Quantifying Oculomotor Fatigability for Early Detection of Myasthenia Gravis.

OBJECTIVES

The aim of this prospective, longitudinal study was to validate video-oculography (VOG) for early detection of myasthenia gravis (MG) in patients with clinical suspicion of MG but lacking confirmatory laboratory results.

METHODS

Thirteen individuals suspected of having MG were studied using a 3-dimensional VOG system. Oculomotor fatigability, defined as the decrement (%) between the second and the last 5 average measures, was calculated.

RESULTS

Significant reductions in oculomotor ranges were found, exceeding previous cutoff values for horizontal saccades (16.4 ± 9.8%), vertical saccades (18.7 ± 12.6%), horizontal smooth pursuit (15.7 ± 6.0%), and vertical smooth pursuit (27.2 ± 17.4%). Despite initially negative laboratory tests, many participants later tested positive on the neostigmine test (92.3%) and repetitive nerve stimulation tests (69.2%).

CONCLUSIONS

VOG is a reliable diagnostic tool for MG, particularly useful for seronegative patients, allowing for earlier and more accurate diagnosis than conventional methods.