Anti-MuSK myasthenia gravis presenting with purely ocular findings.

BACKGROUND Antibodies to a muscle-specific receptor tyrosine kinase (MuSK) have been found in approximately 40% of patients with generalized myasthenia gravis who are seronegative for the antiacetylcholine receptor antibody. Many of the patients with anti-MuSK antibodies have prominent oculobulbar symptoms or weakness of the neck and respiratory muscles, but patients with ocular myasthenia have not been described. OBJECTIVE To report a case of ocular myasthenia due to anti-MuSK antibodies. PATIENT A young woman with ocular myasthenia and antibodies to MuSK. RESULTS Anti-MuSK antibody was detected by radioimmunoassay using highly purified MuSK recombinant antigen. CONCLUSION Ocular myasthenia gravis is a presentation of the anti-MuSK antibody syndrome.