Familial amyloidosis with polyneuropathy - type 1. A neurophysiological study of peripheral nerve function.

Twenty-four consecutive patients with familial amyloidosis with polyneuropathy (type 1), who were at different stages of the disease were investigated. The purpose was to report the electrophysiological features and to compare them with those found in other generalized neuropathies; 12 cases were familiar and 12 cases were sporadic. The diagnosis was confirmed by examining the occurrence of amyloid substance in rectal or skin biopsies or both. Single fiber EMG with fiber density determination showed signs of collateral innervation, prominent in advanced cases, and a disturbance of neuromuscular function similar to that of progressive spinal motorneuron disease. Action potentials from afferent fibers were not obtained in 91% of the nerves in the lower and 49% of the nerves in the upper extremities. When sensory or motor or slightly subnormal. The neurophysiological findings indicate a symmetrical axonal degeneration, starting in the legs. Familial amyloidosis with polyneuropathy should be suspected in cases of rapidly progressing polyneuropathy of axonal type with onset in middle age, irrespective of whether they are hereditary or not.