Muscle Nerve (muscle + nerve)

Distribution by Scientific Domains

Selected Abstracts

Task-specific dystonia in tabla players

Mona Ragothaman MBBS
Abstract Task-specific dystonia significantly impairs the performance of approximately 8% of musicians [Lederman RJ. Muscle Nerve 2003;27:549,561]. We describe hand dystonia in two professional musicians experienced while playing tabla, a percussion instrument. © 2004 Movement Disorder Society [source]

Vascular pathology in dermatomyositis and anatomic relations to myopathology

MUSCLE AND NERVE, Issue 1 2010
Alan Pestronk MD
Abstract The causes of perifascicular myofiber atrophy and capillary pathology in dermatomyositis are incompletely understood. We studied 11 dermatomyositis muscles by histochemistry, immunohistochemistry, and ultrastructure. We found that endomysial capillaries within regions of perifascicular atrophy are not entirely lost, but they have reduced size, endothelial loss, C5b9 complement deposits, and relatively preserved connective tissue molecules and pericytes. In all muscles, the perimysium varies regionally. Some areas contain intermediate-sized vessels. Others are avascular. In dermatomyositis, vascular perimysium contains abnormal vessel fragments, perivascular inflammation, and increased PECAM-1. Perifascicular myofiber atrophy and capillary pathology are concentrated near the avascular perimysium. We conclude that both perimysial intermediate-sized vessels and endomysial capillaries within regions of perifascicular myofiber atrophy are abnormal in dermatomyositis. Capillary damage and myofiber atrophy are concentrated in regions distant from intermediate-sized perimysial vessels. Chronic immune vascular damage and insufficiency in dermatomyositis may cause ischemia, myofiber atrophy, and capillary damage in "watershed" regions of muscle near the avascular perimysium. Muscle Nerve, 2010 [source]

Direct immunofluoresence in vasculitic neuropathy: Specificity of vascular immune deposits

MUSCLE AND NERVE, Issue 1 2010
Michael P. Collins MD
Abstract In suspected vasculitic neuropathy, vasculitis is demonstrated in only 30% of superficial peroneal nerve (SPN)/peroneus brevis muscle (PBM) specimens. Pathologic predictors of vasculitis are thus needed for non-diagnostic cases. Immune deposits in epineurial vessels have an established sensitivity but unknown specificity. In this study we assessed specificity using direct immunofluorescence (DIF) in SPN/PBM biopsies for suspected vasculitic neuropathy. Biopsies from 13 patients with vasculitis, 13 without vasculitis, and 6 with diabetic radiculoplexus neuropathy (DRPN) were stained for immunoglobulin G (IgG), IgM, and complement 3 (C3), and analyzed in a blinded manner. Vascular immunoglobulin or C3 deposits occurred in 12 of 13 nerve or muscle biopsies (11 of 13 nerves, 5 of 13 muscles) in vasculitis vs. 1 of 13 (1 of 13 nerves, 0 of 13 muscles) in controls (P = 0.00003). Specificity was 92%. For DRPN, vascular immune deposits occurred in 5 of 6 nerves or muscles (4 of 6 nerves, 1 of 5 muscles), similar to vasculitis but significantly different from controls. Epineurial/perimysial vascular deposits of immunoglobulin/C3 by DIF are a specific marker of vasculitic neuropathy. Muscle Nerve 000:000,000, 2009 [source]

Disseminated intravascular large-cell lymphoma with initial presentation mimicking Guillain,Barré syndrome

MUSCLE AND NERVE, Issue 1 2010
Qin Li Jiang MD
Abstract We report a patient with intravascular large B-cell lymphoma who initially presented with acute ascending weakness and sensory changes. Electrodiagnostic testing and cerebral spinal fluid (CSF) studies were initially suggestive of a demyelinating polyneuropathy. Further clinical evaluation and testing were consistent with mononeuropathy multiplex. Autopsy revealed disseminated intravascular large-cell lymphoma. Intravascular large-cell lymphoma should be considered in the differential diagnosis of a rapidly evolving neuropathy associated with other organ involvement. Muscle Nerve, 2010 [source]

Sonographic evaluation of the sciatic nerve in patients with lower-limb amputations

