[Ocular involvement in MuSK antibody-positive myasthenia gravis].
BACKGROUND
Antibodies (Ab) against the acetylcholine receptor (AChR) are found in 80 - 90 % of generalized myasthenia gravis (MG), but only in 50 % of pure ocular MG. Furthermore, Ab against the muscle-specific receptor tyrosine kinase (MuSK) were detected in 38 - 54 % of patients with AChR-Ab-negative ("seronegative") MG, but not in pure ocular MG.


METHODS
2 case reports have been analysed: two patients (42 years old and 61 years old) with primary ocular MG were studied. Both patients complained of fluctuating bilateral ptosis and double vision lasting for 2 to 3 months.


RESULTS
AChR-Ab were negative but MuSK-Ab were clearly positive. In spite of treatment with pyridostigmine and prednisolone, the symptoms in patient 1 generalized within 4 weeks causing dysphagia, limb muscle weakness and respiratory crisis. Symptoms immediately responded to plasmapheresis. Patient 2 clearly improved under treatment with pyridostigmine, methylprednisone, and azathioprine. There was no generalization within a course of 12 months.


CONCLUSIONS
Both cases clearly indicate that MuSK-Ab can be found in primary isolated ocular MG lasting for 2 to 3 months. In a primary ocular manifestation of MG the detection of MuSK might indicate the risk for subsequent generalization and might have implications for immunosuppressive therapy. Therefore, seronegative MG requires testing for MuSK-Ab.
Bau
V
V
Klinik und Poliklinik für Augenheilkunde, Martin-Luther-Universität Halle-Wittenberg, Halle/Saale. viktoria.bau@medizin.uni-halle.de
Hanisch
F
F
Hain
B
B
Zierz
S
S
D000328:Adult; D001323:Autoantibodies / Q000032:analysis*; D001327:Autoimmune Diseases / Q000175:diagnosis* / Q000188:drug therapy / Q000276:immunology; D001379:Azathioprine / Q000009:adverse effects / Q000627:therapeutic use; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D008775:Methylprednisolone / Q000009:adverse effects / Q000627:therapeutic use; D008875:Middle Aged; D009157:Myasthenia Gravis / Q000175:diagnosis* / Q000188:drug therapy / Q000276:immunology; D011239:Prednisolone / Q000009:adverse effects / Q000627:therapeutic use; D011729:Pyridostigmine Bromide / Q000009:adverse effects / Q000627:therapeutic use; D020794:Receptor Protein-Tyrosine Kinases / Q000276:immunology*; D011950:Receptors, Cholinergic / Q000276:immunology*
D001323:Autoantibodies; D011950:Receptors, Cholinergic; D011239:Prednisolone; C095714:MUSK protein, human; D020794:Receptor Protein-Tyrosine Kinases; D011729:Pyridostigmine Bromide; D001379:Azathioprine; D008775:Methylprednisolone