Evolution of biomarker research in autoimmunity conditions for health professionals and clinical practice.

Medical abzymology has made a great contribution to the development of general autoimmunity theory: it has put the autoantibodies (Ab) as the key brick of the theory to the level of physiological functionality by providing such Ab with the ability to catalyze and mediate direct and independent cytotoxic effect on cellular and molecular targets. Natural catalytic autoantibodies (abzymes) while being a pool of canonical Abs and possessing catalytic activity belong to the new group of physiologically active substances whose features and properties are evolutionary consolidated in one functionally active biomolecule. Therefore, further studies on Ab-mediated autoAg degradation and other targeted Ab-mediated proteolysis may provide biomarkers of newer generations and thus a supplementary tool for assessing the disease progression and predicting disability of the patients and persons at risks. This chapter is a summary of current knowledge and prognostic perspectives toward catalytic Abs in autoimmunity and thus some autoimmune clinical cases, their role in pathogenesis, and the exploitation of both whole molecules and their constituent parts in developing highly effective targeted drugs of the future to come, and thus the therapeutic protocols being individualized.

Comparative Performance of Different Respiratory Test Parameters for Detection of Early Respiratory Insufficiency in Patients With ALS.

BACKGROUND AND OBJECTIVES: To compare the performance of different respiratory function testing parameters in a multidisciplinary amyotrophic lateral sclerosis (ALS) clinic. METHODS: Demographics, clinical data, and respiratory testing parameters were abstracted from the medical records of patients who attended a multidisciplinary ALS clinic from 2008 to 2016. We compared the performance of the 3 primary respiratory test parameters used by Medicare for the initiation of noninvasive ventilation (NIV) (forced vital capacity [FVC] < 50% predicted, maximum inspiratory pressure [MIP] < 60 cm H2O, and abnormal overnight pulse oximetry [OvOx]) on how they related to several clinically relevant attributes. RESULTS: Four hundred seventy-six patients were identified who underwent at least 1 respiratory test. Abnormalities of OvOx, MIP, and FVC occurred at a median of 1.6, 1.5, and 3.8 years from disease onset, respectively (p < 0.00001). Patients with bulbar-onset ALS exhibited earlier abnormalities in MIP and FVC than in spinal-onset ALS (p < 0.005). The median survival after an abnormal OvOx, MIP, or FVC test was 1.4, 1.4, and 0.9 years, respectively (p < 0.0001). Using the ALS Functional Rating Score respiratory subscales, at the time of reported respiratory symptoms there were abnormalities in OvOx (60%), MIP (69%), and FVC (19%). Conversely, when respiratory parameter abnormalities preceded reported respiratory symptoms, this occurred with frequencies in OvOx (79%), MIP (42%), or FVC (24%). Four hundred forty-three patients (93.1%) developed at least 1 abnormal respiratory measure meeting Medicare criteria for NIV consideration, but fewer than 50% in our cohort demonstrated NIV use. Improved survival in subjects using NIV was statistically significant in patients with bulbar-onset ALS. DISCUSSION: Abnormalities in OvOx and MIP perform better than FVC at early detection of neuromuscular respiratory weakness in ALS. Initiation of NIV in patients with respiratory insufficiency may improve the overall survival in ALS. In the setting of the COVID-19 pandemic, FVC and MIP have not been routinely performed because of infectious aerosol generation. OvOx, which we now routinely mail to patients' homes, has been used exclusively during the COVID-19 pandemic and allows for continued remote monitoring of the respiratory status of patients with ALS. CLASSIFICATION OF EVIDENCE: This cohort study provides Class III evidence that in people with ALS, OvOx and MIP are valuable respiratory parameters for the detection of early respiratory insufficiency.

Assessing electrodiagnostic skills among residents and fellows: Relationships between workplace-based assessments using the Electromyography Direct Observation Tool and other measures of trainee performance.

