Carbon Monoxide Headquarters
Chronic CO Poisoning:
Ryan, Christopher M., 1990
Neuropsychiatric sequelae are a common feature of acute carbon monoxide (CO) poisoning - particularly when the patient has experienced an episode of CO-induced unconsciousness. In this case report, we present neuropsychological test data demonstrating the presence of mild cognitive impairments following a chronic (3-year) history of low level CO exposure that never produced loss of consciousness. Deficits were limited to concentration and memory; performance on measures of general intelligence, visuospatial functioning, and speed and dexterity were well within the normal range.
Patient: 48 year-old married woman, with education including 2 years of business school. 3-year history of constant headaches, lethargy and memory problems. Had trouble recalling new information - no problem with recall of distant past. Also, had difficulties with depression and anxiety, and was having problems in her marriage. She had no history of alcohol or drug abuse, no history of head trauma, no family history of psychiatric problems, and no known exposure to other toxic chemicals.
Exposure: Ran typing service out of her basement in a tighly insulated home. Her furnace was found to be releasing 180 ppm CO - possibly for up to three years. No carboxyhemoglobin measurement was available; she had never been unconscious.
Residual: Her headaches stopped when furnace was replaced, but her memory difficulties continued. Neuropsychological evaluation revealed the following: The woman was of average intelligence. She performed at the 4th percentile on the Recurring Word test. She had trouble with the Verbal Learning test, scoring in the lowest 25th percentile, and had especial difficulty with delayed recall. Both short- and longterm visual memory was also found to be impaired in this woman. Administration of the MMPI gave scores consistent with the woman's complaints of chronic subjective distress, her feelings of depression and anxiety, her complaints of memory problems and mental confusion, and her complaints of non-specific physical symptoms including dizziness and headaches.
From: Ryan, C.M. (1990) Memory disturbances following chronic, low-level carbon monoxide exposure. Arch. Clin. Neuropsychol., 5, 59-67.
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