bluuebunny/crossref_metadata_2025 huggingface dataset:
Patterns of selective involvement of thigh muscles in neuromuscular disease
Authors: Schwartz Martin S. , Swash Michael , Ingram David A. , Davis Graham R. , Thompson Alan J. , Thakkar Chandra , Hart Geoffrey
Published: January 2005

In 14 patients with limb girdle muscular dystrophy, polymyositis, and type 3 spinal muscular atrophy, CT scans of the thigh muscles were correlated with single fiber EMG studies in vastus lateralis, semimembranosus and biceps femoris muscles. There was a relation between the extent of CT scan abnormality and increased fiber density in the three muscles studied, except in the most severely affected muscles in which in some muscles the fiber density values were lower than expected. These results were independent of the underlying pathology. Correlative CT/SFEMG studies provide insights into the pattern of selective involvement of certain muscles in neuromuscular disorders.
Muscle function in patients with primary hyperparathyroidism
Authors: Joborn Charlotte , Rastad Jonas , Stålberg Erik , Åkerström Göran , Ljunghall Sverker
Published: January 2005

The muscle contraction of the anterior tibial muscle was investigated by measurements of electrically stimulated and computer‐analyzed muscle twitches in 18 unselected patients with primary hyperparathyroidism (HPT) and in 20 healthy control persons. The HPT patients had a lower muscle twitch tension (TT) at single stimulation, compared with the control group [76 ± 24 N (SD) and 99 ± 33 N respectively, P < 0.05]. At high‐frequency stimulation the difference in muscle force increased, and at 20 Hz stimulation the force in the HPT patients was 73% of that in the controls (P < 0.01). There were no differences between the HPT patients and the control persons in neither contraction time nor half relaxation time at single muscle twitch nor in twitch potentiation after 20 and 90 seconds maximal voluntary contraction. The results indicate that patients with primary HPT have an impaired muscle function of probable importance for their symptoms of weakness and generalized fatigue.
The thoracic outlet syndrome: Controversies, overdiagnosis, overtreatment, and recommendations for management
Authors: Cuetter Albert C. , Bartoszek David M.
Published: January 2005

This review is an objective critique of the thoracic outlet syndrome, with emphasis on the need to separate true neurogenic and vascular syndromes from nonspecific ones. Major controversies in the diagnosis and management of thoracic outlet syndromes are discussed, with an analysis of major pitfalls encountered in the diagnosis and treatment of patients with nonspecific syndromes. Recommendations to improve diagnostic methods in patients with chronic neurovascular abnormalities in the upper extremities are outlined.
Autosomal recessive motor and sensory neuropathy with excessive myelin outfolding
Authors: Ohnishi Akio , Murai Yoshiyuki , Ikeda Masato , Fujita Tsutomu , Furuya Hirokazu , Kuroiwa Yoshigoro
Published: January 2005

Two Japanese persons with consanguinous parents had a motor and sensory neuropathy of the hypertrophic type with excessive myelin outfolding in the myelinated fibers. A morphometric analysis of the biopsied sural nerve was made. Excessive myelin outfolding, segmental demyelination, and re‐myelination and decrease in the density of both large and small myelinated fibers were evident. Using linear regression, myelin spiral length was shorter relative to axonal area. These patients may have a new variant of hereditary motor sensory neuropathy.
Localization of dystrophin in cultures of human muscle
Authors: Ecob‐Prince Marion S. , Hill Mark A. , Brown Aileen E.
Published: January 2005

Dystrophin is a protein present in normal human muscle but absent in patients with Duchenne muscular dystrophy (DMD). Using a specific antibody, we have investigated the expression of dystrophin in human muscle which had regenerated in culture in the presence of nerve cells. Dystrophin was present and was correctly localized in the cultures of normal muscle but was absent from cultures of muscle from patients with DMD. Its control and function can now be studied.
Modulation of the bulbocavernosus reflex during voiding: Loss of inhibition in upper motor neuron lesions
Authors: Sethi Rajesh K. , Bauer Stuart B. , Dyro Frances M. , Krarup Christian
Published: January 2005

The bulbocavernosus reflex (BCR) is a sacral segmental reflex which is suppressed throughout most of micturition. The BCR was evaluated by recording the associated EMG activity using a concentric needle electrode placed in the external urethral sphincter. The influence of the central nervous system (CNS) on the BCR was studied in 29 neurologically normal individuals and in 33 patients with upper motor neuron (UMN) lesions and voiding dysfunction. Ninety percent (26/29) of the neurologically normal patients did not have a BCR during most of micturition. By comparison, all the patients with an UMN lesion had a positive BCR beginning early during voiding. The finding of suprasegmental modulation of the BCR during voiding demonstrated by external urethral sphincter EMG was a more sensitive although slightly less specific sign of UMN bladder dysfunction than detrusor sphincter dyssynergia; uninhibited bladder contractions were neither sensitive nor specific for UMN lesions.
Sparing of the flexor carpi ulnaris in ulnar neuropathy at the elbow
Authors: Campbell William W. , Pridgeon Rhonda M. , Riaz Ghazala , Astruc Juan , Leahy Marilyn , Crostic E. Gay
Published: January 2005

