Dominik Straumann, MD
Department of Neurology, University Hospital Zurich, Switzerland
Ocular vestibular evoked myogenic potentials as a test for myasthenia gravis.
Valko Y, Rosengren SM, Jung HH, Straumann D, Landau K, Weber KP.
Neurology 2016;86(7):660-8.
http://www.ncbi.nlm.nih.gov/pubmed/26791146
Comment
Isolated ocular myasthenia gravis is often a diagnostic challenge, as most common ancillary tests, such as acetylcholine receptor autoantibodies and repetitive nerve stimulation, are frequently negative. The authors developed a simple, quick and non-invasive test for myasthenia based on ocular vestibular evoked myogenic potentials (oVEMP). The novel technique utilizes repetitive stimulation of the otolith organs with bone-conducted vibration to elicit an extraocular muscle response decrement. This characteristic decrement is quantified with surface EMG directly from the eye muscles, which are primarily affected in the disease. The authors demonstrated that – unlike any other test for myasthenia – its diagnostic accuracy is equally high in isolated ocular compared to generalized disease. Therefore, repetitive oVEMP stimulation has the potential to become a valuable, non-invasive standard test for ocular myasthenia. The new technique can easily be implemented with standard EMG equipment, so that any clinical electrophysiology unit will be able to offer the test.
Video-Link:http://www.vertigocenter.ch/wek/oVEMP.mp4
Key points:
· Repetitive oVEMP stimulation is a promising, novel and non-invasive diagnostic tool for ocular myasthenia.
· Unlike any other test for myasthenia, repetitive oVEMP stimulation is equally sensitive in isolated ocular compared to generalized disease.
· The new technique can easily be implemented on standard EMG equipment.