In 10–20% of patients with generalised myasthenia gravis and in up to 50% of patients with ocular myasthenia gravis there are no detectable antibodies to the acetylcholine receptor (AChR). In such cases the disease is commonly referred to as seronegative myasthenia gravis. Seronegative myasthenia gravis has been recognised as an antibody mediated disease, and recently antibodies to muscle specific kinase (MuSK) were demonstrated in the sera of patients with generalised seronegative myasthenia gravis.¹ Anti-MuSK antibodies were not found in seropositive myasthenia gravis. Myasthenia gravis patients with these antibodies have been described as having more prominent bulbar and neck weakness and more respiratory crises.^2–4 These studies differ in the degree of ocular involvement reported, however, only one previous case of anti-MuSK antibodies being found in purely ocular myasthenia gravis has been described.⁵ We would like to describe a further case of seronegative ocular myasthenia gravis associated with anti-MuSK antibodies.

CASE REPORT

A 21 year old male student presented with a four month history of variable diplopia and bilateral ptosis. He did not complain of …