bluuebunny/crossref_metadata_2025 huggingface dataset:
The blood–nerve barrier in Wallerian degeneration: A sequential long‐term study
Authors: Seitz Rüdiger J. , Reiners Karlheinz , Himmelmann Frank , Heininger Kurt , Hartung Hans‐Peter , Toyka Klaus V.
Published: January 2005

The blood–nerve barrier (BNB) for serum proteins was studied after a crush lesion of the murine sciatic nerve or after transsection with persistent Wallerian degeneration. Using single intraperitoneal injections of biotinylated human albumin, transferrin, IgG, and complement components as tracers, the integrity of the BNB during degeneration and regeneration was determined over time. In Wallerian degeneration induced by crush the BNB became increasingly leaky, with a maximum in the distal stump 8 days after crush (i.e., during early regeneration). When regeneration potentials could first be elicited from the small foot muscles and when thinly myelinated nerve fibers were present, the BNB gradually regained its barrier function and was nearly intact on day 30 after crush. After transsection breakdown of the BNB persisted beyond 30 days. The BNB leakage may foster repair by allowing exchange of trophic factors of large molecular size during nerve regeneration.
Muscle fatigue, effects of training and disuse
Authors: Hainaut Karl , Duchateau Jacques
Published: January 2005

The study of muscle fatigue started about a century ago, when it was proposed that the observed decrease in force during prolonged voluntary contractions resulted from changes in central processes which reduced the motor drive. In the middle of this century it was noticed that this loss of force could not be restored by maximal electrical stimulation of the motor nerve, and thus the importance of peripheral mechanisms, located beyond the motoneuron, was emphasized. However, it was not clear which peripheral site was most important in decreasing the muscle mechanical capacity during fatigue. More recently, the comparison between peripheral failures during sustained and intermittent contractions indicated that recorded mechanical changes underwent deterioration which was not closely related to the recorded electrical changes. It was thus proposed that muscle intracellular processes dominate the force decrease during muscle fatigue. This concept has been substantiated by the study of standard fatigue tests performed in control, trained, and disused human muscles, as reviewed in this paper.
Ephaptic transmission in hemifacial SPASM: A single‐fiber EMG study
Authors: Sanders Donald B.
Published: January 2005

In two patients with hemifacial spasm (HFS), single‐fiber EMG recordings in facial muscles demonstrated low jitter in the late responses produced by stimulation of peripheral branches to other facial muscles. Surgical decompression of the facial nerve in one patient was followed by clinical improvement and disappearance of the abnormal late responses. These observations are consistent with the hypothesis that there is ephaptic transmission among peripheral branches of the facial nerve at the site of compression in HFS.
AAEE case report #19: Ischemic monomelic neuropathy
Authors: Levin Kerry H.
Published: January 2005

A case study of a 50‐year‐old man who awakened from aortobifemoral bypass graft surgery with painful burning and numbness of the left foot is reported. Angiography showed embolic occlusion of the left popliteal artery proximal to the knee. Nerve conduction studies performed 1 year after occlusion showed loss or severe reduction of distal left sensory and motor amplitudes, and needle electrode examination showed fibrillation potentials in foot and distal leg muscles. The findings were felt to represent the result of acute ischemic nerve damage in the left leg. The clinical and electromyographic features of this entity will be described and comparisons will be drawn to experimental ischemic neuropathy and diabetic neuropathy.
Position of the elbow in determination of abnormal motor conduction of the ulnar nerve across the elbow
Authors: Bielawski Martin , Hallett Mark
Published: January 2005

Routine evaluation of patients for suspected ulnar neuropathy includes testing of motor conduction velocity across the elbow, although the best position of the elbow for this test is controversial. The preferred testing position—elbow flexion or extension—was studied by determining the yield of abnormality at both positions in patients selected for possible ulnar nerve abnormalities unrelated to motor conduction. We found no major differences between the flexed or extended position of the elbow except that normal values for each of these positions varied. The yield of abnormal findings was greatest from measuring absolute motor conduction velocity across the elbow as opposed to comparing the difference in velocities between the elbow and either adjacent segment.
Recurrent myoglobinuria and HIV seropositivity: Incidental or pathogenic association?
Authors: Younger David S. , Hays Arthur P. , Uncini Antonio , Lange Dale J. , Lovelace Robert E. , DiMauro Salvatore
Published: January 2005

