestri G. , Manfredi G. , Sabatelli M. , di Muzio A. , Ricci E. , Mirabella M. , di Mauro S. , Tonali P.
Published: January 2005

This article describes a 37‐year‐old woman with progressive external ophthalmoplegia, peripheral neuropathy, and chronic intractable diarrhea. Laboratory studies disclosed lactic acidosis, ragged red fibers lacking cytochrome c oxidase, high‐normal muscular mitochondrial enzymes, demyelinating neuropathy, leukoencephalopathy and multiple mitochondrial DNA deletions. This is the fourth patient described with this clinical syndrome, which represents a separate entity among multisystemic mitocnondrial disorders. The patient described here is the first with this syndrome to have multiple mitochondrial DNA deletions. © 1994 John Wiley & Sons, Inc.
The dropped head syndrome with chronic inflammatory demyelinating polyneuropathy
Authors: Hoffman Donald , Gutmann Ludwig , Griggs Robert C. , Mendell Jerry R. , Miller Robert G.
Published: January 2005

The dropped head syndrome occurs in a variety of neuromuscular disorders. We present a woman with chronic inflammatory demyelinating polyneuropathy who developed this syndrome, likely reflecting severe demyelination of nerves to cervical paraspinal muscles. © 1994 John Wiley & Sons, Inc.
Physiological properties of single thenar motor units in the F‐response of younger and older adults
Authors: Doherty Timothy J. , Komori Tetsuo , Stashuk Daniel W. , Kassam Ariff , Brown William F.
Published: January 2005

The purpose of this study was to characterize the properties of single thenar motor units in the F‐response of healthy younger (n = 15; age 33 = 11 years) and older subjects (n = 15: age 68 = 3 years). Trains of 300 stimuli at intensities evoking M‐potentials 10%, 20%, and 30% of the peak‐to‐peak amplitude of the maximum M‐potential, were delivered to the median nerve. In the young, observed firing probabilities of surfacedetected motor unit action potentials (S‐MUAPs) extracted from the F‐response ranged from less than 1–10%, the S‐MUAPs varied in size from 0.015% to 5.3% of the maximum M‐potential negative peak area, and they were similar in size to the population of S‐MUAPs collected by multiple point stimulation of the median nerve. The percentage difference between the slowest and fastest conducting fibers for individual subjects ranged from 8% to 20%, which translated to conduction velocities (CVs) of 48–68 m · s−1 (mean 59 ± 4). The preceding were all independent of stimulus intensity. The S‐MUAP sizes were significantly larger in older subjects (39%), and the range and distribution of motor unit CVs (38–61 m · s−1; mean 52 ± 3) were markedly shifted to reflect a slower population of motor fibers. These findings suggest that age‐related axonal slowing may uniformly affect all median motor fibers. © 1994 John Wiley & Sons, Inc.
Motor unit number estimates based on the automated analysis of F‐responses
Authors: Stashuk Daniel W. , Doherty Timothy J. , Kassam Ariff , Brown William F.
Published: January 2005

An automated technique for estimating the number of motor units based on single motor unit action potentials in the F‐response is described. The average surface detected motor unit action potential (SMUAP) was calculated from the datapoint‐by‐datapoint average of a sample of S‐MUAPs automatically selected from a population of F‐responses. The technique was applied to the thenar muscles of young (n = 18, aged 31 ± 11 years) and older (n = 15, aged 68 ± 3) subjects, Motor unit number estimates based on the automated selection of S‐MUAPs from the F‐responses compared well with those derived using a computer‐assisted manual method for selecting S‐MUAPs from the F‐response (automated 245 ± 105 vs. manual 241 ± 100, r = 0.93) and were similar to estimates obtained using multiple point stimulation (219 ± 77). The advantages of the automated technique for collecting S‐MUAPs from the F‐response include the ready tolerance of the technique by subjects, the minimal amount of operator interaction required, and the additional information relating to the conduction velocities and latencies of single motor axons. © 1994 John Wiley & Sons, Inc.
Metabolic and nonmetabolic components of fatigue monitored with 31P‐NMR
Authors: Baker Anthony J. , Carson Paul J. , Miller Robert G. , Weiner Michael W.
Published: January 2005

