Seronegative myasthenia gravis: comparison of neurophysiological picture in MuSK+ and MuSK- patients.
The aim of this study was to compare the neurophysiological and clinical pictures of a large sample of seronegative myasthenia gravis (SNMG) patients with and without anti-MuSK antibodies. Fifty-two consecutive SNMG patients were retrospectively evaluated. They had undergone an extended neurophysiological evaluation: repetitive nerve stimulation (RNS), single fiber EMG (SFEMG), and electromyography (EMG) with nerve conduction study. A muscle biopsy was performed in 11 of 52 patients, the edrophonium test in 44 of 52 patients and anti-AChR antibodies and anti-MuSK antibodies were tested in all patients. Anti-MuSK antibodies were detected in 25 SNMG patients (48.1%). The number of women in the MuSK+ group was significantly higher (P = 0.01) than in the MuSK- group. Seronegative MuSK+ patients are more severely affected and the deficit often involves the bulbar and the respiratory muscles. No statistically significant differences were observed in the edrophonium test between MuSK+ and MuSK- groups. The RNS test was abnormal in a significantly higher number of MUSK- patients than MUSK+ patients (P < 0.00001). With regard to SFEMG data, MuSK- patients were characterized to have more severe neurophysiological pattern. Our observations showed several differences between the clinical and neurophysiological pictures of MUSK+ and MUSK- patients.
Padua
L
L
Department of Neuroscience, Catholic University, Rome, Italy. lpadua@rm.unicatt.it
Tonali
P
P
Aprile
I
I
Caliandro
P
P
Bartoccioni
E
E
Evoli
A
A
D000328:Adult; D000906:Antibodies / Q000378:metabolism; D004558:Electric Stimulation / Q000379:methods; D004576:Electromyography / Q000379:methods; D005071:Evoked Potentials / Q000502:physiology / Q000528:radiation effects; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009157:Myasthenia Gravis / Q000145:classification / Q000276:immunology / Q000378:metabolism / Q000503:physiopathology; D009431:Neural Conduction / Q000502:physiology* / Q000528:radiation effects; D011930:Reaction Time / Q000502:physiology / Q000528:radiation effects; D020794:Receptor Protein-Tyrosine Kinases / Q000276:immunology*; D011950:Receptors, Cholinergic / Q000276:immunology*; D012701:Serotonin / Q000378:metabolism*; D018709:Statistics, Nonparametric
D000906:Antibodies; D011950:Receptors, Cholinergic; D012701:Serotonin; C095714:MUSK protein, human; D020794:Receptor Protein-Tyrosine Kinases