A common misconception attributes sparing of the flexor carpi ulnaris (FCU) in ulnar neuropathy at the elbow (UNE) to its innervating branch arising “at or above the elbow.” We examined the relationship of FCU branches to the medial epicondyle (ME) and humeroulnar aponeurotic arcade (HUA) in 30 cadaver elbows. In only three did the first FCU branch arise at or proximal to the ME. In 36 UNE cases with fibrillations in the first dorsal interosseous, the FCU was normal in 10, mildly abnormal in 11, and severely abnormal in 15. FCU involvement correlated with the severity of the neuropathy and with whether compression was retroepicondylar or at the HUA. We conclude that sparing of the FCU in UNE is unrelated to the level of origin of its innervating branch, but rather is related to the internal neural topography and to the severity and level of compression.
Functional evaluation of acute vincristine toxicity in rat skeletal muscle
Authors: Di Gregorio Franco , Favaro Giorgio , Fiori Mario G.
Published: January 2005

Vincristine sulfate (VCR) was administered intravenously to rats at doses of 0.25, 0.5, and 0.75 mg/kg. During the first week following VCR treatment, extensor digitorum longus (EDL) muscle contraction strength and fiber electrophysiologic parameters were measured. At all doses tested, VCR strongly reduced twitch and tetanic tension. EDL fiber resting membrane potential was affected in a dose‐dependent manner, and membrane depolarization was associated with the loss of excitability. Local membrane hyperpolarization by intracellular current application restored the capacity to produce action potential (AP). However, to elicit APs with a normal rate of rise, polarizing current had to be maintained for 3–5 minutes, indicating that the removal of Na+ channel inactivation followed a slow kinetics. Minor alterations in spontaneous synaptic transmission and in evoked transmission during high‐frequency repetitive stimulation were seen only at the highest dose. It is suggested that VCR impairs skeletal muscle function by affecting primarily the contractile apparatus, whereas sarcolemmal alterations are evident at increased doses of the drug.
Excitation contraction coupling in normal and mdx mice
Authors: Hollingworth Stephen , Marshall Michael W. , Robson Eliska
Published: January 2005

The protein dystrophin is absent from patients with Duchenne muscular dystrophy and from the muscles of mdx mice. Recent studies have shown that dystrophin is located at the surface membrance and at the triadic junction, where it is associated with the transverse tubular membrane. Since the triadic junction is the site of excitation‐contraction (EC) coupling, we have investigated whether intramembrane charge movement, a step in EC coupling, is modified by the absence of dystrophin. Charge movements are thought to arise from the transverse tubular membrane and to underlie the dependence of sarcoplasmic reticulum Ca2+ release on transverse tubular membrane potential. We find no differences between intramembrane charge movements or passive membrane electrical properties measured in muscles from mdx mice compared with normal mice. If dystrophin does play a role in EC coupling, that role is likely to be subsequent to the charge movement step.
Excessive plasma K+ increase after ischemic exercise in myotonic muscular dystrophy
Authors: Wevers Ron A. , Joosten Ed M. G. , van de Biezenbos J. B. Margot , Theewes Ad G. M. , Veerkamp Jacques H.
Published: January 2005

Changes in plasma electrolyte levels upon ischemic forearm exercise were studied in myotonic muscular dystrophy (MyD) patients, disease control groups, and healthy volunteers. Significant differences were observed in the pH and the concentrations of creatine kinase and Na+ before exercise between healthy volunteers and MyD patients. In comparison with healthy volunteers a lower pH and higher concentrations of both CK and Na+ were found in MyD patients. The concentrations of K+, inorganic phosphate, lactate, and ammonia increase upon exercise in all groups. The mean increase in plasma K+ for healthy volunteers amounted to 0.8 mM (=23%). In MyD patients a significantly higher increase in plasma K+ was found [mean 2.2 mM (= 65%)]. No abnormal release of K+ from muscular tissue was found in the disease control groups. Data on the postexercise increase in the concentration of other muscular constituents such as creatine kinase, inorganic phosphate, or creatine exclude the possibility of a generally increased membrane permeability in MyD. The abnormally high increase of plasma K+ upon muscular exercise seems to be specific for MyD and may be related to the biochemical defect in this disease.
The neurophysiological profile of vitamin B12 deficiency
Authors: Fine Edward J. , Soria Emlllo , Paroski Margaret W. , Petryk Diane , Thomasula Linda
Published: January 2005

Reports of the incidence and severity of physiological abnormalities of vitamin B12 deficiency sharply differ. To resolve these controversies we performed evoked response and nerve conduction studies in 10 males with vitamin B12 deficiency. The minimum criteria for this diagnosis were diminished position and vibration sensation and vitamin B12 levels <220 pg/ml. We found normal BAERs in 9/10 patients. The central interpeak latencies of the median and peroneal SERs were abnormal in 4/10 and 818 patients, respectively. The VERs were abnormal in 7/10 patients. Wefound absent or diminished amplitudes of sural sensory and peroneal motor action potentials in 8/10 patients. Abnormal peroneal F response chronodispersion was present in 7/10 patients. Nerve conduction velocities (NCV) were normal in 9/10 patients. EMG demonstrated abnormalities consistent with denervation in lower extremity muscles in 8/10 patients. These studies present a profile of vitamin B12 deficiency: essentially normal BAERs, mildly abnormal VERs and median SERs, and markedly abnormal peroneal SERs. NCV studies are consistent with sensory‐motor axonopathy.
Edrophonium responsiveness not necessarily diagnostic of myasthenia gravis
Authors: Oh Shin J. , Cho Hyo K.
Published: January 2005