The goal of this study was to determine the roles of metabolic and nonmetabolic factors in muscle fatigue. Rat gastrocnemius muscles were fatigued by stimulation of the nerve (n = 6) or muscle (n = 4, after 2 days of denervation). 31Phosphorus nuclear magnetic resonance spectroscopy was used to measure levels of intracellular inorganic phosphate (Pi) and hydrogen ions (H+) (which are thought to inhibit contraction) and the high‐energy phosphates, phosphocreatine (PCr), and ATP. For both indirect and direct stimulation, with fatigue to ≈60% initial tetanic force, [Pi] increased from ≈3.5 mmol/L to ≈20 mmol/L and [PCr] decreased from ≈27 mmol/L to ≈9 mmol/L. However, with continued fatigue to 25–35% initial tetanic force, neither [Pi] or [PCr] changed further. [ATP] and pH changed only slightly during fatigue. The results are consistent with early fatigue arising from metabolic inhibition of contraction; but later fatigue arising independent of metabolites, due to impaired activation beyond the neuromuscular junction. © 1994 John Wiley & Sons, Inc.
Assessment of variability in the shape of the motor unit action potential, the “jiggle,” at consecutive discharges
Authors: Stålberg Erik V. , Sonoo Masahiro
Published: January 2005

A method for quantifing shape variability, the jiggle, of motor unit potentials (MUPs) recorded with conventional EMG electrodes is presented. Amplitude variability at each point of time of the MUP was analyzed. Two new parameters are proposed: the normalized value of the consecutive amplitude differences (CAD), and the crosscorrelational coefficient of the consecutive discharges (CCC). Simulations showed that increased jitter of the constituent single fiber potentials increases the jiggle as expressed by an increase in CAD and decrease in CCC values. Even when the jitter value of each component was fixed, increased temporal dispersion increased the jiggle whereas an increased number of fibers decreased the jiggle. This new method has been applied in normal subjects, patients with chronic neurogenic diseases and patients with ALS. Jiggle was significantly increased in the ALS group, in agreement with visual observations. We believe that this method for quantifying jiggle will increase the information obtainable from routine EMG investigations. © 1994 John Wiley & Sons, Inc.
Autonomic involvement in Guillain–Barre syndrome: A review
Authors: Zochodne Douglas W.
Published: January 2005

Autonomic neuropathy is an important and common complication of Guillain‐Barré syndrome (GBS). Manifestations be present in cardiovascular, sudomotor, gastrointestinal and other systems involving both sympathetic and parasympathetic fibers. Some apparently selective acute autonomic neuropathies may be subvarieties of GBS. Experimental work in animal models, pathological studies of GBS patients, and autonomic function studies have provided some help in the understanding of this complication. In managing GBS patients with autonomic dysfunction there are important practical considerations that can improve their care. In this article we review the literature on autonomic neuropathy in GBS and propose a management scheme to accommodate it in the overall treatment of the neuropathy. © 1994 John Wiley & Sons, Inc.
Phonomyogram of the diaphragm during unilateral and bilateral phrenic nerve stimulation and changes with fatigue
Authors: Petitjean Michel , Bellemare Francois
Published: January 2005

As previously demonstrated in humans, contracting skeletal muscles vibrate laterally and generate sound. The amplitude of this acoustic signal, called the phonomyogram (PMG), is related to muscle force production. As in limb muscles, the diaphragm might produce mechanical tissue vibrations and a PMG. We recorded diaphragm twitches during phrenic nerve stimulation in normal subjects at FRC. Diaphragmatic compound motor action potentials (CMAP) were recorded on each side of the chest by surface electrodes over the eighth intercostal space. Condenser microphones were fixed to the skin close to the electrodes, and esophageal and gastric balloons employed to measure transdiaphragmatic pressure (Pdi). For unilateral and bilateral supramaximal single shocks (O.1 ms), PMG onset latencies from either side (12.4 ± O.6 ms) were intermediate between those of CMAP (7.3 ± O.7 ms) and of Pdi (20.3 ± 2.8 ms). By varying stimulation intensity, significant linear relationships were obtained between CMAP and PMG amplitudes on each side. A significant linear relationship was also found between PMG for each side and Pdi peak values. PMG and Pdi both decreased with fatigue of the diaphragm. We conclude that PMG in response to single phrenic nerve shocks is a noninvasive index of electromechanical coupling, recruitment, and transdiaphragmatic pressure generation by the diaphragm. © 1994 John Wiley & Sons, Inc.
Brainstem reflexes in patients with olivopontocerebellar atrophy
Authors: Valls‐Solé Josep , Lou Jau‐Shin , Hallett Mark
Published: January 2005

