Sodium Cyanate Induced Polyneuropathy in Patients with Sickle-Cell Disease

Two patients with sickle-cell disease who were receiving sodium cyanate for 440 and 600 days, respectively, in doses of up to 44 and 41 mg/kg body weight · day, respectively, had polyneuropathy confirmed by physical examination, quantitative sensory evaluation, nerve conduction test, electromyography (EMG), and sural nerve biopsy. The polyneuropathy clinically improved with no specific treatment after cessation of cyanate administration. Nerve conduction studies were done in 27 patients and needle EMG on 2 patients maintained on sodium cyanate for various periods. Mean duration of treatment of 16 patients with nerve conduction abnormalities was 478 days as opposed to a mean of 278 days for 11 patients without conduction abnormalities. Mean maximum dose of cyanate for the group with conduction abnormalities was 38 mg/kg body weight · day as opposed to 33 mg/kg body weight · day for those without. Patients with nerve conduction abnormalities achieved a higher carbamylation of their hemoglobin than those without and showed a mean weight loss of 9% as opposed to minimal weight change in patients without conduction abnormalities.