Amyotrophic lateral sclerosis and multifocal motor neuropathy with conduction block.

Dear Sir, minor trauma of the shoulder, with a progressive paresis of We read with interest the article by Veugelers et al. the left brachial plexus followed by contralateral plexus (1996) about an unusual case of autopsy-proven amyotinvolvement and a successive weakness of the neck rophic lateral sclerosis (ALS) and multifocal motor neuromuscles. Upper motor neuron signs were unequivocal with pathy (MMN) with conduction block. overactive tendon reflexes in the lower limbs and a left We have also previously reported cases of two patients Babinski sign. with fatal progressive weakness and amyotrophy in which In spite of steroid treatment, the patient rapidly worseclinical and electrophysiological findings of motor neuron ned and two months later died from respiratory failure. disease (MND) and MMN coexisted (Pelliccioni et al., The most consistent electrophysiological finding was the 1993, 1994). We found a high titer of anti-GM1 antibodies multifocal asymmetric conduction blocks recorded espe(1:1200) only in one of our patients (case [1), however, cially in the left arm, between Erb’s point and the axilla in the electrophysiological conduction studies revealed multithe median and ulnar nerves. In the lower limbs, a ple motor conduction blocks in both cases. conduction block was present only in the left peroneal In case [1, the symptoms were slowly progressive with nerve between the fibula head and the poplitea fossa. The bulbar muscle impairment, generalized weakness, muscular antidromic sensory conduction was normal for the sural as atrophy with cramps and fasciculations. The patient did not well as the ulnar and median nerves and across the brachial respond to treatments with dexamethasone, plasmapheresis plexus. Also in this case, needle examination detected and cyclophosphamide. Fatal exitus occurred 6 months fibrillation and fasciculation potentials more evident in the after onset. Motor nerve conduction was performed in the left shoulder muscles, but present, in small amounts, also radial, ulnar, median, common peroneal and tibial nerves in the right shoulder muscles and the lower limbs. Longbilaterally, using surface electrodes and conventional elecduration polyphasic high-amplitude motor units were tromyographic equipment (Kimura, 1983). The motor evident, in particular, in the muscles innervated by the conduction studies revealed, in this patient, a multiple suprascapular, axillary and long thoracic nerves, on the conduction block between Erb’s point and the axilla in the right. right and left median and ulnar nerves, and a moderate Based on these two cases we would agree with Veugeldispersion of conduction between the elbow and wrist in ers et al. (1996) that there may be a rare possibility that the left median nerve. At needle examination, a denervasome patients presenting MMN actually have MND. This tion pattern was present in the four limbs and, particularly, unusual combination may provide an important clue in in the facial and tongue muscles. elucidating the pathogenesis of MND. In the other patient (case [2), the clinical symptoms The diagnosis of MND in case [1 is supported by the started, as in the patient of Veugelers et al. (1996), after a rapid progression of bulbar signs towards a fatal exitus, lack of response to steroids, plasmapheresis and immuno-