MUSCLE AND NERVE, Issue 6 2010
A. Salim Göktepe MD
Abstract Hypertrophy of the sciatic nerve after lower-limb amputation in patients with sarcomas has been previously reported by magnetic resonance imaging; however, sonographic evaluation of the sciatic nerve after lower-limb amputation due to nonmalignant causes has not been done before. Therefore, the aim of this study was to perform imaging of the sciatic nerve in lower-limb amputees and to find out whether sonographic findings were related to clinical characteristics. Twenty-three males with lower-limb amputations due to traumatic injuries were enrolled. Sonographic evaluations were performed using a linear array probe (Aloka UST-5524-7.5 MHZ). Sciatic nerve diameters were measured bilaterally at the same level, and the values of the normal limbs were taken as controls. Sciatic nerve width and thickness values were found to be greater on the amputated sides than the normal sides (P = 0.001). The thickness values were greater in above-knee amputees than below-knee amputees (P = 0.05). Subjects with a neuroma also had thicker sciatic nerves (P = 0.04). The diameters were found not to change between subjects with different liners (P > 0.05), but they were correlated with time after amputation (r = 0.6, P = 0.006; r = 0.4, P = 0.05, respectively). Our results clearly show that the sciatic nerves were wider and thicker on the amputated sides. Amputation level, duration, and the presence of a neuroma seem to affect the eventual diameters of the nerves. Muscle Nerve, 2010 [source]

The inhibitory effect of a chewing task on a human jaw reflex

MUSCLE AND NERVE, Issue 6 2010
Pauline Maillou BDS
Abstract This study was undertaken to investigate whether an inhibitory jaw reflex could be modulated by experimentally controlled conditions that mimicked symptoms of temporomandibular disorders. Reflecting on previous work, we anticipated that these conditions might suppress the reflex. Electromyographic recordings were made from a masseter muscle in 18 subjects, while electrical stimuli were applied to the upper lip. An inhibitory reflex wave (mean latency 47 ms) was identified and quantified. Immediately following an accelerated chewing task, which in most cases produced muscle fatigue and/or pain, the size of the reflex wave decreased significantly by about 30%. The suppression of inhibitory jaw reflexes by fatigue and pain may result in positive feedback, which may contribute to the symptoms of temporomandibular disorders. Future studies of temporomandibular disorder sufferers will help to determine whether such reflex changes reflect the underlying etiology and/or are a result of the temporomandibular disorder itself. Muscle Nerve, 2010 [source]

Dorsal caudal tail and sciatic motor nerve conduction studies in adult mice: Technical aspects and normative data

MUSCLE AND NERVE, Issue 6 2010
Robin H. Xia MD
Abstract Mice provide an important tool to investigate human neuromuscular disorders. The variability of electrophysiological techniques limits direct comparison between studies. The purpose of this study was to establish normative motor nerve conduction data in adult mice. The dorsal caudal tail nerve and sciatic nerve motor conduction studies were performed bilaterally on restrained anesthetized adult mice. The means and standard deviations for each electrophysiological parameter were determined in normal mice. Data were compared with inflammatory demyelinating polyneuropathy mice to determine whether these parameters discriminate between normal and abnormal peripheral nerves. Normal adult mice had a distal latency of 0.89 (±0.17) ms and 0.75 (±0.09) ms, distal compound motor unit action potential amplitude of 13.2 (±5.9) mV and 28.1 (±8.3) mV, and conduction velocity of 74.6 (±9.0) m/s and 76.5 (±8.3) m/s, respectively. These data were validated by the finding of statistically significant differences in several electrophysiological parameters that compared normal and polyneuropathy-affected mice. A standardized method for motor nerve conduction studies and associated normative data in mice should facilitate comparisons of disease severity and response to treatment between studies that use similar models. This would assist in the process of translational therapeutic drug design in neuromuscular disorders. Muscle Nerve, 2010 [source]

