Synergistic Effects of Temperature and Salinity on the Gene Expression and Physiology of Crassostrea virginica

The eastern oyster, Crassostrea virginica, forms reefs that provide critical services to the surrounding ecosystem. These reefs are at risk from climate change, in part because altered rainfall patterns may amplify local fluctuations in salinity, impacting oyster recruitment, survival, and growth. As in other marine organisms, warming water temperatures might interact with these changes in salinity to synergistically influence oyster physiology. In this study, we used comparative transcriptomics, measurements of physiology, and a field assessment to investigate what phenotypic changes C. virginica uses to cope with combined temperature and salinity stress in the Gulf of Mexico. Oysters from a historically low salinity site (Sister Lake, LA) were exposed to fully crossed temperature (20°C and 30°C) and salinity (25, 15, and 7 PSU) treatments. Using comparative transcriptomics on oyster gill tissue, we identified a greater number of genes that were differentially expressed (DE) in response to low salinity at warmer temperatures. Functional enrichment analysis showed low overlap between genes DE in response to thermal stress compared with hypoosmotic stress and identified enrichment for gene ontologies associated with cell adhesion, transmembrane transport, and microtubule-based process. Experiments also showed that oysters changed their physiology at elevated temperatures and lowered salinity, with significantly increased respiration rates between 20°C and 30°C. However, despite the higher energetic demands, oysters did not increase their feeding rate. To investigate transcriptional differences between populations in situ, we collected gill tissue from three locations and two time points across the Louisiana Gulf coast and used quantitative PCR to measure the expression levels of seven target genes. We found an upregulation of genes that function in osmolyte transport, oxidative stress mediation, apoptosis, and protein synthesis at our low salinity site and sampling time point. In summary, oysters altered their phenotype more in response to low salinity at higher temperatures as evidenced by a higher number of DE genes during laboratory exposure, increased respiration (higher energetic demands), and in situ differential expression by season and location. These synergistic effects of hypoosmotic stress and increased temperature suggest that climate change will exacerbate the negative effects of low salinity exposure on eastern oysters.

Exosomal cargo including microRNA regulates sensory neuron to macrophage communication after nerve trauma

Following peripheral axon injury, dysregulation of non-coding microRNAs (miRs) occurs in dorsal root ganglia (DRG) sensory neurons. Here we show that DRG neuron cell bodies release extracellular vesicles, including exosomes containing miRs, upon activity. We demonstrate that miR-21-5p is released in the exosomal fraction of cultured DRG following capsaicin activation of TRPV1 receptors. Pure sensory neuron-derived exosomes released by capsaicin are readily phagocytosed by macrophages in which an increase in miR-21-5p expression promotes a pro-inflammatory phenotype. After nerve injury in mice, miR-21-5p is upregulated in DRG neurons and both intrathecal delivery of a miR-21-5p antagomir and conditional deletion of miR-21 in sensory neurons reduce neuropathic hypersensitivity as well as the extent of inflammatory macrophage recruitment in the DRG. We suggest that upregulation and release of miR-21 contribute to sensory neuron–macrophage communication after damage to the peripheral nerve.

Exosomes are known to contain microRNAs (miRs). Here the authors show that dorsal root ganglion neurons release exosomes containing miR-21-5p, which contributes to inflammatory cell recruitment following peripheral nerve injury.

Proresolving and cartilage-protective actions of resolvin D1 in inflammatory arthritis

Rheumatoid arthritis (RA) is a debilitating disease characterized by persistent accumulation of leukocytes within the articular cavity and synovial tissue. Metabololipidomic profiling of arthritic joints from omega-3 supplemented mice identified elevated levels of specialized proresolving lipid mediators (SPM) including resolvin D1 (RvD1). Profiling of human RA synovial fluid revealed physiological levels of RvD1, which - once applied to human neutrophils - attenuated chemotaxis. These results prompted analyses of the antiarthritic properties of RvD1 in a model of murine inflammatory arthritis. The stable epimer 17R-RvD1 (100 ng/day) significantly attenuated arthritis severity, cachexia, hind-paw edema, and paw leukocyte infiltration and shortened the remission interval. Metabololipidomic profiling in arthritic joints revealed 17R-RvD1 significantly reduced PGE₂ biosynthesis, while increasing levels of protective SPM. Molecular analyses indicated that 17R-RvD1 enhanced expression of genes associated with cartilage matrix synthesis, and direct intraarticular treatment induced chondroprotection. Joint protective actions of 17R-RvD1 were abolished in RvD1 receptor-deficient mice termed ALX/fpr2/3^-/- . These investigations open new therapeutic avenues for inflammatory joint diseases, providing mechanistic substance for the benefits of omega-3 supplementation in RA.