INTRODUCTION/AIMS: Graduate medical education programs must ensure residents and fellows acquire skills needed for independent practice. Workplace-based observational assessments are informative but can be time- and resource-intensive. In this study we sought to gather "relations-to-other-variables" validity evidence for scores generated by the Electromyography Direct Observation Tool (EMG-DOT) to inform its use as a measure of electrodiagnostic skill acquisition. METHODS: Scores on multiple assessments were compiled by trainees during Clinical Neurophysiology and Electromyography rotations at a large US academic medical center. Relationships between workplace-based EMG-DOT scores (n = 298) and scores on a prerequisite simulated patient exercise, patient experience surveys (n = 199), end-of-rotation evaluations (n = 301), and an American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM) self-assessment examination were assessed using Pearson correlations. RESULTS: Among 23 trainees, EMG-DOT scores assigned by physician raters correlated positively with end-of-rotation evaluations (r = 0.63, P = .001), but EMG-DOT scores assigned by technician raters did not (r = 0.10, P = .663). When physician and technician ratings were combined, higher EMG-DOT scores correlated with better patient experience survey scores (r = 0.42, P = .047), but not with simulated patient or AANEM self-assessment examination scores. DISCUSSION: End-of-rotation evaluations can provide valid assessments of trainee performance when completed by individuals with ample opportunities to directly observe trainees. Inclusion of observational assessments by technicians and patients provides a more comprehensive view of trainee performance. Workplace- and classroom-based assessments provide complementary information about trainee performance, reflecting underlying differences in types of skills measured.

Does limited EMG denervation in early primary lateral sclerosis predict amyotrophic lateral sclerosis?

Objective: We assessed whether a cohort of patients with primary lateral sclerosis (PLS) and limited electromyography (EMG) motor unit denervation changes evolve into amyotrophic lateral sclerosis (ALS) with prolonged follow-up. Methods: We initially ascertained all PLS patients diagnosed at Mayo Clinic-Rochester (1990-2016). Of 64 total cases, 43 had normal EMGs ("pure" PLS) during the first 4 years after symptom onset and were the focus of a prior publication, documenting absence of evolution to ALS. The remaining 21 patients had limited motor unit changes on EMG needle examination (denervation and most with fibrillation or fasciculation potentials) but insufficient to raise a strong suspicion of ALS; these 21 patients were followed to determine whether they evolved into ALS. Results: Of these 21 patients, the median follow-up was 7 years' disease duration (range: 4-27 years; IQR 5-8.5). They included 11 females (52%) with median onset-age of 57 years (range: 42-72 years). Two patients (10%) subsequently met revised El Escorial criteria for ALS after 7 and 13 years, respectively. The remainder had stable EMG changes with a persistent PLS phenotype. Among these remaining 19 patients, the PLS course was somewhat more aggressive than our previously reported series of 43 patients devoid of EMG denervation. The paraparetic variant was more common than the hemiparetic and bulbar variants, similar to "pure" PLS. Conclusions: Among PLS patients with definite but limited EMG denervation, 2/21 (10%) later developed ALS. The patients in this series had a more progressive clinical course compared to our previously reported pure PLS cases.

Diagnostic accuracy of gray scale muscle ultrasound screening for pediatric neuromuscular disease.

OBJECTIVE: Gray scale ultrasound (US) has been demonstrated to be a sensitive and specific tool in the diagnosis of pediatric neuromuscular disease (NMD). With recent advances in genetic testing, the diagnostic work up for NMD has evolved. The purpose of this study was to compare the current diagnostic value of gray scale US to previously defined sensitivities and specificities to determine when this test can add value to a patient's diagnostic workup. METHODS: Standardized quantitative gray scale US imaging was performed on 148 pediatric patients presenting for electrodiagnostic testing to evaluate for NMD. Patients were categorized as having an NMD, a non-NMD, or as "uncertain." The US results were defined as normal, borderline or abnormal based on echointensity values. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of the test were calculated. RESULTS: Forty-five percent of the patients had an NMD, 54% a non-NMD, and in 1% the diagnosis remained uncertain. US was abnormal in 73% of myopathies, 63% of neuromuscular junction disorders, 60% of generalized neuropathies and 58% of focal neuropathies. After excluding patients in whom muscle US was not expected to be abnormal (eg, sensory neuropathy), sensitivity was 83%, specificity 79%, PPV 75%, NPV 86%, and accuracy 81%. CONCLUSIONS: Quantitative gray scale muscle US still has good diagnostic value as a screening tool in pediatric NMD. As with any diagnostic test, muscle US is best used in conjunction with history and physical examination to increase specificity and diagnostic yield.

