bluuebunny/crossref_metadata_2025_split huggingface dataset:
Single‐fiber electromyography in experimental autoimmune myasthenia gravis
Authors: Verschuuren Jan J. G. M. , Spaans Frank , De Baets Marc H. 
Published: January 2005

AbstractThe sensitivity of stimulated single‐fiber electromyography in the detection of early abnormalities in neuromuscular transmission in experimental autoimmune myasthenia gravis (EAMG) was tested. Increased jitter and blocking were seen up to 3 weeks before clinical illness or decrement developed. Stimulation at 10 Hz appeared more sensitive in detection of abnormalities than stimulation at 3 or 5 Hz. Jitter values did not correlate with anti‐Torpedo acetylcholine receptor (AChR), nor with anti‐rat AChR antibody titer. No correlation was found between jitter and AChR loss or AChR‐antibody complexes in muscle. It is concluded that, in addition to AChR loss and the presence of AChR‐Antibody complexes, other factors must determine the neuromuscular dysfunction in EAMG and possibly myasthenia gravis.
Motor reflex responses elicited by cutaneous stimulation in the regenerating nerve of man: Axon reflex or ephaptic response?
Authors: Montserrat Luis , Benito Manuel 
Published: January 2005

AbstractIn 57 of 60 nerves (29 median and 31 ulnar) sutured at the wrist, forearm and arm, we recorded motor responses in thenar or hypothenar muscles by electrical stimulation of the corresponding fingers. Recordings were made at different times during the process of regeneration, ranging from 3 months up to 11 years. The responses showed a constant shape and latency to every stimulation (simple or repetitive). The latency was shorter the more distal the level of injury and the greater the elapsed time from the reinnervation. The point of „reflexion”︁ of the responses is at or very near the line of nerve suture. The electrophysiological behavior of the responses fits well with either the criterion of axon reflex or ephaptic response. We discuss both possibilities and conclude that it is not possible, with the electrophysiological technique that we used, to distinguish between an axon reflex and an ephaptic response.
Amyotrophic lateral sclerosis: Macro–EMG and twitch forces of single motor units
Authors: Dengler Reinhard , Konstanzer Annette , Küther Gerald , Hesse Stefan , Wolf Werner , Strupplerdr Albrecht 
Published: January 2005

AbstractMacro–EMG potentials (MEP)s and twitch contractions (spike–triggered–averaging) of single motor units (MUs) have been recorded in the first dorsal interosseus muscle (FDI) of 10 control subjects and 20 patients with amyotrophic lateral sclerosis (ALS). MUs over the full range of voluntary recruitment thresholds were studied. Patients with slightly affected FDIs (5) mainly showed MUs with enlarged MEPs and increased twitch forces. Incontrast, the patients with more severely affected FDIs (15) revealed decreased twitch forces, especially in the MUs with higher thresholds. The corresponding MEPs could be enlarged as well as normal. It apperas that MU sprouting and the resulting increase of twitch force can compensate for the loss of motoneuron in early stages of ALS. In more advanced stages, however, a decline of the force of the surviving MUs, especialy of those with higher thresholds, seems to contribute to the progressive muscle weakness, in addition to the corticospinal degeneration and the reduction in the number of motoneurons.
Increased muscular β‐hydroxyacyl CoA dehydrogenase with McArdle's disease
Authors: Turk William R. , Heller Scott L. , Norris Beverly J. , Nemeth Patti M. 
Published: January 2005

AbstractEnzymes of energy production were measured in muscle homogenates and in individual muscle fibers from 5 patients with McArdle's disease. Individual fibers were investigated to determine whether fibers of all types were completely devoid of glycogen phosphorylase activity and whether the involved fibers might be biochemically altered in a fiber type dependent manner to enhance the energy‐generating capabilities of the cells through other metabolic pathways. Using highly sensitive biochemical assays, a complete absence of glycogen phosphorylase, a and b, activity was found in fibers of all types in the McArdle's patients. Levels of enzymes representing glycolysis, the Krebs cycle, and high energy phosphate metabolism were essentially normal in each fiber type, indicating an apparent lack in metabolic adaptation of these energy pathways to the absence of fatty acids (β‐hydrosyacyl CoA dehydrogenase, βOAC) was elevated in all patients, and substantially in 4 of the 5. This suggested that lipid substrates can provide support for oxidative endurance capacity in some patients. Individual fiber analysises indicated that the compensation involved fibers of all types.
Triphasic behavioral response of motor units to submaximal fatiguing exercise
Authors: Dorfman Leslie J. , Howard Jane E. , McGill Kevin C. 
Published: January 2005

