Molecular analysis of the AGL gene: Identification of 25 novel mutations and evidence of genetic heterogeneity in patients with Glycogen Storage Disease Type III

PurposeGlycogen Storage Disease Type III (limit dextrinosis; Cori or Forbes disease) is an autosomal recessive disorder of glycogen metabolism caused by deficient activity of glycogen debranching enzyme in liver and muscle (Glycogen Storage Disease Type IIIa) or liver only (Glycogen Storage Disease Type IIIb). These two clinically distinct phenotypes are caused by mutations in the same gene (amylo-1,6-glucosidase or AGL). Although most patients with Glycogen Storage Disease Type III have private mutations, common mutations have been identified in some populations, and two specific mutations in exon 3, c.18_19delGA (p.Gln6HisfsX20) and c.16C>T (p.Gln6X), are associated with the Glycogen Storage Disease Type IIIb phenotype.MethodsTo further examine the heterogeneity found in Glycogen Storage Disease Type III patients, we have sequenced the AGL gene in 34 patients with a clinically and/or biochemically confirmed diagnosis of Glycogen Storage Disease Type III.ResultsWe have identified 38 different mutations (25 novel and 13 previously reported) and have compiled a list of all mutations previously reported in the literature.DiscussionWe conclude that Glycogen Storage Disease Type III is a highly heterogeneous disorder usually requiring full gene sequencing to identify both pathogenic mutations. The finding of at least one of the two exon 3 mutations in all of the Glycogen Storage Disease Type IIIb patients tested allows for diagnosis of this subtype without the need for a muscle biopsy.     

Echocardiographic manifestations of Glycogen Storage Disease III: Increase in wall thickness and left ventricular mass over time

PurposeGlycogen Storage Disease Type III, glycogen debranching enzyme deficiency, causes accumulation of glycogen in liver, skeletal, and cardiac muscle. Some patients develop increased left ventricular thickness by echocardiography, but the rate of increase and its significance remain unclear.MethodsWe evaluated 33 patients with Glycogen Storage Disease Type III, 23 with IIIa and 10 with IIIb, ages 1 month to 55.5 years, by echocardiography for wall thickness, left ventricular mass, shortening and ejection fractions, at 1 time point (n = 33) and at 2 time points in patients with more than 1 echocardiogram (13 of the 33).ResultsOf 23 cross-sectional patients with type IIIa, 12 had elevated left ventricular mass, 11 had elevated wall thickness. One type IIIb patient had elevated left ventricular mass but four had elevated wall thickness. For those with multiple observations, 9 of 10 with type IIIa developed increased left ventricular mass over time, with three already increased at first measurement. Shortening and ejection fractions were generally normal.ConclusionElevated left ventricular mass and wall thickness is more common in patients with type IIIa but develops rarely in type IIIb, although ventricular systolic function is preserved. This suggests serial echocardiograms with attention to left ventricular thickness and mass are important for care of these patients.     

Neuromuscular features in Marfan syndrome

Marfan syndrome is a clinically and allelic heterogeneous, heritable connective tissue disorder with infrequently reported neuromuscular features. This study is the first to delineate these symptoms in a non-selected population. Neuromuscular involvement was evaluated in 10 Marfan patients through a standardized questionnaire, physical examination, nerve conduction study (NCS), needle electromyography (EMG), muscle ultrasound, laboratory investigation, and muscle biopsy. Existing neuroimages were screened for dural ectasia and spinal meningeal cysts. Twenty healthy controls with similar age distribution completed the questionnaire.
The results showed that various neuromuscular symptoms occur more frequently in the patients. Four older patients reported muscle weakness, five patients had a mild-to-moderate reduction in vibration sense, and all older patients mentioned mild functional impairments. NCS showed axonal polyneuropathy in four and EMG myopathic and neurogenic changes in all patients. Increased echo intensity and atrophy on muscle ultrasound was found in more than half of the patients. Muscle biopsies obtained in two patients showed myopathic changes in the older, female patient.
In conclusion, the majority of Marfan patients exhibited neuromuscular symptoms characterized as myopathy or polyneuropathy or both, and signs of lumbosacral radiculopathy, with symptoms being most pronounced in the older patients. Although meriting corroboration, these findings indicate a need to further the awareness of neuromuscular involvement in this population.     

