Late-onset Myasthenia Gravis Research Articles

Titin antibodies in patients with late onset myasthenia gravis: clinical correlations.

We have tested sera from 21 thymectomized patients with onset of MG after 40 years of age and without thymoma for antibodies against titin, using ELISA with the titin peptide MGT-30. Titin is a myofibrillar protein unique to striated muscle and important for the elastic recoil of muscle cells. Titin antibodies were detected in 9 of the 21 sera. MG symptoms as assessed by a 6 point disability score (0-5) were significantly more severe in the titin antibody positive patients both at peak of illness; 3.7 vs. 3.1 (p < 0.02) and at latest follow up; 2.1 vs. 0.8 (p < 0.01). All titin antibody positive patients were on immunosuppressive drug treatment at least follow-up, whereas only 3 of 12 patients without titin antibodies used immunosuppressive drugs. The presence of circulating titin antibodies in late-onset non-thymoma MG patients indicates a more severe disease.

Late-onset myasthenia gravis (LOMG): a report of 17 cases

Late-onset myasthenia gravis (LOMG): a report of 17 cases

Antibodies to skeletal muscle in myasthenia gravis: Part 2. Prevalence in non-thymoma patients

Anti-skeletal muscle antibodies (AMA) were measured in 340 non-thymoma patients with myasthenia gravis (MG) by both an ELISA with citric acid muscle extract and by immunofluorescence assay. Three a-AChR negative but AMA-positive patients were found. The occurrence of AMA was related to the age at onset in patients with an onset of MG beyond 40 years and with duration of disease in patients with an earlier onset of MG. This stresses the heterogeneity of late onset and early onset MG. Serial measurements in individual patients revealed no evidence for a thymic role in the generation of AMA. There was no difference in specificity of AMA in early and late onset patients. The presence of AMA in CT-negative patients is not necessarily suggestive of a radiological shortcoming in the detection of thymoma since in 16 AMA-positive patients from our series no thymoma was found at operation or obduction.

Heart Muscle Antibodies in Myasthenia Gravis

Myasthenia gravis (MG) may in some patients, especially in those with a thymoma, involve the heart. Using an ELISA, we measured heart muscle antibodies in sera from 75 MG patients and in 173 control sera. Heart muscle antibodies were detected in 29/30 thymoma MG patients, in none of 30 young onset MG patients with thymic hyperplasia and in 7/15 late onset MG patients with thymic atrophy. Among the controls, four sera had a very low concentration of heart muscle antibodies. Absorption studies showed that the heart muscle antibodies cross-react with skeletal muscle, but are unrelated to acetylcholine receptor antibodies.

Thymectomy in late-onset myasthenia gravis.

Between 1977 and 1979, 12 consecutive patients with myasthenia gravis who were over the age of 55 years were treated by thymectomy. In all, their conditions improved clinically; 11 of the 12 became free of the generalized features of myasthenia gravis. Nine patients required no further medication. Acetylcholine-receptor antibody titers did not change significantly. Although five patients had atrophic thymus glands, their conditions also improved. We conclude that (1) thymectomy is a safe and effective therapy for patients with myasthenia gravis who are over the age of 55 years; (2) steroids and anticholinesterase agents are not essential in the management of late-onset myasthenia gravis; and (3) reduction in acetylcholine-receptor antibody titer is not essential for beneficial clinical response.