Comorbid Human Immunodeficiency Virus (HIV) and Muscle-Specific Kinase (MuSK) Myasthenia Gravis: A Case Report and Literature Review

BACKGROUND HIV infections with concomitant immunologically-mediated disorders have been frequently described but there has been little research on the association between HIV and myasthenia gravis. MuSK myasthenia gravis coexisting with HIV is an even a rarer entity and can occur as a part of immune restoration disease. We report the case of a patient with asymptomatic HIV infection who presented with new-onset MuSK myasthenia gravis. CASE REPORT A 44-year-old African-American woman with HIV since 2004 and on highly active antiretroviral therapy (HAART) presented to the ED with complains of double vision and difficulty swallowing for 2 weeks. The patient was intermittently on HAART therapy. On examination, she had bilateral ptosis, weak orbicularis oris and orbicularis oculi, along with mild lateral gaze palsy of the left eye. Her CD4 count was 383 and the viral load was undetectable. An MRI of the brain produced normal results and a CT chest did not show thymus enlargement. Due to worsening symptoms and high suspicion for myasthenia gravis, she was started on IVIG at 0.4 mg/kg/day for 5 days, and her symptoms markedly improved. She was found to have strongly positive MuSK antibody and negative Ach receptor antibody. Repetitive nerve stimulation showed a 13% decrease in the right median nerve, which confirmed the diagnosis. She was subsequently discharged to home on pyridostigmine. Azathioprine was added at clinic follow-up. The patient continues to improve. CONCLUSIONS As the use of antiretroviral therapy increases, immune reconstitution syndromes have become more common. Rare associations like HIV and MuSK myasthenia gravis are being increasingly reported. The use of immunosuppressants in the treatment of these conditions should be carefully evaluated.