Rigid spine syndrome (vacuolar variant). A quantitative electromyograhic study

BACKGROUND: Quantitative electromyography (EMG) using different needle techniques was performed as part of a complete systems review on 9 patients diagnosed with the vacuolar variant of rigid spine syndrome (RSS). Purpose: To establish statistically: (1) correlations between clinical features (patient age, disease duration, degree of weakness) and quantitative EMG; (2) correlation between different EMG parameters; (3) differences in quantitative EMG comparing patients with a healthy control group; and (4) correlate EMG with muscle pathology findings. METHODS: Nerve conduction studies and needle EMG (motorunit analysis, MacroEMG, SFEMG) were performed on Mm. triceps brachii and tibialis anterior according to standard techniques on 9 RSS patients. RESULTS: Nerve conduction studies were normal. Overall, clinical parameters did not correlate well with motorunit analysis and MacroEMG results. Motorunit analysis and MacroEMG results were significantly different comparing patients with controls. Motorunit analysis and MacroEMG correlated well with muscle biopsy findings. SFEMG results were within normal limits. CONCLUSION: Comprehensive EMG study results were compatible with a benign myopathic process. Results were consistent amongst patients within the study group, but differed significantly from the control group. Stable neuromuscular junction physiology did not accurately reflect evidence of muscle fiber degeneration and regeneration observed on muscle biopsies.     

Food-borne botulism cases in Van region in eastern Turkey: importance of electromyography in the diagnosis

OBJECTIVES: Food-borne botulism is an acute form of poisoning that results from ingestion of a toxin produced by Clostridium botulinum. Botulism toxin causes its major effect by blocking neuromuscular transmission in autonomic and motor nerve terminals. METHODS: In this study, we present the features of eleven cases of food-borne botulism admitted to our hospital in 2001. All of the cases were caused by home-prepared foods; green beans. In these cases, the main symptoms and signs were generalized muscular weakness, dry mouth, dysphagia, disponea and diplopia. Electrophysiological studies were performed on four patients. RESULTS: Motor conduction studies showed that compound muscle action potentials were decreased with normal latencies and conduction velocities. The needle electromyography showed signs of denervation potentials like fibrillation and positive waves in four patients. Repetitive nerve stimulation with high frequency (20 Hz) induced an increment close to 100% in the amplitudes in 2 of 4 patients. CONCLUSION: Although toxin could not be detected in the patients, the electromyographic findings supported our diagnosis. We concluded that electromyography has an important role in diagnosis of botulism, especially in the condition that serologic tests are negative or cannot be performed.     

Single fiber electromyography (SFEMG) in mitochondrial diseases (MD)

Conventional EMG, nerve conduction studies and SFEMG were performed in 18 patients with various phenotypes of MD. 14 cases showed findings consistent with mild myopathy, 2 patients signs of sensory-motor axonal neuropathy and 2 cases a mixture of myopathy and axonal neuropathy. Motor unit fiber density was mild increased in 8 out of 13 tested cases. Jitter was abnormal in 10 out of 18 tested patients. Jitter abnormalities were not related to myopathic or neurogenic features in the EMG study, and may be observed in muscles without clinical weakness. The results suggest the existence of neuromuscular transmission disturbances in patients with MD.     