Neutrophil-derived microvesicles enter cartilage and protect the joint in inflammatory arthritis

Microvesicles (MVs) are emerging as a new mechanism of intercellular communication by transferring cellular lipid and protein components to target cells, yet their function in disease is only now being explored. We found that neutrophil-derived MVs were increased in concentration in synovial fluid from rheumatoid arthritis patients compared to paired plasma. Synovial MVs overexpressed the proresolving, anti-inflammatory protein annexin A1 (AnxA1). Mice deficient in TMEM16F, a lipid scramblase required for microvesiculation, exhibited exacerbated cartilage damage when subjected to inflammatory arthritis. To determine the function of MVs in inflammatory arthritis, toward the possibility of MV-based therapeutics, we examined the role of immune cell-derived MVs in rodent models and in human primary chondrocytes. In vitro, exogenous neutrophil-derived AnxA1(+) MVs activated anabolic gene expression in chondrocytes, leading to extracellular matrix accumulation and cartilage protection through the reduction in stress-adaptive homeostatic mediators interleukin-8 and prostaglandin E2. In vivo, intra-articular injection of AnxA1(+) MV lessened cartilage degradation caused by inflammatory arthritis. Arthritic mice receiving adoptive transfer of whole neutrophils displayed abundant MVs within cartilage matrix and revealed that MVs, but not neutrophils themselves, can penetrate cartilage. Mechanistic studies support a model whereby MV-associated AnxA1 interacts with its receptor FPR2 (formyl peptide receptor 2)/ALX, increasing transforming growth factor-β production by chondrocytes, ultimately leading to cartilage protection. We envisage that MVs, either directly or loaded with therapeutics, can be harnessed as a unique therapeutic strategy for protection in diseases associated with cartilage degeneration.

Annexin A1-containing extracellular vesicles and polymeric nanoparticles promote epithelial wound repair

Epithelial restitution is an essential process that is required to repair barrier function at mucosal surfaces following injury. Prolonged breaches in epithelial barrier function result in inflammation and further damage; therefore, a better understanding of the epithelial restitution process has potential for improving the development of therapeutics. In this work, we demonstrate that endogenous annexin A1 (ANXA1) is released as a component of extracellular vesicles (EVs) derived from intestinal epithelial cells, and these ANXA1-containing EVs activate wound repair circuits. Compared with healthy controls, patients with active inflammatory bowel disease had elevated levels of secreted ANXA1-containing EVs in sera, indicating that ANXA1-containing EVs are systemically distributed in response to the inflammatory process and could potentially serve as a biomarker of intestinal mucosal inflammation. Local intestinal delivery of an exogenous ANXA1 mimetic peptide (Ac2-26) encapsulated within targeted polymeric nanoparticles (Ac2-26 Col IV NPs) accelerated healing of murine colonic wounds after biopsy-induced injury. Moreover, one-time systemic administration of Ac2-26 Col IV NPs accelerated recovery following experimentally induced colitis. Together, our results suggest that local delivery of proresolving peptides encapsulated within nanoparticles may represent a potential therapeutic strategy for clinical situations characterized by chronic mucosal injury, such as is seen in patients with IBD.

Cutting-edge analysis of extracellular microparticles using ImageStream(X) imaging flow cytometry

Interest in extracellular vesicle biology has exploded in the past decade, since these microstructures seem endowed with multiple roles, from blood coagulation to inter-cellular communication in pathophysiology. In order for microparticle research to evolve as a preclinical and clinical tool, accurate quantification of microparticle levels is a fundamental requirement, but their size and the complexity of sample fluids present major technical challenges. Flow cytometry is commonly used, but suffers from low sensitivity and accuracy. Use of Amnis ImageStream^X Mk II imaging flow cytometer afforded accurate analysis of calibration beads ranging from 1 μm to 20 nm; and microparticles, which could be observed and quantified in whole blood, platelet-rich and platelet-free plasma and in leukocyte supernatants. Another advantage was the minimal sample preparation and volume required. Use of this high throughput analyzer allowed simultaneous phenotypic definition of the parent cells and offspring microparticles along with real time microparticle generation kinetics. With the current paucity of reliable techniques for the analysis of microparticles, we propose that the ImageStream^X could be used effectively to advance this scientific field.

