Diagnostic yield of electromyography in children with myopathic disorders

Development and Preliminary Validation of an Electromyography-Scoring Protocol for the Assessment and Grading of Muscle Involvement in Patients With Juvenile Idiopathic Inflammatory Myopathies

INTRODUCTION

We performed a pilot study in order to investigate the feasibility of an electromyography (EMG)-scoring protocol for the assessment of disease activity in juvenile idiopathic inflammatory myopathies (JIIM).

METHODS

Children with JIIM followed up in a tertiary-level care center underwent standardized clinical, laboratory, and EMG assessment. An EMG-scoring protocol was devised by a consensus panel including a pediatric neurophysiologist and two pediatric rheumatologists, based on a combined score obtained as the sum of (1) the presence of denervation signs (fibrillation potentials) and (2) motor unit remodeling (mixed pattern of short- and long-duration motor unit action potentials). The EMG-scoring protocol was then validated following the Outcome Measures in Rheumatoid Arthritis Clinical Trials filter for outcome measures in rheumatology and the consensus-based standards for the selection of health measurement instruments methodology.

RESULTS

Thirteen children (77% females) were included in the study, with a median age of 10 years (interquartile range: 7-17 years) and median disease duration of 11.8 months (interquartile range: 2.1-44.5). A total of 39 EMG examinations were evaluated. A strong positive association between a standardized tool for muscle strength assessment and the combined score was observed. No significant associations were found with both creatine kinase and erythrocyte sedimentation rate levels.

DISCUSSION

Our EMG-scoring protocol is the first standardized and reproducible tool for the neurophysiologic evaluation and grading of muscle involvement in patients with JIIM and could provide relevant additional information in the assessment and follow-up of these rare conditions.

Utility and practice of electrodiagnostic testing in the pediatric population: An AANEM consensus statement

Nerve conduction studies and needle electromyography, collectively known as electrodiagnostic (EDX) studies, have been available for pediatric patients for decades, but the accessibility of this diagnostic modality and the approach to testing vary significantly depending on the physician and institution. The maturation of molecular diagnostic approaches and other diagnostic technologies such as neuromuscular ultrasound indicate that an analysis of current needs and practices for EDX studies in the pediatric population is warranted. The American Association of Neuromuscular & Electrodiagnostic Medicine convened a consensus panel to perform literature searches, share collective experiences, and develop a consensus statement. The panel found that electrodiagnostic studies continue to have high utility for the diagnosis of numerous childhood neuromuscular disorders, and that standardized approaches along with the use of high-quality reference values are important to maximize the diagnostic yield of these tests in infants, children, and adolescents.

Differentiating Congenital Myopathy from Congenital Muscular Dystrophy

The congenital muscular dystrophies and congenital myopathies are a heterogenous group of diseases with a wide variety of presentations and outcomes. With the growing understanding of genetic involvement, and developing therapies, having a genetically confirmed diagnosis with phenotype correlation is essential. To achieve this, a structured approach is warranted to each child to ensure that mimickers are excluded. By structuring the evaluation appropriately, the clinician can help expedite the evaluation of these infants in a cost-effective manner. Understanding the pitfalls of each step of testing will allow the clinician to better understand variants in presentation and avoid cognitive errors in the process.

A new method for measurement of motor unit action potential duration based on correlation, a pilot study

We present a new, automatic, correlation-based method for measuring the duration of motor unit action potentials (MUAPs). The method seeks to replicate the way an expert elctromyographer uses his or her eyes, calculating the start and end of the MUAP waveform on the basis of the degree of similarity of non-excluded discharges. We analysed 68 potentials from normal deltoid muscles during slight contraction. For each MUAP, two experienced electromyographers manually determined start and end marker positions, which were used as gold standard duration positions (GSP) in our subsequent tests. The novel method was compared with Nandedkar's method and a wavelet transform-based method. To compare the three methods, the differences between the automatic marker positions and GSPs were statistically evaluated using one-factor ANOVA, the estimated mean square error, and a Chi-square test on the numbers of automatic marker placements with gross errors. All these parameters showed smaller values for the novel method and in most of the cases were statistically significant. In addition, the parameters of the new method were subjected to a sensitivity study, showing its good performance within a range of clinically useful parameter values. The new automatic method determined start and end markers in a more accurate and reliable manner than both of the acknowledged state-of-the art methods used in our comparison study. Graphical abstract The description of a new automatic duration measurement algorithm based on the similarity among discharges of the same MUAP. This method gave better results than the Nandedkar method and a highly regarded wavelet-based method. The new correlation-based method also had the lowest rate of gross aberrant errors in automatic placements.

Consensus-based recommendations for the management of juvenile dermatomyositis

Background

In 2012, a European initiative called Single Hub and Access point for pediatric Rheumatology in Europe (SHARE) was launched to optimise and disseminate diagnostic and management regimens in Europe for children and young adults with rheumatic diseases. Juvenile dermatomyositis (JDM) is a rare disease within the group of paediatric rheumatic diseases (PRDs) and can lead to significant morbidity. Evidence-based guidelines are sparse and management is mostly based on physicians' experience. Consequently, treatment regimens differ throughout Europe.

Objectives

To provide recommendations for diagnosis and treatment of JDM.

Methods

Recommendations were developed by an evidence-informed consensus process using the European League Against Rheumatism standard operating procedures. A committee was constituted, consisting of 19 experienced paediatric rheumatologists and 2 experts in paediatric exercise physiology and physical therapy, mainly from Europe. Recommendations derived from a validated systematic literature review were evaluated by an online survey and subsequently discussed at two consensus meetings using nominal group technique. Recommendations were accepted if >80% agreement was reached.

Results

In total, 7 overarching principles, 33 recommendations on diagnosis and 19 recommendations on therapy were accepted with >80% agreement among experts. Topics covered include assessment of skin, muscle and major organ involvement and suggested treatment pathways.

Conclusions

The SHARE initiative aims to identify best practices for treatment of patients suffering from PRD. Within this remit, recommendations for the diagnosis and treatment of JDM have been formulated by an evidence-informed consensus process to produce a standard of care for patients with JDM throughout Europe.

A Practical Approach to Juvenile Dermatomyositis and Juvenile Scleroderma

Juvenile dermatomyositis and juvenile scleroderma are rare multisystem autoimmune disorders. Although they share some pathognomonic hallmarks with adult onset myositis or scleroderma, there are significant differences in presentation, characteristics and associated features when the diseases present in childhood. In view of this, and the rarity of the conditions, it is important for care to be led by teams with expertise in pediatric rheumatology conditions. Prognosis has improved significantly in the West; likely due to early diagnosis and aggressive treatment with immunosuppressive medications. However, this trend is not replicated in the developing world. Early recognition of these diseases is crucial to achieve rapid and sustained remission and prevent disease or medication associated complications. This article aims to provide a practical overview for recognition, diagnosis and treatment of these conditions.

Neonatal hypotonia

Neonatal hypotonia is a common problem in the neonatal intensive care unit. The genetic differential diagnosis is broad, encompassing primary muscular dystrophies, chromosome abnormalities, neuropathies, and inborn errors of metabolism. Recognition of hypotonia is relatively straightforward, but determining the cause can be challenging. It is important for the neonatologist to have an organized approach to the assessment of neonatal hypotonia. Physical examination and history alongside basic laboratory testing and imaging aid in the differential diagnosis. Identification of the cause is essential for determining prognosis, associated morbidities, and recurrence risk. The prevailing therapeutic modality is physical, occupational, speech/feeding, and respiratory therapy.