Eliciting Latent Myasthenia Gravis Eye Signs Utilizing ‘The Mary Walker Effect’

Abstract

Abstract Current standardized tests to induce fatigability in the Myasthenia Gravis (MG) patient do not take into consideration that in real-world situations the patient is using more than one muscle group at a time. In 1895 the German physician Frederick Jolly, who is famed for coining the name Myasthenia Gravis, observed that exhaustion of one group of voluntary muscles in a patient with MG induced weakness in other groups that had not been stimulated. This phenomenon was also noted by Dr Mary Walker and was named the Walker effect in 1938. The Novel ocular motility technique described in this paper is designed to engage the extraocular muscles (EOM) simultaneously with another muscle group namely the bulbar, specifically testing for lip weakness. This test was named The SLOW Test (Simultaneous Lip and Ocular Weakness). It was found that observable Myasthenia Gravis Eyes Signs (MGES) were quicker to elicit and more obvious when performing the SLOW Test. The SLOW Test is a method designed to confirm the presence of MG signs quickly and effectively, even when there appear to be no obvious fatigable signs with current testing regimes. The test combines ‘old knowledge’ by testing for the ‘Mary Walker Effect’ with current ophthalmic testing for MG, which increases fatigue and allows for a higher suspicion level of GMG as the bulbar muscle group is simultaneously tested. The development of clinical methods for identifying latent fatigable muscle weakness is critical to reducing the cases of missed MG diagnosis, testing methods such as the SLOW Test have the potential to improve patients’ quality of life by enabling earlier diagnosis and initiating earlier treatment.