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

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 facial muscles, 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
generalized MG as another 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.