SPECIAL ASPECTS OF CHILDHOOD MYASTHENIA WITH MUSCLE-SPECIFIC TYROSINE KINASE ANTIBODIES

Abstract

The article presents a case report of autoimmune myasthenia gravis with antibodies to muscle specific tyrosine kinase (MuSK) in a girl of 5 and half years old. Till the age of 10 years she has had only isolated ocular syndrome: symmetrical ptosis, diplopy and progressive oculomotor disturbances. Taking into account the detection of mutation in the mitochondrial genome of the gene 16S r RNA (Homoplasmia) in the girl, in her mother and brother, mitochondrial genetically confirmed myopathy was initially diagnosed to the patient. The generalization of myasthenia occurred at the age of 10–11 years, bulbar paralysis, weakness of facial and respiratory muscles and muscles of neck and limbs joined to the eye syndrome. Serum examination did not reveal antibodies to the acetylcholine receptors (AChRs), but found out significant increase of the MuSK antibodies level. The special aspects of the case are the absence of neuromuscular transmission defects in clinically affected muscles, intolerance of anticholinesterase drugs, and insensibility to traditional pathogenetic drugs: glucocorticoids (GCS) and azathioprine. At the same time benefit from immunoglobulin G was revealed. Combined therapy with azathioprine and Sandimmune managed to reach medical remission, including fully regression of oculomotor disturbances. Thymectomy was taken after several unsuccessful attempts to reduce the doses of immunosuppressive drugs. Thoracoscopic thymectomy at the age of 12 years caused a long-term remission and exempted the patient from a pharmacological dependence.