Central nervous system and muscle involvement in dengue patients: A study from a tertiary care center

BackgroundNeurological involvement in dengue virus (DENV) infection is being increasingly reported. There is paucity of studies evaluating the relative frequency of central nervous system (CNS) and muscle involvement in dengue.ObjectivesTo evaluate the frequency and prognosis of neurological and muscle involvement in dengue, and correlate these with dengue subtypes.Study designConsecutive dengue patients were included, and their clinical features, laboratory investigations and cerebrospinal fluid (CSF) findings were recorded. Cranial MRI was done in unconscious patients and electromyography and nerve conduction study in patients with flaccid weakness. Patients were categorized into encephalopathy, encephalitis, immune mediated and dengue associated muscle dysfunction (DAMD). Outcome at 1 month and its predictors were evaluated.Results116 patients aged 5–70 years were included; 82 had dengue fever (DF), 18 had dengue hemorrhagic fever (DHF), and 16 had dengue shock syndrome (DSS). Neurological manifestations were present in 92 (79%); encephalopathy in 17 (15%), encephalitis in 22 (19%), transverse myelitis in 1 (1%) and DAMD in 52 (45%) patients. Central nervous system (CNS) involvement was commoner in DHF/DSS compared to DF (44% vs 26%). 10 patients with CNS involvement died versus 1 with DAMD. The patients in the CNS group had more frequent hypotension, renal dysfunction and respiratory failure compared to the DAMD group, and had worse outcome. DENV2 and DENV3 were the commonest serotypes, but serotypes did not differ between CNS and DAMD groups.ConclusionsDAMD is commoner than CNS involvement in dengue. CNS involvement however, is associated with more serious illness and predicts poorer outcome.     

A case of myasthenia gravis proven by ultrastructural study

Although light microscopic features of muscle are not pathognomonic in most cases of myasthenia gravis (MG), careful examination of neuromuscular junction by electron microscopy (EM) can reveal important clues for this disease. We report here a case of MG confirmed by EM study to emphasize that tissue diagnosis is still the best adjuvant to confirm the diagnosis. An 18-year-old female visited our hospital complaining of progressive muscle weakness for 3 years. She had difficulty in running, going upstairs and doing routine activities. Symptoms were aggravated with continuous work and resolved after rest. She had weakness of bilateral masseter and facial muscles and proximal portions of extremities without definite diurnal variation. Electromyography showed myopathic changes in proximal muscles of extremities. MG was considered but tensilon test was equivocal. Repetitive nerve stimulation tests revealed 20-30 percent decrease in responses to low and high rate stimulation. Muscle biopsy revealed selective type 2 atrophy. Ultrastructurally, abnormalities of neuromuscular junctions, i.e., wide primary synaptic cleft, and wide and shallow secondary synaptic clefts with mild myopathic features were present. These findings were pathognomonic for MG. Later, her symptoms were improved completely 3 months after thymectomy. The histologic finding of thymus was follicular hyperplasia.     

Inclusion body myositis : clinical and histopathological features of 36 patients

Summary Thirty-six patients (15 females, 21 males) with inclusion body myositis (IBM) were studied. The diagnosis was established according to clinical and histopathological criteria. Clinical features were insidious onset of slowly progressive muscle weakness and wasting with depressed or absent tendon reflexes especially in the lower limbs. The pattern of muscle weakness was variable. The majority of patients (58%) showed proximal and symmetrical weakness usually most prominent in the legs. Isolated distal (6%) and asymmetrical weakness (19%) was less frequently observed. Myalgia occurred in 42% of the patients. The age at onset of symptoms ranged from 20 to 73 years (mean 47 years). Serum creatine kinase levels were normal (11%) or mildly elevated (89%). Needle electromyography revealed myopathic features in about 80% of the patients, and results of nerve conduction studies were normal in most of the cases. The predominant histopathological findings were numerous muscle fibers with rimmed vacuoles (100% of the patients), groups of atrophic fibers (92%), and inflammatory infiltrates (89%). The inflammatory infiltrates were located predominantly at endomysial sites and were composed mainly of T8 cells. Electron microscopy showed characteristic intracytoplasmic filamentous inclusions in all 36 cases. Immunosuppressive treatment in 16 patients failed to prevent disease progression in all but one patient with an associated Sjögren's syndrome. It is concluded that the consistent combination of typical histopathological findings and characteristic clinical features offers a firm basis for the diagnosis of IBM. IBM should be suspected in any adult patient presenting with clinical signs of a chronic polymyositis unresponsive to immunosuppressive therapy. The etiology and pathogenesis of IBM remain to be established.Abbreviations IBM inclusion body myositis - CK creatine kinase - MHC major histocompatibility complex     