There have been few cases of polymyositis in patients with AIDS, and polymyositis is rarely a cause of myoglobinuria. We studied a 20‐year‐old homosexual man with recurrent myoglobinuria. He was asymptomatic between episodes. Each episode was accompanied by muscle pain, limb weakness, high serum levels of creatine kinase, and pigmenturia. Muscle biopsy showed active necrosis without inflammation or abnormalities of glycolytic or other energy‐generating enzymes. Antibodies to HIV were present in serum. Clinical evidence of AIDS has not developed in 2 years. Recurrent myoglobinuria may be another consequence of HIV infection.
Reversible axonal neuropathy from the treatment of AIDS and related disorders with 2′,3′‐dideoxycytidine (ddc)
Authors: Dubinsky Richard M. , Yarchoan Robert , Dalakas Marinos , Broder Samuel
Published: January 2005

A total of 20 patients with acquired immune deficiency syndrome (AIDS) or AIDS‐related complex (ARC) received the anti‐retroviral drug 2′,3′,dideoxycytidine in a phsae I study at doses ranging from 0.03 mg/kg every 8 hours to 0.25 mg/kg every 8 hours. Of the 11 patients who participated in the study for more than 5 weeks, 9 developed symptoms and signs of a mainly sensory painful neuropathy that was confirmed by electromyography to be mixed sensory and motor neuropathy of axonal type. The neuropathy which developed on dideoxycytidine occurred between 9 and 12 weeks of treatment. One patient, who had the drug stopped at 3 weeks owing to thrombocytopenia, developed a similar clinical picture of a sensory peripheral neuropathy after 2 weeks off dideoxycytidine. However, he did not have electromyographic evidence of a neuropathy, and he subsequently returned to normal clinically while taking a lower dose of dideoxycytidine in an alternating regimen. Five patients were withdrawn from the study because of the neuropathy. The pattern of this neuropathy was different from that of the slowly progressive painful neuropathy of AIDS, in that there was (1) a sudden onset of intense burning discomfort in both feet sparing the hands at about the tenth week (mean 10.4 weeks) of treatment, (2) there was motor involvement in some patients without progression, and (3) onset of the neuropathy was temporally related to the administration of dideoxycytidine and began to resolve 3–5 weeks after its discontinuation. We believe that dideoxycytidine can be an axonal toxin, especially when given in high dose continuous regimens. We are now exploring whether a low‐dose regimen or regimens that incorporate a drug rest period can obviate this toxicity.
AAEE case report #20: Hereditary motor and sensory neuropathy, type I
Authors: Chad David A.
Published: January 2005

A case study is reported regarding a 32‐year‐old man with classic clinical and electrophysiologic features of hereditary motor and sensory neuropathy, type I (HMSN I), a slowly progressive autosomal dominant condition marked by slow motor and sensory velocities and generalized segmental demyelination. Another clinically similar autosomal dominant neuropathy (HMSN II) is distinguished from HMSN I by nearly normal nerve conduction velocity. Acquired demyelinating neuropathy may occasionally resemble HMSN I clinically, but the former demonstrates electrophysiologic features not seen in the latter such as conduction block, dispersed compound muscle action potentials, and differential slowing of conduction velocity. Neuropathologic studies of HMSN I suggest that both neuronal and Schwann cell distrubances play a role in pathogenesis.
Median to radial latency difference test in mild carpal tunnel syndrome
Authors: Pease William S. , Cannell Christopher D. , Johnson Ernest W.
Published: January 2005

Electrodiagnostic assessment of carpal tunnel syndrome (CTS) is hampered by the normal variability of conduction velocity, amplitude and duration of evoked responses, and hand temperature. Comparative testing of other nerves in the same hand may control for these variables and improve sensitivity for detection of mild focal entrapment. In consecutive cases referred for evaluation, antidromic sensory latencies were recorded from the thumb over 10 cm segments of the median and radial nerves, and the difference between these latencies was calculated. Median sensory antidromic conduction to digit III, ulnar sensory conduction, and median motor latency measurements were also made. Three hundred and thirty‐three upper limbs were studied in 262 patients. All tests were normal in 73 arms. Mild conduction slowing was identified in 86 median nerves. The median–radial latency difference was increased in 87% of these mild cases. The median–ulnar latency difference was diagnostic in 88%. Either median–radial or median–ulnar latency differences were abnormal in all confirmed cases. The routine median motor and sensory distal latency tests had sensitivities of 29% and 52%, respectively. Radial responses were elicited in 99% of the hands studied. The median–radial latency difference in digit I is a sensitive indicator of mild CTS that can be measured quickly with a minimum of discomfort.
Ultrastructural localization of calcium binding sites on human muscle cell surface
Authors: Moggio M. , Jann S. , Adobbati L. , Prelle A. , Gallanti A. , Fagiolari G. , Pellegrini G. , Scarlato G.
Published: January 2005