Natural History of "Pure" Primary Lateral Sclerosis.

OBJECTIVE: To assess whether primary lateral sclerosis (PLS), classified as pure when the EMG is normal, converts to amyotrophic lateral sclerosis (ALS) after longitudinal follow-up. METHODS: Retrospective chart review was performed of patients with pure PLS at Mayo Clinic in Rochester, MN (1990-2016). Inclusion criteria required a normal EMG during the first 4 years of symptoms. RESULTS: Forty-three patients had pure PLS (25 female, 58%) with a median onset age of 50 years (range 38-78 years) and median follow-up at 9 years' disease duration (range 4-36 years). The ascending paraparesis phenotype (n = 30, 70%) was most common, followed by hemiparetic onset (n = 9, 21%) and bulbar onset (n = 4, 9%). Among the 30 paraparetic-onset cases, bladder symptoms (n = 18, 60%) and dysarthria (n = 15, 50%) were more common than pseudobulbar affect (n = 9, 30%) and dysphagia (n = 8, 27%). By the last follow-up, 17 of 30 (56%) used a cane and 6 (20%) required a wheelchair. The paraparetic variant, compared with hemiparetic and bulbar onset, had the youngest onset (48 vs 56 vs 60 years, respectively; p = 0.02). Five patients died; 1 patient required a feeding tube; and none required permanent noninvasive ventilation. Two patients developed an idiopathic multisystem neurodegenerative disorder, which surfaced after 19 and 20 years. Two patients developed minor EMG abnormalities. The remainder 39 had persistently normal EMGs. CONCLUSIONS: Pure PLS did not convert to ALS after a median of 9 years' disease duration follow-up in our study population. The ascending paraparetic phenotype was most common, with earlier onset and frequent bladder involvement. After years of pure PLS, <5% develop a more pervasive neurodegenerative disorder.

Improving accuracy of myasthenia gravis autoantibody testing by reflex algorithm.

OBJECTIVE: To improve myasthenia gravis (MG) autoantibody testing. METHODS: MG serologic tests with confirmatory or refuting clinical-electrodiagnostic (EDX) testing and cancer evaluations were reviewed over 4 years (2012-2015). All patients had acetylcholine receptor-binding (AChR-Bi), modulating (AChR-Mo), and striational (STR) autoantibody testing, and negatives reflexed to muscle-specific kinase (MuSK). Thymoma and cancer occurrences were correlated with STR and reflexed glutamic acid decarboxylase 65 (GAD65), ganglionic acetylcholine receptor (α3), collapsin response mediating protein-5, and voltage-gated potassium channel complex autoantibodies. RESULTS: Of 433 samples tested, 133 (31%) met clinical-EDX criteria for MG. Best sensitivity (90%) occurred at AChR-Bi >0.02 nmol/L, leaving 14 negative (6 ocular MG, 7 generalized MG, 1 MuSK MG) with specificity 90% (31 false-positives). Using AChR-Mo antibodies (>20% loss), specificity was better (92%, 24 false-positives), but sensitivity dropped (85%). Specificity improved (95%) by testing AChR-Mo when AChR-Bi are positive, resulting in 45% reduction of false-positives (31-17), maintaining AChR-Bi 90% sensitivity. Cutoff values recommended by area under the curve analysis did not outperform this approach. AChR-Bi and AChR-Mo values were significantly higher in true-positives. CT evaluations in 121 MG samples revealed 16 thymomas. Historical or subsequent cancers occurred in 22. STR and reflexed autoantibodies were not more common in MG with thymoma or other cancers. Full-body CT (n = 34) was performed in those with STR and reflex autoantibody positivity, but without additional cancers found. CONCLUSION: Accuracy of MG serologic testing is improved by reflexing AChR-Bi-positive cases to AChR-Mo. STR and other reflexed cancer evaluation autoantibodies did not provide value beyond standard CT chest imaging at the time of MG diagnosis. Diagnostic certainty is informed by AChR-Bi and AChR-Mo with higher values increasing specificity.

