bluuebunny/crossref_metadata_2025 huggingface dataset:
Soleus‐specific myopathy induced by passive stretching under local tetanus
Authors: Mizuno Yoshihiko , Chou Samuel M.
Published: January 2005

Twenty‐four adult albino rats were injected with tetanus toxin into the right gastrocnemius muscle and then subjected to sustained dorsiflexion of the right ankle joint for 2 to 14 days. Histologic examinations of the soleus after this procedure showed myopathic changes, characterized by variations in fiber diameters, myonecrosis with opaque fibers, interstitial fibrosis, and small groups of regenerated fibers. Electron microscopy revealed derangement of T‐tubules immediately adjacent to the sarcolemma in the early degenerative stage. The size and wet weight of soleus increased compared to that of the control side between 2 and 5 days post‐tetanus. Serum GOT, LDH, and creatine kinase (CK) levels were elevated especially in the early degenerative stages. Peri‐ and endomysial fibrosis developed gradually from about 3 days post‐tetanus. Pathomechanisms inducing these changes were discussed.
Central changes in hypothyroid myopathy: A case report
Authors: Evans Rebecca M. , Watanabe Itaru , Singer Philip A.
Published: January 2005

A muscle biopsy from a patient with hypothyroid myopathy showed striking central changes. “Cores” were seen in most type 1 fibers with oxidative enzyme prepartions. Electron microscopy of these areas revealed Z disc streaming, myofilament disruption, and absent mitochondria. The myopathy rapidly improved with thyroxine treatment. This biopsy is of interest, as numerous “cores” have not previously been reported in hypothyroid myopathy.
Time course of sprouting during muscle reinnervation in vitamin E‐deficient rats
Authors: Cuppini Riccardo , Cecchini Tiziana , Cuppini Carla , Ciaroni Sandra , Del Grande Paolo
Published: January 2005

A typical aspect of motoneuron plasticity is the sprouting which occurs during muscle reinnervation, resulting in a transitory multiple innervation of the muscle cells. In order to verify the effect of a decreased protection from free radical attack on the sprouting, the multiple innervation in the extensor digitorum longus muscle, following sciatic nerve crush and regeneration, was studied in vitamin E‐deficient rats. Thus, the innervated end‐plates and the end‐plates with multiple innervation were studied with histochemical and electrophysiological techniques. The percentage of innervated end‐plates was similar in both groups at 30 as well as at 60 days after nerve crush. Nevertheless, multiple innervation was found in a larger part of the muscle and it lasted longer in the deficient rats. This finding is discussed in relation to some of the major hypotheses of sprouting; it may be relevant in the treatment of some lesions of peripheral nerve.
Effects of low calcium and calcium antagonists on skeletal muscle staircase and fatigue
Authors: Williams Jay H.
Published: January 2005

The purpose of this investigation was to determine the effects of low extracellular calcium and calcium antagonists on skeletal muscle staircase and fatigue. Initial experiments revealed that, brief exposure (10 minutes) of single frog sartorius muscle to diltiazem, D‐600 (5 and 30 m̈M) and low calcium Ringer's solution (LCR, calcium replaced by magnesium and EGTA) had little effect on isometric twitches evoked every 30 seconds. However, when stimulated at 1 per second for 15 minutes, the calcium antagonists significantly decreased the magnitude and time course of the staircase, whereas LCR decreased only the time course. Each experimental condition significantly increased the rate of fatigue while diltiazem and D‐600 both increased the magnitude of fatigue. Following the stimulation period, caffeine (10 mM) elicited contractures from all muscles whereas high potassium (180 mM) elicited contractures from control muscles only. These results indicate that calcium channel antagonists depress the skeletal muscle staircase response. They also indicate that these compounds as well as LCR enhance the fatigue process. Extracellular calcium influx may therefore have some influence on skeletal muscle twitches during prolonged repetitive activity.
Polyglucosan body disease
Authors: Cafferty Maureen S. , Lovelace Robert E. , Hays Arthur P. , Servidel Serenella , Dimauro Salvatore , Rowland Lewis P.
Published: January 2005

Adult polyglucosan disease has been described in 15 cases. All had signs of peripheral neuropathy, upper motor neuron signs, and 12 of the 15 had sphincter problems. Dementia was prominent in 8 of 15 cases. We reported 2 cases that contained these clinical features. Electrophysiological studies showed axonal neuropathy. Somatosensory evoked potentials on the second patient were abnormal. Sural nerve biopsy showed clusters of polyglucosan bodies. Although the presence of polyglucosan bodies in biopsy is nonspecific, the number as well as the clinical features are necessary to make the diagnosis. Branching enzyme activity in muscle extracts of the muscles were normal. Hence, a specific enzyme abnormality is not yet known.
Synchronous positive and negative myoclonus due to pontine hemorrhage
Authors: Palmer Jeffrey B. , Tippett Donna C. , Wolf James S.
Published: January 2005

We report a case of synchronous positive and negative myoclonus following pontine hemorrhage. Constant synchronous jerking of the eyes, tongue, face, mandible, larynx, pharynx, and diaphragms persisted during sleep. Jerking of limb muscles occurred during volitional activities, but not at rest. Inability to sustain glottic adduction during phonation contributed to severe dysarthria. Electromyography (EMG) revealed positive myoclonus of the branchial musculature with synchronous negative myoclonus in a generalized distribution Treatment with trazodone reduced the ocular myoclonus but worsened the dysphagia. We suggest that a single neural rhythm generator may produce both positive and negative myoclonus.
Dystrophin expression in myotubes formed by the fusion of normal and dystrophic myoblasts
Authors: Huard Johnny , Labrecque Claude , Dansereau Guy , Robitaille Lynda , Tremblay Jacques P.
Published: January 2005