Pediatric sciatic neuropathies: a 30-year prospective study

OBJECTIVE

The incidence, cause, and prognosis of sciatic neuropathy in children is not well understood. We report our 30-year experience of 53 patients with pediatric sciatic neuropathies (SN).

METHODS

Prospective review of the history, physical examination, electrophysiologic findings, and clinical course of children with SN.

RESULTS

The etiology of SN injury was varied and included trauma (13), iatrogenic causes (13) (8 orthopedic surgeries and 5 miscellaneous surgeries), prolonged extrinsic compression and immobilization (6), tumors (7), vascular (5), idiopathic and progressive (4), infantile and nonprogressive (2), and unknown, presumed postviral (3). Electrophysiologic studies demonstrated abnormalities in motor conduction studies of the peroneal nerve in 44/53 (83%) or tibial nerve in 35/51 (67%). Sensory conduction studies were abnormal in sural nerve in 34 of 43 cases (79%), and superficial peroneal nerves in 15/25 (60%). Needle EMG was abnormal in peroneal innervated muscles in all subjects, in tibial nerve innervated muscles in 43/51 (84%), and in the hamstrings in 18/29 (62%). Prognosis for recovery was variable and depended on the etiology and the severity of the nerve injury.

CONCLUSIONS

SN is an uncommon mononeuropathy in children. The causes of SN are varied in children compared to adults. Electrophysiologic studies in children may be limited by poor tolerance but play an important role in establishing the diagnosis.

Clinically disparate stiff-person syndrome with GAD65 autoantibody in a father and daughter

Stiff-person syndrome (SPS) is a sporadic autoimmune disorder characterized by muscle stiffness with painful spasms and usually a high level of GAD65 antibody. The authors report familial SPS associated with GAD65 antibody. The clinical presentations were disparate; the father had an appendicular form of SPS and the daughter's axial SPS presented with episodic opisthotonos.

Pseudomeningoencephalitic presentation of pediatric Guillain-Barré syndrome

Guillain-Barré syndrome is an acute, autoimmune polyradiculoneuropathy that improves with immune-modulating treatment if instituted early in the illness. Preliminary diagnosis relies on the clinician's recognition of the typical symptoms and signs as supporting evidence of the illness, such as nerve conduction studies, which may not be available emergently. We report eight children with Guillain-Barré syndrome in whom the initial presentation was atypical and suggested a primary central nervous system illness. In these patients, the predominant clinical symptoms included drowsiness, headache, irritability, and meningismus, although the classic features of Guillain-Barré syndrome (weakness, hyporeflexia) were also present. The atypical presentation caused delay in diagnosis in some cases. It is important to recognize this variant of pediatric Guillain-Barré syndrome to ensure expeditious diagnosis and treatment.

Acute care pediatric electromyography

The recognition of uncommon pediatric motor unit disorders or unusual clinical presentations of common illnesses, such as Guillain-Barré syndrome (GBS), have increased the need for electromyography (EMG) in childhood critical care units. There are two different clinical sets, one appropriate to newborns and infants and the other to older children. Some illnesses that present as an acute floppy infant are not found in the differential diagnosis of motor unit disorders in the older child or adult. These include spinal muscular atrophy, postvaccine poliomyelitis, intrauterine GBS, infantile botulism, and severe myopathies, such as myotonia dystrophy, and some glycogen storage diseases. An appreciation of the neurophysiological maturational norms is essential to an effective pediatric EMG consultation for children ages 0-3 years. Additionally, the neuromuscular complications of extended intubation and sepsis in children are gaining broader recognition. An increased dialogue between clinical neurophysiologists and pediatric neurologists and intensivists in both neonatal and pediatric intensive care units is essential.

