title: [Seronegative myasthenia gravis].
abstract: Myasthenia gravis (MG) is an acquired autoimmune disorder of neuromuscular transmission in which antibodies to acetylcholine receptor (AChRAB) attack the postsynaptic membrane of the neuromuscular junction. Circulating AChRAB are present in 80-90% of patients with the generalised form of MG and in 55-70% of patients with the ocular form of disease. Contrary in 10-20% of patients with typical symptoms of MG, the standard immunoprecipitation test for AChRAB is negative. Those patients contain a group of seronegative MG (SNMG). The aim of this study was the examination of frequency of SNMG in patients with different types of MG according to Osserman's classification. The establishment a relation between the fact of non-marking AChRAB in the plasma and the clinical state of the patients was also done. 74 patients with diagnosed MG and 30 healthy controls were evaluated. The diagnosis of MG was based on clinical features and one or more of the following factors: response to edrophonium chloride, electrophysiologic studies and demonstration of circulating AChRAB. In all of persons standard neurological examination was performed and measurement of the level of AChRAB was done. AChRAB were determined with a radioimmunoassay using 125-l-alpha-bungarotoxin. The myasthenic patients were classified according to Osserman's classification. The Oosterhuis' personal disability scoring system was used to indicate disease severity. In all of healthy controls the levels of AChRAB were within normal standards. 27% of myasthenic patients were seronegative. Statistically significant differences in the frequency of occurrence cases with SNMG in different types of MG according to Osserman have not been observed. The differences in the frequency of occurrence cases with SNMG in different classes according to Oosterhuis scale were indicated, but they did not reach statistical function. Negative titers of AChRAB can be found in all types of MG irrespective of the clinical state of the patients. It proves the diagnostic difficulties in MG and shows that the results of the measurement of AChRAB should be interpreted in relation with results of other examinations used in MG diagnosis.
authors.affiliation: Katedra i Klinika Neurologii Dorosłych AM, Gdańsku. bilimal@poczta.wp.pl
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Bilińska
mesh_terms: D000328:Adult; D000368:Aged; D002038:Bungarotoxins; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009157:Myasthenia Gravis / Q000175:diagnosis* / Q000276:immunology*; D009460:Neurologic Examination; D011863:Radioimmunoassay; D011950:Receptors, Cholinergic / Q000276:immunology*
chemical_list: D002038:Bungarotoxins; D011950:Receptors, Cholinergic