Mdx mouse dystrophy is characterized by the absence in the muscle cytoplasmic membrane of a high molecular weight protein called dystrophin. A possible avenue for treatment of muscular dystrophies is to inject normal myoblasts in a dystrophic muscle to form hybrid muscle fibers. Hybrid myotubes were formed in vitro by the fusion of normal rat and dystrophic mouse (mdx) myoblasts. Staining with Hoechst dye 33258 permitted the clear distinction of mouse and rat nuclei. Immunostaining demonstrated that dystrophin was present over the entire membrane of all hydrid myotubes even when nuclei ratio normal/dystrophic was low.
Intraoperative recordings of spinal somatosensory evoked potentials to tibial nerve and sural nerve stimulation
Authors: Pelosi Luciana , Caruso Giuseppe , Cracco Roger Q. , Cracco Joan B. , Balbi Piero
Published: January 2005

Somatosensory evoked potentials (SSEPs) to stimulation of the tibial nerve at the knee (TN‐K) and ankle (TN‐A), and the sural nerve at the ankle (SN‐A), were recorded from 3 or 4 spinal levels during surgery for scoliosis in 11 neurologically normal subjects. With stimulation of all 3 nerves, the propagation velocity along the spine was nonlinear: it was faster over cauda equina and midthoracic cord than over caudal spinal cord. Over the midthoracic cord, TN‐K SSEP propagation was faster than that of TN‐A and SN‐A SSEPs, whereas over the caudal spinal cord these values were similar on stimulation of all 3 nerves. These data suggest that fast conducting second order afferent fiber systems contribute to spinal cord SSEPs evoked by stimulating both mixed and cutaneous peripheral nerves.
Tocainide therapy in muscle cramps and spasms due to neuromuscular disease
Authors: Puniani Trilok S. , Bertorini Tulio E.
Published: January 2005

Significant improvement in symptoms of disabling cramps and muscle spasms was obtained in 9 patients with motor neuron diseases, tetany, and myotonic disorders who were treated with tocainide, a lidocaine analog. No significant side effects were observed except for light‐headedness and fatigue in 1 patient, who also showed slight prolongation of intraventricular conduction time. Tocainide is useful in treating disabling muscle spasms and cramps associated with conditions characterized by neuromuscular irritability. This effect is probably based on stabilization of the membrane potential at various levels (motor neurons, peripheral nerve, or muscle fiber membrane).
Invited review: Electrodiagnostic assessment and monitoring of motor unit changes in disease
Authors: Stålberg Erik
Published: January 2005

The motor unit characteristics change dynamically with disease. This is the basis for the use of neurophysiologic methods for diagnostic purposes and for long‐term monitoring. A great variety of nerve conduction and EMG parameters are available to study the motor unit. They reflect different aspects of motor unit function. Therefore, the electromyographer must choose his technique and optimal parameters depending on the situation, type of condition, whether the purpose is diagnosis or monitoring, and so on. In this presentation the relationship between EMG parameters and physiologic and morphologic counterparts in some pathologic conditions will be discussed.
Muscle regeneration following segmental necrosis in tenotomized muscle fibers
Authors: Baker James H. , Poindextor Christine E.
Published: January 2005

The aim of this study was to determine how the new myotendinous junctions were re‐established at the proximal and distal ends of the soleus muscle after tenotomy. Both proximal and distal tendons of the soleus muscle in mature female rats were severed. The animals were killed and the soleus muscles were removed and prepared for light and electron microscopic examination 1, 3, 5, 7, 14, 21, 28, and 42 days after the operation. It was found that segmental fiber destruction followed by removal by macrophages occurred at the ends of the soleus muscle fibers. This resulted in the liberation and myogenic activation of satellite cells. By 3 days after tenotomy the fusion of myoblasts to form myotubes could be seen. The myotubes developed within the original basal lamina and reattached to the surviving non‐necrotic segments and grew in both length and width so that by 6 weeks postoperation, normal myotendinous junctions had been reformed. This study is the first to show that re‐establishment of the myotendinous junction following tenotomy is accomplished by regeneration of the necrotic ends of the tenotomized fibers.
The natural history of minicore‐multicore myopathy
Authors: Penegyres Peter K. , Kakulas Byron A.
Published: January 2005

To determine the natural history of minicore‐multicore myopathy (MMM) we studied 5 patients who were found to have this disorder from 6 to 16 years ago. Four of these patients had improved muscle strength since their original assessment and one patient had deteriorated. There were no clinical electrophysiological or pathological features that distinguished this last patient from the others. We conclude, therefore, that most patients with MMM may be expected to improve as time passes but, for unknown reasons, a minority may deteriorate. This information should be helpful to clinicians in their prognostic advice to new patients.
Infantile Pompe's disease, lipid storage, and partial carnitine deficiency
Authors: Verity M. Anthony
Published: January 2005