Diagnosis of pediatric neuromuscular disorders in the era of DNA analysis

Extraordinary breakthroughs in the molecular pathogenesis of muscle and nerve disease have resulted in an evolving genetic classification of neuromuscular disorders and the development of new diagnostic methods. This remarkable progress has introduced new genetic tests and has changed the indications for use of certain invasive diagnostic procedures in the evaluation of children with presumed disorders of the motor unit. In this review, we present the current diagnostic approach to the more common neuromuscular diseases of infancy and childhood and define the diagnostic role of muscle biopsy and pediatric electromyography/nerve conduction studies in the era of genetic analysis.

Guillain-Barré syndrome: perspectives with infants and children

An acute flaccid paraparesis or ascending quadriparesis in an infant or child constitutes a very important pediatric neurology emergency. The Guillain-Barré syndrome (GBS) is the most frequent cause. This is primarily an autoimmune, post-infectious, demyelinating, peripheral nervous system process. A small percentage of children develop a primary axonal process not unlike that identified more commonly in China. Because of the potential for acute respiratory compromise, any child suspected of having GBS needs immediate hospitalization. The major considerations in differential diagnosis include transverse myelitis, toxic neuropathies, tick paralysis, infantile botulism, myasthenia gravis, and dermatomyositis. On occasion, some younger children present with an acute severe pain syndrome that may mask as a pseudo-encephalopathy. Another clinical variant is the Miller-Fisher syndrome characterized by ataxia, ophthalmoparesis, and areflexia. This is associated with a high frequency of the anti-GQ-1-b antibodies. Although most children with GBS have a relatively benign clinical course, some become very ill and require intubation with intensive care monitoring. Immunomodulating treatment should be used for any child who loses the ability to walk. To date, no well-controlled study has been completed analyzing the relative merits of the two most commonly used therapies, namely plasmapheresis or intravenously administered immunoglobulin.

Mutilating hand syndrome in an infant with familial carpal tunnel syndrome

A 7-month-old infant, son of consanguinous Indian parents, presented with recurrent chewing of his digits in a median nerve distribution as the primary manifestation of carpal tunnel syndrome, in conjunction with features consistent with congenital insensitivity to pain. Electromyography (EMG) demonstrated severe median nerve entrapment at the wrist bilaterally, but other nerves were normal. In spite of clinical evidence of diffuse pain insensitivity, sural nerve and skin biopsies were normal, and he had no evidence of autonomic dysfunction. Hand findings evolved with scarring and infection of median innervated digits and loss of fine motor skills. Carpal tunnel release resulted in complete clinical resolution and significant EMG improvement. Milder symptoms and EMG evidence of median nerve entrapment were demonstrated in both parents, paternal grandparents, and several of his father's siblings. We hypothesize this child may be homozygous for a mutant allele that in its heterozygous state predisposes to familial autosomal dominant carpal tunnel syndrome. Homozygosity for this or another mutant allele may be responsible for his congenital insensitivity to pain.

Infantile phosphofructokinase deficiency with arthrogryposis: clinical benefit of a ketogenic diet

We report a 2-year-old boy with phosphofructokinase deficiency presenting in the newborn period with congenital arthrogryposis and severe myopathy, who has had significant improvement on a ketogenic diet since its institution at 4 months of age. We provide a rationale for use of this treatment and hypothesize it may be beneficial in other patients with phosphofructokinase deficiency and progressive muscular involvement. Confirmation awaits further clinical trials in carefully selected patients.

Studies of the hydrodynamic volume changes that occur during refolding of lysozyme using size-exclusion chromatography

A size-exclusion chromatography-based refolding process (SEPROS) has successfully been used to renature lysozyme at high concentrations. This process is based on the different hydrodynamic characteristics of folded and unfolded proteins and their interaction with gel filtration media. In this paper we have quantified the changes in Stokes radius, hydrodynamic volume and partition coefficient that occur when lysozyme is refolded from urea in a size-exclusion column. In 8 M urea partially folded and unfolded lysozyme were resolved using Superdex 75 HR. These two species were present at approximately the same concentration. As the urea concentration was decreased the unfolded species gradually decreased until at 4 M urea only partially folded lysozyme remained, which continued to fold on further reduction of the urea concentration. Using these results the initial mechanism for size exclusion chromatography protein refolding has been confirmed.

