Brain perfusion defects following carbon monoxide poisoning: Relationship to MRI, quantitative MRI, and neuropsychological findings

Abstracts of 16th Annual Meeting

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sychological examination to provide evidence concerning presence or absence of orbital area damage. This project studied 39 consecutive cases of litigated mild traumatic brain injury, using olfactory assessment to study functional status of cranial nerve one. Study involving combined use of standardized (Sensonics 40-item stimulus array) and opportunistic (e.g., peanut butter) stimuli revealed reasonable equivalency among scents for such purposes. Comprehensive neuropsychological testing by at least one examiner had documented brain injury of at least moderate severity. Microsmia was documented in 31 of 39 cases, with evidence of anosmia in four cases. Symptoms indicative of anosmia with orbital medical frontal syndrome were noted in two of the four cases where anosmia was documented. By documenting symptomatology compatible with structural (i.e., tear injury) damage, findings from microsmia testing can support likelihood of traumatic etiology to at least some portion of positive neuropsychological findings when other neuropsychological findings support injury of this nature.

Gale, S. D., Hopkins, R. O., Weaver, L. K., Bigler, E. D., Booth, E. J., & Biatter, D. D. Brain Perfusion Defects Following Carbon Monoxide Poisoning: Relationship to MRI, Quantitative MRI, and Neuropsychological Findings. Carbon Monoxide (CO) poisoning has been shown to result in neuropathologic changes due to anoxia (Okeda et al., 1981). Cognitively, research has demonstrated memory impairments in these patients (Barger, Hopkins, & Weaver, 1991; Hopkins & Weaver, 1991; Myers & Messier, 1987). Recently, Hopkins et al. (1995) demonstrated the usefulness of quantitative magnetic resonance imaging (QMRI) in evaluating patients with anoxia. Preliminary findings have also been published using similar methods in CO patients (Hopkins, Weaver, & Kesner, 1993). However, no study to date has examined whether these patients demonstrate perfusion defects as measured by Single Photon Emission Computed Tomography (SPECT). The present study was performed to investigate whether these consistently correlate with MRI findings. Thirteen patients with documented CO poisoning who received neuroimaging and Neuropsychological studies were included in this investigation. All patients received QMRI and twelve of the patients had SPECT studies. The QMRI and SPECT studies occurred on consecutive days. Studies were carried out at least 1 year following the CO exposure. Results indicate that 67% had abnormal SPECT findings and 62% had abnormal MRI exams. However, only 33% had abnormal findings on both exams. The most common area of perfusion defect was in the parietal region (50%). Perfusion deficits also were found in frontal (25%), temporal (24%) and diffuse areas in 8% of patients. The most common finding on MRI was diffuse atrophy (38%). One-third of the patients with abnormal SPECT findings had negative MR exams. Neuropsychological studies demonstrated memory impairments in 62% of subjects and impaired attention in 38%. Psychologic screening instruments (BDI, BAI, SCL-90-R) indicated affective disturbance in 90% of patients. QMRI data demonstrated significantly elevated ventricle-to-brain ratios (VBR), an objective indicator of cerebral atrophy. Findings suggest that some patients may have normal MRI exams while demonstrating perfusion defects. This study demonstrates that CO patients may have abnormal SPECT, MRI, QMRI, and Neuropsychological studies. Our preliminary data indicate that QMRI and SPECT studies may be sensitive to the neuropathological changes following CO poisoning. Garay, M. T., M. A., & Caplan, B. Fractionating the Hooper: Development of a Multiple- Choice Response Format. Like most neuropsychological tests, the Hooper Visual Organization Test (HVOT) is multifactorial, requiring several subskills for adequate performance. Although the HVOT clearly assesses certain visual perceptual functions, it also demands at least one type of verbal ability,