A diagnosis of infantile Pompe's disease (glycogenosis type II) was made by muscle biopsy on a 6‐month‐old infant boy seen with hypotonia, weakness, and developmental regression. Histochemistry and electron microscopy revealed a vacuolar myopathy with massive glycoge accumulation associated with increased neutral lipid as demonstrated on Oil Red O reactions. Pleomorphic, hypertrophic mitochondria with distortion of cristae and electron‐dense deposits within the matrix were identified. Acid α−1,4‐glucosidase activity was absent but associated with increased neutral maltase activity and a variable compensatory rise in activity of other lysosomal enzymes. Biochemical studies demonstrated low free carnitine, normal acylcarnitine, increased activity of carnitine palmityl and acyl transferases, and other enzymes of β‐oxidation with the notable exception of low normal β‐hydroxyacyl‐CoA dehydrogenase activity. The explanation for the lipid accumulation is uncertain but is likely related to the combination of low carnitine concentration in muscle, low β‐hydroxyacyl CoA dehydrogenase, representing a rate limiting enzyme of β‐oxidation, and nonspecific defective mitochondrial function.
Real‐time sonography of acute and chronic muscle denervation
Authors: Gunreben Gerd , Bogdahn Ulrich
Published: January 2005

Presented are real‐time ultrasound findings in partially and completely denervated muscles of 30 patients with focal neurpathy and various other disorders of the second motor neuron. Sonographic scans of affected muscles are analyzed in conjunction with unaffected muscles of the same individual, under identical examination conditions. Initial pathological ultrasound changes could be detected as soon as 2 weeks after an acute neurogenic lesion. In denervation, the echodensity of the muscle was high and the normal intramuscular pattern was decomposed. Findings were more intense in severe and longstanding denervation. Ultrasoudn‐indicated pathology correlated highly (chi‐square: P < 0.001) with pathological sponteneous activity detected by electromyography. Focal and systemic neuropathies showed no differences in ultrasound pathology. Six cases with central motor palsy had normal sonograms. Poor spatial resolution of real‐time ultrasonography–as compared with CT and MRI–is compensated by its bedside availability, frequent repeatability without patient risk and discomfort, and its in vivo correlation of muscle morphology with muscle function.
Relationship between electrical and vibratory output of muscle during voluntary contraction and fatigue
Authors: Zwarts Machiel J. , Keidel Matthias
Published: January 2005

Measurements were done on the biceps muscles of 6 healthy volunteers to record simultaneously the surface electromyogram (EMG) and vibromyogram (VMG) by means of a piezoelectric device (accelerometer). The VMG is generated by mechanical waves due to the contraction mechanism and often measured as sound. The frequency spectrum and integrated value (IEMG and IVMG) of both signals were calculated. Both IEMG and IVMG showed a clear linear correlation with force, although at high forces, the variability of the VMG became rather high. Two series of experiments were performed to study the EMG and VMG changes in relation to changes induced by fatigue: (1) during constant force at 50% of the maximal voluntary contraction (MVC) and recovery; (2) for one 1 minute during declining force at MVC. The main finding was that the IVMG was related to the absolute force, irrespective of the fatigue state of the muscle. In contrast, the IEMG showed the well‐known changes during fatigue, such as an increase during endurance. The spectral changes of the two measurements also showed a divergence. The spectra of the EMG shifted to lower frequencies in both fatigue protocols. In contrast, the spectra of the vibratory signal did not shift, except for several measurements at MVC. However, the shape did change to a somewhat flatter spectrum with less pronounced peaks. Possible explanations for this different behavior are discussed. It is concluded that the vibratory energy generated by the contraction mechanism is linearly related to force. Changes induced by fatigue do not alter this relationship: this contrasts with the behavior of the EMG. The combination of these two measurements give supplemental information regarding the state of the working muscle.
Fatigue in type I fiber predominance: A muscle force and surface EMG study on the relative role of type I and type II muscle fibers
Authors: Linssen Wim H. J. P. , Stegeman Dick F. , Joosten Ed M. G. , Binkhorst Rob A. , Merks Mieke J. H. , Laak Henk J. Ter , Notermans Servaas L. H.
Published: January 2005

The relative proportions of fiber types within muscle and the characteristics of these fiber types are important determinants of the surface electromyogram (SEMG) during fatigue. In this study, patients suffering from congenital myopathy characterized by a strong type I fiber predominance were studied. Six patients with 95‐100% type I fibers, 2 patients with 80% type I fibers, and 12 healthy volunteers participated in an ischemic, isometric, intermittent exercise test of m. quadriceps femoris at 80% MVC. Considering the results of the morphometric analysis of muscle biopsy specimen and of the anthropometric estimated muscle‐bone volume, it was found that type I muscle fibers had a lower force generating capacity than type II fibers. The initial conduction velocity along the muscle fiber membrane (MFCV) was low in patients with 95‐100% type I fibers. During the ischemic exercise test, the 95‐100% type I fibers showed less fatigability than type II fibers, which was reflected by a nearby absent decrease of the muscle membrane excitability as measured by the MFCV, and only a slight increase of the SEMG amplitude compared with patients having 80% type I fibers and controls. The absence of a definite MFCV decrease was related to the nearby lacking lactate formation in 95‐100% type I fibers.
Progressive motor neuron disease associated with electrical injury
Authors: Sirdofsky Michael D. , Hawley Rollin J. , Manz Herbert
Published: January 2005

A patient in perfect health prior to electrical shock developed an ALS‐like syndrome after the shock. Onset of the disease occurred in the limb through which the shock entered, and subsequently followed a course well‐described in previous case reports. Possible mechanisms of disease are discussed.
Fibrillation and accelerated achr degradation in long‐term muscle organ culture
Authors: Wetzel Daniel M. , Salpeter Miriam M.
Published: January 2005