Pediatric radial mononeuropathies: a clinical and electromyographic study of sixteen children with review of the literature

Sixteen pediatric radial mononeuropathies were seen among 2077 electromyograms performed in the electromyography laboratory at The Children's Hospital, Boston, during 16.5 years, 1979-1995. Eight (50%) of these radial neuropathies, including 2 in newborns with apparent prenatal onset, were atraumatic, primarily related to compression in 6 and entrapment in 2. The other 8 (50%) were traumatic related to fractures or lacerations. Electromyography documented the radial neuropathy to be localized to the proximal main radial nerve trunk in 2 (13%), distal main radial nerve trunk in 9 (56%), and posterior interosseous nerve in 5 (31%) children. Significant improvement was noted in 13 of the 16 radial neuropathies--within 6-12 weeks for demyelinating lesions and up to 17 months for axonal injuries. Rarely, a child with a chronic progressive radial neuropathy or a postfracture radial neuropathy that does not improve in 3 months may require exploration.

Childhood Guillain-Barré syndrome: clinical presentation, diagnosis, and therapy

A rapidly progressive, generally symmetric, ascending flaccid paraparesis or quadriparesis that develops in an infant or child constitutes an uncommon but important pediatric neurologic emergency that requires immediate evaluation and treatment. The differential diagnosis primarily includes acute neuropathies, most commonly the childhood Guillain-Barré syndrome and, rarely, acute transverse myelitis or infantile poliomyelitis. A clinical distinction may be difficult in the younger child in whom detailed sensory examination is not possible. Although most children with Guillain-Barré syndrome usually have a benign and relatively limited clinical illness, some become severely ill, requiring intubation and careful intensive monitoring. To date, no well-controlled multi-institutional studies of treatment with either plasmapheresis or intravenously administered immunoglobulin have been developed in children despite the success of these modalities in adults. A review of the data available using these therapies is included in this study.

Intrauterine onset of a mononeuropathy: peroneal neuropathy in a newborn with electromyographic findings at age one day compatible with prenatal onset

Mononeuropathies are unusual at birth, and electromyographic (EMG) definition the first day of life has not been reported previously. Although neonatal mononeuropathies may be related to obstetric complications, prenatal mechanisms also merit consideration. We report an infant, born with a peroneal neuropathy, whose EMG was performed 18 h after birth. An isolated peroneal nerve lesion with lack of compound muscle action potential and the presence of fibrillation potentials, confined to the tibialis anterior muscle, suggested a primary intrauterine mechanism for this mononeuropathy. Because of an infant's small size, the temporal profile used in adults for appearance of EMG signs of wallerian degeneration may not apply. Inaccurate conclusions may result if the EMG standards for timing adult nerve injury are applied to newborns. To our knowledge, previous published cases of neonatal mononeuropathies have not included babies whose first EMG was performed before age 4 days. Therefore, an EMG study shortly after birth needed to be accomplished if strong support for the hypothesis of a prenatal onset were to be generated. Our findings are compatible with an intrauterine onset of this baby's peroneal neuropathy.

Guillain-Barré syndrome in children

The Guillain-Barré syndrome is a pediatric neurologic emergency and the most common cause in children of rapidly evolving, usually flaccid, weakness with associated areflexia. Two treatable illnesses, namely tick paralysis and acute cord compression, demand immediate differential diagnosis. Rarely, poliomyelitis still mimics infantile Guillain-Barré syndrome. Specific precursor infections, such as Campylobacter jejuni, are now recognized to affect the clinical presentation of Guillain-Barré syndrome. Cerebrospinal fluid evaluation and electromyography are usually diagnostic; new modalities, such as anti-GM1 antibodies, magnetic resonance imaging, and magnetic stimulation, are being evaluated in childhood Guillain-Barré syndrome. Although most cases of Guillain-Barré syndrome have benign courses, all require initial respiratory and autonomic monitoring to prevent fatal outcomes. No well-controlled pediatric studies comparing plasmapheresis with intravenous immunoglobulin have occurred. Results of treatment with either modality are encouraging. A synopsis of these reports is included in this review.