Plasma creatinine and oxidative stress biomarkers in amyotrophic lateral sclerosis.

Objective: To determine the associations between plasma creatinine (PCr), plasma uric acid (PUA), and urinary oxidative stress (OS) biomarkers with the ALSFRS-R at baseline and survival in a large epidemiological cohort study (ALS COSMOS) with a well-phenotyped patient population (N = 355).Methods: Fasting plasma and first void urine samples were obtained. PCr, PUA, urinary 8-oxo-deoxy guanosine (8-oxodG), and 15-F2t-isoprostane (IsoP) were analyzed at baseline, near the midpoint of follow-up, and at the final blood draw (before death or withdrawal from study). We estimated associations between these biomarkers and the ALSFRS-R at baseline and survival.Results: At baseline, PCr correlated with ALSFRS-R (Spearman r = 0.30), percent (%) FVC (r = 0.20), PUA (r = 0.37), and 8-oxodG (r = -0.13, all p < 0.05). Baseline PCr significantly predicted survival (adjusted hazard ratio 0.28, p < 0.001). Time to death from baseline was shortest for those in the lowest two PCr quartiles relative to the highest two quartiles. PCr and ALSFRS-R values were significantly correlated at all three time points (baseline: r = 0.29, midpoint: r = 0.23, final: r = 0.38, all p < 0.001). PCr and PUA significantly declined over time, whereas OS biomarkers significantly increased over time.Conclusions: To date, PCr predicted survival the best, compared to PUA, 8-oxodG, and IsoP. Although PCr represents the degree of muscle mass, it may also represent complex biochemical changes in ALS. Because the field has no reliable prognostic biomarkers, the importance of PCr warrants further investigation through clinical studies in ALS.

Establishing Normal Values for F-Wave Latencies in Diagnosing Peripheral Neuropathies for the Pediatric Population.

PURPOSE: We present a unique technique applying F-wave latencies to assist in the diagnosis of peripheral neuropathy within the pediatric age group. METHODS: We calculated an F-wave estimated deviance adjusted for limb length measurements, distal motor conduction velocity, and distal motor latencies. We compared the F-wave estimated deviance from the normal subjects with those with peripheral neuropathy (both axonal and demyelinating) to establish diagnostic accuracy in pediatric patients. RESULTS: The normal range for the F-wave estimated deviance in the upper limb was -1 to +6 ms and in the lower limb was -8 to +5 ms. When compared with 82 subjects with peripheral neuropathy, there was a significant difference between the normal subjects and those with neuropathy (P values between 0.002 and 0.0005 for each of the individual nerves tested). CONCLUSIONS: The F-wave estimated deviance is independent of age and can be accurately applied to the electrodiagnostic testing of pediatric patients with suspected neuropathy.

Nerve conduction normal values for electrodiagnosis in pediatric patients.

INTRODUCTION: Existing normal value references for pediatric nerve conduction studies (NCS) are based on limited sample sizes with uncertain reliability, suggesting a need for better normative data. METHODS: Electronic medical records were reviewed for pediatric patients (0 to <18 years) with normal findings on electromyography and NCS during the period from January 1, 1997 through September 20, 2017. Electrodiagnostic and demographic data were collected. Gaussian and descriptive statistics were used to establish normal values by age group. RESULTS: In this study we analyzed 1,918 normal NCS on 1,849 unique pediatric patients. Patients were stratified by age: 0 to <1 month; 1 to <6 months; 6 to <12 months; 12 to <24 months; 2 to <3 years; 3 to <4 years; 4 to <5 years; 5 to <10 years; 10 to <15 years; and 15 to <18 years. Normal reference ranges for amplitude, conduction velocity, and distal latency were established for each age group for 4 motor and 4 sensory nerves. DISCUSSION: The large sample size of this study provides reliable reference values for interpreting pediatric NCS. Muscle Nerve 60: 155-160, 2019.