Uneqivocally positive edrophonium tests, both clinically and electrophysiologically, were observed in a classic case of the Lambert–Eaton myasthenic syndrome. A review of the literature revealed that a positive edrophonium response has been reported in a majority of cases of myasthenia gravis (MG) and overlap myasthenic syndrome and in some cases of the Lambert–Eaton myasthenic syndrome, botulism, congenital myasthenic syndrome, drug‐induced myasthenic syndrome, the Guillain‐Barre syndrome, and amyotrophic lateral sclerosis. From this, we conclude that anunequivocally positive edrophonium test alone is not necessarily diagnostic of MG and that the diagnosis of MG should be based on the clinical features together with edrophonium‐responsiveness and other laboratory findings.
Long‐duration polyphasic motor unit potentials in myopathies: A quantitative study with pathological correlation
Authors: Uncini Antonino , Lange Dale J. , Lovelace Robert E. , Solomon Murray , Hays Arthur P.
Published: January 2005

In most myopathies, the duration of motor unit action potentials (MUAPs) is shorter than normal. However, polyphasic MUAPs of duration longer than 20% of the control mean, (long‐duration polyphasic potentials, or LDPPs) may be seen. We therefore analyzed the incidence and meaning of LDPPs using quantitative MUAP analysis in 41 patients with different myopathies. The mean duration of all potentials was reduced in only 64% of patients because LDPPs increased the mean. When only simple potentials were considered, however, the mean duration was decreased in 95% of patients. This observation confirms the need to exclude LDPPs when calculating the mean duration of MUAPs for diagnosis. We found LDPPs most often in chronic polymyositis and in one patient with Becker Muscular Dystrophy. LDPPs are attributed to desynchronization of single‐fiber potentials within the MUAP and may be due to slow conduction in regenerating muscle fibers.
Twitch response in a myopathy with impaired relaxation but no myotonia
Authors: Quinlan John G. , Iaizzo Paul A. , Gronert Gerald A. , Lambert Edward H.
Published: January 2005

A patient with slow muscle relaxation but without accompanying motor unit or myotonic electrical activity had a unique staircase twitch response to repeated nerve stimulation. During 1‐Hz stimulation, twitches recorded by measurement of the ankle dorsiflexor group displayed progressively increasing relaxation times with successive stimuli (37% increase) unlike the progressively decreasing relaxation time of the normal response (12–37% decrease). The response may be diagnostic of this unusual myopathy; the test methods are noninvasive and easily tolerated.
Electrophysiological and histological follow‐up study in 15 Friedreich's ataxia patients
Authors: Santoro Lucio , Perretti Anna , Crisci Claudio , Ragno Michele , Massini Riccardo , Filla Alessandro , De Michele Giuseppe , Caruso Giuseppe
Published: January 2005

A clinical and electrophysiological follow‐up was carried out for 3 to 7 years on 15 patients with Friedreich's ataxia (FA). Sural nerve biopsy was performed once in all patients, and a second time 6–7 years later in three of them. Clinical worsening and progression of disturbance were evaluated according to IAP and IACR scales. Sensory orthodromic conduction along median and tibial nerves was typical of FA and did not change between first and last examinations, nor were there morphological changes between the first and the second sural nerve biopsies. Peripheral nerve involvement is thought to be a result of defective development of the largest neurons and to remain stable from a very early stage of the disease; the clinical worsening may then be due to a progressive involvement of the pyramidal tracts and the cerebellar pathways.
Serum parvalbumin, an indicator of muscle disease in murine dystrophy and myotonia
Authors: Jockusch Harald , Friedrich Gudrun , Zippel Monika
Published: January 2005

The soluble Ca++ ‐binding protein parvalbumin (PV) is highly concentrated in fast muscle fibers of the wild type mouse. Employing Sandwich ELISA, we have shown that PV is present in the serum of normal mice and that its level is indicative of the disease status of muscle. Elevated PV levels were found in mice with X‐linked dystrophy (mdx) and reduced levels in myotonic (ADR) mice. Serum creatine kinase (CK) levels were elevated in mdx and normal in ADR mice. Because myotonic mouse muscle has a strongly reduced PV content, the reduced PV serum levle in ADR mice indicated that serum PV is derived from skeletal muscle. Serum PV in mdx mice, in which muscle PV content is close to normal, is a measure of the necrosis of fast muscle fibers. Serum levels of PV and CK were not significantly elevated in heterozygous (mdx/+) carrier females. Serum PV in Duchenne patients was below the limit of detection.
The electrophysiologic profile of Dejerine–Sottas disease (HMSN III)
Authors: Benstead Timothy J. , Kuntz Nancy L. , Miller Robert G. , Daube Jasper R.
Published: January 2005