Pediatric median mononeuropathies: a clinical and electromyographic study

Seventeen children, 6 girls and 11 boys, aged 5-17 years with pediatric median mononeuropathies (PMM) were identified among 1809 who had EMGs primarily in the electromyographic laboratory at The Children's Hospital, Boston, between 1979 and 1993. Electromyography documented the PMM to be at the wrist in 7 children, including 3 children with idiopathic carpal tunnel syndrome (CTS)--1 whose symptoms were accentuated by skiing--2 with a systemic illness (mucolipidosis III and scleroderma), and in 1 child each the distal PMM was secondary to a cast or laceration. A proximal PMM was identified in 10 children, including 8 with trauma, 1 with an osteoid osteoma, and 1 with juvenile cutaneous mucinosis. Five children (3 with CTS and 1 each with mucolipidosis III and juvenile cutaneous mucinosis) had bilateral disease. The localization (59% proximal) and cause of these PMMs differed greatly from our experience with adult median neuropathies.

Electromyography and biopsy correlation with suggested protocol for evaluation of the floppy infant

Eighty infants with nonarthrogrypotic floppy infant syndrome (FIS) were evaluated between 1979 and 1990. Electromyographic data were correlated with results of muscle and nerve biopsies in 41 of 80 who had concomitant biopsies (38) or other diagnostic analyses (3). A diagnosis was made of Werdnig-Hoffmann disease (WHD) in 15, a congenital infantile polyneuropathy (IPN) in 3, neuromuscular transmission defect (NMTD) in 2, myopathy in 12, and presumed "central" hypotonia in 9. A very positive correlation rate between nerve conduction studies with electromyography and biopsy results was found in 93% (14 of 15) with WHD and 100% in IPN (3 of 3). However, only 4 of 10 infants (40%) with biopsy-proven myopathy had an abnormal EMG. Only once did the results of electromyography and biopsy conflict.

Pediatric peroneal mononeuropathy: a clinical and electromyographic study

Seventeen children with pediatric peroneal mononeuropathies evaluated between 1979 and 1991 are reported. Twelve boys and 5 girls, ranging in age from 1.5 months to 17 years, were referred for footdrop in 16 children (94%) or for lower extremity pain in 1 child (6%). Causes included compression in 10 children (59%), trauma in 3 children (18%), entrapment in 3 children (18%), and indeterminate in 1 child (5%). Based on nerve conduction studies and electromyography, the level of the pediatric peroneal mononeuropathic lesion was the common peroneal nerve in 10 children (59%), the deep peroneal nerve in 2 children (12%), and the superficial peroneal nerve in 1 child (5%). In 4 other children (24%), pediatric peroneal mononeuropathy at the knee was not more precisely identified. Surgical exploration in 3 children with progressive pediatric peroneal mononeuropathy was valuable. Improvement occurred in 13 of 17 children (76%).

McArdle's disease with late-onset symptoms: case report and review of the literature

McArdle's disease with late-onset symptoms is an unusual cause for muscle disease in older patients. The case of a patient with McArdle's disease whose symptoms began at 60 years of age is presented, and seven previous cases of late-onset McArdle's disease reported since 1963 are discussed. In five of the eight patients, the clinical presentation was similar to the early onset disorder with exercise intolerance, cramps, and myoglobinuria. In contrast, the remaining three patients presented with fixed proximal limb and bulbar weakness. Electromyography confirmed a myopathic process in four of four patients. Results of the forearm ischaemic exercise test were positive in seven of seven patients with complete myophosphorylase deficiency; results of muscle biopsies were diagnostic in all patients. McArdle's disease with late-onset symptoms is rare and clinically more variable than the early onset disorder.

Guillain-Barré syndrome in children: clinical course, electrodiagnosis, and prognosis

The electrodiagnostic features of acute childhood Guillain-Barré syndrome (GBS) have not been distinguished from those in the adult. We report nerve conduction and electromyographic data from 23 children. Sixty-one percent (14 of 23) fulfilled strict electrodiagnostic criteria for a demyelinating neuropathy, and the remainder demonstrated demyelination in at least one nerve. Reduced compound muscle action potential (CMAP) amplitude was the most common finding overall. Children less than 10 years old demonstrated significantly greater slowing of motor CV than children greater than 10 years old. Electrodiagnostic criteria associated with poor outcome (low mean CMAP and fibrillation potentials) in previous studies, primarily of adult patients, occurred in 39% (9 of 23 children). All patients on whom follow-up data were obtained recovered without residual disability. We conclude that electrodiagnostic prognostic indicators identified in general series of GBS may not apply to children.

