Axonal Degeneration in Sodium Cyanate-Induced Neuropathy

Two patients with sickle cell disease who had been maintained on sodium cyanate therapy for periods of 440 and 600 days on dosages up to 44 and 41 mg/kg per day developed a motor and sensory neuropathy. In both, definite abnormalities of myelinated and unmyelinated fibers were found. In one, the predominant abnormality of myelinated fibers was segmental demyelination and remyelination; in the other, there were histological features typical of axonal degeneration. It seems unlikely that the brunt of the metabolic derangement was on Schwann cells in the first case and on the nerve cell in the second. Probably, in both cases, the primary effect was on the nerve, with Schwann cell changes being concomitant or secondary. The clustered distribution of the segmental demyelination favors the latter.