Electrophysiologic studies in 11 patients with Dejerine‐Sottas disease (hereditary motor and sensory neuropathy type III, HMSN II) showed median and ulnar motor nerve conduction velocities less than 6 m/sec in all but 1 patient. Marked temporal dispersion without conduction block was present in all patients. Uniform slowing in adjacent motor nerves was consistent with other studies of inherited neuropathies, although marked temporal dispersion may make HMSN III more difficult to distinguish from acquired neuropathies than other hereditary conditions. The electrophysiologic features of HMSN III patients were significantly different from a series of patients with other hereditary neuropathies chosen because of very slow nerve conduction velocity.
To what extent is hindlimb suspension a model of disuse?
Authors: Michel Robin N. , Gardiner Phillip F.
Published: January 2005

The extent to which the remaining active or passive components of musclemechanical stress not associated with weightbearing are involved in preserving muscle morphological and functional characteristics in the rodent hindlimb suspension model is not known. Such information would be relevant to the construction of appropriate countermeasures for the disuse atrophy associated with muscle unloading. This question was addressed by superimposing 2 weeks of hindlimb suspension and neuromuscular quiescence, achieved by the chronic neural application of the sodium channel blocker tetrodotoxin. A major portion of the muscle size characteristics of the fast anti‐gravity gastrocnemius and plantaris, and the functional characteristics of the plantaris, were maintained by the full range voluntary activity remaining after suspension. Muscle mass of the slow soleus was compromised regardless of this residual activity. Indeed, for fast ankle extensors, hindlimb unloading resembles more closely a model of normal usage than of disuse, but forslow extensors this condition appears to be extremely detrimental.
Rats immunized with cholinergic synaptosomes: A model for Lambert‐Eaton syndrome
Authors: Chapman Joab , Rabinowitz Ruth , Korczyn Amos D. , Michaelson Daniel M.
Published: January 2005

Lambert‐Eaton myasthenic syndrome (LEMS) is an autoimmune disorder characterized by reduced acetylcholine release at the neuromuscular junction. We report a model of the disease developed by active immunization of rats with purely cholinergic nerve terminals (synaptosomes) isolated from the Torpedo electric organ. Electromyographic studies of neuromuscular transmission in these rats showed a weak initial response followed by a pronounced incremental response to paired supramaximal stimuli (8 msec apart). There was no such response in control rats. There was no evidence of a postsynaptic transmission deficit in the synaptosomes immunized rats. We conclude that immunizing rats with Torpedo cholinergic nerve terminals causes a specific presynaptic dysfunction and may serve as a model for the study of LEMS.
Critical review of gangliosides and thyrotropin‐releasing hormone in peripheral neuromuscular diseases
Authors: Bradley Walter G.
Published: January 2005

The lack of effectve therapy for many of the chronic neuromuscular diseases such as amyotrophic lateral sclerosis, hereditary motor sensory neuropathy (Charcot—Marie–Tooth disease), spinocerebellar degenerations and idiopathic polyneuropathy has led to a search for substances that may stimulate peripheral nerve regeneration. Two such agents that have been proposed are gangliosides (mixed purified bovine brain gangliosides, Cronassial) and thyrotropin releasing factor (TRH). Studies on both of these agents were initially reported with enthusiasm to be successful, but later double‐blind controlled studies have failed to confirm these findings. This review provides critical analysis of the designs of studies of potentially effective agents in chronic neuromuscular diseases, and emphasizes the power of the placebo response, and the importance of designing placebos which are indistinguishable from the trial medication other than in the active effect.
Expression of a fast fiber enzyme profile in the cat soleus after spinalization
Authors: Jiang Bian , Roy Roland R. , Edgerton V. Reggie
Published: January 2005

This study was designed to determine the effects of reduced neuromuscular activity on the expression of proteins associated with contractile and metabolic functions and the size of single muscle fibers in the cat soleus. Adult cats were spinalized (Sp) at T12‐T13 and maintained in a healthy condition for 6 months. Some of the cats were trained to weight‐support (Sp‐WS) for 30 minutes per day beginning one month posttransection. Cross‐sectional area (CSA), succinate dehydrogenase (SDH), alpha‐glycerophosphate dehydrogenase (GPD), and myofibrillar adenosine triphosphatase (ATPase) activities were determined in a population of single fibers identified in frozen serial cross‐sections. Each fiber was categorized as either light or dark based on its staining density for qualitative myosin ATPase, alkaline preincubation (pH 8.75). The Sp (45%) and Sp‐WS (31%) groups had significantly higher percentages of dark ATPase fibers than control (<1%). All dark ATPase fibers were shown to react positively for a fast myosin heavy chain monoclonal antibody, while some of these fibers showed a reaction to both fast and slow myosin heavy chain antibodies. Overall mean fiber CSA were significantly smaller (∼25%) than control in both Sp groups. In the Sp‐WS, but not the Sp cats, the dark fibers were larger than the light fibers (P < 0.05), suggesting a preferential effect of postural training on the ATPase converted fibers. There were no significant differences among the three groups in any of the mean enzyme activities for either ATPase type fiber. However, there was a general tendency for the Sp cats to have elevated GPD and ATP activities per muscle; this appeared to be directly related to the percentage of fibers staining darkly for myosin ATPase. These data indicate that 6 months after spinalization some of the fibers of the slow muscle developed fast myosin staining patterns and oxidative and glycolytic enzyme profiles that are normally exhibited in fast fatigue‐resistant motor units. Periods of daily weight‐support appear to ameliorate some of these adaptations to spinalization. Further, the observation that SDH activities are maintained at control values in spinalized adult cats as well as in spinalized kittens (unpublished observations) suggest that, at least in the soleus, skeletal muscle fibers can maintain their oxidative potential even though there is a marked reduction in neuromuscular activity for 6 months.
A review of techniques employed to estimate the number of motor units in a muscle
Authors: Slawnych Michael P. , Laszlo Charles A. , Hershler Cecil
Published: January 2005