In 4 patients with familial olivopontocerebellar atrophy (OPCA) we have recently described an abnormal movement of facial muscles characterized by rhythmic muscle twitching during voluntary activation (facial action myoclonus). In the present article, we present the results of a neurophysiologicel study of brainstem reflexes in those 4 patients, in 4 other patients with OPCA but without facial action myoclonus, in 3 patients with pure cerebellar cortical atrophy, and in 6 normal volunteers used as control subjects. All patients had similar clinical features, but only the patients with facial action myoclonus and only one of the other patients with OPCA had brainstem atrophy detected on magnetic resonance imaging. Electrophysiological abnormalities were found in all patients with facial action myoclonus and consisted of myokymia in perioral muscles at rest, spread of spontaneous and reflex blinking to the orbicularis oris, and enhanced long‐latency facial reflex responses to stimuli applied to the facial or trigeminal nerve. Other relevant electrophysiological abnormalities were the absence of jaw jerk in 2 patients, the absence of an R1 response of the blink reflex in 1 patient, and a markedly reduced compound muscle action potential of the facial nerve in another patient. Comparable electrophysiological abnormalities were found in only 1 of the patients with OPCA but without facial action myoclonus, and in none of the patients with pure cerebellar cortical atrophy. Facial action myoclonus is a clinical manifestation of a global brainstem functional derangement that may characterize a subgroup of patients with OPCA or constitute a distinctive step in the natural evolution of some forms of the disease. © 1994 John Wiley & Sons, Inc.
Limb girdle muscular dystrophy: Description of a phenotype
Authors: StüBgen Joerg‐Patrick
Published: January 2005

The phenotype is reported of 20 patients with autosomal recessive or sporadic, pelvifemoral limb girdle muscular dystrophy (LGMD). Selective wasting of muscles was observed at the moderately advanced stage of illness. The pattern of weakness was uniform. Attention to clinical detail allowed the identification of a phenotype different from a hypothetical scheme of LGMD based on previous literature, and other causes of limb girdle weakness. These patients may represent yet another nosologic entity within the autosomal recessive dystrophies; molecular genetic studies are awaited. A limited magnetic resonance imaging (MRI) study of muscle was of little consequence. Although additional detail was obtained, no pathognomonic distribution of the dystrophic process was observed; interindividual variation existed even among closely matched siblings. The severity of MRI signal change did not consistently correlate with the degree of weakness in an individual. When a diagnosis is uncertain, however, the added detail may be useful. © 1994 John Wiley & Sons, Inc.
Mixed nerve action potentials in acquired demyelinating polyneuropathy
Authors: Luciano Carlos A. , Gilliatt Roger W. , Conwit Robin A.
Published: January 2005