Three cases of manifesting female carriers in patients with Duchenne muscular dystrophy

Duchenne muscular dystrophy usually affects males. However, females are also affected in rare instances. Approximately 8% of female Duchenne muscular dystrophy (DMD) carriers are manifesting carriers and have muscle weakness to some extent. We investigated the clinical features of 3 female patients with dystrophinopathy diagnosed by clinical, pathological, and genetic studies at our neuromuscular disease clinic. The onset age of manifesting symptoms varied (8-28 years). Muscle weakness grade varied as follows: patient 1 showed asymmetrical bilateral proximal upper and lower extremities weakness, patient 2 showed asymmetrical bilateral upper extremities weakness similar to scapulohumoral muscular dystrophy, and patient 3 had only bilateral asymmetric proximal lower extremities weakness. Two patients had familial histories of DMD (their sons were diagnosed with DMD), but the 1 remaining patient had no familial history of DMD. The serum creatine kinase level was elevated in all patients, but it was not correlated with muscular weakness. An electromyography study showed findings of myopathy in all patients. One patient was diagnosed with a DMD carrier by a muscle biopsy with an immunohistochemical stain (dystrophin). The remaining 2 patients with familial history of DMD were diagnosed by multiplex ligation-dependent probe amplification (MLPA). There were inconsistent clinical features in the female carriers. An immunohistochemical analysis of dystrophin could be useful for female carrier patients. Also, multiplex ligation-dependent probe amplification is essential for the diagnosis of a manifesting female carrier DMD in female myopathic patients because conventional multiplex PCR could not detect the duplication and is less accurate compared to MLPA.     

Glycogen Storage Disease Type III diagnosis and management guidelines

PurposeGlycogen storage disease type III is a rare disease of variable clinical severity affecting primarily the liver, heart, and skeletal muscle. It is caused by deficient activity of glycogen debranching enzyme, which is a key enzyme in glycogen degradation. Glycogen storage disease type III manifests a wide clinical spectrum. Individuals with glycogen storage disease type III present with hepatomegaly, hypoglycemia, hyperlipidemia, and growth retardation. Those with type IIIa have symptoms related to liver disease and progressive muscle (cardiac and skeletal) involvement that varies in age of onset, rate of disease progression, and severity. Those with type IIIb primarily have symptoms related to liver disease. This guideline for the management of glycogen storage disease type III was developed as an educational resource for health care providers to facilitate prompt and accurate diagnosis and appropriate management of patients.MethodsAn international group of experts in various aspects of glycogen storage disease type III met to review the evidence base from the scientific literature and provided their expert opinions. Consensus was developed in each area of diagnosis, treatment, and management.ResultsThis management guideline specifically addresses evaluation and diagnosis across multiple organ systems (cardiovascular, gastrointestinal/nutrition, hepatic, musculoskeletal, and neuromuscular) involved in glycogen storage disease type III. Conditions to consider in a differential diagnosis stemming from presenting features and diagnostic algorithms are discussed. Aspects of diagnostic evaluation and nutritional and medical management, including care coordination, genetic counseling, hepatic transplantation, and prenatal diagnosis, are addressed.ConclusionsA guideline that will facilitate the accurate diagnosis and appropriate management of individuals with glycogen storage disease type III was developed. This guideline will help health care providers recognize patients with all forms of glycogen storage disease type III, expedite diagnosis, and minimize stress and negative sequelae from delayed diagnosis and inappropriate management. It will also help identify gaps in scientific knowledge that exist today and suggest future studies.     

