Cognitive impairment after carbon monoxide (CO) poisoning is known but has been rarely studied and reported. The present paper evaluates such disturbances in 5 patients and correlates the findings with a neuroanatomical study.

Two men and 3 women, average age 25 years, were examined several months after acute CO poisoning. Neuropsychological testing assessed memory and intellectual, executive, visuo-spatial and constructional functions, language, praxis and gnosis. Cerebral MRI was performed using axial, sagittal and coronal slices with T1, T2 and FLAIR images. None of the patients had been treated with hyperbaric oxygen. They were treated with 7.5 mg bromocriptine per day.

All patients manifested cognitive disorders including severe long term memory impairment associated with a severe defect in recall compared to recognition.Visual memory was more affected than verbal. There were also moderate disturbances in intellectual, executive, visuo-spatial and constructional performance. One patient was alexic and agraphic with a severe visual disturbance and constructional and dressing apraxia. Four patients were depressed and one showed psychic akinesia. MRI showed that all patients had bilateral pallidal necrosis and hippocampal atrophy with moderate generalised cortical atrophy. Fornix atrophy was found in 2 patients and mamillary body atrophy in 3. Other lesions found were: bilateral cerebellar atrophy in 2 cases and cortical atrophy in 3. Treatment with bromocriptine was effective in 3 but there was no improvement in 2 patients treated 14 months and 5 years after poisoning.

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