Uncertainty about motor and sensory contributions in abnormal nerves has limited the use of mixed nerve action potentials (MNAPs). We recorded MNAPs in 21 patients with an acquired demyelinating neuropathy, 18 age‐matched control subjects, and 10 patients with an axonal polyneuropathy. Bipolar and unipolar recordings from median and ulnar nerves were made above the elbow after electrical stimulation of the nerves at the wrist. Antidromic digital sensory action potentials and motor conduction velocity were also recorded for both nerves. In 19 median and 12 ulnar nerves from demyelinating polyneuropathy patients, compared with control subjects, MNAP amplitudes were significantly reduced (mean, 6 μV vs. 31 μV), MNAP velocities were mildly reduced (mean, 50 m/s vs. 62 m/s), motor conduction velocities were significantly reduced (mean, 33 m/s vs. 57 m/s), and MNAPs were significantly dispersed, with markedly prolonged rise times (mean, 2.0 ms vs. 1.0 ms). Compared with the axonal polyneuropathy group, MNAP amplitudes from the median nerve were similarly reduced (mean, 8 μV vs. 9 μV), MNAP velocities were only slightly slower (mean, 52 m/s vs. 58 m/s), but the rise times were significantly prolonged (mean, 2.0 ms vs. 1.2 ms). We conclude that, in acquired demyelinating neuropathies, the onset and, in some cases, the whole MNAP is from afferent fibers, which can be abnormally dispersed, and that, over the same segment, MNAP velocity is less affected than motor conduction velocity. 1995.© 1995 John Wiley &Sons, Inc.
Influence of baclofen upon the alpha‐motoneuron in spasticity by means of f‐wave analysis
Authors: Dressnandt Jürgen , Auer Carola , Conrad Bastian
Published: January 2005

Intrathecal baclofen dramatically improves severe spastic syndromes. This improvement is likely related to reduced excitability of alphamotoneurons. To investigate the influence of baclofen upon the alphamotoneuron, we analyzed F‐waves before and after intrathecal baclofen bolus injection (usually 50 μg) as well as after administration of different, constantly delivered doses (60–200 μg/day). Intrathecal baclofen bolus decreased the maximum F‐wave amplitude (Fp) from an initial value of 9% of the maximum M amplitude (Mmax) (=F/M‐ratio) to 2.4% of the Mmax after 130–180 min, reduced the mean F‐wave amplitude 60% within 150 min, and shortened the mean duration by 40–60% after 130–180 min. Constantly delivered baclofen of 100 μg/day reduced the F/M‐ratio from 5% to 2%, the mean F‐wave amplitude by 40–80%, and the F‐wave mean duration by 40–80%. The minimum F‐wave latency did not change after bolus or during steady state administration. The findings indicate that the F‐wave mean and maximum amplitude as well as the mean duration are altered in a quantifiable manner following intrathecal baclofen application.© 1995 John Wiley &Sons, Inc.
Nerve conduction changes and fine structural alterations of extra‐ and intrafusal muscle and nerve fibers in streptozotocin diabetic rats
Authors: Weis Joachim , Schröder J. Michael , Dimpfel Wilfried
Published: January 2005

Streptozotocin‐induced diabetes mellitus in known to cause a reduction of both conduction velocity and axon caliber in sciatic nerves and also a decrease in muscle fiber size. The present study investigates whether the distal parts of the peripheral nervous system, including extra‐ and intrafusal muscle fibers, are more severely affected than the proximal segments in the diabetic state. Proximal and distal sensory nerve conduction velocities were monitored during a period of 3 months in rats rendered diabetic by injection of streptozotocin. Segments of the sciatic and ventral coccygeal nerves, and of the biceps femoris and lumbrical muscles, were studied by light and electron microscopy, including morphometric analysis. In contrast to previous studies, daily suboptimal insulin injections were given to prevent acute metabolic complications. Sensory conduction velocity in the ventral coccygeal nerve was significantly (P > 0.05) decreased in the diabetic rats compared to controls. Proximal and distal nerve segments were equally affected. Mean cross‐sectional axon area of the sciatic nerve was moderately, but significantly (P < 0.05), smaller in insulin‐treated diabetic rats than in controls. In both the sciatic nerve and the terminal, intrafusal nerve segments, occasional axons showed moderate dystrophic changes. Fibers of the intrafusal nerve segments appeared to be equally affected compared to the fibers in the sciatic nerve, although no quantitative comparison was made. The increase of small caliber skeletal muscle fibers in experimental streptozotocin‐induced diabetes was confirmed. These findings indicate that proximal and distal segments of peripheral nerves are affected equally in the early stages of experimental diabetic neuropathy.© 1995 John Wiley &Sons, Inc.
Classic neurogenic thoracic outlet syndrome in a competitive swimmer: A true scalenus anticus syndrome
Authors: Katirji Bashar , Hardy Russell W.
Published: January 2005