AbstractWe have measured the firing rate and amplitude of 4551 motor unit action potentials (MUAPs) recorded with concentric needle electrodes from the brachial biceps muscles of 10 healthy young adults before, during, and after 45 minutes of intermittent isometric exercise at 20% of maximum voluntary contraction (MVC), using an automatic method for decomposition of electromyographic activity (ADEMG). During and after exercise, MUAPs derived from contractions of 30% MVC showed progressive increase in mean firing rate (P ⩽ .01) and amplitude (P ⩽ .05). The firing rate increase preceded the rise in mean amplitude, and was evident prior to the development of fatigue, defined as reduction of MVC. Analysis of individual potentials revealed that the increase in firing rate and in amplitude reflected different MUAP subpopulations. A short‐term (<1 minute) reduction in MUAP firing rates (P ⩽ .05) was also observed at the onset of each test contraction. These findings suggest that motor units exhibit a triphasic behavioral response to prolonged submaximal exercise: (1) short‐term decline and stabilization of onset firing rates, followed by (2) gradual and progressive increase in firing rates and firing variability, and then by (3) recruitment of additional (larger) motor units. The (2) and (3) components presumably compensate for loss of force‐generating capacity in the exercising muscle, and give rise jointly to the well‐known increase in total surface EMG which accompanies muscle fatigue.
Creatine kinase and fibrillation potentials in patients with late sequelae of polio
Authors: Nelson Kevin R. 
Published: January 2005

AbstractThe incidence of an elevated creatine kinase (CK) in a group of polio patients with delayed weakness (15/29) did not differ from polio patients without delayed weakness (9/31) or others with amyotrophic lateral sclerosis (ALS; 10/21). Mean CK in polio patients withoutdelayed weakness (151 IU/L) was lower than the CK in those with delayed weakness (270 IU/L) or ALS (224 IU/L) (P > 0.05). An elevated CK in polio patients with delayed weakness did not correlate with new or residual weakness. These findings suggest that muscle overuse is either not important or inadequately measured by CK. Widely distributed fibrillations were associated with an elevated CK for all polio patients combined (P > 0.01). Fibrillations occurred in more muscles of polio patients with delayed weakness (P > 0.01) and implies that late denervation may play a role in the development of newweakness in some polio patients.
An automated technique for measuring the recovery cycle of human nerves
Authors: Stys Peter K. , Ashby Peter 
Published: January 2005

AbstractAction potentials conducted along a nerve fiber leave in their wake consistent alterations in excitability, including the absolute and relative refractory periods, a supernormal period (SNP) and a late phase of subnormality. We describe an automated technique for reliably determining the recovery cycle of human sensory nerve fibers bydelivering series of paried stimuli and precisely measuring the latencies (to within 0.5 μsec) of the compound action potentials. Therecovery cycle can be compiled from the differences in latency between the two responses of a pair. Consistent changes in conduction velocity are demonstrated during each phase of altered excitability. Possible physiological mechanisms underlying the recovery cycle are discussed, and the effects of cold, ischemia, prior tetanization and subcutaneous lidocaine are presented. This technique may prove to be a useful and more sensitive tool for the study of certain disorders of peripheral nerves.
Use of single fiber EMG and macro EMG in study of reinnervation
Authors: Stålberg Erik 
Published: January 2005

AbstractThe use of single iber EMG and macro EMG in studies of reinnervation is discussed. SFEMG gives information about changes in the topography of the motor unit and in function of transmission in terminal nerve, motor endplate and muscle fiber. Dynamics of reinnervation may be studied with this technique. The amount of reinnervation is obtained from macro EMG studies. The capacity for reinnervation is discussed for a few conditions as well as factors that limit the reinnervation process.
Measurement of the amplitude of the EMG envelope
Authors: Nandedkar Sanjeev D. , Sanders Donald B. 
Published: January 2005