A long-term follow-up study of patients with post-poliomyelitis neuromuscular symptoms

A "post-polio" syndrome characterized by new neuromuscular symptoms, including muscle weakness, may develop years after recovery from acute paralytic poliomyelitis. We studied 27 patients (mean age, 50.6 years) in whom new muscle weakness developed a mean of 28.8 years after recovery from acute polio. We reevaluated these patients during a mean follow-up period of 8.2 years (range, 4.5 to 20) after they were originally studied at the National Institutes of Health. The total mean follow-up period after the onset of new weakness was 12.2 years (range, 6 to 29). The patients were assessed with quantitative muscle testing, muscle biopsy, electromyography, and virologic and immunologic examination of the cerebrospinal fluid. Muscle strength had declined in all patients. The rate of decline averaged 1 percent per year. The decrease was irregular, with subjective plateau periods that ranged from 1 to 10 years. None of the patients had amyotrophic lateral sclerosis. Oligoclonal bands (IgG) were found in the cerebrospinal fluid of 7 of 13 patients studied, but no specific elevation of antibodies to poliovirus was observed in the cerebrospinal fluid. The newly affected muscles that were evaluated longitudinally with follow-up muscle biopsies and electromyography showed signs of chronic and new denervation. Groups of atrophic muscle fibers (group atrophy) and "neurogenic jitter" were not present. New post-polio muscle weakness is not a life-threatening form of motor-neuron deterioration. It appears that this weakness is not due to a loss of whole motor neurons, as in amyotrophic lateral sclerosis, but that it is due to a dysfunction of the surviving motor neurons that causes a slow disintegration of the terminals of individual nerve axons.     

A complex phenotype of peripheral neuropathy, myopathy, hoarseness, and hearing loss is linked to an autosomal dominant mutation in MYH14

Both peripheral neuropathy and distal myopathy are well-established inherited neuromuscular disorders characterized by progressive weakness and atrophy of the distal limb muscles. A complex phenotype of peripheral neuropathy, myopathy, hoarseness, and hearing loss was diagnosed in a large autosomal dominant Korean family. A high density single nucleotide polymorphism (SNP)-based linkage study mapped the underlying gene to a region on chromosome 19q13.3. The maximum multipoint LOD score was 3.794. Sequencing of 34 positional candidate genes in the segregating haplotype revealed a novel c.2822G>T (p.Arg941Leu) mutation in the gene MYH14, which encodes the nonmuscle myosin heavy chain 14. Clinically we observed a sequential pattern of the onset of muscle weakness starting from the anterior to the posterior leg muscle compartments followed by involvement of intrinsic hand and proximal muscles. The hearing loss and hoarseness followed the onset of distal muscle weakness. Histopathologic and electrodiagnostic studies revealed both chronic neuropathic and myopathic features in the affected patients. Although mutations in MYH14 have been shown to cause nonsyndromic autosomal dominant hearing loss (DFNA4), the peripheral neuropathy, myopathy, and hoarseness have not been associated with MYH14. Therefore, we suggest that the identified mutation in MYH14 significantly expands the phenotypic spectrum of this gene.     

Corticosteroid-sparing benefit of intravenous immunoglobulin in systemic sclerosis-associated myopathy: A comparative study in 52 patients

IntroductionLittle is known about systemic sclerosis (SSc)-associated myopathy (SScAM) treatment. Herein we evaluated the use of intravenous immunoglobulin (IVIg) in SScAM.MethodsWe conducted a retrospective study of patients with SScAM in the Internal medicine department of Cochin University Hospital between 1993 and 2017.ResultsFifty-two patients were included comprising 18 (34.6%) with limited SSc and 34 (65.4%) with diffuse SSc. SScAM occurred at a median [interquartile range (IQR)] time of 1 month [0–15] after SSc diagnosis. Thirty-four patients (65.4%) had muscle weakness, 28 (53.8%) had myalgia and 24 (46.2%) had dysphagia. Fifty patients (96.2%) had increased creatine kinase, 22/26 (84.6%) had myopathic electromyography, 10/12 (83.3%) had a high intensity signal of girdle muscles on MRI and 49/50 (98%) had abnormal muscle biopsy. Eighteen (34.6%) patients received IVIg. Severe adverse events occurred in 3/18 (16.7%) patients. When compared to patients who did not receive IVIg, patients who received IVIg had a significantly higher maximal corticosteroid (CS) dose ever, a greater decrease of CS at 3 months, and a lower CS dose at one year and at the end of follow up.ConclusionsThis study suggests the benefit of IVIg as adjunctive therapy, with an acceptable tolerance profile, and supports its use as a CS-sparing agent, in SScAM.     

