MuSK-Myasthenia Gravis Unmasked by Hydroxychloroquine.

Area of Science:

• Neurology
• Immunology

Background:

• Muscle-specific tyrosine kinase (MuSK) antibody positive myasthenia gravis (MuSK-MG) is a rare and challenging diagnosis.
• Typical presentations involve facial, oculo-bulbar, neck, and respiratory muscle weakness, often misdiagnosed.

Observation:

• A young female patient developed severe muscle weakness, including ocular, bulbar, and neck paralysis with breathing difficulties, after starting hydroxychloroquine (HCQ).
• Her symptoms improved significantly after discontinuing HCQ and initiating steroid and immunosuppressive therapy.

Findings:

• The patient was negative for acetylcholine receptor antibodies (AChR-Ab) but positive for MuSK antibodies (MuSK-Ab).
• This case demonstrates that HCQ can unmask or induce MuSK-MG.

Implications:

• Increased awareness of drug-induced or unmasked myasthenia gravis is critical for accurate diagnosis and management.
• Failure to identify drug-induced MG can lead to severe morbidity and mortality.
• Prompt drug withdrawal and appropriate treatment are essential for patient recovery.