Neurogenic thoracic outlet syndrome (TOS) is caused by compression of the lower branchial plexus usually by a cervical rib or a fibrous band. We describe a 16‐year‐old girl with weakness and wasting of her right hand, which progressed over the ensuing years. She had been a competitive long distance freestyle and butterfly swimmer since age 8 years. A neurological exam at age 20, revealed severe atrophy and weakness of all intrinsic right hand muscles, more so of the thenar muscles, and hypesthesia along the ulnar aspect of the hand and forearm. EMG, which showed a severe chronic axon loss lower trunk brachial plexopathy with minimal fibrillations, was typical for classic neurogenic TOS. Chest and cervical spine X‐rays and MRI of the cervical spine were normal. A supraclavicular exploration confirmed the absence of a cervical rib or band. The lower trunk was thickened under the scalenus anticus which was sectioned. Neurolysis was also done. She was advised to abandon swimming. A clinical and EMG follow‐up 2.5 years later showed no significant changes. This is the first case of true neurogenic TOS caused by scalenus anticus compression occurring in a competitive swimmer.© 1995 John Wiley &Sons, Inc.
Can the size principle be detected in conventional emg recordings?
Authors: Ertas Mustafa , Stålberg Erik , Falck Björn
Published: January 2005

According to Henneman's size principle, small motor units are recruited before large ones. It is commonly believed that this can be detected in routine conventional EMG recordings even among the earliest recruited motor units. That is, the MUP amplitude, area, and thickness should increase with recruitment order. We studied the first four motor unit potentials (MUPs) recruited within the pickup area of the electrodes. Data were obtained from 179 different sites in monopolar recordings and in 153 concentric recordings from 5 health subjects. In the pooled material, amplitude, area, and thickness increased slightly between consecutively recruited MUPs. However, at individual recording sites the size of consecutively recruited MUPs varied considerably. At some recording sites the first recruited MUP had the largest amplitude and the later MUPs has successively smaller amplitudes. We conclude that, at individual recording sites, the size principle cannot be detected in low threshold motor units with monopolar or concentric EMG electrodes. The reason for this is the small uptake area of these electrodes in relation to the motor unit territory. © 1995 John Wiley & Sons, Inc.
CT muscle imaging and the clinical assessment of neuromuscular disease
Authors: Swash Michael , Brown Martin M. , Thakkar Chandra
Published: January 2005

Twenty patients with neurogenic disorders, polymyositis, or muscular dystrophies were assessed clinically and by CT imaging of limb, limb girdle, and trunk muscles, using a standard protocol. On each side of these patients 26 movements were graded by the MRC scale, and 20 muscles were assessed by CT imaging. The clinical and CT findings could be compared, in a blind evaluation, in 10 muscles on each side. A quantitative assessment of the CT muscle images were also made. The CT images showed striking abnormalities, even in many muscles of normal strength by clinical testing. Asymmetrical involvement of muscles was found in all the disorders studied, even when not suspected on clinical examination. Muscles in patients with muscular dystrophy were more abnormal than those in patients with neurogenic disorders. In polymyositis the attenuation values were intermediate to the other two groups. A “washed‐out” appearance with very low attenuation values was very suggestive of muscular dystrophy. Involvement of paraspinal and rectus abdominis muscles was uncommon in neurogenic disorders. The gracilis muscle was relatively resistant to degeneration. CT imaging can enhance the clinical assessment of patients with neuromuscular disease, often revealing unexpected abnormalities. © 1995 John Wiley & Sons, Inc.
AAEM minimonograph #16: Instrumentation and measurement in electrodiagnostic medicine–part II
Authors: Gitter Andrew J , Stolov Walter C.
Published: January 2005