Electrodiagnostic examination of lumbosacral radiculopathies

To determine the diagnostic efficacy of late responses and of magnetic stimulation in the electrodiagnostic evaluation of lumbosacral radiculopathies, 42 patients with acute monoradiculopathies of L5 or S1 were examined. We performed conventional nerve conduction studies, F-wave studies, needle electrode examination (NEE) and magnetic stimulation. The results were compared with a control group of 36 persons. In the patients with weakness, we found a diagnostic sensitivity for NEE of 90% in L5 and of 80% in S1. F-waves had the same sensitivity as NEE in the patients with weakness and were more sensitive in the group of patients without weakness (L5 80%, S1 67%). Magnetic stimulation had a sensitivity of 40% in all groups. There were also abnormalities of NEE and of F-wave studies in the patients with abnormal magnetic stimulation. It is concluded that NEE is the single most effective method in acute LSR and that F-wave studies are able to provide complementary information. Magnetically evoked motor nerve root stimulation was not found of clinically relevant diagnostic value.     

Facioscapulohumeral muscular dystrophy. A quantitative electromyographic study

BACKGROUND: Quantitative electromyography (EMG) using different needle techniques has not been performed or reported on a relatively large group of patients with facioscapulohumeral muscular dystrophy (FSHD). Purpose: To establish statistically: (1) correlations between clinical features of patients (age, disease duration and degree of weakness) and quantitative needle EMG/SFEMG,; (2) correlations between different EMG parameters in the patient group, and (3) quantitative EMG differences comparing patients with a healthy control group. METHODS: Nerve conduction studies, and needle EMG (motorunit analysis, MacroEMG, SFEMG) were performed on Mm. triceps brachii and Mm. tibialis anterior according to standard techniques on 20 patients with FSHD. RESULTS: Nerve conduction studies were normal. In Mm. triceps brachii and, to a lesser extent, Mm. tibialis anterior motorunit analysis and MacroEMG showed myopathic changes, that correlated with patient clinical parameters. In Mm. triceps brachii (but not in Mm. tibialis anterior) EMG results were statistically different in patients compared to control group data. The most sensitive indicators of a myopathy were MUP duration (motorunit analysis) and MUP area (MacroEMG). In the Mm. triceps brachii SFEMG revealed correlations between worsening pooled MCD data and patient clinical parameters. Pooled MCD results did not correlate with other MUP parameters. SFEMG showed abnormal jitter only in 2 patients with the longest disease duration. CONCLUSION: Quantitative EMG results are compatible with a mild, slowly progressive myopathy. The most sensitive indicators of early muscle disease were MUP duration (motorunit analysis) and MUP area (MacroEMG) that would not be detected on "routine" EMG SFEMG showed subtle, progressive worsening of neuromuscular junction physiology. However, quantitative EMG and SFEMG showed that muscle fiber degeneration and loss followed a course independent of muscle fiber regeneration and reinnervation.     

Mild Muscular Features in Tenascin-X Knockout Mice,A Model of Ehlers–Danlos Syndrome