Evaluation of the precise molecular dynamics of endplate maintenance and reorganization has been limited by the lack of available in vitro preparations. We describe an organ culture preparation of mouse diaphragm muscle which permits long‐term maintenance of muscle viability. Spontaneous fibrillations, increased levels of extrajunctional acetylcholine receptors, accelerated rates of junctional acetylcholine receptor turnover and maintenance of fine structure of denervated mouse diaphragm muscle in organ culture was evaluated under different culture conditions. Of several standard tissue culture media tested with and without fetal calf serum, medium 199 plus fetal calf serum was best for maintaining this muscle for greater than 2 weeks. The serum component could be partially eliminated by addition of nonglucose energy substrates such as D‐b̃‐hydroxybutyric acid and L‐glutamine. This preparation will permit a more controlled examination of the molecular components of endplate diseases.
Clinical correlations of Anti‐Gm1 antibodies in amyotrophic lateral sclerosis and neuropathies
Authors: Lamb Nancy L. , Patten Bernard M.
Published: January 2005

Clinical correlations of antiganglioside GM1 antibodies are important because high titers of these antibodies may have therapeutic significance. To further evaluate this significance, we reviewed our experience with 78 patients who had the following diagnoses: amyotrophic lateral sclerosis (ALS), ALS syndromes in patients with gammopathy or thyroid abnormalities, cervical spondylosis simulating ALS, motor neuropathies, and chronic inflammatory demyelinating polyneuropathies (CIDP). Antiganglioside antibody titers were measured “blind” by ELISA assay at the neuromuscular clinical laboratory, Johns Hopkins School of Medicine. We conclude that anti‐GM1 antibodies are found in a wide variety of neuromuscular conditions. Patients with classical ALS had a mean anti‐GM1 antibody titer significantly lower than patients with CIDP or motor neuropathy. Patients with ALS associated with gammopathy or thyroid disorders had higher anti‐GM1 titers than seen in classical ALS. The highest mean titer occurred in patients with CIDP, a treatable neuropathy.
Role of electromyography in amyotrophic lateral sclerosis
Authors: Behnia Mehrdad , Kelly John J.
Published: January 2005

We reviewed the role of electrodiagnostic testing in amyotrophic lateral sclerosis (ALS) in a large ALS clinic. Over 31 months, 133 patients with a clinical diagnosis of ALS were tested. In most, nerve conduction studies were normal, and needle electrode examination showed active denervation in the upper and lower limbs or the limbs and bulbar muscles (Lambert's criteria). However, 50 of 133 patients did not fulfill Lambert's criteria at presentation because of abnormal nerve conduction studies (11 patients), abnormal F‐wave latencies (6 patients), or insufficiently distributed fibrillation potentials (40 patients). This study reveals that a large proportion of patients with a clinical diagnosis of ALS fail to have classical findings on initial electrodiagnostic studies, and reveals several caveats of electrodiagnostic testing in these patients: (1) Conduction studies may be unreliable in motor nerves with markedly low compound muscle action potential (CMAP) amplitudes. (2) Sensory nerve action potential (SNAP) amplitudes may be abnormal in a small percentage of otherwise typical ALS patients. However, better controls for elderly subjects are needed. (3) Needle electrode examination may not show widespread active denervation early in the disease. (4) Some patients may have a mild polyneuropathy. (5) The classic diagnostic criteria may need to be modified to allow earlier acceptance of many ALS patients into therapeutic trials.
Enzyme and size profiles in chronically inactive cat soleus muscle fibers
Authors: Graham Scot C. , Roy Roland R. , Navarro Christine , Jiang Bian , Pierotti David , Bodine‐Fowler Sue , Reggie Edgerton V.
Published: January 2005

Spinal isolation (SI), i.e., the isolation of the lumbar spinal cord via a rostral and a caudal cord transection and bilateral dorsal rhizotomy, was used to determine the effects of chronic (6 months) inactivity on the size and metabolic properties of fibers in the cat soleus. Fibers were classified as dark or light, based on their staining reactions to myosin ATPase, alkaline preincubation, and immunohistochemically as expressing fast and/or slow myosin heavy chains (MHC). Succinate dehydrogenase (SDH) and α‐glycerophosphate dehydrogenase (GPD) activities were assessed histochemically. Following SI, both the light and the dark ATPase fibers in the SI cats were significantly smaller than the light ATPase fibers in the controls. Normally 100% of the fibers were light ATPase and reacted exclusively with the slow antibody. After SI, ∼45% of the fibers were dark ATPase fibers, many reacting with both fast and slow MHC antibodies. The total amount and concentration of GPD were higher in the light and dark ATPase fibers in SI compared with light ATPase fibers in controls. In contrast, although the total amount of SDH per fiber was decreased, reflecting the decrease in fiber size, the mean SDH concentration per fiber was unchanged following SI. These data indicate that there is a close coordination in the regulation of GPD activity and the type of myosin. SDH activity, on the other hand, appears to be resistant to decreased levels of activity and unloading, i.e., there seems to be a minimum level of oxidative potential in the soleus that is independent of activity level. Fiber sizes, however, are very sensitive to less‐than‐normal amounts of neuromuscular activity and/or loading.
Failure to detect HTLV‐I by in situ hybridization in the biopsied muscles of viral carriers with polymyositis
Authors: Higuchi Itsuro , Nerenberg Michael , Yoshimine Kosei , Yoshida Mitsuaki , Fukunaga Hidetoshi , Tajima Kazuo , Osame Mitsuhiro
Published: January 2005