Immunopathogenesis of juvenile dermatomyositis

MUSCLE AND NERVE, Issue 5 2010
Sahil Khanna MBBS
Abstract There is increasing evidence for involvement of the mechanisms of the innate immune system in the pathogenesis of idiopathic inflammatory myopathies (IIMs), especially in the adult and juvenile forms of dermatomyositis. Juvenile dermatomyositis (JDM) is the most common form of childhood IIM, and this review focuses on recent advances in understanding the actions of the innate immune system in this condition. Over the last few years, great strides have been made in understanding immune dysregulation in IIM, including JDM. Novel autoantibodies have been identified, and new genetic contributions have been described. Among the most striking findings is type I interferon activity in JDM tissue and peripheral blood. This is in conjunction with the description of dysregulation of the major histocompatibility complex (MHC) class I gene and identification of plasmacytoid dendritic infiltrates as the possible cellular source of type I interferons. These findings also point toward the potential prognostic value of muscle biopsies and have helped expand our understanding of the etiopathogenesis of IIM. Muscle Nerve 41: 581,592, 2010 [source]

Ultrasonography in patients with ulnar neuropathy at the elbow: Comparison of cross-sectional area and swelling ratio with electrophysiological severity

MUSCLE AND NERVE, Issue 5 2010
Ayse Oytun Bayrak MD
Abstract The aim of this study was to determine the diagnostic value of ultrasonographic measurements in ulnar neuropathy at the elbow (UNE) and to assess the relationship between the measurements and the electrophysiological severity. The largest anteroposterior diameter (LAPD) and cross-sectional area (CSA) measurements of the ulnar nerve were noted at multiple levels along the arm, and the distal-to-proximal ratios were calculated. Almost all of the measurements and swelling ratios between patients and controls showed statistically significant differences. The largest CSA, distal/largest CSA ratio, CSA at the epicondyle, and proximal LAPD had larger areas under the curve than other measurements. The sensitivity and specificity in diagnosing UNE were 95% and 71% for the largest CSA, 83% and 85% for the distal/largest CSA ratio, 83% and 81% for the CSA at the epicondyle, and 93% and 43% for the proximal LAPD, respectively. There was a statistically significant correlation between the electrophysiological severity scale score (ESSS) and the largest CSA, the CSA at the epicondyle and 2 cm proximal to the epicondyle, and the LAPD at the level of the epicondyle (P < 0.05). None of the swelling ratios showed a significant correlation with the ESSS. The largest CSA measurement is the most valuable ultrasonographic measurement both for diagnosis and determining the severity of UNE. Muscle Nerve, 2010 [source]

Effects of stimulation frequency and pulse duration on fatigue and metabolic cost during a single bout of neuromuscular electrical stimulation

MUSCLE AND NERVE, Issue 5 2010
Julien Gondin PhD
Abstract We have investigated the effects of stimulation frequency and pulse duration on fatigue and energy metabolism in rat gastrocnemius muscle during a single bout of neuromuscular electrical stimulation (NMES). Electrical pulses were delivered at 100 Hz (1-ms pulse duration) and 20 Hz (5-ms pulse duration) for the high (HF) and low (LF) frequency protocols, respectively. As a standardization procedure, the averaged stimulation intensity, the averaged total charge, the initial peak torque, the duty cycle, the contraction duration and the torque-time integral were similar in both protocols. Fatigue was assessed using two testing trains delivered at a frequency of 100 Hz and 20 Hz before and after each protocol. Metabolic changes were investigated in vivo using 31P-magnetic resonance spectroscopy (31P-MRS) and in vitro in freeze-clamped muscles. Both LF and HF NMES protocols induced the same decrease in testing trains and metabolic changes. We conclude that, under carefully controlled and comparable conditions, the use of low stimulation frequency and long pulse duration do not minimize the occurrence of muscle fatigue or affect the corresponding stimulation-induced metabolic changes so that this combination of stimulation parameters would not be adequate in the context of rehabilitation. Muscle Nerve, 2010 [source]

Chronic inflammatory demyelinating polyneuropathy associated with tumor necrosis factor-, antagonists

