Diagnostic value of repeated ice tests in the evaluation of ptosis in myasthenia gravis

The Icepack Test in the Diagnosis of Myasthenia Gravis with Ocular Features: A Systematic Review of Diagnostic Accuracy, Technique, and Economic Utility

BACKGROUND

The diagnosis of myasthenia gravis (MG) may be challenging and require multiple specialised testing modalities. Accessing these investigations can involve significant waiting time and costs. The bedside icepack test (IPT) has been proposed to assist with the diagnosis of MG with ocular features, and may prove an economically viable; however, there have been there is heterogeneity in the literature evaluating the IPT.

OBJECTIVES

A systematic review was performed examining the accuracy, described techniques, and economic implications of the IPT for the diagnosis of MG with ocular features.

METHOD

The databases EMBASE, PubMed, and the Cochrane Library were searched from inception to July 2022. The systematic review adhered to PRISMA guidelines. Eligibility determination was undertaken with a standardised form using appropriate inclusion criteria. The Cochrane risk of bias assessment tool for diagnostic test accuracy was employed to evaluate studies that presented the diagnostic performance of the IPT. The Johanna Briggs Institute Critical Appraisal Checklist for Economic Evaluations was used for the assessment of studies presenting economic evaluations of the IPT.

RESULTS

20 articles met the specified criteria and included a total of 1264 participants. The IPT had a sensitivity ranging from 38.5% to 100%. Specificity was found to be > 95% in six studies. Excluding two outlier results of 25% and 31.3%, the lowest specificity recorded was 62.5%. The most commonly described method of evaluating the IPT involved applying ice to both eyelids and using a >2 mm change as a threshold for a positive test (evaluated with a ruler). There were no adverse effects described with the IPT. There were no studies that formally examined the economic implications of the IPT.

CONCLUSIONS

The IPT is a well-tolerated and readily available diagnostic tool that has an important role in the evaluation of possible MG with ocular features in specific contexts. Despite limited economic evaluation of this test, it is likely the use of the IPT may result in significant financial and time savings.

DCAF12 and HSPA1A May Serve as Potential Diagnostic Biomarkers for Myasthenia Gravis

Background

Myasthenia gravis (MG) is an autoimmune disease that severely affects the life quality of patients. This study explores the differences in immune cell types between MG and healthy control and the role of immune-related genes in the diagnosis of MG.

Methods

The GSE85452 dataset was downloaded from the Gene Expression Omnibus (GEO) database and analyzed using the limma package to determine differentially expressed genes (DEGs) between patients with MG and the control group. Differentially expressed immune cells were analyzed using single-sample gene set enrichment analysis (GSEA), while immune cell-associated modules were identified by weighted gene coexpression network analysis (WGCNA). Then, the expression of the identified hub genes was confirmed by RT-PCR in peripheral blood mononuclear cells (PBMCs) of MG patients. The R package pROC was used to plot the receiver operating characteristics (ROC) curves.

Results

The modules related to CD56^bright natural killer cells were identified by GSEA and WGCNA. The proportion of CD56^bright natural killer cells in the peripheral blood of MG patients is low. The results of RT-PCR showed that the levels of DDB1- and CUL4-associated factor 12 (DCAF12) and heat shock protein family A member 1A (HSPA1A) were significantly decreased in peripheral blood mononuclear cells of MG patients compared with healthy controls. The ROC curve results of DCAF12 and HSPA1A mRNA in MG diagnosis were 0.780 and 0.830, respectively.

Conclusions

CD56^bright NK cell is lower in MG patients and may affect MG occurrence. DCAF12 and HSPA1A are lowly expressed in PBMCs of MG patients and may serve as the diagnostic biomarkers of MG.

Bedside and laboratory diagnostic testing in myasthenia

Myasthenia gravis (MG) and congenital myasthenic syndromes (CMS) are a group of disorders with a well characterised autoimmune or genetic and neurophysiological basis. We reviewed the literature from the last 20 years assessing the utility of various neurophysiological, immunological, provocative and genetic tests in MG and CMS. Diagnostic sensitivity of repetitive nerve stimulation test ranges between 14 and 94% and specificity between 73 and 100%; sensitivity of single-fibre EMG (SFEMG) test ranges between 64 and 100% and specificity between 22 and 100%; anti-acetylcholine receptor (AChR) antibody sensitivity ranges from 13 to 97% and specificity ranges from 95 to 100%. Overall, SFEMG has the highest sensitivity while positive anti-AChR antibodies have the highest specificity. Newer testing strategies that have been investigated over the last couple of decades include ocular vestibular-evoked myogenic potentials, otoacoustic emissions and disease-specific circulating miRNAs in serum for autoimmune myasthenia, as well as next-generation sequencing for genetic testing of CMS. While there has been significant progress in developing newer testing strategies for diagnosing MG and CMS over the last couple of decades, more research is needed to assess the utility of these newer tools regarding their sensitivity and specificity.

Diagnostic yields and clinical features of ocular myasthenia gravis

To investigate clinical features and diagnosis process of ocular myasthenia gravis (OMG) in ophthalmology department.A total of 36 patients with ptosis or diplopia who had follow-up for at least 3 months between March 2016 and December 2019 were included in this study. Clinical symptoms of patients and the test results were analyzed. According to the positivity of serologic test, these patients were divided into 2 groups (confirmed OMG and possible OMG with relief of symptoms after antimyasthenic treatment) for comparison.Ptosis was present in 12 (33.33%) patients, diplopia was present in 14 (38.89%) patients, and both ptosis and diplopia were present in 10 (27.78%) patients. Acetylcholine receptor auto-antibody (AchR Ab) was positive in 14 (38.89%) of 36 patients and ice test was positive in 15 (71.43%) of 21 patients with ptosis. Unequivocal response to pyridostigmine was observed in 31 (86.11%) patients. For seropositive cases, AchR Ab titer was significantly higher in the group with 2 clinical symptoms than that in the 1 clinical symptom (P = .011).This study presents the usefulness and diagnostic validity of antimyasthenic treatment for OMG, especially seronegative OMG, with detailed symptom analysis.