Proximal median neuropathies: electromyographic and clinical correlation

Results of electrophysiologic and clinical findings in 17 patients with proximal median neuropathy were reviewed. The cause of neuropathy was trauma in 5 patients, overuse of the pronator teres in 3 patients, postinfectious in 2 patients, secondary to a congenital lesion in 1 patient, and undetermined in 6 patients. The neuropathy involved the main branch of the median nerve at or proximal to the pronator teres muscle (high median neuropathy) in 14 patients, and the anterior interosseous portion of the nerve in 3 patients. Electrophysiologic findings, especially needle electromyography (EMG), were more definitive than findings expected from clinical examinations. EMG and operative findings demonstrated that median nerve compression by the pronator teres produces denervation of this muscle as well as distal muscles. EMG cannot differentiate a median nerve lesion at the pronator teres from a more proximal lesion. Follow-up data were available in 7 of 10 nonsurgically managed patients, and in 6 of 7 patients with surgical decompression. Six patients in each group were either improved or normal.

Extracranial cerebrovascular disease

The prevention, management, and prognosis of patients with transient ischemic attack or stroke caused by extracranial cerebrovascular disease depend on the underlying pathophysiologic mechanisms involved. Atherosclerotic vascular disease is the predominant pathophysiologic mechanism. Management of this entity remains controversial and should be individualized. Recent data have clearly confirmed that carotid endarterectomy is better than medical therapy. Patients with a critically tight carotid stenosis appropriate in location to their symptoms are considered for carotid endarterectomy. This procedure should be performed only in the setting of excellent neuroradiologic support and surgical expertise, however, with a cumulative complication risk of less than 3%. Intimal dissection appears to be associated with a good prognosis with or without treatment. However, patients with symptoms should receive short-term therapy with antiplatelet or anticoagulant agents to prevent distal embolization. Corticosteroids are the drugs of choice for treatment of patients with extracranial arteritis. The presence of fibromuscular dysplasia in the cerebrovascular system has not proved to be a definitive risk for stroke or transient ischemic attack.

Childhood peroneal neuropathy from bone tumors

Nontraumatic childhood peroneal mononeuropathy is uncommon and should initiate a search for surgically correctable causes. In 3 children, 2 age 12 years and 1 age 13 years, unilateral footdrop developed over a few days to a month. Electrodiagnostic findings demonstrated lesions with maximal or exclusive involvement of the deep peroneal nerve. Radiologically, bony exostoses were identified at or near the fibular head in each patient. In 2 patients, the lesions were clinically occult. An osteochondroma was removed from each patient and 2 patients had excellent clinical recoveries.

Vertebral haemangioma causing acute recurrent spinal cord compression

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EMG evaluation of the floppy infant: differential diagnosis and technical aspects

Electromyographic examination of the newborn and young infant provides a relatively uncommon challenge to most electromyographers. The usual reason for referral for electromyographic studies in the newborn and young infant is to evaluate a floppy baby. The electromyographer must not only be aware of important differences in normal physiologic parameters but must also be familiar with a spectrum of diseases that are not typically encountered in the adult. The results of electromyography must also be correlated with the normal maturation of neuromuscular function. Although the most common pathophysiologic mechanisms affecting the peripheral motor unit are infantile motor neuron disease and the congenital myopathies, a large number of other disease entities warrant careful consideration.

Neurological manifestations of infective endocarditis. Review of clinical and therapeutic challenges

The nervous system is frequently involved in patients with infective endocarditis. When a careful review of presenting complaints is undertaken, neurological symptoms have been found in as high as 29% of patients. Because these manifestations may be so protean in nature, for example, stroke or transient ischaemic attack (the most common), toxic encephalopathy, meningitis, brain abscess, visual loss, seizures, headache, backache, or acute mononeuropathy, the neurologist needs to consider infective endocarditis as a possible diagnosis in many patients. During the past two decades, infective endocarditis has occurred in an ever widening clinical setting. It may often be found in persons unknown to have predisposing cardiac disease. This is particularly true in certain subsets of the population, including the elderly, patients subjected to various invasive procedures leading to nosocomial infection, and drug abusers. New diagnostic studies, including refined bacteriological culture techniques, echocardiography, computed tomography, magnetic resonance imaging, and greater availability of skillful cerebral angiography, make earlier diagnosis of infective endocarditis possible. Despite this, patients with neurological complications continue to have an uncertain prognosis.