MUSCLE AND NERVE, Issue 5 2010
Amer Alshekhlee MD
Abstract Biologic therapy with tumor necrosis factor (TNF)-, antagonists for rheumatoid arthritis has been well established. We describe two patients with rheumatoid arthritis who developed chronic inflammatory demyelinating polyneuropathy (CIDP) during their course of therapy with TNF-, antagonists. A 45-year-old woman and a 49-year-old man, both with a history of rheumatoid arthritis, were treated with etanercept and infliximab, respectively. Clinical signs of peripheral neuropathy developed 2 weeks and 12 months after the initiation of TNF-, antagonists. Electrodiagnostic studies at variable points during the disease course showed signs of acquired demyelination consistent with CIDP. Cerebrospinal fluid examination showed albuminocytologic dissociation (total protein concentration 118 mg/dl and 152 mg/dl, respectively). Both patients failed to improve after discontinuation of the offending agent, and they responded poorly to corticosteroids. However, there was clinical and electrophysiologic recovery after initiation of intravenous immunoglobulin (IVIg) therapy. CIDP may occur early or late during the treatment course with TNF-, antagonists. IVIg may reverse and stabilize the inflammatory process. Muscle Nerve 41: 742,747, 2010 [source]

Use of evans blue dye to compare limb muscles in exercised young and old mdx mice

MUSCLE AND NERVE, Issue 4 2010
Christine I. Wooddell PhD
Abstract Evans blue dye (EBD) is used to mark damaged and permeable muscle fibers in mouse models of muscular dystrophy and as an endpoint in therapeutic trials. We counted EBD-positive muscle fibers and extracted EBD from muscles sampled throughout the hindlimbs in young adult and old mdx mice to determine if the natural variability in morphology would allow measurement of a functional improvement in one limb compared to the contralateral limb. Following one bout of rotarod or treadmill exercise that greatly increased serum creatine kinase levels, the number of EBD+ muscle fibers in 12,19-month-old mdx mice increased 3-fold, EBD in the muscles increased, and, importantly, contralateral pairs of muscles contained similar amounts of EBD. In contrast, the intra- and interlimb amounts of EBD in 2,7-month-old mdx mice were much too variable. A therapeutic effect can more readily be measured in old mdx mice. These results will be useful in the design of therapy protocols using the mdx mouse. Muscle Nerve, 2010 [source]

The 6-minute walk test as a new outcome measure in Duchenne muscular dystrophy

MUSCLE AND NERVE, Issue 4 2010
Craig M. McDonald MD
Abstract Walking abnormalities are prominent in Duchenne muscular dystrophy (DMD). We modified the 6-minute walk test (6MWT) for use as an outcome measure in patients with DMD and evaluated its performance in 21 ambulatory boys with DMD and 34 healthy boys, ages 4 to 12 years. Boys with DMD were tested twice, ,1 week apart; controls were tested once. The groups had similar age, height, and weight. All tests were completed. Boys who fell recovered rapidly from falls without injury. Mean ± SD [range] 6-minute walk distance (6MWD) was lower in boys with DMD than in controls (366 ± 83 [125,481] m vs. 621 ± 68 [479,754] m; P < 0.0001; unpaired t -test). Test-retest correlation for boys with DMD was high (r = 0.91). Stride length (R2 = 0.89; P < 0.0001) was the major determinant of 6MWD for both boys with DMD and controls. A modified 6MWT is feasible and safe, documents disease-related limitations on ambulation, is reproducible, and offers a new outcome measure for DMD natural history and therapeutic trials. Muscle Nerve, 2010 [source]

A Patient with neurofibromatosis type 1 and Charcot,Marie,Tooth disease type 1B

MUSCLE AND NERVE, Issue 4 2010
Eric Lancaster MD
Abstract We describe a patient with both neurofibromatosis type 1 and Charcot,Marie,Tooth disease type 1B. Although one might expect an overwhelming tumor burden due to the combination of these two disorders, the two mutations did not appear to interact. Muscle Nerve 41: 555,558, 2010 [source]

Familial, demyelinating sensory and motor polyneuropathy with conduction block

MUSCLE AND NERVE, Issue 4 2010
Stephen N. Scelsa MD
Abstract Both multifocal, demyelinating features and prednisone responsiveness are rare in Charcot,Marie,Tooth (CMT) disease. We report a mother and son with a prednisone-responsive, multifocal, demyelinating, predominantly sensory polyneuropathy that was associated with an isoleucine92valine polymorphism of lipopolysaccharide-induced TNF-alpha factor (LITAF). The mother had a multifocal, acquired, demyelinating sensory and motor polyneuropathy (MADSAM)-like presentation. The son developed left peroneal neuropathy during acute Lyme disease with a subsequent relapsing, MADSAM-like illness, despite antibiotic treatment. Both shared prednisone responsiveness and multifocal, demyelinating features electrophysiologically. MADSAM may be familial (FaDSAM) and respond to prednisone. Muscle Nerve 41: 558,562, 2010 [source]