Calcium (Ca2+) is mainly bound to anionic phospholipids and to sialic acid at the cell surface. We studied the ultrastructural localization of these Ca2+ binding sites in normal human muscle fibers, using Polymyxin B as a marker for anionic phospholipids and the lectin Limulus Polyphemus as a probe for sialic acid. We found that anionic phospholipids have a patchy distribution along the muscle sarcolemma, with a preferential localization at the I band level and at the junction between the I and A band. Sialic acid has an uniform distribution along the muscle plasma membrane and basal lamina. Our observations suggest that the plasma membrane, basal lamina, and transverse tubular system play an important role in providing the negative charge of the human muscle cell surface and that these structures may be involved in the binding of calcium.
Automatic analysis of heart rate variation: II. Findings in patients attending an EMG laboratory
Authors: Nogués Martin A. , Stålberg Erik V.
Published: January 2005

An automatic method was used to measure the heart rate variation with breathing in patients with different neuromuscular conditions attending a laboratory of electromyography (EMG). The objective was to determine the frequency of abnormalities in various conditions and the relationship between R‐R variation and different nerve conduction parameters. The percentages of reduced R‐R variation were 73% in diabetics, 35% in Guillain–Barré syndrome, 22% in amyotrophic lateral sclerosis, and 50% in amyloidosis. R‐R variation in diabetics was significantly correlated to most parameters of nerve conduction. In Guillain–Barré syndrome it correlated significantly with the ulnar and median M‐response amplitudes. Most patients with myopathies showed normal R‐R variation.
Are there motor fibers in the sural nerve?
Authors: Liguori Rocco , Trojabodrg Werner
Published: January 2005

A case of anomalous innervation of the abductor digiti quinti of the foot (ADQ)via the sural nerve is described. A muscle action potential from the ADQ could be elicited by stimulation of both the sural and the posterior tibial nerves.
Quantitative EMG in inflammatory myopathy
Authors: Barkhaus Paul E. , Nandedkar Sanjeev D. , Sanders Donald B.
Published: January 2005

Fifty‐four quantitative electromyographic (EMG) studies were made in 37 patients with inflammatory myopathy (IM) at different points in their clinical course and tretment. All studies were performed in the biceps brachii which varied in clinical strength. Motor unit action potentials (MUAPs) in 45 studies and EMG interference pattern (IP) in 48 studies were recorded using a concentric needle electrode. Macroelectromyographic (Macro‐EMG) MUAPs were recorded from 10 patients in 14 studies. MUAP analysis revealed a myopathic pattern (decreased duration and/or area: amplitude ratio) in 69% of studies. IP analysis was more sensitive than MUAP analysis, demonstrating a myopathic pattern in 83% of studies. Macro‐EMG MUAP amplitudes were reduced in two studies, minimally increased in one study and normal in the remainder; in 6 (40%) studies, fiber density was slightly increased. Thus, reinnervation does not seem to play an important role in motor unit remodeling in IM.
Nerve regeneration and reinnervation after limb amputation and replantation: Clinical and physiological findings
Authors: Krarup Christian , Upton Joseph , Creager Mark A.
Published: January 2005

A 22‐year‐old male was studied 3½–&4½ years after a traumatic section‐avulsion amputation of the left upper extremity at the level of the distal humerus. The arm was reattached after a cold ischemia time of 4–5 hours and good vascularization was obtained. The ulnar nerve was repaired early with an end‐to‐end juncture while the median and radial nerves were repaired after seven months delay using a combination of vascularized radial nerve and nonvascularized sural nerve grafts. Some intrinsic hand muscle function had recovered. Pin‐prick and touch sensation was present in all digits, although localization of touch stimulation was poor. Evoked motor responses had recovered by 25–50% of control amplitude in ulnar‐innervated and by 10–25% in median‐innervated muscles. Amplitudes of sensory responses from digit V had recovered by 25% and from digits I and III by 1–5%. Fast‐adapting touch receptors had become reinnervated. There was electrophysiological evidence of aberrant sensory regeneration and of abnormal connections between sensory and motor fibers. Digital blood flow measurements suggested the presence of vascular obstruction in vessels of the replanted upper extremity. However, the digital vasconstriction during cold exposure indicated regeneration of sympathetic nerve fibers.
Invited review: Limitations in predicting pathologic abnormality of nerves from the EMG examination
Authors: Dyck Peter James
Published: January 2005