AbstractWhen the force of muscle contraction is increased, the amplitude of the EMG envelope (ENAMP) increases. The ENAMP is usually assessed subjectively and its value in EMG analysis has been established. In this article we describe a method to make automatic measurements of the ENAMP. This method was tested on recordings of the EMG interference pattern (IP) from the biceps muscle of normal subjects. Normal values of this feature in the biceps muscle are described. There was a good concordance between the ENAMP measurements made by subjectve assessment and by automatic analysis and the ENAMP values correlated strongly with a previously described feature of the IP called the upper centile amplitude. We infer that ENAMP is a robust feature of the IP that reflects the amplitude of the largest MUAP in the IP.
Electrophysiological spectrum of inclusion body myositis
Authors: Joy Juan L. , Oh Shin J. , Baysal Ali I. 
Published: January 2005

AbstractWe present electrodiagnostic data on 30 patients with inclusion body myosistis (IBM) in order to better delineate its electrophysiological features. Comprehensive electromyography (EMG) and nerve conduction studies (NCS) were performed in all cases. Twelve patients had single fiber electromyography (SFEMG). EMG showed abundant short‐small motor unit potentials (MUP) with fibrillations and positive sharp waves in 56.6% of patients, and a mixed pattern of large and small MUP in 36.7%. In 6.7%, only “neurogenic” features were seen. NCS were slow in 33.3%. SFEMG revealed a mildly abnormal jitter and a slightly increased fiber density. IBM demonstrates a heterogeneous EMG profile. A pattern of large and small MUP is highly suggestive of IBM but is seen in only about one third of cases.
Sensitivity for detecting fibrillation potentials: A comparison between concentric and monopolar needle electrodes
Authors: Sherman Howard B. , Walker Francis O. , Donofrio Peter D. 
Published: January 2005

AbstractThe sensitivity of monopolar and concentric electrodes for detecting fibrillation potentials (FP) has never been formally compared. We studied 35 muscles with FP, sampling 20 sites each with concentric and monopolar needles. The concentric needle identified 0.88 ± 3.44 (mean ± standard deviation) more sites with spontaneous activity. Although statistically significant (Wilcoxon signed rank test P < .03), this difference in sensitivity did not appreciably affect diagnostic interpretation. Subjects described the concentric needles as more painful. Needle insertions in 25 other muscles demonstrated that needle movement generated the majority of FP. We suggest that the increased tissue injury caused by concentric needles may account for both their increased sensitivity and discomfort.
The electrodiagnostic findings in polyneuropathies associated with IgM monoclonal gammopathies
Authors: Kelly John J. 
Published: January 2005

AbstractElectrodiagnostic studies were analyzed in patients with neuropathy associated with IgM monoclonal proteins, 7 with anti‐myelin associated glycoprotein reactivity (MAG) and 7 nonreactive to MAG. The findings were distinctly different in the two groups. The electrodiagnostic studies of all the MAG‐reactive patients had demyelinating features with slowing of conduction and prolonged distal latencies while only one of the MAG‐nonreactive patients had a demyelinating pattern. In fact, the MAG‐nonreactive patients were a heterogeneous group, both electrodiagnostically and clinically. This study supports the concept that MAG‐reactive polyneuropathy is demyelinating in type, and is caused by the activity of the IgM M‐protein directed at an antigen in the myelin sheath.
Spatial distribution of muscle fibers within the territory of a motor unit
Authors: Bodine‐Fowler Sue , Garfinkel Alan , Roy Roland R. , Edgerton V. Reggie 
Published: January 2005

AbstractThe spatial distribution of muscle fibers belonging to a motor unit was studied in the soleus (SOL) and tibialis anterior (TA) of adult cats to provide a detailed description of the spatial patterns which exist within the territory of a motor unit. Glycogen depletion of the motor unit was achieved through repetitive stimulation of either the intracellularly identified motoneuron or the functionally isolated motor axon. Muscle fibers belonging to the stimulated unit were identified in serial cross‐sections, and in the cross‐section which contained the most depleted fibers the centroid of each depleted fiber was determined. Subsequently, three spatial analyses, ie, a quadrat analysis, a point‐to nearest neighbor analysis and an interfiber distance analysis, were used to determine if motor unit fibers were distributed randomly throughout the territory of the unit. Motor unit fibers tended to be localized within the muscle cross‐section and were not evenly or homogenously distributed throughout the territory. In general, the analyses suggested that motor unit fibers may be arranged in clusters or subgroups of varying size. The data demonstrate three different quantitative analyses for studying the organization of muscle fibers of normal motor units, which can be used for objective assessment and diagnosis of neuromuscular diseases.
Single motor end‐plates in myasthenia gravis and lems at different firing rates
Authors: Trontelj Jože V. , Stǎlberg Erik 
Published: January 2005

