[Diagnostics and treatment of myasthenia gravis in children].
BACKGROUND
Myasthenia gravis (MG) is an autoimmunologic disorder. It is characterized by various clinical symptoms and their dependency upon the exertion and the rest as well.


OBJECTIVE
It was analysis of the diagnostic parameters in MG and also types and results of its therapy.


METHODS
Between 2002-2007 in the Neurophysiology Laboratory at the Department of Pediatric Neurology, Chair of Pediatric and Adolescent Neurology, Jagiellonian University in Krakow, the electrophysiological repetitive nerve stimulation study were performed in 44 children. The clinical picture and positive electro-physiological test were the ground to diagnose MG in 15 of them (11 girls and 4 boys). The mean age at onset of MG in the examined group was 12.93 years. In 5 patients the diagnosis was completed using edrophonium test. In 8 patients the titer of AchRAb was also tested. In 12 patients with MG the radiological examinations of the chest were performed. In 9/15 patients with MG the control electrophysiological testing was performed 2 to 8 months after the first one.


RESULTS
The generalized MG was diagnosed in 12 patients, ocular in 2, and bulbar in 1 of them. The amplitude of electro-physiological testing was normal during the first response in all patients, but the decrement of amplitude 4:1 in patients with MG was 26% to 88%. In 3 patients with MG the persisted thymus, while in 6 hypertrophy of thymus and in 2 thymoma was detected. Only in 1 child the result of chest examination was normal. Among 5/8 patients (62.5%) with positive AChRAb, in one ocular MG was diagnosed, in the other bulbar MG and in 3 generalized MG. The titer of AChRAb was between 0.4 and 30.8 nmol/l (mean 9.44 nmol/l), and the decrement of amplitude 4:1 was 33 to 58%. In 3/8 (37.5%) children the antibodies titer AChRAb was negative. In the treatment pirydostygmine bromide (Mestinon) was used in all children, however in 3 of them together with azathioprine, and in 6 with steroids. In the treatment of myasthenic crisis in 3 patients plasmapheresis was performed. In 40% of patients thymectomy was performed during the first year after diagnosis. The clinical remission was succeed in 88,9% patients. The electrophysiological control examination detected the decrement of amplitude 4:1 in 1% to 80% (mean 36%). The electrophysiological remission, correlating with clinical remission was achieved in 2 patients. In 6/9 patients with clinical remission, the decrement of amplitude 4:1 in electrophysiological examination continued to be at the level similar to initial examination. In 1 patient remission was complete allowing significant reduction of doses of Mestinon, even though in the electrophysiological test the decrement was 80%.


CONCLUSIONS
(1) Among hospitalized children, the generalized myasthenia was the most common. (2) Repetitve nerve stimulation is the fundamental diagnostic method to confirm myasthenia in children. (3) The correlation of the clinical state and electrophysiological results was not established. (4) Early simplify partial or total clinical remission.
Kroczka
Sławomir
S
Pracownia Neurofizjologii Kliniki Neurologii Dziecigcej. neupedkr@cm-uj.krakow.pl
Steczkowska
Małgorzata
M
Nowak
Agnieszka
A
Kaciński
Marek
M
D000293:Adolescent; D001379:Azathioprine / Q000627:therapeutic use; D002648:Child; D004594:Electrophysiology; D005260:Female; D006801:Humans; D008297:Male; D009157:Myasthenia Gravis / Q000175:diagnosis* / Q000628:therapy*; D010956:Plasmapheresis; D011044:Poland; D011729:Pyridostigmine Bromide / Q000627:therapeutic use; D013934:Thymectomy
D011729:Pyridostigmine Bromide; D001379:Azathioprine