A reappraisal of diagnostic tests for myasthenia gravis in a large Asian cohort

Lo, Yew Long; Najjar, Raymond P.; Teo, Kelvin; Tow, Sharon; Loo, Jenny Hooi Yin; Miléa, Dan

doi:10.1016/j.jns.2017.03.016

Cited by 18 publications

(22 citation statements)

References 15 publications

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“…The sensitivity of axon-stimulated facial muscle SFEMG for MG is 0.80 to 0.97 according to previous reports. [14][15][16][17][18] However, previously reported specificity is quite variable-ranging from 0.21 to 0.97, [17][18][19][20][21] probably because of varied definitions of control. Nonetheless, both the sensitivity and specificity from our study are within these ranges.…”

Section: Discussionmentioning

confidence: 99%

Dispersion of mean consecutive differences in single‐fiber electromyography increases diagnostic sensitivity for myasthenia gravis

et al. 2021

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Introduction: In this study we aimed to investigate the dispersion of mean consecutive difference (MCD) of concentric needle jitter studies of patients with myasthenia gravis (MG) and its effect on diagnostic sensitivity for MG.Methods: One hundred fifty-three patients, including 76 patients with MG and 77 controls with possible MG who later received another diagnosis, underwent stimulated concentric needle jitter studies of the frontalis muscle. MCD mean, standard deviation (SD), and coefficient of variation (CV) were calculated. Diagnostic sensitivity and specificity were determined using receiver operating characteristic (ROC) analyses.Results: MG patients showed a significantly greater MCD mean (MG: control, 26.3 μs; 13.5 μs [median]; P < .0001), MCD SD (MG: control, 12.8 μs; 5.1 μs [median]; P < .0001), and MCD CV (MG: control, 46.1; 37.5 [median]; P < .001) than those without MG. An ROC curve of SD showed a large area under the curve (0.88), and a cut-off value of 7.2 μs, which was calculated by maximum Youden index, exhibited high diagnostic sensitivity (86%) for MG. Combined MCD mean, outliers, and SD criteria showed higher sensitivity (88%) than conventional criteria alone (82%), at the expense of lower specificity. Five MG patients with normal MCD mean and abnormal MCD SD had only ocular symptoms.Discussion: The dispersion of MCD as measured by MCD SD greater than 7.2 μs is significantly increased in patients with MG and may be a useful measure of abnormal jitter in the diagnosis of MG, especially for identifying patients with mild disease.

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Section: Discussionmentioning

confidence: 99%

Dispersion of mean consecutive differences in single‐fiber electromyography increases diagnostic sensitivity for myasthenia gravis

et al. 2021

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“…RNS has limited sensitivity in patients with OMG. In different studies, positivity rates ranged from 16.7 to 44% (19,(60)(61)(62), consistently associated with high specificity (63). SF-EMG, when performed in the orbicularis oculi muscle, was found to be 79-100% sensitive for the detection of OMG (19,(63)(64)(65)(66), but it is time consuming and not largely available.…”

Section: Electrophysiological Studiesmentioning

confidence: 99%

Controversies in Ocular Myasthenia Gravis

Evoli

Iorio

2020

Front. Neurol.

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Myasthenia gravis (MG) with symptoms limited to eye muscles [ocular MG (OMG)] is a rare disease. OMG incidence varies according to ethnicity and age of onset. In recent years, both an increase in incidence rate, particularly in the elderly, and a lower risk for secondary generalization may have contributed to the growing disease prevalence in Western countries. OMG should be considered in patients with painless ptosis and extrinsic ophthalmoparesis. Though asymmetric muscle involvement and symptom fluctuations are typical, in some cases, OMG can mimic isolated cranial nerve paresis, internuclear ophthalmoplegia, and conjugate gaze palsy. Diagnostic confirmation can be challenging in patients negative for anti-acetylcholine receptor and anti-muscle-specific tyrosine kinase antibodies on standard radioimmunoassay. Early treatment is aimed at relieving symptoms and at preventing disease progression to generalized MG. Despite the absence of high-level evidence, there is general agreement on the efficacy of steroids at low to moderate dosage; immunosuppressants are considered when steroid high maintenance doses are required. The role of thymectomy in non-thymoma patients is controversial. Prolonged exposure to immunosuppressive therapy has a negative impact on the health-related quality of life in a proportion of these patients. OMG is currently excluded from most of the treatments recently developed in generalized MG.

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“…SFEMG is touted as one of the best diagnostic modalities for MG including OMG with a sensitivity of greater than 95% in prospective studies and a high negative predictive value 69,70 . Some, however, have found the specificity of SFEMG may not be as robust 71 . Other disease entities, including myopathy and disorders with ongoing denervation and reinnervation, can lead to increased jitter 71‐74 .…”

Section: Clinical Presentationmentioning

confidence: 99%

Challenges in diagnosing coexisting ocular myasthenia gravis and thyroid eye disease

Claytor

2020

Muscle and Nerve

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Ocular myasthenia gravis (OMG) and thyroid eye disease are two autoimmune conditions that have several overlapping clinical features, and these coexist with a small but not insignificant frequency. Segregating these diagnoses is typically straightforward, but, when the two diseases co‐occur in the same individual, making a diagnosis of OMG can be very challenging. In this review we address what is known about the coexistence of OMG and thyroid eye disease and we highlight the clinical features that are suggestive of overlapping conditions. We also describe the major testing approaches used in the diagnosis of these two entities, with special emphasis on the potential shortcomings of individual tests in patients with overlapping disease. In patients with thyroid eye disease, securing a diagnosis of OMG may not be possible on the basis of a single positive test. A multimodal approach using clinical, serologic, imaging, and electrodiagnostic data, is typically required.

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A reappraisal of diagnostic tests for myasthenia gravis in a large Asian cohort

Cited by 18 publications

References 15 publications

Dispersion of mean consecutive differences in single‐fiber electromyography increases diagnostic sensitivity for myasthenia gravis

Dispersion of mean consecutive differences in single‐fiber electromyography increases diagnostic sensitivity for myasthenia gravis

Controversies in Ocular Myasthenia Gravis

Challenges in diagnosing coexisting ocular myasthenia gravis and thyroid eye disease

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