Linearity and reliability of the mechanomyographic amplitude versus dynamic torque relationships for the superficial quadriceps femoris muscles

MUSCLE AND NERVE, Issue 3 2010
Matthew S. Stock MS
Abstract The purpose of this investigation was to examine the linearity and reliability of the mechanomyographic (MMG) amplitude versus dynamic torque relationships for the vastus lateralis (VL), rectus femoris (RF), and vastus medialis (VM) muscles. Nine healthy men and 11 healthy women performed submaximal to maximal, concentric, isokinetic muscle actions of the leg extensors at 30° s,1 on two occasions. Surface MMG signals were detected from the VL, RF, and VM of the dominant thigh during both trials. The ranges of the coefficients of determination for the MMG amplitude versus dynamic torque relationships were 0.01,0.94 for the VL, 0.01,0.84 for the RF, and 0.19,0.96 for the VM. The intraclass correlation coefficients for the linear MMG amplitude versus torque slope coefficients were 0.823 (VL), 0.792 (RF), and 0.927 (VM). These results indicate that, when analyzed for individual subjects, the MMG amplitude versus dynamic torque relationships demonstrated inconsistent linearity. When using MMG in the clinical setting, dynamic muscle actions of the superficial quadriceps femoris muscles do not appear to be appropriate for assessing changes in muscle function during strength training. Muscle Nerve, 2009 [source]

Sonographic measurements of longitudinal median nerve sliding in patients following nerve repair

MUSCLE AND NERVE, Issue 3 2010
Ertan Erel FRCS
Abstract Nerve sliding may be restricted following nerve repair. This could result in increased tension across the repair site and lead to poor functional recovery of the nerve. Ultrasound was used to examine longitudinal median nerve sliding in 10 patients who had previously undergone nerve repair surgery following complete division of the median nerve. The median longitudinal movement in the forearm in response to metacarpophalangeal (MCP) joint movements was 2.15 mm on the injured side, compared with 2.54 mm on the uninjured side, a difference that was significant. There was a significant reduction in nerve sliding following repair (median = 8%, range ,8% to 54%; P = 0.02), which correlated with time from injury to surgery (rho = 0.87; P = 0.001). These results indicate that ultrasound can be used as an adjunct assessment tool to monitor both morphology and sliding of the nerve through the repair site. It may have future application in the investigation of patients with persisting functional impairment following primary nerve repair. Muscle Nerve, 2009 [source]

Effects of coil characteristics for femoral nerve magnetic stimulation

MUSCLE AND NERVE, Issue 3 2010
Katja Tomazin PhD
Abstract The aim of this study was to compare the efficiency of two coils used for femoral nerve magnetic stimulation and to compare them with electrical stimulation in inducing maximal response of the quadriceps. The mechanical and electromyographic (EMG) responses were dependent on the coil used. The 45-mm double coil showed greater efficiency to elicit a maximal quadriceps response, which was similar to electrical stimulation. Muscle Nerve, 2010 [source]

Clinical and electrophysiological parameters distinguishing acute-onset chronic inflammatory demyelinating polyneuropathy from acute inflammatory demyelinating polyneuropathy

MUSCLE AND NERVE, Issue 2 2010
Annie Dionne MD
Abstract Up to 16% of chronic inflammatory demyelinating polyneuropathy (CIDP) patients may present acutely. We performed a retrospective chart review on 30 acute inflammatory demyelinating polyneuropathy (AIDP) and 15 acute-onset CIDP (A-CIDP) patients looking for any clinical or electrophysiological parameters that might differentiate AIDP from acutely presenting CIDP. A-CIDP patients were significantly more likely to have prominent sensory signs. They were significantly less likely to have autonomic nervous system involvement, facial weakness, a preceding infectious illness, or need for mechanical ventilation. With regard to electrophysiological features, neither sural-sparing pattern, sensory ratio >1, nor the presence of A-waves was different between the two groups. This study suggests that patients presenting acutely with a demyelinating polyneuropathy and the aforementioned clinical features should be closely monitored as they may be more likely to have CIDP at follow-up. Muscle Nerve, 2010 [source]