Direct infection of muscle fibers by human T‐lymphotropic virus type I (HTLV‐I) has recently been reported in a patient with polymyositis infected with both HTLV‐I and human immunodeficiency virus (HIV). Coinfections of these viruses are frequently found in the United States. In Kagoshima, Japan, patients with polymyositis have a significantly increased incidence of seropositivity to HTLV‐I alone, when compared with the general population of Kagoshima. In this study, we examined muscle tissue from 6 HTLV‐I‐positive patients with polymyositis from Kagoshima. To detect HTLV‐I products, sensitive immunohistochemistry and in situ hybridization analysis were performed. These were compared with muscle fibers from a well‐characterized transgenic mouse model which expressed HTLV‐I tax. 10 No specific signals were detected in the biopsied muscles of patients with polymyositis infected with HTLV‐I alone. HIV co‐infection may, therefore, augment HTLV‐I expression through either immunosuppression or direct viral interactions.
Influence of peripheral afferents on cortical and spinal motoneuron excitability
Authors: Komori Tetsuo , Watson Bradley V. , Brown William F.
Published: January 2005

The objective of this study was to establish to what extent muscle, cutaneous, and joint afferents alter the excitability of spinal and cortical motor neurons. This question was examined by studying the impact of electrical stimulation of the second and third digits, the median nerve at the wrist, and the recurrent thenar motor branch on the F/H and magneto‐electrical cortical motor responses (MEPs) of the thenar muscles. The firing frequencies of single F/H motor unit action potentials were unaltered by the foregoing conditioning peripheral stimuli. MEPs conditioned by motor threshold stimulation of the median nerve at the wrist or the recurrent motor branch were significantly increased in size at conditioning to test intervals of 50 to 80 milliseconds. No significant change in MEP size resulted from conditioning stimulation of the digital nerves. We conclude that muscle afferents were primarily responsible for the increase in MEP size. Conditioning stimuli may allow examiners to assess central motor conduction where it would otherwise be impossible.
Absence of malignant hyperthermia contractures in Becker‐Duchenne dystrophy at age 2
Authors: Gronert Gerald A. , Fowler William , Cardinet George H. , Grix Arthur , Ellis William G. , Schwartz Marshall Z.
Published: January 2005

Two 2‐year‐old males underwent muscle biopsy that established the histopathologic diagnosis of Becker dystrophy in one, and Duchenne dystrophy in the other. Concomitant contracture testing with caffeine or halothane was normal for malignant hyperthermia (MH). The results suggest that acute hypermetabolism or acute rhabdomyolysis during anesthesia, in patients with these disorders, is related to the X‐linked myopathy and its associated muscle deterioration, rather than to the autosomal dominant MH.
Deficiency of acetylcholine receptors in a case of end‐plate acetylcholinesterase deficiency: A histochemical investigation
Authors: Jennekens Frans G. I. , Hesselmans Laura F. G. M. , Veldman Henk , Jansen Ernst N. H. , Spaans Frank , Molenaar Peter C.
Published: January 2005

A young boy is described who, since early infancy, suffered from weakness of predominantly proximal limb muscles. Electromyography revealed impairment of neuromuscular transmission. There were no antibodies against acetylcholine receptors. The amplitude of miniature end‐plate potentials was reduced. Neuromuscular junctions showed somewhat coarse postsynaptic junctional folds and degeneration products in the synaptic clefts and in postsynaptic areas. Using qualitative and semiquantitative histochemical methods, at light‐ and electronmicroscopical levels, acetylcholinesterase (AChE) activity and acetylcholine receptors (AChRs) were demonstrated to be deficient. This patient demonstrates that the clinical picture of congenital myasthenia may closely resemble a congenital myopathy. The findings provide evidence that AChR deficiency offers protection from some of the effects of AChE deficiency. The clinical features of AChE deficiency depend, not only on the level of residual enzyme activity, but also on the degree of AChR reduction, if present.
Effect of low Ca2+ solution on muscle contraction of developing, preclinical dystrophic (DY2J) mice
Authors: Dangain Josette , Neering Ian R.
Published: January 2005

EDL muscles from normal and dystrophic (dy2j) mice aged 7 to 21 days of postnatal life were examined. Muscles were divided into 2 groups according to age, 7 to 14 days and 16 to 21 days postnatal, so as to assess age‐ and/or phenotype‐related differences in the muscle response to low Ca2+ solution. Tension production was already much impaired in “predystrophic” muscles. At this stage, however, there was essentially no difference in twitch kinetics between normal and dystrophic muscles. Upon exposure to low Ca2+ solution, twitch responses of both normal and dystrophic muscles declined in a similar manner. In the youngest animals studied (7 to 14 days), the tetanic responses of both normal and dystrophic muscles to low Ca2+ solution were also similar. In animals 15 to 21 days old, however, the tetanic tension developed in low Ca2+ solution by dystrophic muscles, was significantly less than that of normal. Moreover, under these conditions (i.e., in low Ca2+ solution), and following tetanic stimulation, the membrane potential of dystrophic muscles in this age group was significantly more depolarized than that of normal muscles. Our results suggest that the ability of the cell to deal with extracellular Ca2+ is normal in predystrophic muscles up to 21 days of postnatal life. The results also clearly point to the fragility of the membrane in these muscles.
Case‐of‐the‐month: Autosomal recessive myotonia congenita: Marked muscle weakness in a 16‐year‐old boy
Authors: Miller Robert G. , Buchthal Fritz
Published: January 2005