Musculocutaneous neuropathy.

INTRODUCTION: Isolated musculocutaneous neuropathy is uncommon. In this study we aimed to determine its causes and clinical presentation and interpret the electrodiagnostic findings associated with this condition. METHODS: Our investigation was a retrospective review of patients diagnosed with musculocutaneous neuropathy at the Mayo Clinic (Rochester, Minnesota) electromyography (EMG) laboratory between 1997 and 2015. RESULTS: Thirty-two patients with musculocutaneous neuropathy and 5 patients with lateral antebrachial cutaneous neuropathy were identified. The most common cause was acute trauma or surgery (65%). Fourteen percent of the cases were idiopathic and 14% were inflammatory. Pain and sensory disturbance were more common presentations than weakness. Weakness from nerve injury was not noted in 2 patients, suggesting that other muscles may provide adequate elbow flexion/supination. The bilateral absence of lateral antebrachial cutaneous nerve sensory responses suggests an inflammatory cause. DISCUSSION: Musculocutaneous neuropathy usually results from trauma or iatrogenic injury. Nerve conduction studies alone are insufficient to confirm neuropathy, and needle EMG examination should be a routine part of the diagnostic evaluation. Muscle Nerve 58: 726-729, 2018.

Triple Furrowed Atrophic Tongue of Myasthenia Gravis.

The authors present a case and image of a patient with refractory tongue weakness and characteristic triple furrowed pattern of atrophy due to autoimmune myasthenia gravis.

Autosomal dominant distal myopathy due to a novel ACTA1 mutation.

Mutations in skeletal muscle α-actin 1-encoding gene (ACTA1) cause autosomal dominant or recessive myopathies with marked clinical and pathological heterogeneity. Patients typically develop generalized or limb-girdle pattern of weakness, but recently a family with scapuloperoneal myopathy was reported. We describe a father and 2 children with childhood-to-juvenile onset distal myopathy, carrying a novel dominant ACTA1 variant, c.757G>C (p.Gly253Arg). Father had delayed motor development and developed significant proximal weakness later in life; he was initially misdiagnosed as having spinal muscular atrophy based on electromyographic findings. His children had predominant anterior distal leg and finger extensor involvement. Nemaline rods were abundant on the daughter's biopsy, absent on the father's initial biopsy, and extremely rare on the father's subsequent biopsy a decade later. The father's second biopsy also showed myofibrillar pathology and rare fibers with actin filament aggregates. The present family expands the spectrum of actinopathy to include a distal myopathy.

Safety of intrathecal autologous adipose-derived mesenchymal stromal cells in patients with ALS.

OBJECTIVE: To determine the safety of intrathecal autologous adipose-derived mesenchymal stromal cell treatment for amyotrophic lateral sclerosis (ALS). METHODS: Participants with ALS were enrolled and treated in this phase I dose-escalation safety trial, ranging from 1 × 107 (single dose) to 1 × 108 cells (2 monthly doses). After intrathecal treatments, participants underwent standardized follow-up, which included clinical examinations, revised ALS Functional Rating Scale (ALSFRS-R) questionnaire, blood and CSF sampling, and MRI of the neuroaxis. RESULTS: Twenty-seven patients with ALS were enrolled and treated in this study. The safety profile was positive, with the most common side effects reported being temporary low back and radicular leg pain at the highest dose level. These clinical findings were associated with elevated CSF protein and nucleated cells with MRI of thickened lumbosacral nerve roots. Autopsies from 4 treated patients did not show evidence of tumor formation. Longitudinal ALSFRS-R questionnaires confirmed continued progression of disease in all treated patients. CONCLUSIONS: Intrathecal treatment of autologous adipose-derived mesenchymal stromal cells appears safe at the tested doses in ALS. These results warrant further exploration of efficacy in phase II trials. CLASSIFICATION OF EVIDENCE: This phase I study provides Class IV evidence that in patient with ALS, intrathecal autologous adipose-derived mesenchymal stromal cell therapy is safe.

