Delayed movement disorders after carbon monoxide poisoning

Of 242 patients with carbon monoxide (CO) poisoning examined between 1986 and 1996, delayed movement disorders were diagnosed in 32 (13.2%). There were 15 men and 17 women. Ages at insult ranged from 9 to 69 years (mean 45.3 years). Of the 32 patients with delayed movement disorders, 23 (71.9%) had parkinsonism, 5 dystonia, 3 chorea and 1 myoclonus. All were associated with delayed CO encephalopathy. The median latency between CO poisoning and the onset of movement disorders was 4 weeks for parkinsonism, 51 weeks for dystonia, 4 weeks for chorea and 8 weeks for myoclonus. The latency of dystonia onset after CO poisoning was longer than that of other types of movement disorders. The CT findings in delayed movement disorders after CO poisoning were variable, and there was no correlation between the sites of imaging and the development of movement disorders. Abnormal dyskinesias disappeared within 8 weeks, and patients recovered from parkinsonism within 6 months. In conclusion, delayed movement disorders after CO poisoning are not rare, and usually appear as a part of delayed CO encephalopathy. The prognosis is good.