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A syndrome of continuous muscle-fibre activity
Authors: Isaacs H
Year published: 1961
Number of times cited: 480
Evolution of Isaacs syndrome from case studies that described continuous ectopic activity through to an understanding as a multisystem autoimmune condition
Six decades ago, Dr Hyam Isaacs reported a new clinical syndrome in the Journal of Neurology, Neurosurgery and Psychiatry.1 Isaacs used the term ‘syndrome of continuous muscle-fibre activity’ or the more descriptive ‘armadillo disease’ for the condition which now has become known as Isaacs syndrome or acquired autoimmune neuromyotonia. In his landmark series, Isaacs described a phenotype of progressive muscle stiffness, with widespread fasciculation leading to weakness. A key finding was continuous muscle activity on electromyography, occurring at rest and unaffected by local nerve blockade. The original report also detailed a number of unsuccessful treatment approaches, as well as an astonishing improvement produced by sodium diphenyl hydantoinate (phenytoin) treatment.
Over the past 60 years, while we have learnt much more about the pathophysiology of Isaacs syndrome, there are still many elements that remain unresolved. A critical factor in understanding the Isaacs jigsaw puzzle came with the identification of the autoimmune basis for the disorder by the group led by John Newsom-Davis …