M.P.1.10 Anti-MuSK antibodies are not associated with prolonged pure ocular symptoms

Abstract

Background: Anti-MuSK antibodies are present in the sera of upto one-half of generalized seronegative myasthenia gravis (MG) patients. Although it was initially held that anti-MuSK antibodies are not associated with purely ocular MG, several more recent reports suggested that this may not be the case. Objective: The main objective of this study was to investigate the presence of anti-MuSK antibodies in seronegative MG which remained confined to ocular muscles (with or without the use of corticosteroids) for at least 2 years. We also looked at our anti-MuSK positive patients, all of whom have generalized MG, to see what percentage started with ocular symptoms and the period of time it took to generalize. Methods: The charts of patients with purely ocular symptoms for at least 2 years were reviewed and anti-MuSK antibodies were searched for in those with no anti-AChR antibodies. The charts of anti-MuSK positive patients with ocular onset were also reviewed to note the time period to generalization. Results: None of the fourteen patients with purely ocular MG for at least 2 years had anti-MuSK antibodies. Among the 39 anti-MuSK positive patients, disease started with ocular symptoms in one-third (13 patients). The time to generalization was 5 days to 12 months in 11 patients and 18 months in two patients. In fact, most of the patients generalized in the first few weeks-months. Conclusions: Thus, none of the patients with seronegative MG had anti-MuSK antibodies if the symptoms remained confined to ocular muscles for 2 years. None of the anti-MuSK positive MG patients had purely ocular symptoms after 1.5 years. These findings suggest that anti-MuSK antibodies are not associated with purely ocular symptoms for a prolonged period of time.