Challenges in diagnosing coexisting ocular myasthenia gravis and thyroid eye disease

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.

What is in the Neuromuscular Junction Literature?

This update begins with myasthenia gravis and the roles of anti-agrin and cortactin antibodies. Regarding diagnosis, a report on repeated ice pack testing is highlighted as are several reports on the close correlation of electrodiagnostic testing with clinical features and the response to treatment. The incidence of head drop and associated clinical and ventilatory features are gleaned from a retrospective study. We also discuss a study that assessed the predominantly symmetric and conjugate ocular findings in MuSK-myasthenia gravis. Other topics that are covered include quality of life and preoperative risk. We then summarize the positive treatment trials of subcutaneous immunoglobulin and eculizumab. Turning to Lambert-Eaton Myasthenic Syndrome, we report on an epidemiologic study performed on the veteran affairs population, the results of the DAPPER study of 3, 4 diaminopyridine, and look to the future for other treatment options involving calcium gating modifiers.

Evaluating the temperature effects of ice and heat tests on ptosis due to Myasthenia Gravis

AIMS

The aims of this study are as follows: (1) to describe a standardised methodology for the ice test, and where necessary a heat test; (2) to determine the effects of local cooling vs. heating on ptosis in myasthenia gravis (MG) patients.

METHODS

Twenty-three MG patients with ptosis were identified from a tertiary referral neuroimmunology clinic, seventeen with significant ptosis ≥2 mm. Latex party balloons were filled with ice and cold tap water for the ice test, or with water heated to 45 °C for the heat test. Each test was performed for 2 min, with ruler measurement and photographs taken of the palpebral aperture before and immediately after each test.

RESULTS

This standardised method was efficient in a clinical setting while maintaining efficacy. In all 23 patients, the mean improvements in ptosis with the ice, rest, and heat tests were 2.3 (±1.5) mm, 1.3 (±1.1) mm, and 0.33 (±1.4) mm respectively. In the 17 patients with significant ptosis, the mean improvements in ptosis with the ice, rest, and heat tests were 2.9 (±1.2) mm, 1.8 (±0.92) mm, and 0.83 (±1.4) mm, respectively. In these 17 patients, the ice test improved ptosis by 1.3 mm more than rest (p < 0.0001). The heat test improved ptosis by 1.1 mm less than rest (p = 0.0013). The ice test improved ptosis by 2.3 mm more than the heat test (p < 0.0001).

CONCLUSIONS

The standardised methodology of ice and heat testing was safe, easily reproducible and effective. We confirm that temperature had a significant effect on ptosis in MG, and therefore refute the notion that measured changes are purely due to the associated rest.

Efficacy of Gaze Photographs in Diagnosing Ocular Myasthenia Gravis

Background and Purpose

The various tests that are routinely used to diagnose generalized myasthenia gravis, such as the edrophonium test, serum anti-acetylcholine-receptor antibodies (AChR-Ab), and repetitive nerve stimulation (RNS) tests, have lower diagnostic sensitivity in ocular myasthenia gravis (OMG). Diagnosing OMG becomes even more difficult when the clinical symptoms are subtle. There is no gold-standard diagnostic test available for OMG patients, and so this study compared the diagnostic sensitivity of gaze photographs with conventional tests in OMG.

Methods

Records of gaze photographs were available for 25 of 31 consecutive patients diagnosed with OMG. Each patient underwent a neuro-ophthalmologic examination, serum AChR-Ab, RNS, edrophonium test, ice tests, and the acquisition of gaze photographs. The margin reflex distance 1 (MRD1) was measured on each of the gaze photographs, with MRD1 <2 mm or an interlid MRD1 difference of ≥2 mm on any of the gaze photographs defined as a positive sign of OMG. The diagnostic sensitivities of the tests were assessed.

Results

The mean age at onset was 38.5 years (range, 2–76 years), and 13 patients (52%) were men. The diagnostic sensitivities of the RNS test, AChR-Ab test, gaze photographs, and ice test were 56%, 64%, 80%, and 73%, respectively.

Conclusions

The diagnostic sensitivity was higher for gaze photographs than for the other tests applied to OMG patients.

Positive ice test in a patient with a lymphomatous infiltration of the levator palpebrae superioris

The ice test is known to be specific for the diagnosis of ocular myasthenia gravis in patients with ptosis, with reported specificities of 97%-100%. We report a patient with diffuse large B-cell lymphoma who showed a positive result to the ice test. A 53-year-old woman presented with left eyelid ptosis of 3 weeks' duration. She had finished chemotherapy and radiotherapy for diffuse large B-cell lymphoma a year previously. On ophthalmological examination, her best-corrected visual acuity was 20/20 in each eye. Marginal reflex distances were +4 in the right eye and -1 in the left eye. Levator palpebrae superioris functions were 11 mm in the right eye and 8 mm in the left eye. Ptosis improved after 5 minutes' application of ice to both eyelids, after which marginal reflex distances were +4 in the right eye and +1 in the left eye. Thyroid function tests, anti-acetylcholine receptor antibody test, and the repetitive nerve stimulation test were all negative. Magnetic resonance imaging showed fusiform masslike enlargement of the left superior rectus muscle and left levator palpebrae superioris muscles, with enhancement suggesting metastatic infiltration.