Diagnostic accuracy and clinical utility of bed side tests versus laboratory tests in the diagnosis of ocular myasthenia

Cogan's Lid Twitch for Myasthenia Gravis: A Systematic Review

INTRODUCTION

Myasthenia gravis is an autoimmune condition affecting the neuromuscular junction of skeletal muscles and may be difficult to diagnose. Several clinical signs may have diagnostic utility, including Cogan's lid twitch. This systematic review aims to synthesise the literature on the accuracy of Cogan's lid twitch for diagnosing myasthenia gravis.

METHODS

A systematic search of the databases PubMed/MEDLINE, Embase and CENTRAL was performed from inception to August 2022. Risk of bias analysis and data extraction were performed in accordance with the PRISMA 2020 guidelines.

RESULTS

Seven articles satisfied the inclusion criteria. The results showed that for the diagnosis of myasthenia gravis, Cogan's lid twitch has a sensitivity between 50% and 99% and specificity between 75% and 100%.

CONCLUSIONS

Cogan's lid twitch is a physical examination finding with moderate diagnostic performance in the diagnosis of myasthenia gravis with ocular involvement. Future studies may seek to evaluate the performance of Cogan's lid twitch in conjunction with other signs of myasthenia gravis with ocular involvements, such as fatigable ptosis or a positive icepack test.

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.