AbstractThe jitter and frequency of blocking was studied at single motor end‐plates in 10 patients with myasthenia gravis (MG) and in a patient with Lambert‐Eaton myasthenic syndrome (LEMS), using single fiber EMG (SFEMG) with axonal microstimulation at rates varying from 0.5 Hz to 20 Hz. While some myasthenic motor end‐plates showed lowest degrees of transmission disturbance at the lowest rates and most pronounced abnormality at the highest rates of stimulation, over one‐half were most abnormal at intermediate rates and improved at higher rates. In 1 patient, all end‐plates behaved in this way. On the other hand, all end‐plates in the LEMS patient showed the expected improvement of the abnormal jitter and blocking on increasing the stimulation rate. It is argued that improvement of jitter and blocking at higher rates, unless dramatic, does not necessarily suggest a presynaptic abnormality.
Peripheral neuropathy in cold agglutinin disease
Authors: Thomas T. Darrell , Donofrio Peter D. , Angelo Jean 
Published: January 2005

AbstractCold agglutinin disease (CAD) characteristically presents as anemia and cold‐induced rash. We report a man with purpura, anemia, cold agglutinins, and a sensory‐autonomic polyneuropathy. Treatment with corticosteroids and plasma exchange resulted in resolution of the anemia and polyneuropathy. We propose that CAD may be associated with a reversible sensory‐autonomic neuropathy in the absence of cryoglobulinemia. Although unsupported by pathologic findings, pathogenetic hypotheses for the neuropathy in CAD are similar to those proposed for cryoglobulinemic neuropathy.
Light and electron microscopic studies on localization of myoglobin in skeletal muscle cells in neuromuscular diseases
Authors: Kawai Hisaomi , Sebe Toshihiko , Nishino Hiroshi , Nishida Yoshihiko , Saito Shiro 
Published: January 2005

AbstractThe localizations of myoglobin in skeletal muscle cells of patients with Duchenne muscular dystrophy (DMD), myotonic dystrophy (MyD), and amyotrophic lateral sclerosis (ALS) were studied by immunohistochemistry and immunoelectron microscopy. In normal skeletal muscle cells, myoglobin was localized mainly in the I‐band region. In degenerating muscle cells of patients with DMD and MyD, myoglobin was also demonstrated in the distended lumen of the internal membrane system and in the intermyofibrillar space, through which it seemed to pass into the extracellular space. No myoglobin was detected in opaque fibers or in some of small‐sized fibers in DMD muscle. In patients with ALS the staining intensities of myoglobin varied in different muscle cells, but myoglobin was restricted to the I‐band region in many muscle cells. These findings suggest that changes in the localization of myoglobin in skeletal muscle cell sensitively reflect the pathologic status of muscle cells.
Mononeuropathy in sickle cell anemia: Anatomical and pathophysiological basis for its rarity
Authors: Shields Robert W. , Harris John W. , Clark Malcolm 
Published: January 2005

AbstractPeripheral neuropathy is a rare complication of sickle cell disease. We report a young black woman with sickle cell anemia, who developed a proximal median mononeuropathy in the setting of sickle cell crisis. The clinical and electrodiagnostic features are consistent with an ischemic mechanism from the sickling process. The pathophysioiogical basis for the rarity of this complication may be related to the rich anastomotic microvasculature of peripheral nerve and the unique large size of the capillaries of this vascular network.
AAEM case report #3: Myasthenia gravis
Authors: Jablecki Charles K. 
Published: January 2005

AbstractReported here are the electrodiagnostic findings in a patient with myasthenia gravis who had dysarthria, dysphagia, and dyspnea. The use of repetitive nerve stimulation and single fiber electromyography studies for the evaluation of patients suspected of myasthenia gravis is reviewed.
Electrophysiological improvement following decompression surgery in tarsal tunnel syndrome
Authors: Oh Shin J. , Arnold Thomas W. , Park Kyu H. , Kim Doo E. 
Published: January 2005