A review of instrumentation and measurement in electrodiagnostic medicine is continued in this Part II which focuses on digital instrumentation principles, gain and sweep effects, noise, nerve stimulation, and conduction measurement limitations. With the adoption of microprocessor‐based equipment, the neurophysiologic signal must undergo analog‐to‐digital conversion (ADC) before analysis and display on a video monitor. ADC resolution and sampling rates affect accuracy and measurement precision. Following waveform display, the visual assessment of latency and duration may be influenced by sweep and gain settings, often overlooked sources of error. Undesired signal or noise typically originates from power‐line interference, electronic amplifier noise, background muscle activity, or nerve stimulation artifact. Noise often interferes with clinical studies but techniques exist to reduce noise to acceptable levels in virtually all situations. An awareness and understanding of these technical issues will lead to an appreciation of the limitations of electrodiagnostic testing and improve interpretation and clinical decision‐making. © 1995 John Wiley & Sons, Inc.
High‐frequency fatigue in rat skeletal muscle: Role of extracellular ion concentrations
Authors: Cairns Simeon P. , Dulhunty Angela F.
Published: January 2005

High‐frequency fatigue (HFF), the decline of force during continuous tetanic stimulation (lasting 4–40 s), was studied in isolated bundles of rat skeletal muscle fibers. HFF was slower in slow‐twitch soleus fibers than in fast‐twitch red or white sternomastoid fibers; denervation accelerated fatigue in soleus. Maximal 200‐mmol/L potassium contractures of normal amplitude were induced in fatigued fibers, suggesting that crossbridge cycling and the voltage activation of excitation–contraction coupling could still occur maximally, but that activation by action potentials was impaired. An increase in [Na+]o slowed HFF, while a small increase in [K+]o or reduction in [Cl−]o accelerated HFF. Increasing the tetanic stimulation frequency exacerbated fatigue. Recovery from HFF proceeded rapidly since force increased markedly within a few seconds when stimulation ceased. These results support the hypothesis that a redistribution of Na+, K+, and Cl− across the transverse tubular membranes during repeated action potential activity induces fatigue by reducing the amplitude and conduction of action potentials. © 1995 John Wiley & Sons, Inc.
Conduction velocity distributions compared to fiber size distributions in normal human sural nerve
Authors: van Veen Benno K. , Schellens Ronald L. L. A. , Stegeman Dick F. , Schoonhoven Ruurd , Gabreëls‐Festen Anneke A. W. M.
Published: January 2005

Compound action potentials (CAPs) were recorded from the sural nerve of healthy volunteers. A mathematical technique (inverse modeling) was used to compute conduction velocity (CV) histograms from the data. Results were compared to the morphology of age‐matched normal sural nerve biopsies. Coefficients of variation (CoVs) revealed the statistical relationship between morphological data (diameter histograms) and electrophysiological data (CV histograms and conventional CAP parameters). No differences were found for the thick fiber group when comparing the CoVs of the diameter histogram parameters with the corresponding CV histogram parameters. Apparently, the same inherent biological interindividual variability is encountered. The CoVs of the CVs of the CAP's main phases are in good agreement with the CoVs of the estimated mean velocity of the thick fiber group. Inverse modeling increases the reliability of the estimation of the number of active fibers as compared to direct CAP amplitude interpretation.© 1995 John Wiley & Sons, Inc.
Effect of β‐endorphin on the contractile responses in mouse skeletal muscle
Authors: Khan Salim , Smith Margaret E.
Published: January 2005

Tension development in response to direct and indirect electrical stimulation was studied in an isolated phrenic nerve hemidiaphragm preparation of the mouse. β‐Endorphin (β‐EP) caused an increase in the preparation of the mouse. β‐Endorphin (β‐EP) caused an increase in the response to low frequency stimulation of the nerve. Upon direct stimulation of the muscle the peptide had no effect. The actions of β‐EP were abolished in the presence of the opioid antagonist naloxone and mimicked by β opioid agonists. Upon high frequency stimulation of the nerve, β‐EP caused an increase in the initial, maximum, and mean tension. It also prevented the fall in the final tension seen in the control preparations with repeated periods of stimulation. The findings are consistent with β‐EP having a role to improve neuromuscular function and deley fatigue, and indicate the possible therapeutic potential of opioid substances in conditions where muscle weakness is present. © John Wiley & Sons, Inc.
Myogenic cells derived from rat bone marrow mesenchymal stem cells exposed to 5‐azacytidine
Authors: Wakitani Shigeyuki , Saito Tomoyuki , Caplan Arnold I.
Published: January 2005