Spontaneous reinnervation of a free muscle flap

A latissimus dorsi muscle flap was used to repair a severe traumatic avulsion defect of the dorsum of the foot in a 3-year-old girl. The severed peroneal nerve apparently regenerated across a large gap and spontaneously reinnervated the denervated muscle flap. This resulted in a functional flap as demonstrated clinically and electromyographically. Surgical methods of muscle reinnervation and the influence of neurotrophic factors are discussed.

Sciatic neuropathies in childhood: a report of ten cases and review of the literature

Primary lesions affecting the sciatic nerve are uncommon, especially in children. Isolated sciatic nerve involvement was found in ten patients during an 8 1/2-year period at a metropolitan children's hospital. Etiologic mechanisms included three with compression and one each with stretch injury after operation using the lithotomy position, stretch injury after closed reduction of hip dislocation, puncture wound, lymphoma, hypersensitivity vasculitis associated with hypereosinophilia, indeterminate lesion associated with transverse myelitis, and idiopathic progressive lesion with negative findings on exploration. Neonatal injuries associated with breech delivery or intragluteal injections were not causative factors in this series. Children with sciatic neuropathies have a variable prognosis depending on the etiology. Compression was the only potentially preventable pathophysiologic mechanism.

Acute fulminating fatal leukoencephalopathy as the only manifestation of human immunodeficiency virus infection

A case of acute human immunodeficiency virus (HIV) infection manifested by a rapidly fulminating, necrotizing, demyelinating encephalopathy that led to brain death in 5 days is reported. Autopsy demonstrated predominant white matter lesions, acute neuronal damage, and scanty cellular response. Cultures of cerebrospinal fluid were positive for HIV, suggesting an acute infection.

Bilateral hypoglossal nerve injury after bilateral carotid endarterectomy

A case of severe bilateral injury to the hypoglossal nerves after two-stage carotid endarterectomy is described. Injury to the hypoglossal nerve occurs in up to 20% of patients undergoing carotid endarterectomy and may result in mild or unnoticed deficits. These injuries must be carefully searched for in patients who will undergo a similar procedure on the opposite side since a bilateral deficit of the hypoglossal nerve is poorly tolerated, causing potentially serious impairment of speech and risk of aspiration.

Intramuscular vitamin E repletion in children with chronic cholestasis

Progressive spinocerebellar degeneration was identified in six children with chronic cholestatic liver disease and attributed to severe vitamin E deficiency. In addition to areflexia, ataxia, dysmetria, and diminished vibratory and position sense, three patients had pigmentary retinopathy. Abnormalities were present on electromyography, nerve conduction studies, and electroretinography. Because the vitamin E deficiency was not corrected by oral administration of massive doses of vitamin E, vitamin E was administered by the intramuscular route. With doses of 50 to 100 mg of vitamin E every three to seven days, over a 32-month interval (range, 15 to 44 months), vitamin E deficiency and abnormal red blood cell peroxide hemolysis were corrected. Other than discomfort and occasional edema at the site of injection, there were no side effects of parenteral vitamin E therapy. In several other studies intramuscular vitamin E therapy has produced significant neurologic improvement in patients with similar characteristics. In this study clinical progression of spinocerebellar degeneration was arrested but improvement could not be demonstrated despite adequate vitamin E replacement.

Clinical value of electrodiagnostic studies in neuromuscular disorders

EMG and conduction studies provide the physician with a precise means of defining the multiple diseases affecting the peripheral motor-sensory unit. These studies frequently provide clues that may be useful in arriving at the appropriate therapeutic decisions and in determining prognosis. Normal results may also support a suspected clinical diagnosis of inorganic illness, providing no evidence of central nervous system disease can be defined. Like any other test, however, results of EMG may be false-negative in bona fide neuromuscular disorders. This is particularly true early in a disease process; in neuropathies restricted primarily to small, unmyelinated nerve fibers; and in certain of the less virulent diseases of muscle and muscle energy metabolism.