Sensitivity of electrophysiological tests for upper and lower motor neuron dysfunction in ALS: A six-month longitudinal study

MUSCLE AND NERVE, Issue 2 2010
Mamede de Carvalho MD
Abstract By following a group of amyotrophic lateral sclerosis (ALS) patients longitudinally using lower motor neuron (LMN) and upper motor neuron (UMN) markers of dysfunction it may be possible to better understand the functional relationships between these motor systems in this disease. We used neurophysiological techniques to follow UMN and LMN dysfunction in a group of 28 patients with ALS, in comparison with the ALS functional rating scale (ALS-FRS) score and the forced vital capacity (FVC). We used motor unit number estimation (MUNE), compound muscle action potential (CMAP) amplitude, and the Neurophysiological Index (NI) to quantify the LMN disorder, and transcranial motor stimulation to study cortical motor threshold, motor-evoked response amplitude, central motor conduction time, and cortical silent period (CSP). The patients were studied shortly after diagnosis and then 6 months later, using both abductor digiti minimi muscles (ADM); ADM strength was initially >MRC 3 (Medical Research Council, UK). The NI and MUNE changed more than any other variable. CSP increased by about 30%, a change more marked than the slight increase observed in the cortical motor threshold (9%). The normal increase of CSP after acute muscle fatigue was preserved during disease progression. The CSP increase correlated with the MUNE rate of decay but not to the NI reduction, perhaps because NI includes F-wave frequency in itscalculation. There was no definite correlation between UMN and LMNdysfunction or progression, but there was a link between CSP and LMN changes in ALS. The CSP may be a useful variable in following UMN dysfunction in clinical practice and in clinical trials. Muscle Nerve, 2010 [source]

Sensory ataxic neuropathy dysarthria and ophthalmoparesis (SANDO) in a sibling pair with a homozygous p.A467T POLG mutation

MUSCLE AND NERVE, Issue 2 2010
John C. McHugh MRCPI
Abstract Two siblings who developed fifth-decade-onset, concurrent progressive sensory ataxia, dysarthria, and ophthalmoparesis were found to be homozygous for the p.A467T mutation of the polymerase gamma (POLG) gene. The clinical course in both subjects was progression to severe disability. The enlarging spectrum of sensory ataxic neuropathies associated with mitochondrial DNA (mtDNA) instability and POLG mutations should be recognized and considered in the differential diagnosis of this unusual presentation. Muscle Nerve, 2010 [source]

Predicting the effect of muscle length on fatigue during electrical stimulation

MUSCLE AND NERVE, Issue 4 2009
M. Susan Marion PhD
Abstract Mathematical models have been developed to predict fatigue during functional electrical stimulation, but the predictive accuracy at different muscle lengths is unknown. The objectives of our study were to: (1) experimentally determine the relationship between knee extension angle (20°, 40°, 65°, and 90°) and fatigue of the quadriceps muscles, and (2) predict that relationship using a mathematical model. A computer-controlled stimulator sent trains of pulses to surface electrodes on the thighs of five subjects while forces were measured at the ankle. A two-component mathematical model was developed. One component accounted for force, and the other accounted for fatigue. The model was fit to the data, and parameters were identified at 90°. The fitted subject-averaged r2 value was 0.89. The model was used to predict fatigue at the remaining angles, and the subject-averaged r2 values were >0.75. Therefore, at least 75% of the variability in the measurements was explained by the model. The force model is explicitly dependent on angle, and the fatigue model is explicitly dependent on force; therefore, the dependence of fatigue on knee angle was implicit. Muscle Nerve, 2009 [source]