Association Between Dietary Intake and Function in Amyotrophic Lateral Sclerosis.

IMPORTANCE: There is growing interest in the role of nutrition in the pathogenesis and progression of amyotrophic lateral sclerosis (ALS). OBJECTIVE: To evaluate the associations between nutrients, individually and in groups, and ALS function and respiratory function at diagnosis. DESIGN, SETTING, AND PARTICIPANTS: A cross-sectional baseline analysis of the Amyotrophic Lateral Sclerosis Multicenter Cohort Study of Oxidative Stress study was conducted from March 14, 2008, to February 27, 2013, at 16 ALS clinics throughout the United States among 302 patients with ALS symptom duration of 18 months or less. EXPOSURES: Nutrient intake, measured using a modified Block Food Frequency Questionnaire (FFQ). MAIN OUTCOMES AND MEASURES: Amyotrophic lateral sclerosis function, measured using the ALS Functional Rating Scale-Revised (ALSFRS-R), and respiratory function, measured using percentage of predicted forced vital capacity (FVC). RESULTS: Baseline data were available on 302 patients with ALS (median age, 63.2 years [interquartile range, 55.5-68.0 years]; 178 men and 124 women). Regression analysis of nutrients found that higher intakes of antioxidants and carotenes from vegetables were associated with higher ALSFRS-R scores or percentage FVC. Empirically weighted indices using the weighted quantile sum regression method of "good" micronutrients and "good" food groups were positively associated with ALSFRS-R scores (ß [SE], 2.7 [0.69] and 2.9 [0.9], respectively) and percentage FVC (ß [SE], 12.1 [2.8] and 11.5 [3.4], respectively) (all P < .001). Positive and significant associations with ALSFRS-R scores (ß [SE], 1.5 [0.61]; P = .02) and percentage FVC (ß [SE], 5.2 [2.2]; P = .02) for selected vitamins were found in exploratory analyses. CONCLUSIONS AND RELEVANCE: Antioxidants, carotenes, fruits, and vegetables were associated with higher ALS function at baseline by regression of nutrient indices and weighted quantile sum regression analysis. We also demonstrated the usefulness of the weighted quantile sum regression method in the evaluation of diet. Those responsible for nutritional care of the patient with ALS should consider promoting fruit and vegetable intake since they are high in antioxidants and carotenes.

Electromyographic Findings in Gracilis Muscle Grafts Used to Augment Elbow Flexion in Traumatic Brachial Plexopathy.

BACKGROUND: Gracilis muscle graft transplantation is one of the last resort surgical options to restore elbow flexion in patients with chronic traumatic upper-trunk brachial plexopathies. METHODS: We retrospectively identified 34 patients who underwent surgeries between 1997 and 2014, and had postoperative follow-up for at least 12 months. Demographic, clinical, and electromyographic preoperative and postoperative data were analyzed. RESULTS: The median age of injury was 30 years old. Most subjects had a complete loss of elbow flexion preoperatively (n = 28, 82.4%). Median time from injury to surgery was 20 months (range = 3-226 months). It did not correlate with the time to reinnervation on EMG (r = 0.35, 95% CI = 0.007-0.62) or with the time improvement in muscle strength (r = 0.35, 95% CI = 0.007-0.62). The mean postoperative follow-up interval was 22.35 months. During that period, 32 of 34 (94%) patients achieved reinnervation. Median times from surgery to graft innervation and to any improvement in elbow flexor muscle power were the same (8.5 months) with overlapping time to event curves. CONCLUSION: Despite the long-standing and complete loss of elbow flexion in most of our patients, gracilis transfer surgeries have helped most of them to achieve reinnervation and start to regain function. Electromyography is a helpful tool, which along with the clinical examination, can predict postoperative improvement.