The compound 5‐azacytidine has been previously shown to convert cells of the rat embryonic fibroblastic cell line, C3H/10T1/2, into myoblasts, adipocytes, and chondrocytes. Rare, resident cells of bone marrow and periosteum, referred to as mesenchymal stem cells, have been shown to differentiate into a number of mesenchymal phenotypes including bone, cartilage, and adipocytes. Rat bone marrow‐derived mesenchymal stem cells were exposed to 5‐azacytidine beginning 24 h after seeding twice‐passaged cells into culture dishes. After an exposure of 24 h, long, multinucleated myotubes were observed in some of the dishes 7–11 days later. Cells containing Sudan black‐positive droplets in their cytoplasm were also observed. Thus, culture‐propagated rat bone marrow mesenchymal stem cells appear to have the capacity to be induced to differentiate in vitro into myogenic and adipocytic phenotypes, although nonmesenchymal cells (rat brain fibroblasts) cannot be so induced. Taken together, these observations provide support for the suggestion that mesenchymal stem cells in the bone marrow of postnatal organisms may provide a source for myoprogenitor cells which could function in clinically relevant myogenic regeneration. © 1995 John Wiley & Sons, Inc.
Applications of manganese‐enhanced magnetic resonance imaging (MEMRI) to imaging of the heart
Authors: Wendland Michael F.
Published: January 2005

The use of manganese‐based MRI contrast materials, either manganese salts or chelates, has spanned the entire timeframe of cardiac MRI. However interest in Mn compounds for cardiac MRI has been sporadic because of concerns over cardiotoxicity associated with significant concentration of free Mn2+ and notable success of gadolinium chelates in cardiac application. Initial strategies to overcome cardiotoxicity included chelation of Mn2+ to reduce the concentration of the free ion in vivo, and addition of Ca2+ in combination with Mn2+ to competitively reduce binding of Mn2+ to Ca2+ channels in the heart. Both approaches met with mixed success, but were subsequently discontinued in favor of gadolinium‐based approaches. However Mn2+‐based media potentially offer unique advantages for characterizing heart pathology over conventional Gd‐based contrast media because Mn2+ is taken up by heart cells and retained for hours. Cellular uptake occurs through calcium channels so contrast on delayed images may be interpreted according to regional or global functional status. Since Mn2+ is retained in the heart, Mn‐based media can be administered outside the magnet and the contrast pattern measured hours later to provide assessment of uptake. A key issue is whether sufficient accumulation of Mn2+ in heart cells for imaging can occur without cardiotoxicity, and findings to date indicate this is possible. This review examines the current status of Mn2+‐enhanced MRI of heart with particular focus on the hypothesis that Mn2+ uptake can be interpreted in terms of heart function. Copyright © 2004 John Wiley & Sons, Ltd.
Isolation and chemical nature of the receptor for d‐tubocurarine in nerve‐ending membranes of the cerebral cortex
Authors: De Robertis E. , Fiszer Sara , Pasquini Juana M. , Soto E. F.
Published: January 2005

The binding capacity of isolated acetylcholinesterase‐rich nerve‐ending membranes of the cat cerebral cortex for dimethyl‐14C‐d‐tubocurarine (1.5 × 10−6 M) was studied with an in vitro technique. After treatment of the membranes with organic solvents, most of the radioactivity was found in the extract and bound either to the lipids or proteolipids, but not to the gangliosides.

Comparing the binding capacity per milligram of proteolipid protein of the M1 1.0 nerve‐ending fraction with that of myelin, there was a tenfold increase in specific activity in the former. This layer cromatography of a lipid extract, previously passed through Sephadex G 25 fine, showed that the radioactivity remained at the point of origin together with the proteolipids. The use of a special technique with Sephadex LH20 demonstrated that the bound dimethyl‐14C‐d‐tubocurarine was eluted together with a protein peak which had no cholesterol and negligible amounts of phospholipids.