Lyme disease serology in amyotrophic lateral sclerosis

MUSCLE AND NERVE, Issue 4 2009
Muddasir Qureshi MD
Abstract Lyme disease is sometimes part of the differential diagnosis for amyotrophic lateral sclerosis (ALS). Herein we report on 414 individuals with ALS at the Massachusetts General Hospital who underwent laboratory testing for Lyme disease. Twenty-four (5.8%) were seropositive, but only 4 (0.97%) had confirmed past immunoreactive infection. Two of these patients received ceftriaxone for 1 month without clinical improvement. Lyme disease was rare in 414 patients with ALS and is not likely to be causative. Muscle Nerve, 2009 [source]

Electromyographic sensitivity of peroneus tertius relative to abductor hallucis in assessment of peripheral neuropathy

MUSCLE AND NERVE, Issue 4 2009
Andrea J. Boon MD
Abstract The objective of this study was to compare the sensitivity of needle electromyography of the abductor hallucis and peroneus tertius muscles in the diagnosis of mild length-dependent peripheral neuropathy (PN). Nerve conduction studies and needle examination were performed on 50 patients with clinical evidence of mild PN. Results demonstrated that the peroneus tertius is as sensitive and is more specific than the abductor hallucis. It is particularly useful when more proximal muscles, such as the tibialis anterior and medial gastrocnemius, are not yet involved. Muscle Nerve, 2009 [source]

A RYR1 mutation associated with recessive congenital myopathy and dominant malignant hyperthermia in Asian families

MUSCLE AND NERVE, Issue 4 2009
Danielle Carpenter PhD
Abstract In this study we present 3 families with malignant hyperthermia (MH), all of Indian subcontinent descent. One individual from each of these families was fully sequenced for RYR1 and presented with the non-synonymous change c.11315G>A/p.R3772Q. When present in the homozygous state c.11315*A is associated with myopathic symptoms. Muscle Nerve, 2009 [source]

Spinal angiography and epidural venography in juvenile muscular atrophy of the distal arm "Hirayama disease"

MUSCLE AND NERVE, Issue 2 2009
Bakri Elsheikh MBBS
Abstract We studied two 16-year-old males with juvenile muscular atrophy of the distal arm, "Hirayama disease," resulting in asymmetric atrophy and weakness of the distal upper extremities. Pathogenic theories include a compressive myelopathy with or without ischemia, and occasional cases are accounted for by genetic mutations. To specifically address the ischemia hypothesis we performed spinal angiography and epidural venography. Neck flexion during spinal angiography showed a forward shift of a nonoccluded anterior spinal artery without impedance to blood flow. Epidural venography demonstrated engorgement of the posterior epidural venous plexus without obstruction to venous flow. The findings do not support large vessel obstruction as a contributory factor. The Hirayama hypothesis continues to best explain the disease pathogenesis: neck flexion causes tightening of the dura and intramedullary microcirculatory compromise with resultant nerve cell damage. The age-related factor can most likely be accounted for by a growth imbalance between the vertebral column and the cord/dural elements. Resolution of progression is associated with cessation of body growth, after which the symptoms plateau or modestly improve. Muscle Nerve 40: 206,212, 2009 [source]

Modulation of the soleus H-reflex following galvanic vestibular stimulation and cutaneous stimulation in prone human subjects

MUSCLE AND NERVE, Issue 2 2009
Catherine R. Lowrey MSc
Abstract There is evidence to suggest that vestibular and somatosensory inputs may interact when they are processed by the central nervous system, although the nature of the individual sensory contributions to this interaction is unknown. We examined the effects of a combined vestibular and cutaneous conditioning stimulus on the motoneuron pool that supplies the soleus muscle via the Hoffman reflex (H-reflex). We applied galvanic vestibular stimulation (GVS; bipolar, binaural, 500 ms, 2.5-mA square-wave pulse) and cutaneous stimulation (medial plantar nerve; 11 ms, three-pulse train, 200 HZ) to prone human subjects and examined changes in the amplitude of the H-reflex. GVS alone caused facilitation (approximately 20%) of the H-reflex, whereas ipsilateral cutaneous stimulation alone caused a 26% inhibition. Paired GVS and cutaneous stimulation resulted in a linear summation of the individual conditioning effects. H-reflex amplitudes observed after paired conditioning with GVS and cutaneous stimulation could be predicted from the amplitudes observed with individual conditioning. These results suggest that in the prone position, when the muscles are not posturally engaged, vestibular and somatosensory information appear to sum in a linear fashion to influence the reflex response of lower limb motoneurons. Muscle Nerve 40: 213,220, 2009 [source]

Acetylcholine receptor-, subunit expression in myasthenia gravis: A role for the autoantigen in pathogenesis?