Although electromyography (EMG = nerve conduction and needle electromyographic examination) is among the most sensitive and reliable approaches to detect and even to characterize certain aspects of nerve disease, it is important for physicians to appreciate that EMG has limited value in (1) inferring symptoms and neuropathic deficit (particularly the overall deficit recorded by clinical neurologists), (2) inferring involvement of small‐diameter fibers, (3) inferring underlying biochemical or other pathophysiologic derangement, (4) inferring the presence and type and pathologic alterations in single fibers or Schwann cells, or (5) inferring interstitial pathologic abnormality. For 1 and 2, an adequate neurologic history and examination in needed. For 2, quantitative sensory (QSE) and quantitative autonomic (QAE) examination and histologic study of nerve often are especially helpful. For 3, clinical evaluation and a variety of laboratory examinations are needed. For 4 and 5, clinical evaluation and/or pathologic study of nerve may be needed

Electromyography has deservedly gained considerable acceptance as a worthwhile evaluative procedure for the study of neuromuscular disease. For some purposes, however it is of limited value and other evaluative procedures are more informative. In this review, I trace the history of some of the reasons for the popularity of EMG and highlight some of its limitations. The purpose is not to diminish EMG or to elevate the procedure of nerve biopsy, rather to provide a conceptual framework for how these techniques and the clinical and other laboratory examinations can be used together in the assessment and follow‐up of neuropathy.
Clinical use of the magnetic stimulator in the investigation of peripheral conduction time
Authors: Britton Thomas C. , Meyer Bernd‐Ulrich , Herdmann Jörg , Benecke Reiner
Published: January 2005

The application of rapidly changing magnetic fields (magnetic stimulation) over the neck or lower back elicits EMG responses in the muscles of the arm or leg respectively. Such responses have stable onset latencies but their amplitudes vary depending on the position of the coil over the neck or lower back. Supramaximal responses could not be obtained. Comparison of onset latencies with estimates of peripheral conduction time using a conventional F‐wave technique suggest that the site of excitation of the motor axons is about 1.3 msec conduction time distal to the cervical motoneurons and 3 msec distal to the lumbosacral motoneurons. Response configuration after paravertebral magnetic stimulation was similar to that of the standard electrically evoked M‐wave in the small hand muscles but not in lower limb muscles. Responses in lower limb muscles after paravertebral magnetic stimulation may consist of additional F‐wave and H‐reflex components. The possible clinical role of paravertebral magnetic stimulation in the investigation of peripheral and central motor pathways is discussed in the light of these findings.
Enhancement of K+ conductance improves in vitro the contraction force of skeletal muscle in hypokalemic periodic paralysis
Authors: Grafe Peter , Quasthoff Stefan , Strupp Michael , Lehmann‐Horn Frank
Published: January 2005

An abnormal ratio between Na+ and K+ conductances seems to be the cause for the depolarization and paralysis of skeletal muscle in primary hypokalemic periodic paralysis. Recently we have shown that the „k+ channel opener”︁ cromakalim hyperpolarizes mammalian skeletal muscle fibers. Now we have studied the effects of this drug on the twitch force of muscle biopsies from normal and diseased human skeletal muscle. Cromakalim had little effect on the twitch force of normal muscle whereas it strongly improved the contraction force of fibers from patients suffering from hypokalemic periodic paralysis. Recordings of intracellular K+ and Cl− activities in human muscle and isolated rat soleus muscle support the view that cromakalim enhances the membrane K+ conductance (gK+). These data indicate that ”︁K+ channel openers„ may have a beneficial effect in primary hypokalemic periodic paralysis.
Single‐fiber electromyography in experimental autoimmune myasthenia gravis
Authors: Verschuuren Jan J. G. M. , Spaans Frank , De Baets Marc H.
Published: January 2005

The 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

In 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

Macro–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

Enzymes 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

We 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

The 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

Action 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

The 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

When 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

We 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

The 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

Electrodiagnostic 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

The 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.
AAEM case report #1: Ulnar neuropathy at the elbow
Authors: Miller Robert G.
Published: January 2005

A patient with bilateral cubital syndrome complicated by anomalous innervation is presented. The electrodiagnostic approach to patients with this neuropathy is reviewed emphasizing new developments. The interpretation of the findings in this patient centers around issues of pathophysiology and methodology.
Single motor end‐plates in myasthenia gravis and lems at different firing rates
Authors: Trontelj Jože V. , Stǎlberg Erik
Published: January 2005