Being the smallest functional units under neural control, motor units play an integral role in muscle physiology. However, at the present time, there does not exit any widely accepted technique for quantifying or estimating the number of motor units in a muscle. Specifically, the existing techniques are the increment‐counting technique, a technique based on spike‐triggered averaging, and a macro‐EMG based technique which vary in invasiveness from noninvasive to highly invasive, respectively. We discuss each of these techniques, along with their associated shortcomings, in detail.
Inhibition of motoneuron discharge by peripheral nerve stimulation: An f response analysis
Authors: Fisher Morris A.
Published: January 2005

F waves were recorded from the abductor pollicis brevis stimulating the median nerve at the wrist. These data were compared to responses obtained after preceding supramaximal stimulation of digital fibers of the second (II) finger or the median nerve at the wrist. The time between conditioning and test stimuli were 50 msec. Following conditioning stimuli, F wave latencies were significantly increased while F amplitudes, durations, and persistences were all decreased. Chronodispersion was not significantly affected. These changes were associated with increased repetition of individual F responses. The most prominent changes were found after stimulation of fibers of digit II but only at levels of stimulation supramaximal for the sensory nerve action potential. Some, but relatively limited, changes were present after stimulation of digital fibers of the fifth finger. The results are consistrent with afferent fiber, probably A delta, inhibition of antidromic motoneuron activation with associated decrease in central motor neuron pool excitability. The study also demonstrates that, except for chronodispersion, changes in F waves found with peripheral nerve injury may also occur due to physiological changes in the central nervous system.
Expression of sodium channel subtypes during development in rat skeletal muscle
Authors: Schotland Donald L. , Fieles William , Barchi Robert L.
Published: January 2005

This study contrasts the developmental patterns of expression of 2 subtypes of the voltage‐dependent sodium channel in rat muscle that are differentiated by their immunoreactivity with monoclonal antibodies raised to the purified muscle sodium channel protein. One subtype is found in the transverse tubular (T) system of slow twitch fibers as well as the plasma membrane of fast and slow twitch fibers in the anterior tibial and soleus muscles. The second is present in the plasma membrane in all fibers of both muscles. The transverse tubular subtype exhibits 2 immunocytochemical staining patterns within muscle fibers, reticular and homogeneous, which may represent labeling of the developing T tubular system and of a cytoplasmic pool of alpha subunits of the sodium channel respectively. The reticular pattern eventually disappears in fast twitch fibers but persists into the adult stage in slow twitch fibers. The homogeneous pattern is also seen with antibodies to the plasma membrane subtype and disappears in early development as immunoreactivity to both subtypes gradually appears in the surface membrane. A reticular pattern is never seen with the plasma membrane subtype. The factors that modulate the expression of these subtypes is unknown.
AAEM case report #21: Hemifacial spasm: Preoperative diagnosis and intraoperative management
Authors: Harper C. Michel
Published: January 2005

A 75‐year‐old man developed progressive involuntary hemifacial spasm. Electrophysiologic evidence of abnormal cross‐transmission between neurons of the facial nerve was demonstrated. Electrodiagnostic studies were used to confirm the diagnosis preoperatively and determine the adequacy of vascular decompression of the facial nerve intraoperatively.
Why are slow and fast muscles differentially affected during prenatal undernutrition?
Authors: Ward Stephanie S. , Stickland Neil C.
Published: January 2005

The biceps brachii and soleus muscles (fast and slow twitch muscles, respectively) were taken from guinea‐pig fetuses, undernourished via maternal dietary intake to 60% of ad lib, and examined for differences from their controls. At birth, muscle fiber number was found to be reduced by 26% in the biceps brachii but was unaltered in the soleus muscle. An examination of the muscles at ages through gestation revealed that any reduction in fiber number was associated with a reduction in the secondary/primary fiber ratio. There was a stage in soleus myogenesis at which fiber number was significantly lower than the control. The deficit was corrected by the continuation of secondary fiber hyperplasia beyond the time of usual cessation. A similar delay was found in the biceps brachii but it did not enable recovery to a full complement of fibers. The difference between the 2 muscles was thought to be related to the relative proportions of primary fibers in the muscles, primary fiber development being apparently unaffected by undernutrition in utero.
Midbrain vs. pontine medial longitudinal fasciculus lesions: The utilization of masseter and blink reflexes
Authors: Hopf H. C. , Thömke F. , Gutmann L.
Published: January 2005

Masseter (MR) and blink reflexes (BL) were investigated in 51 patients with internuclear ophthalmoplegia (INO) due to multiple sclerosis (28) and lacunar infarction (23). The MR was abnormal in 20 of 23 cases with bilateral INO and in 21 of 28 with unilateral INO. The R1 component of the BL (BL‐R1) was abnormal in 7 of 23 patients with bilateral INO and 10 of 28 with unilateral INO. Combined MR and BL‐R1 changes occurred in 8 of 28 cases with unilateral INO and 7 of 23 with bilateral INO. The findings provide evidence for a rostral/caudal localization of lesions within the medial longitudinal fasciculus causing INO on the basis of MR and BL‐R1 abnormalities. An abnormality limited to MR suggests a midbrain location in 58.8% of patients while abnormal BL‐R1 with or without an associated MR change suggests a rostral pontine location in 35.3%.
Myofibrillar disruption in the rabbit soleus muscle after one‐week hindlimb suspension
Authors: Anzil Archinto P. , Sancesario Giuseppe , Massa Roberto , Bernardi Giorgio
Published: January 2005