Experiments using precipitation with ether of the proteolipid protein and passage through the Sephadex LH20 column gave similar results and confirmed that the receptor properties for d‐tubocurarine may be in a special type of proteolipid present in the nerve‐ending membrane, probably at the junctional complex. These results are discussed in relation to previous attempts, reported in the literature, to isolate a cholinergic receptor.
Relationship between catecholamines and serotonin in sympathetic nerves of the rat pineal gland
Authors: Zweig Mark , Axelrod Julius
Published: January 2005

Sympathetic nerves of the pineal gland contain both serotonin and norepinephrine. Inhibition of norepinephrine synthesis with a tyrosine hydroxylase inhibitor, α‐methyl‐p‐tyrosine (αMPT), causes an elevation of pineal serotonin. The administration of dopamine or norepinephrine blocks the elevation of pineal serotonin by αMPT. When sympathetic nerves to the pineal are interrupted αMPT no longer causes a rise in pineal serotonin. Tryptophan causes a marked increase in pineal serotonin; αMPT enhances and norepinephrine blocks this rise.
Acetoxycycloheximide effect on synthesis and metabolism of glucosamine‐containing macromolecules in brain and in nerve endings
Authors: Barondes Samuel H. , Dutton Gary R.
Published: January 2005

Carbohydrate‐containing macromolecules of brain were substantially labeled after intracerebral injection of C14‐glucosamine. The “half‐life” of the labeled macromolecules, as measured in these experiments, was about one week. Acetoxycycloheximide inhibited incorporation of C14‐glucosamine into these substances. This appears to be secondary to inhibition of synthesis of polypeptide chains which act as “acceptors” for carbohydrate residues. Acetoxycycloheximide inhibited incorporation of C14‐glucosamine (and its derivatives) into the soluble carbohydrate‐containing macromolecules of nerve endings far less than that of the other subcellular fractions of brain. This suggests that the polypeptide “acceptors” of carbohydrate residues at nerve endings are not synthesized locally but are transported to the nerve endings. Final incorporation of carbohydrates into carbohydrate‐containing macromolecules occurs at nerve endings. The “turnover” of these substances in nerve endings was found to be relatively rapid. Evidence suggesting reversible incorporation and removal of some carbohydrate residues of carbohydrate‐containing macromolecules of brain was found and the possible regulatory role of this process is considered.
Nerve electrical activity; depression by puromycin not related to inhibited protein synthesis
Authors: Dahl Nancy Ann
Published: January 2005

Puromycin (1 mM) causes a reversible decrease in spike potential and positive after potential amplitudes of rabbit vagus nerve in vitro. This failure is independent of the rate of stimulation in contrast to the failure following sodium pump inhibition by ouabain. Puromycin does not inhibit brain Na‐K ATPase in vitro. There is no reduction in the action potential by either of the protein synthesis inhibitors, chloramphenicol or cycloheximide. Puromycin inhibits even in the presence of cycloheximide, a compound which blocks the release of abnormal polypeptides by puromycin. Puromycin aminonucleoside does not have the puromycin effect nor does dibutyryl‐cyclic‐3′,5′‐AMP protect the nerve against puromycin.

Puromycin can inhibit ribosomal protein synthesis and interfere with purine metabolism but these actions do not appear to be the basis of the action potential decrease. A more likely site of action is interference with glycolipid and glycoprotein formation or a direct effect on the membrane. It is concluded that neither mitochondrial nor ribosomal protein synthesis is critical to the short term maintenance of the action potential.
Neuroplasmic transport in the nervous system of the cockroach Periplaneta americana
Authors: Smith Barry H.
Published: January 2005

Neuroplasmic transport phenomena were studied in the nervous system of the cockroach, Periplaneta americana. For proteins, at least two major rates of movement can be resolved by liquid scintillation counting of incorporated C14‐labelled amino acids in serial slices of nerve cord. The slower of the two rates is 1−2 mm/day and appears identical to the “slow” flow well documented for vertebrate neurons. Evidence for an even faster movement is presented.

The suitability of the cockroach nerve cord as a model system for the study of the mechanism and control of the movement of the neuroplasmic constituents is discussed.