The 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

Cold 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

The 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

Peripheral 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

Reported 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

Planter 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

Serial 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

A 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

Magnetic 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

Concentric 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.
Calcium‐tension relationships of muscle fibers from patients with periodic paralysis
Authors: Ruff Robert L.
Published: January 2005

Lateral gastrocnemius muscle biopsies from a 26‐year‐old man with hyperkalemic periodic paralysis and a 23‐year‐old man with hypokalemic periodic paralysis were studied. Both patients came from families in which older relatives had developed a vacuolar myopathy in association with their periodic paralysis. Muscle fibers were chemically skinned, and individual fibers were studied with a low‐compliance strain gauge. The tension generated by fibers was studied in baths with calcium concentrations from 10‐8 mol/L to 2.5 × 10‐5 mol/L. The Ca‐tension relationships and maximal tensions (normalized to fiber cross‐sectional area) of fast and slow twitch fibers were indistinguishable from those found in fibers from 5 normal subjects. The results reinforce earlier findings which suggested that loss of Ca‐induced myofibril contraction was not the cause of paralysis in periodic paralysis.
Conduction block in diabetic neuropathy
Authors: Abu‐Shakra Sawsan R. , Cornblath David R. , Avila Orlando L. , Chaudhry Vinay , Freimer Miriam , Glass Jonathan D. , Reim Johannes W. , Ronnett Gabriele V.
Published: January 2005

Symmetric sensorimotor polyneuropathy is a common complication of diabetes. Sensory and motor evoked amplitudes and conduction velocities are reduced. Both demyelination and axon loss have been reported in pathologic studies. Conduction block (CB), a manifestation of segmental demyelination, has not been previously studied in diabetic neuropathy. We determined the prevalence of conduction block in patients with diabetes by analyzing electrodiagnostic data from 24 diabetics. Conduction block was defined as a >20% drop in peak‐to‐peak amplitude, and a <15% change in negative‐peak duration between proximal and distal stimulation sites. A total of 76 nerve segments were studied. The criteria for conduction block were met in only 6 segments in 6 patients. The mean decrease in peak‐to‐peak amplitude between stimulation sites was 28% (range 21% to 40%). We conclude that conduction block over long nerve segments is uncommon in diabetic neuropathy, and, if present, suggests that other causes for neuropathy in diabetic patients should be sought.
Nerve conduction studies in experimental non‐freezing cold injury: II. Generalized nerve cooling by limb immersion
Authors: Kennett Robin P. , Gilliatt Roger W.
Published: January 2005

After immersion of the hind limb of the rabbit, up to the lower thigh, in a waterbath, at 1°C for 10 to 14 hours under light anesthesia, there was evidence of persistent nerve damage to the tibial nerve, which varied in severity in different animals. Nerve conduction studies, carried out within 24 hours of removal from the bath, showed that in a proportion of the motor and/or afferent fibers, there was conduction failure between the knee and ankle. This was followed, over the next 48 hours, by distal degeneration of the affected fibers. No persistent conduction block was seen. After distal degeneration had occurred, maximal conduction velocity was mildly reduced, suggesting that the fastest‐conducting motor and afferent fibers had been particularly affected. Morphological studies confirmed preferential large myelinated fiber degeneration, the earliest lesions being seen in the leg at the level of the upper calf. Limb edema was not seen after cooling, and there was no histological evidence of muscle necrosis or damage to blood vessels. No abnormalities were seen in 4 control animals after hind limb immersion for 12 hours at temperatures of 30 to 35°C. Possible reasons for the proximal site of myelinated nerve fiber damage during hindlimb cooling are discussed.
Muscular dystrophy with separate clinical phenotypes in a large family
Authors: Udd Bjarne , Kääriänen Helena , Somer Hannu
Published: January 2005

This report describes a large consanguineous family with muscular dystrophy in 23 patients showing intrafamilial variation of clinical expression. One main variant appeared in the first decade with proximal muscle weakness progressing over the next 20 years to wheelchair confinement, and appeared compatible with classical limb‐girdle muscular dystrophy. The other main variant showed onset of distal muscle weakness in lower limbs in the third or fourth decade, progressing very slowly without greater disability throughout the lifetime. Tibial muscle weakness and wasting were clinical landmarks in this variant, but computed tomography of skeletal muscle revealed focal areas of fatty degeneration also in truncal, pelvifemoral, and distal leg muscles in a way not previously reported in distal myopathy. The overall difference in clinical findings between these main variants would suggest 2 separate genetic entities, genealogical data makes a common genetic background possible.