A 16‐year‐old boy had a 10‐year history of stiffness in leg muscles. There was marked weakness of neck flexors, shoulder abductors, and ankle dorsiflexors, with hypertrophy of most muscle groups and both action and percussion myotonia. The parents were normal. Motor unit potential mean duration was reduced in the weakest muscle (tibialis anterior), and a biopsy of the same muscle showed only minimal abnormalities. Exercise and repetitive stimulation (30 Hz) of the tibialis anterior disclosed a decline in the compound muscle action potential that appeared to correlate with the muscular weakness.
Myasthenogenicity of a human acetylcholine receptor α‐subunit peptide: Morphology and immunology
Authors: Matsuo Hidenori , Tsujihata Mitsuhiro , Satoh Akira , Takeo Gou , Yoshimura Toshiro , Nagataki Shigenobu
Published: January 2005

Each of 10 rats inoculated with a synthetic peptide comprising residues 125–147 (without a disulfide bond) of human acetylcholine receptor (AChR) α‐subunit (Hα) had deposits of IgG and C3 (immune complexes) and showed morphological changes in the fine structure at the motor end‐plates 5 weeks after a single immunization. Antibody to the Hα peptides was elevated 1 week after immunization, but, antibody levels to solubilized human or rat AChR were very low in 8 of the 10 rats. These results suggest that the immune response to peptide Hα is the myasthenogenic site, which induces morphological change at the end‐plates.
Proximal median neuropathies: Electromyographic and clinical correlation
Authors: Gross Paul T. , Jones H. Royden
Published: January 2005

Results of electrophysiologic and clinical findings in 17 patients with proximal median neuropathy were reviewed. The cause of neuropathy was trauma in 5 patients, overuse of the pronator teres in 3 patients, postinfectious in 2 patients, secondary to a congenital lesion in 1 patient, and undetermined in 6 patients. The neuropathy involved the main branch of the median nerve at or proximal to the pronator teres muscle (high median neuropathy) in 14 patients, and the anterior interosseous portion of the nerve in 3 patients. Electrophysiologic findings, especially needle electromyography (EMG), were more definitive than findings expected from clinical examinations. EMG and operative findings demonstrated that median nerve compression by the pronator teres produces denervation of this muscle as well as distal muscles. EMG cannot differentiate a median nerve lesion at the pronator teres from a more proximal lesion. Follow‐up data were available in 7 of 10 nonsurgically managed patients, and in 6 of 7 patients with surgical decompression. Six patients in each group were either improved or normal.
Single fiber EMG in the frontalis muscle in ocular myasthenia: Specificity and sensitivity
Authors: Rouseev R. , Ashby P. , Basinski A. , Sharpe J. A.
Published: January 2005

Patients (n = 41) with isolated weakness of the eyelids or extraocular muscles, who had been referred for single fiber electromyography (SFEMG), were followed up after 4 to 24 months, At follow‐up the patients were classified as “definite ocular myasthenia gravis” (MG), “definite other diagnosis,” or “no definite diagnosis” on the basis of the completed investigations and subsequent course. The original SFEMG findings in the frontalis muscle were then reviewed. The specificity and sensitivity of SFEMG for “definite ocular MG” could be maximized by using as criteria for abnormality >8/20 pairs with jitter >45 μs, or a mean jitter of 20 pairs of >50 μs. Patients with abnormal SFEMG according to these criteria have MG, and are likely to require treatment in the immediate future. Patients who have normal SFEMG according to these criteria (and no other demonstrated disorder) may have MG, but it is so mild that they are unlikely to require treatment. Two patients whose final diagnosis was progressive external ophthalmoplegia had normal SFEMG according to these criteria.
Neuromuscular function and polymorphism of the acetylcholine receptor gamma gene
Authors: Degli‐Esposti Mariapia A. , Dallas Peter B. , Dawkins Roger L.
Published: January 2005

Examination of inbred and wild mice has shown that the gene coding for the acetylcholine receptor gamma subunit is polymorphic and the polymorphism correlates with differences in neuromuscular function tested by two different methods. Polymorphism of the AChR γ gene was demonstrated after digestion of genomic DNA with Pstl and Xbal. These two restriction enzymes demonstrated RFLP patterns specific for C57Bl/6J (PsXs) and C3H/HeJ (PRXR) mice, respectively. Examination of F1 (C3H/HeJ × C57Bl/6J) and F2 hybrid populations, and other murine inbred strains, showed the inheritance and strain specificity of the RFLPs. Testing wild mice demonstrated that the PSXS form of the AChR γ gene is the most common in the wild. The AChR γ and AChR δ subunits are closely linked and carried on the same chromosome as several contractile proteins. Because these genes are essential for correct neuromuscular development and activity, we investigated the possibility that the observed AChR γ polymorphisms mark a haplotype which correlates with variations in neuromuscular function. Analysis of exercise times showed a correlation between AChR γ polymorphism and neuromuscular function. To our knowledge, this is the first description of AChR polymorphism cosegregating with variations in neuromuscular function.
Sural nerve biopsies in Guillain‐Barre syndrome: Axonal degeneration and macrophage‐associated demyelination and absence of cytomegalovirus genome
Authors: Hughes Richard , Atkinson Penny , Coates Philip , Hall Susan , Leibowitz Sidney
Published: January 2005