Relevant muscle‐ and species‐specific differences may be found in the reaction of muscles to hindlimb suspension. This problem has been studied in 5 rabbits following a one‐week hindlimb suspension, and in 5 ground‐based controls. The soleus and the tibialis were prepared for light and transmission electron microscopy. In suspension the animals occasionally extended and flexed the hindlimbs, but, when standing still, their hindfeet were plantar‐flexed to an angle of 180°. In this position the length of the soleus was determined to be 35% less than in controls, whereas that of the tibialis was 30% more. Histologically, the tibialis fibers usually exhibited a preserved sarcomeric pattern, whereas soleus fibers displayed a regular sequence of areas of shortened sarcomeres, alternating with areas of myofibrillar disruption. These findings demonstrated that hindlimb suspension induces a focal breakdown of the soleus myofibrils, probably dependent on the reduced longitudinal tension of the suspended soleus and its phasic contractions against no load. It is conceivable that similar factors could also be responsible for soieus muscle atrophy induced by hypogravity as well as by other clinical conditions during which a stressful plantar flexion of the feet occurs against no load.
Basal lamina and superfast myosin expression in regenerating cat jaw muscle
Authors: Hoh Joseph F. Y. , Hughes Suzanne
Published: January 2005

We investigated the possible role of extracellular matrix in specifying the expression of superfast myosin during cat jaw muscle regeneration. Equal proportions of muscle tissue from jaw and limb were minced together after killing cellular elements from one source. We allowed the mince to regenerate in the bed of a fast limb muscle. Regenerates were analyzed immunocytochemically at 71 to 294 days after operation. Fibers in control regenerates containing live cells from both sources expressed fast, superfast or slow myosins, or a mixture of these myosins. In regenerates containing only one type of live cells, we detected only myosins appropriate to the live cells. Our results suggest that during regeneration the original extracellular matrix of jaw‐closing or limb muscle is unable to specify the expression of superfast or fast myosins, respectively; they point to the cellular elements, probably the satellite cells, as determinants of muscle specificity during regeneration.
Correlation of motor units with strength and spectral characteristics in polio survivors and controls
Authors: Rodriquez Arthur A. , Agre James C.
Published: January 2005

The purpose of this study was to determine whether quantitative motor unit analysis in postpolio individuals correlates with muscle strength, endurance, work capacity, or power spectral characteristics of surface EMG and to determine whether power spectrum differentiates postpolio from control subjects. This study was designed to compare these variables in 34 symptomatic postpolio, 16 asymptomatic postpolio, and 41 control subjects. Quantitative motor unit analysis of the quadriceps femoris muscle was performed using a concentric needle electrode. Isometric knee extension peak torque, endurance (time to exhaustion) at 40% of maximal torque, work capacity (tension time index), and recovery of force through 10 minutes postexhaustion were determined. Median frequency of the surface power spectrum was determined during the above testing. Power spectrum histograms were compared at the onset and termination of endurance exercise. Motor unit action potential variables did not correlate with isometric peak torque, tension time index, endurance time, recovery of strength, or with median frequency. Surface power spectrum did not differentiate postpolio from control subjects.
Usefulness of chromosome 19 RFLP haplotypes in the diagnosis of myotonic dystrophy
Authors: Nokelainen Pekka T. , Alanen‐Kurki Leena , Somer Hannu V. K. , Pihko S. Helena , Peltonen Leena
Published: January 2005

Three DNA probes (APOC2, PSC11, and LDR152) detecting RFLP polymorphisms were used to test the usefulness of the RFLP approach in myotonic dystrophy (MD) families from the isolated Finnish population. The informativeness of these polymorphisms did not differ from that reported in more mixed populations: in the 13 families of the study most of the 79 meiotic events studied were informative. One known recombinant is included in the study. The highest lod score obtained in the multilocus linkage analysis was z = 5.941 at recombination fraction θ = 0.02. The RFLP results significantly facilitated genetic counseling in problematic cases among the families studied. Although evidence could be found for linkage disequilibrium of the RFLP haplotypes formed in Finnish MD patients, our results do not exclude the possible existence of more than one ancient MD mutation in this population.
Slowly conducting myelinated fibers in peripheral neuropathy
Authors: Shefner Jeremy M. , Buchthal Fritz , Krarup Christian
Published: January 2005