Introduction: Tenascin-X (TNX) is an extracellular matrix (ECM) glycoprotein, the absence of which in humans leads to a recessive form of Ehlers–Danlos syndrome (EDS), a group of inherited connective tissue disorders characterized by joint hypermobility, skin hyperextensibility, and tissue fragility. A mouse model of TNX-deficient type EDS has been used to characterize the dermatological, orthopedic, and obstetrical features. The growing insight in the clinical overlap between myopathies and inherited connective tissue disorders asks for a study of the muscular characteristics of inherited connective tissue diseases. Therefore, this study aims to define the muscular phenotype of TNX knockout (KO) mice. Materials and methods: We performed a comprehensive study on the muscular phenotype of these TNX KO mice, consisting of standardized clinical assessment, muscle histology, and gene expression profiling of muscle tissue. Furthermore, peripheral nerve composition was studied by histology and electron microscopy. Results: The main findings are the presence of mild muscle weakness, mild myopathic features on histology, and functional upregulation of genes encoding proteins involved in ECM degradation and synthesis. Additionally, sciatic nerve samples showed mildly reduced collagen fibril density of endoneurium. Discussion: The muscular phenotype of TNX KO mice consists of mild muscle weakness with histological signs of myopathy and of increased turnover of the ECM in muscle. Furthermore, mildly reduced diameter of myelinated fibers and reduction of collagen fibril density of endoneurium may correspond with polyneuropathy in TNX-deficient EDS patients. This comprehensive assessment can serve as a starting point for further investigations on neuromuscular function in TNX KO mice.     

Electrophysiologic evaluation of Emery-Dreifuss muscular dystrophy. A single fiber and quantitative EMG study

A 16-year-old boy, the only affected member of the family, noticed early onset contracture of the elbows, and developed slowly progressive humeroperoneal weakness and atrophy, and bilateral equinus. The severe restriction of the forward flexion of the neck and thoracolumbar spine, resembled a rigid spine syndrome. An electrocardiogram showed atrioventricular conduction abnormalities. Muscle biopsy was consistent with mild myopathy. The overall conventional findings of a detailed electromyographic study in the limbs and erector trunci muscles, as well as the results of conduction velocity, automatic analysis of the voluntary pattern and single fiber electromyography studies were consistent with myopathy, although some atypical findings were found. The controversy about neurogenic and myopathic features in Emery-Dreifuss disease is discussed. The unspecific value of the flexion limitation of the spine, and the uncertain nosological position of the rigid spine syndrome are also commented.     

Lumbosarcral radiculopathties--the importance of EDX information other than needle electromyography

OBJECTIVE: This study evaluates the importance of varying electrodiagnostic (EDX) parameters abnormalities in patients with possible lumbosacral radiculopathies (LSR). METHODS: 34 patients referred for EDX studies with clinical findings consistent with a LSR without other causes for their symptoms were evaluated. Studies included not only standard (Routine EDX) nerve conduction studies (NCS) including F-waves and needle electromyography (nEMG) but also a multiparameter automated analysis system using prefabricated nerve conduction electrodes without nEMG (NC-stat EDX). RESULTS: Abnormal Routine EDX was present in 24 of the patients. Abnormal nEMG was present in only 14 of these patients, all of whom also had other relevant NCS abnormalities. Abnormal NC-stat EDX was found in 29 of the patients. In all but one patient there was agreement in the radicular localization between Routine and NC-stat EDX. In 30 patients, there was recent computed tomography or magnetic resonance imaging of the lumbosacral region. Comparable statistical agreements with the radiographic information were obtained for Routine EDX and NC-stat data. This was true including when the analyses were based on the neuroradiological evaluation of likely root injury. CONCLUSION: This study emphasizes the importance of EDX studies other than nEMG in the evaluation of patients with possible LSR and supports the value of a computerized mutliparameter methodology in these patients.     

Needle electromyography in carpal tunnel syndrome

The role of needle electromyography (EMG) in the routine evaluation of carpal tunnel syndrome (CTS) is not clear. The aim of this study was to determine if needle EMG examination of the thenar muscles could provide useful information in addition to the nerve conduction (NC) studies. Electrophysiologic procedures performed on 84 patients (103 hands) consistent with CTS were reviewed. The median thenar motor NC data were matched with the needle EMG findings in the abductor pollicis brevis (APB) muscle. The severity of the needle EMG findings in the APB muscle correlated well with the severity of the motor NC data. As the thenar compound muscle action potential amplitude decreased and the degree of nerve conduction slowing and block across the wrist increased, there was a corresponding increase in the number of enlarged motor units and decrease in the recruitment pattern in the needle EMG findings. Needle EMG examination confined to the thenar muscles in CTS does not seem to provide any further information when the NC data had already established this diagnosis, and it should not be performed routinely.