IgM anti-GM1 antibody titers in patients with monomelic amyotrophy.

BACKGROUND: Monomelic amyotrophy (MMA) is a benign motor neuron disorder, which particularly affects young people and the etiology is still unknown. Gangliosides are located on the outer surface of motor neurons. Anti-GM1 antibodies have been found to be elevated in multi-focal motor neuropathy with conduction block and other neurological diseases, which may have therapeutic implication. AIM: To evaluate IgM anti-GM1 antibody titers in patients of monomelic amyotrophy. SETTING AND DESIGN: prospective controlled study. MATERIALS AND METHODS: Forty-six clinically and electrophysiologically diagnosed cases of MMA were assessed for IgM anti-GM1 antibody titers by enzyme-linked immunosorbent assay (ELISA) method and compared with titers in healthy controls, cases of amyotrophic lateral sclerosis (ALS) and acute inflammatory demyelinating polyneuropathy (AIDP). Titer of 800 units was taken as upper limit of normal (Buhlmann Laboratories AG, Switzerland). STATISTICAL ANALYSIS USED: one-way ANOVA. RESULTS: The mean age of 46 patients with MMA was 24.5 (+/- 7.3) years, with male female ratio of 44:2. The mean age of 19 healthy controls was 24.1 (+/- 3) years with male: female ratio of 18:1. Five (26%) individuals in the healthy control group, 22 (48%) patients of MMA, four (30%) of ALS and five (50%) of AIDP had high titers of IgM anti-GM1 antibody (P> 0.05). CONCLUSIONS: Although larger number of patients with MMA had higher IgM anti-GM1 antibody titers, the difference was not statistically significant from titers of healthy individuals and of patients in the ALS and AIDP group.

Lower motor neuron syndrome associated with anti-GM 1 antibodies

It has been recently recognized that increased titers of serum anti-GM1 antibodies may be associated with motoneurone diseases or with multiple motor neuropathy with or without conduction block and also with chronic sensorimotor neuropathy and Guillain-Barré syndrome. Santoro et al. were the first to note that anti-GM1 antibodies were able to bind to the nodes of Ranvier of the sural nerve of a patient with clinical signs and symptoms mostly resembling amyotrophic lateral sclerosis who also showed, in nerve conduction studies, multifocal motor nerve fibers conduction block and serum IGM anti-GM1 antibodies. The who patients presented in this report had asymetrical motor neurone disease with signs and symptoms of lower motoneurose involvement, and other signs, in the first patient, which suggested the existence of upper motoneurone damage. Besides, the second patient also had clinical sensory impairment in the lower limbs. Electrophysiologically, none of them had nerve conduction block but both showed inexcitable median and sural nerve sensory fibers. Both had high titers of anti-GM1. A sural biopsy of both patients showed immunoglobulins into the sensory fibers. However, we do not know whether the anti-GM1 antibodies bind to a cross-reactive glycolipid other than the GM1 itself. In any case, it seems that the presence of anti-GM1 antibodies might be a marker signalling a potentially treatable immune disorder which may have signs of lower and upper motor neurone disease and, also, clinical and electrophysiological evidence of peripheral sensory involvement.

Perspectivas em doenças neuromusculares: 2. Esclerose lateral amiotrófica / Perspectives in neuromuscular diseases: 2. Amyotrophic lateral sclerosis

Desde a criaçåo clássica de Chacort em 1874, pouco veio å ser acrescentado à esclerose lateral amiotrófica (ELA) sob o ponto de vista clínico, patológico e terapêutico eficaz. Na última década, alguns estudos epidemiológicos, imunológicos e novas tendências terapêuticas levantaram novas hipóteses sobre a patogenia dessa doença. Sob o ponto de vista clínico, melhores conhecimentos foram se acumulando através de estudos da história natural da doença, que permitirá avaliar com mais segurança novas medidas terapêuticas. Abaixo vamos relacionar os principais pontos e que representam linhas de pesquisa, que permitem abrir algumas perspectivas na elucidaçåo do mecanismo básico da ELA

Anticorpos contra glicolípides e glicoproteínas em neuropatias periféricas e doença do neurônio motor imunomediadas / Anti-glycopilid and anti-gycoprotein antibodies in peripheral neuropathies and in immunomediated motor neuron disorders

Os anticorpos contra glicolípides e glicoproteínas ocorrem em títulos elevados em doenças do neurônio motor e neuropatias periféricas. Inicialmente foram observados em neuropatias crônicas desmielinizantes com anti-corpos séricos de classe IgM que aparecem contra a glicoproteína da mielina (MAG). Os anticorpos contra gangliosídeos, fraçäo GMI, aparecem freqüentemente, também, em doenças do neurônio motor e neuropatias periféricas. Os anticorpos contra sulfatídeos podem ocorrer em polineuropatias idiopáticas, axonais, sensitivo-motoras, porém predominantemente sensitivas. Os anticorpos contra a proteína de desenvolvimento neuronal Hu, anti-Hu, se associam a glanglionopatias sensitivas paraneoplásicas; assim como as polineuropatias paraneoplásicas frequentemente revelam anticorpos contra o antígeno p-26