A 62-year-old man with dyspnea.

We describe the case of a 62-year-old man who presented with shortness of breath that had progressed over several years. He had a history of a paralyzed right hemidiaphragm for at least the previous 10 years. He also reported weakness in his proximal legs and daytime sleepiness. On examination, he was found to have thoracoabdominal paradox when in supine position. Pulmonary function testing revealed severe restriction; arterial blood gas showed chronic respiratory acidosis. Electromyography showed chronic phrenic neuropathy bilaterally, with mild proximal myopathy. Serum aldolase level was mildly elevated, but serologic tests for connective tissue disorders were within reference range. After extensive clinical investigations, the patient was found to have severely reduced acid α-glucosidase. Genetic analysis confirmed the diagnosis of adult-onset Pompe disease. The patient started treatment with bilevel positive airway pressure titrated during polysomnography, and acid α-glucosidase enzyme replacement was recommended.

Clinical and Electrophysiological Findings in Hereditary Inclusion Body Myopathy Compared With Sporadic Inclusion Body Myositis.

OBJECTIVE: To compare the clinical and electrophysiological findings in hereditary inclusion body myopathy (hIBM) and sporadic inclusion body myositis (sIBM) patients. METHODS: We retrospectively identified 8 genetically proven hIBM patients and 1 DNAJB6 myopathy with pathological features of hIBM, and compared their clinical, electromyographic, and serological data with a group of 51 pathologically proven sIBM patients. RESULTS: hIBM patients had a younger mean age of onset (36 vs. 60 years, P = 0.0001). Diagnostic delay was shorter in sIBM (6 vs. 15 years, P = 0.0003). Wrist flexors (P = 0.02), digit flexors (P = 0.01), digit extensors (P = 0.02), and quadriceps (P = 0.008) muscles were more frequently affected in sIBM. Fibrillation potentials were more common in sIBM patients (P = 0.03). Electrical myotonia was found in 4 hIBM patients, not significantly different from sIBM patients (P = 0.45). Creatinine kinase was higher in sIBM patients (799 vs 232, P = 0.03). CONCLUSIONS: sIBM and hIBM seem to have similar electromyographic changes. The combination of clinical, serological, and histopathological findings can guide genetic testing to the final diagnosis.

Validity and feasibility of the EMG direct observation tool (EMG-DOT).

OBJECTIVE: To develop a new workplace-based EMG direct observation tool (EMG-DOT) and gather validity evidence supporting its use for assessing electrodiagnostic skills among postgraduate medical trainees. METHODS: The EMG-DOT was developed by experts using an iterative process. Validity evidence from content, response process, internal structure, relations to other variables, and consequences of testing was collected during the 2013-2014 academic year. RESULTS: Of 3,412 studies performed by trainees during the study period, 299 (9%) were assessed using the EMG-DOT. Of these, 203 (68%) involved a physician rater and 96 (32%) involved a technician rater. The 14-item EMG-DOT had excellent internal-consistency reliability (Cronbach α 0.94). Correlations between individual items and criterion-referenced global ratings of performance ranged from 0.36 to 0.72 (all p < 0.001). Mean total scores increased from 70% to 80% over 4 months of the EMG rotation (p < 0.001) despite a corresponding significant increase in case complexity (0.21-0.74 on a 3-point rating scale; p < 0.001). Trainees reported that the observational assessment exercise improved their knowledge or skills in 82% of encounters (188/230) and that feedback generated by the EMG-DOT improved the quality of care provided to patients in 58% (133/230). Trainees were "satisfied" or "very satisfied" with the observational assessment exercise in 96% of encounters (234/243). CONCLUSIONS: This study provides validity evidence supporting the use of EMG-DOT scores to assess electrodiagnostic skills of residents and fellows. The EMG-DOT can be used to inform milestone-based assessments of trainee performance in neurology, child neurology, physical medicine and rehabilitation, neuromuscular, and clinical neurophysiology training programs.