LOWER MOTOR-NEURON SYNDROME-ASSOCIATED WITH ANTI-GM1 ANTIBODIES

It has been recently recognized that increased titers of serum anti-GM 1 antibodies may be associated with motoneurone diseases or with multi ple motor neuropathy with or without conduction block and also with ch ronic sensorimotor neuropathy and Guillain-Barre 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 fibe rs conduction block and serum IGM anti-GM1 antibodies. The two patient s presented in this report had asymetrical motor neurone disease with signs and symptoms of lower motoneurone involvement, and other signs, in the first patient, which suggested the existence of upper motoneuro ne damage. Besides, the second patient also had clinical sensory impai rment in the lower limbs. Electrophysiologically, none of them had ner ve conduction block but both showed inexcitable median and sural nerve sensory fibers. Both had high titers of anti-GM1. A sural biopsy of b oth patients showed immunoglobulins into the sensory fibers. However, we do not know whether the anti-GM1 antibodies bind to a cross-reactiv e glycolipid other than the GM1 itself. In any case, it seems that the presence of anti-GM1 antibodies might be a marker signalling a potent ially treatable immune disorder which may have signs of lower and uppe r motor neurone disease and, also, clinical and electrophysiological e vidences of peripheral sensory involvement.