The main component of the compound sensory action potential reflects the activity of large myelinated sensory fibers with diameters of greater than 9 μm. By recording the averaged potential using a needle electrode placed close to the nerve, small late components can be measured. The latency of these late components can be used to calculate minimum conduction velocity (CV); in normal subjects, average minimum CV is 15 m/s, correspending to conduction in fibers of about 4 μm in diameter. Minimum CV was measured in median, ulnar, and sural nerves of 187 patients with mild to severe neuropathic symptoms. A reduction in minimum CV was a sensitive measure of peripheral nerve dysfunction, often showing abnormalities when measures derived from the main component were normal. Patients with isolated abnormalities in minimum CV tended to have neuropathic symptoms but no signs of neuropathy. In addition, reduced minimum conduction velocity has implications for the pathology of different types of neuropathy. Slowing conducting potentials may originate from regenerating fibers, which may be of particular relevance in patients with neuropathic pain.
Aaem minimonograph #11: Needle examination in clinical electromyography
Authors: Oaube Jasper R.
Published: January 2005

The physiologic and histologic principles underlying clinical electromyographic studies are briefly reviewed as an introduction to the normal and abnormal findings in human subjects. Technical aspects of recordings as well as the specific types of discharges and their, significance are discussed.
“Smoothed histograms”: A visual aid for the analysis of distributions of muscle fiber areas
Authors: Lexell Jan , Taylor Charles
Published: January 2005

The Kernel Density Estimator (KDE) is a versatile nonparametric technique with very good theoretical properties. It is used to obtain “smoothed histograms” which allows several distributions to be presented and analyzed more easily on one graph, and direct combination into average distributions. The application of the KDE method as a visual aid for the analysis of distributions of muscle fiber areas is presented here.
AAEM minimonograph #36: Basic concepts of electricity and electronics in clinical electromyography
Authors: Barry Daniel T.
Published: January 2005

Fundamental principals of electricity provide a basis for understanding the design and operation of electromyography equipment. An intuitive and quantitative explanation of charge, voltage, current, and impedance provides an introduction to the concepts of resistance, capacitance, and input impedance. These concepts form the basis for discussion of filters, amplifiers, electrodes, digital electronics, stimulators, and patient safety. The monograph assumes no specialized training in engineering or mathematics. The topics are discussed at an introductory level to provide understanding for readers with no electronics background and intuitive insight for more experienced readers.
Muscle histology in becker muscular dystrophy
Authors: Kaido Misako , Arahata Kiichi , Hoffman Eric P. , Nonaka Ikuya , Sugita Hideo
Published: January 2005

Twenty patients with Becker muscular dystrophy (BMD), confirmed by dystrophin tests, were studied histologically. There were several morphological differences between younger (≤15‐year‐old) and older (>15‐year‐old) patients. In the younger patients, active muscle fiber necrosis followed by a regenerating process was conspicuous. In the older patients, the active degenerative changes appeared less prominent and, instead, more chronic myopathic changes such as moth‐eaten fibers, fiber splitting, and hypertrophic fibers were evident. These age‐dependent differences in the pathology of BMD were irrespective of the duration of clinical symptoms, i.e., BMD patients of a similar age showed a similar morphological feature regardless of age at onset. Although the presence of mild fiber type grouping and some small angulated atrophic fibers suggested a certain degree of neurogenic involvement, none of biopsies showed significant grouped atrophy as seen in neuropathic disorders. There was no correlation between the histological changes and the specific dystrophin abnormality.
Martin‐Gruber anastomosis and unusual sensory innervation of the fingers: Report of a case
Authors: Valls‐Sole Josep
Published: January 2005

We report the electrophysiological study of a patient with carpal tunnel syndrome who, besides the features of median nerve entrapment at the wrist, showed an aberrant motor innervation of Martin‐Gruber type and an unusual distribution of the sensory innervation of the fingers. Studies based on collision between sensory volleys showed that the fibers supplying the anomalous innervation did not follow the same path as the aberrant motor fibers. This finding is consistent with the hypothesis that Martin‐Gruber anastomosis is made up of motor axons only, and supports the idea that other abnormalities of innervation may be found in patients with Martin‐Gruber anastomosis.
Maximal and minimal motor nerve conduction velocities in patients with motor neuron diseases: Correlation with age of onset and duration of illness
Authors: Iijima Masakazu , Arasaki Keisuke , Iwamoto Hiroyuki , Nakanishi Takao
Published: January 2005

We measured the maximal and minimal motor nerve conduction velocities of the ulnar nerve in 17 patients with spinal muscular atrophy (SMA), 27 patients with amyotrophic lateral sclerosis (ALS), and 40 age‐matched control subjects. Crude values of the maximal and minimal motor nerve conduction velocities were reduced in both patient groups, but their difference in each patient was not statistically different from that of a control subject. The conduction velocities adjusted according to each patient's age were faster in SMA patients than in ALS patients. Among patients with either ALS or SMA, the age‐adjusted conduction velocities were larger in those who had developed the disease at younger ages and suffered from it for shorter periods of time. These findings suggest that the motor nerve fibers regenerate more in younger patients in the early stages of the disease, particularly in SMA.
Autosomal recessive duchenne like muscular dystrophy: Molecular and histochemical results
Authors: McGuire Stephen A. , Fischbeck Kenneth H.
Published: January 2005

An autosomal recessive disorder which mimics Duchenne muscular dystrophy has long been suspected as a cause of muscular dystrophy in karyotypically normal girls and in both boys and girls with consanguineous parents. Analysis of dystrophin now allows confirmation of the existence of this disorder. We report the results of this analysis in a brother and sister who have the typical clinical features of Duchenne muscular dystrophy, but no demonstrable abnormality in dystrophin or its gene.
Invited review: Autonomic dysfunction in peripheral nerve disease
Authors: McLeod James G.
Published: January 2005