MUSCLE AND NERVE, Issue 2 2009
Jian Rong Sheng PhD
Abstract Previous studies have shown increased expression of acetylcholine receptor-alpha (AChR-,) subunit transcripts in myasthenia gravis (MG) and experimental MG (EAMG), but none examined the functional properties of this overexpression. In this study we examined the mRNA and protein expression of AChR-, as well as the pattern of ,-bungarotoxin labeling in muscle tissue from EAMG mice with varying disease severity. AChR-, expression was increased considerably in endplates from mice with severe EAMG, but it was distinct and greatly in excess of ,-bungarotoxin labeling. This "aberrant expression" occurred in mice with morphologic endplate damage, and the pattern of complement and immunoglobulin deposition in muscle from these mice appeared to mirror the pattern of AChR-, expression. The loss of functional AChR in severe MG increases transcription of AChR-, mRNA, but the expressed protein is "functionally inert," failing to compensate for loss of AChR. This enhanced expression of AChR may play a role in driving the ongoing autoimmune response. Muscle Nerve 40: 279,286, 2009 [source]

Glial fibrillary acidic protein as a marker of axonal damage in chronic neuropathies

MUSCLE AND NERVE, Issue 1 2009
Francesca Notturno MD
Abstract We evaluated serum glial fibrillary acidic protein (GFAP) levels by enzyme-linked immunosorbent assay (ELISA) in controls (n = 30) and in patients with chronic sensory-motor axonal neuropathy (CSMAN) (n = 30), chronic inflammatory demyelinating polyneuropathy (CIDP) (n = 30), multifocal motor neuropathy (MMN) (n = 30), and primary muscular spinal atrophy (PMSA) (n = 15). GFAP levels, expressed as optical density, were increased in CSMAN (median = 1.05) compared to controls (median = 0.41; P < 0.05) and CIDP (median = 0.53, P < 0.05). They were also increased in PMSA (median = 0.99) compared to controls (P < 0.05) and MMN (median = 0.66; P < 0.05). To differentiate CSMAN from CIDP and PMSA from MMN, we applied a cutoff of GFAP levels at 0.66, and we obtained good sensitivity and specificity. In neuropathies, serum GFAP correlated with summated sensory nerve action potential amplitudes (r = ,0.57; P = 0.0006) and disease severity (r = 0.37; P = 0.0011). Thus, we propose serum GFAP as a marker of axonal damage and severity in chronic neuropathies. Muscle Nerve 40: 50,54, 2009 [source]

Electrophysiological studies in a mouse model of Schwartz,Jampel syndrome demonstrate muscle fiber hyperactivity of peripheral nerve origin

MUSCLE AND NERVE, Issue 1 2009
Andoni Echaniz-Laguna MD
Abstract Schwartz,Jampel syndrome (SJS) is an autosomal-recessive condition characterized by muscle stiffness and chondrodysplasia. It is due to loss-of-function hypomorphic mutations in the HSPG2 gene that encodes for perlecan, a proteoglycan secreted into the basement membrane. The origin of muscle stiffness in SJS is debated. To resolve this issue, we performed an electrophysiological investigation of an SJS mouse model with a missense mutation in the HSPG2 gene. Compound muscle action potential amplitudes, distal motor latencies, repetitive nerve stimulation tests, and sensory nerve conduction velocities of SJS mice were normal. On electromyography (EMG), neuromyotonic discharges, that is, bursts of motor unit action potentials firing at high rates (120,300 HZ), were constantly observed in SJS mice in all muscles, except in the diaphragm. Neuromyotonic discharges were not influenced by general anesthesia and disappeared with curare administration. They persisted after complete motor nerve section, terminating only with Wallerian degeneration. These results demonstrate that perlecan deficiency in SJS provokes a neuromyotonic syndrome. The findings further suggest a distal axonal localization of the generator of neuromyotonic discharges. SJS should now be considered as an inherited disorder with peripheral nerve hyperexcitability. Muscle Nerve, 2009 [source]