Amyotrophic lateral sclerosis. Impairment of neuromuscular transmission
E. H. Denys and F. H. Norris Jr
Neuromuscular transmission was studied in the ulnar-hypothenar group in 55
patients with amyotrophic lateral sclerosis. A decremental response was
found in 67.0%. The decrement was larger and present more often in muscles
showing atrophy. In addition, muscles with frequent fasciculations showed a
larger decrement than the ones with rare fasciculation. A temperature
effect similar to that in myasthenia gravis was observed, with a reduction
of the decrement following local cooling of the muscles. Administration of
edrophonium chloride improved the synaptic defect. Posttetanic exhaustion
was observed as well. It is thought that the defect of neuromuscular
transmission is due to a decreased trophic function of the neuron followed
by morphological changes at the endplate.
