Continuing decline of memory skills with significant recovery of intellectual function following severe carbon monoxide exposure: Clinical, psychometric, and neuroimaging findings

Extensive clinical, psychometric, and neuroimaging data are presented and i nterpreted with regard to a 35-year-old, White male college graduate who wa s exposed to severe carbon monoxide (CO) poisoning. The patient was comatos e for 21 days following the exposure. Several nl other people, who were in the same loom as the patient, died due to the relic effects of the CO. The patient was employed premorbidly as a systems level lead computer programme r. The patient received medical and neuropsychological follow-up for 3 year s post-CO exposure. Neuropsychological evaluations revealed a gradual, but incomplete recovery of general intellectual function. The patient continued to exhibit severe memory deficits with some evidence for small additional memory decline over time. Characteristic and permanent vestibular and gait disturbances Ir cre also noted, along with a variety of neuropsychological deficits that improved over time with the exception of memory function. The patient also experienced significant affective and personality changes. Ne uroimaging studies reveal a generalized cortical atrophy as shown by signif icantly enlarged ventricles and a ventricle-to-brain ratio that exceeded 4 standard deviations above the norm. The observed atrophic changes are consi stent with CO-induced anoxic type injury, which was also accompanied by bil ateral lesions of the globus pallidus, caudate, and hippocampus. Despite ob taining average levels of general intellectual functioning over time, signi ficant memory impairments, depression , and personality disturbances severe ly impaired the patients' vocational recovery and ability to return to work . (C) 1999 National Academy of Neuropsychology. Published by Elsevier Scien ce Ltd.