The autonomic nervous system is affected, in most peripheral neuropathies. but only in a small number of conditions, such as diabetes, amyloidosis, Guillain‐Barré syndrome, porphyria, and familiar dysautonomia, is autonomic dysfunction of clinical importance. The pathological changes in the peripheral autonomic nervous system are similar to those in the peripheral somatic nerves. Autonomic disturbances are most likely to occur when there is acute demyelination or damage to small myelinated and unmyelinated fibers. Autonomic investigations should include tests of both sympathetic and parasympathetic function. Treatment consists of management of the underlying cause of peripheral neuropathy, physical and pharmacological measures.
Far‐field potentials in circular volumes: Evidence to support the leading/trailing dipole model
Authors: Dumitru Daniel , King John C.
Published: January 2005

The leading/trailing dipole model explains the production of far‐field potentials as an asymmetry in the leading and trailing dipole moments of a propagating action potential detected by a referential montage. This investigation documents the production of far‐field potentials produced by a pure dipole generator in a circular volume conductor. Multiple equipotential waveforms are recorded in an adjoining circular volume conductor attached to the one in which the dipole generator is located. This finding substantiates the “wick electrode” effect that explains the equipotential and instantaneous distribution of far‐field potentials over relatively large distances in volume conductors. The present findings support a number of the leading/trailing dipole model proposals which explain far‐field potential generation.
Fatigue‐related changes in motor unit action potentials of adult cats
Authors: Enoka Roger M. , Trayanova Natalia , Laouris Yiannakis , Bevan Leslie , Reinking Robert M. , Stuart Douglas G.
Published: January 2005

The purpose of this study was to quantify the changes in motor‐unit action potentials (MUAP) and force during a standard motor‐unit fatigue test. MUAP waveforms were characterized by the measurement of amplitude, duration, area, and shape (as reflected in a coefficient of proportionality). Fatigue‐resistant motor units exhibited small, but statistically significant, changes in MUAP amplitude and area during the fatigue test, whereas fatigable motor units displayed variable changes in MUAP amplitude, duration, and area. For all motor‐unit types, the coefficient of proportionality did not change, and hence the change in MUAP area was proportional to the combined changes in amplitude and duration. The between‐ and withintrain changes in MUAP were also distinct for the fatigue‐resistant and fatigable motor units. Although several mechanisms could be responsible for the changes in the MUAP as the fatigue test proceeded, the dissociation of the time courses for MUAP and force indicated that these MUAP changes were not the principal reason for the decline in force under these conditions.
Fiber density in acute and chronic inflammatory demyelinating polyneuropathy
Authors: Gantayat Maya , Swash Michael , Schwartz Martin S.
Published: January 2005

The fiber density in the deltoid, extensor digitorum communis, and first dorsal interosseous muscles was measured using SFEMG in 11 patients with acute and chronic inflammatory demyelinating polyneuropathy. The fiber density was increased in 58% of the muscles studied. The deltoid muscle was the most abnormal of the 3 muscles studied. There was no correlation with the clinical syndrome, with conduction block or slowed motor conduction, or with the distribution of weakness. Changes were noted even in patients studied within 3 weeks of presentation, suggesting that reinnervation begins soon after the onset of the disease.
Denervation increases clenbuterol sensitivity in muscle from young rats
Authors: Maltin Charlotte A. , Delday Margaret I. , Hay Susan M. , Baillie Andrew G. S.
Published: January 2005

Clenbuterol has been shown to ameliorate denervation‐induced atrophy and, therefore, clearly has therapeutic potential in the treatment of muscle wasting conditions in man. Previous studies have used dosages in rats which would be unacceptable in clinical practice, but the present results show that denervated muscle has a greater sensitivity to the drug than innervated or cardiac muscle. Fiber hypertrophy and an increase in protein and RNA content could be observed in denervated muscles but not in innervated muscles at a dose of 10 μg/kg body weight. When considered on a metabolic body weight basis, the effective dose in rats and the "safe" dose in man are surprisingly comparable. The observations imply that there is good reason to suppose that clenbuterol could be effective in ameliorating similar wasting conditions in man.
Lack of anionic phospholipid calcium binding sites in duchenne muscular dystrophy
Authors: Moggio Maurizio , Fagiolari Gigliola , Prelle Alessandro , Gallanti Andrea , Sciacco Monica , Scarlato Guglielmo
Published: January 2005

We studied membrane ultrastructural localization of anionic phospholipids (AP) and sialic acid (SA) calcium binding sites in muscle biopsies from Duchenne muscular dystrophy (DMD) and 3 Becker's muscular dystrophy (BMD) patients using polymyxin B (PXB) and limulus polyphemus (LP) as cytochemical markers. We found that AP calcium binding sites are lacking at muscle cell surface in all DMD muscle tissues, in both intact and degenerating muscle fibers. In BMD, AP have an unusual distribution along plasma membrane. Sialic acid calcium binding sites have the same localization along plasma membrane and basal lamina in DMD, BMD, and control muscles. The absence or alterations of structures involved in calcium binding in DMD and BMD may alter membrane calcium permeability, leading to abnormal Ca2+ influx into cells causing muscle necrosis.