AbstractPlanter nerve conduction studies 14 months to 3.5 years after decompression surgery in 3 cases of tarsal tunnel syndrome showed an improvement in motor conduction as well as in sensory nerve conduction. This electrophysiological improvement was associated with clinical improvement. However, minor abnormalities still existed in sensory nerve conduction in all 3 cases.
Dynamic F waves in neurogenic claudication
Authors: London Scott F. , England John D. 
Published: January 2005

AbstractSerial F waves were elicited before and after ambulation in 2 patients with neurogenic claudication. In both patients dynamic changes in F wave parameters consisting of either unelicitability or increased latencies occurred postexercise. The time course of these changes and their subsequent rapid reversibility over 15 minutes suggest ischemic‐induced conduction block and slowing in proximal motor axons. These physiological changes may account for some of the dynamic neurological symptoms of this disorder. Moreover, F wave exercise testing may provide corroborative information for the diagnosis of neurogenic claudication.
AAEM minimonograph #10: Volume conduction
Authors: Dumitru Daniel , Delisa Joel A. 
Published: January 2005

AbstractA volume conductor is any medium with the capability of passively conducting a current between regions of potential difference. The monophasic positive intracellular action potential produces a monophasic negative extracellular waveform and a triphasic extracellular waveform in a poor and good volume conductor, respectively. The observed waveform characteristics are dependent upon both the recording electrode montage and the type of volume conductor surrounding the excitable tissue. The extracellular current flow associated with an action potential can be divided into two current sources flanking a central current sink. If a recording electrode is located over the negative current sink, a negative potential is observed. When the two current sources approach a recording electrode, a positive potential is recorded. If a positive deflection of the baseline is observed, one may conclude that the wave of depolarization under investigation did not originate under, but traveled toward, the recording location. Electric currents from external sources are free to propagate extraneurally as the body is a good volume conductor. Care must be taken to not activate nearby nerves and, subsequently, obtain a waveform contaminated with potentials from undesired sources. Additionally, electrical activity from neighboring muscles and nerves can summate in the volume conductor and yield responses capable of masking pathology. An understanding of the principles of volume conduction theory can help the electrodiagnostician avoid artifactual errors and erroneous conclusions.
Magnetic resonance imaging of the muscles in patients with polymyositis and dermatomyositis
Authors: Fujino Hiroyuki , Kobayashi Takuro , Goto Ikuo , Onitsuka Hideo 
Published: January 2005

AbstractMagnetic resonance imaging (MRI) of the muscles was performed in patients with polymyositis and dermatomyositis. Lesions with high intensity on T2‐weighted image, but normal intensity on T1‐weighted image, were observed in 7 of 8 patients in the active stage of the disease. Following clinical improvement with corticosteroid therapy in 4 patients, the high intensity lesions reverted to normal. The high intensity lesions seen on T2‐weighted image in the active stage may represent edema and inflammation of the muscle. MRI of the muscle may serve as a diagnostic tool and be useful for follow‐up of the patients with polymyositis or dermatomyositis.
Concentric macro electromyography
Authors: Jabre Joe F. 
Published: January 2005

AbstractConcentric EMG electrodes can record from a few (10 to 15) muscle fibers of a motor unit (MU). Macro EMG, is able to record from the majority of muscle fibers in the MU. The macro EMG electrode uses a single fiber action potential (SFAP) on one channel to trigger the time locked cannula (macro) response on the other channel. To study the concentric motor unit action potential (MUAP), alongside the macro potential, we built a needle electrode combining concentric and macro recording surfaces. The study of 240 motor units in 10 healthy subjects with the single fiber (SF macro) and concentric macro (conmac) electrodes revealed no significant differences between macro potentials areas and amplitudes obtained with either electrode. The ability to study a small and a large section of the motor unit simultaneously offers insights into the local or global nature of motor unit changes not otherwise available to the electromyographer. It also reveals which concentric parameters correlate best with the macro potential and, can even be of great help with the newer EMG signal decomposition techniques; by identifying each motor unit by its concentric and macro waveform simultaneously, it will allow for the “making” of these motor units helping to reduce the risk of their misclassification when the concentric MUAP is used alone.