T‐cell infiltration was detected by immunohistochemistry in only 2 of 10 sural nerve biopsies from patients with Guillain–Barré syndrome (GBS). The number of endoneurial macrophages, identified by the monoclonal antibody MAC 387, was increased, compared with the number in 10 cases of axonal neuropathy. Macrophage‐associated demyelination was identified in 7 and axonal degeneration in 8 cases. Cytomegalovirus (CMV) genome was not detected with the polymerase chain reaction.
Lead uptake in motor axons
Authors: Pamphlett Roger , Bayliss Alexandra
Published: January 2005

In an attempt to determine wheather lead (Pb) in striated muscle can be taken up by motor axon, mice were injected intramuscularly with a 5% nitrate solution, and the passage of Pb through the tissues was traced with electron mocroscopy. Thirty minutes after injection in the tibialis anterior muscle, Pb was seen at the sarcolemma and axolemma of the neuromuscular junction (NMJ) and in the adjacent sarcoplasmic reticulum (SR). Pb was also present in the axoplasm and mitochondria of terminal and preterminal motor axons. The presence of Pb was confirmed with x‐ray elemental microanalysis. The results indicate that there is a pathway for intramuscular Pb to enter terminal motor axons. This supports the hypothesis that some forms of motor neuron disease (MND) may be due to axonal uptake and retrograde transport of Pb.
Motor‐evoked responses in primary lateral sclerosis
Authors: Brown W. F. , Ebers G. C. , Hudson A. J. , Pringle C. E. , Veitch J.
Published: January 2005

Primary lateral sclerosis (PLS) may be distinguished on the basis of clinical and pathological features from amyotrophic lateral sclerosis (ALS). The former is featured by a much longer clinical course, exclusively upper motor neuron findings, losses of precentral pyramidal neurons, and preservation of anterior horn cells. Electrophsiological studies of 7 PLS cases have shown normal peripheral motor conduction, absent or very delayed motor‐evoked poteintials, the occasional late development of denervation activity in distal muscles, and normal somatosensory‐evoked potentials.
Major growth reduction and minor decrease in mitochondrial enzyme activity in cultured human muscle cells after exposure to zidovudine
Authors: Herzberg Nicole H. , Zorn Ina , Zwart Rob , Portegies Peter , Bolhuis Pieter A.
Published: January 2005

Zidovudine‐induced mitochondrial myopathy in AIDS patients reported recently might be due to inhibition of mitochondrial DNA polymerase γ. We investigated the effect of zidovudine on proliferation, differentiation, activity of mitochondrial‐ and nuclear‐encoded enzymes, and mitochondrial DNA (mtDNA), in cultured human muscle cells. Marked inhibition of cell proliferation was found, even in the presence of low (10 μmol/L) zidovudine concentrations. Enzyme activity of the nuclear‐encoded mitochondrial citrate synthase was not affected, and the partially mitochondrial‐encoded cytochrome c oxidase was not decreased, except only after exposure to high concentrations (5 mmol/L) zidovudine. No decrease of mtDNA content and no mtDNA deletions were found in zidovudine‐exposed muscle cells. We propose that the effect of zidovudine on muscle, seen in zidovudine‐treated AIDS patients, results mainly from decrease in proliferation of muscle cells rather than inhibition of mtDNA replication.
AAEM case report #24: Electrodiagnosis in posttraumatic syringomyelia
Authors: Little James W. , Robinson Lawrence R.
Published: January 2005

An adult male with C‐7 quadriplegia developed neck pain. Axillary F central latencies were prolonged, and MRI showed a syrinx extending to C‐1. After shunting, F latencies normalized. At subsequent follow‐up, a rostral syrinx persisted by magnetic resonance imaging (MRI); motor evoked potential (MEP) latencies were prolonged but F latencies were normal. Later, the syrinx was less distended by MRI, MEPs normalized, and strength improved. We discuss the electrophysiologic methods available for diagnosing and monitoring posttraumatic syringomyelia. © 1992 John Wiley & Sons, Inc.
Insulin increases amino acid transport into rat soleus motor axons
Authors: Pickett Jackson B.
Published: January 2005

Hyperosmotic neurosecrtion was used to measure basal and insulin‐stimulated amino acid and myoinosital transport into rat motor nerve terminals. L‐Alanine and α(methylamino)‐isobutyric acid (a nonmetabolizable system A‐specific analog) transport was rapid into motor nerve terminals innervating a fast‐twitch muscle, the extensor digitorum longus, and slow into motor nerve terminals innervating the soleus, a slow‐twitch muscle. A physiological concentration of insulin, 10 μU/mL, increased L‐alanine and α(methylamino)‐isobutyric acid transport into motor nerve terminals in the soleus. Large doses of insulin, 100 or 1000 μU/mL, had no effect on L‐alanine or α(methylamino)‐isobutyric acid transport into nerve terminals in the extensor digitorum longus. There was negligible basal or insulin‐stimulated transport of D‐alanine or myoinsitol into nerve terminals of the soleus or extensor digitorum longus. These studies show that insulin regulates sterospecific amino acid transport into extensor digitorum longus motor axons. Differences in basal and insulin‐stimulated tranpsort suggest that motor axons differ in their metabolism, and might be selectively vulnerable to disease processes.
Muscle fiber conduction velocity and mean power spectrum frequency in neuromuscular disorders and in fatigue
Authors: Yaar Israel , Niles Les
Published: January 2005

This study investigated the relation of muscle fiber conduction velocity (MFCV) to difference power spectrum mean frequency (MF), their fatigue trends, and differences between their values and their fatigue trends in various neuromuscular disorders. Electromyographic interference pattern was recorded inside the biceps in continuous isometric maximal voluntary contractions. Each subject was encouraged to pull for as long as possible. Fatigue was calculated as percent of time to complete inability to sustain contraction. The MFCV was computed by cross‐correlation. The MF was computed by differencing, windowing, FFT, squaring of coefficient, and repeat averaging. There were 33 healthy, 86 polyneuropathic, 28 myasthenic, 13 myotonic, and 32 myopathic patients. Both MFCV and MF changed significantly with fatigue–the MFCV linearly, while the MF in a markedly nonlinear fashion. Both were found to be insensitive to the end stages of muscle fatigue–the MFCV did not change its slope toward complete fatigue, and the MF did not change at all beyond the 40% fatigue point. A statistically sound fatigue regression equation was derived for each, and a nonlinear equation was found to best describe their relationship. Neither MFCV nor its fatigue changes were found to be significantly different across the neuromuscular disorders. The MF, however, was found to be significantly different in some neuromuscular disorders in both its average values and fatigue trends. This study showed, in contrast to the literature, a nonlinear relationship between MFCV and MF. It also shows that neither the MFCV nor the MF had reasonable diagnostic power on its own; however, the MF was very promising to serve as an adjunct to other variables.
Familial amyloid polyneuropathy related to transthyretin Gly42 in a Japanese family
Authors: Uemichi Tomoyuki , Ueno Satoshi , Fujimura Harutoshi , Umekage Tadashi , Yorifuji Shiro , Matsuzawa Yuji , Tarui Seiichiro
Published: January 2005

A Japanese family is described in which 6 persons showed familial amyloid polyneuropathy (FAP). Mean ages of onset were 38 for 4 males and 54 for 2 females. Three of the 6 became emaciated and died after 4 to 10 years. In 5, muscular weakness and autonomic dysfunction were the initial symptoms followed by sensory disturbances. Amyloidotic cardiomyopathy was present in 3 of the subjects. Amyloid deposits showed an immunohistological relation to transthyretin (TTR). Analysis of 1 patient's TTR gene revealed a single base change (A→G) that led to amino acid substitution (Glu42→Gly). This base change produced a new restriction site for endonuclease Cfr13 l in exon 2. Polymorphic analysis of the length of the Cfr13 l‐restriction fragment confirmed the base change, and made it possible to detect the mutant TTR Gly42 gene in the FAP subjects. Amino acid sequencing analysis showed a variant of TTR Gly42 in 1 patient's serum. © 1992 John Wiley & Sons, Inc.
Satellite cells in innervated and denervated muscles treated with clenbuterol
Authors: Maltin Charlotte A. , Delday Margaret I.
Published: January 2005

The sympathomimetic agent, clenbuterol, induces a muscle‐specific hypertrophy in both normal and catabolic muscle. Drug‐induced hypertrophy is not generally associated with an increase in DNA content, thus the role of satellite cells in the response of soleus muscles from weanling rats is questioned. Following simultaneous sciatic section and administration of clenbuterol, responses are similar in innervated and denervated muscles after 4 days. Increased protein accretion in treated muscles is associated with evidence of satellite cell activation, but with little evidence of division. It is speculated that satellite cell production of growth factors may play an important role in the hypertrophic action of clenbuterol, and the clinical implications of the findings are discussed. © 1992 John Wiley & Sons, Inc.
Autonomic surface potential analysis: Assessment of reproducibility and sensitivity
Authors: Hoeldtke Robert D. , Davis Karen M. , Hshieh Paul B. , Gaspar Stephen R. , Dworkin Gerald E.
Published: January 2005

There has been recent interest in measuring sympathetic sudomotor function by autonomic surface potential analysis. The purpose of the present study was to assess factors affecting the reproducibility of the test. We determined the within‐day and between‐day reproducibility in 24 healthy vclunteers. We used an increasing rather than a constant electrical stimulus to minimize habituation. The amplitudes were still highly variable (an average within‐day coefficient of variation in the soles of 35%). Habituation did not, however, affect the latencies of the responses, which were much more reproducible (an average within‐day coefficient of variation in the soles of 8%). Studies of between‐day reproducibility revealed that the mean amplitudes were lower on day 2 vs. day 1 (0.706 ± 0.10 vs. 0.85 ± 0.10 mV in the soles, P < 0.01) but the mean latencies were similar on the different testing days (2.09 ±.04 seconds for the soles on day 1 vs. 2.16 ±.05 seconds on day 2). We also assessed the sensitivity of surface potential analysis and report the results of testing 35 patients with far advanced autonomic neuropathy. © 1992 John Wiley & Sons, Inc.
SEPs and CNS magnetic stimulation in syringomyelia
Authors: Nogués Martin A. , Pardal Ana María , Merello Marcelo , Miguel Miguel A.
Published: January 2005

Somatosensory evoked potentials (SEPs) and motor evoked potentials (MEPs) to transcranial and spinal stimulation from upper and lower limb muscles were elicited in 13 patients with syringomyelia. Seven had an associated Chiari type I anomaly. Diagnosis was confirmed by MRI. In 5 cases, SEPs and MEPs were performed before and after surgical treatment. Prolonged central motor conduction times or absent motor responses in upper or lower limbs were found in most patients. The greatest number of abnormalities was disclosed by measurement of CMCT followed by SEPs after tibial nerve stimulation. Two of 5 cases undergoing surgery improved clinically and showed reduction in CMCT after surgical treatment. Our study shows that MEPs were useful in the evaluation of neurophysiological status in syringomyelia patients, helping to estimate anterolateral spinal cord function.