Effects of hypoxia on the brain: Neuroimaging and neuropsychological findings following carbon monoxide poisoning and obstructive sleep apnea

Abstract

Hypoxia damages multiple organ systems especially those with high oxygen utilization such as the central nervous system. The purpose of this study was to compare the neuropathological and neuropsychological effects of hypoxia in patients with either carbon monoxide poisoning or obstructive sleep apnea. Neuroimaging revealed evidence of hippocampal atrophy in both groups although a linear relationship between hippocampal volume and memory performance was found only for selected tests and only in the sleep apnea group. There were significant correlations between hippocampal volume and performance on measures related to nonverbal/information processing. Generalized brain atrophy, as measured by the ventricle-to-brain ratio, was more common in the carbon monoxide poisoning group compared to the obstructive sleep apnea group. Performance on tests of executive function improved following treatment with nasal continuous positive airway pressure treatment in the obstructive sleep apnea group but there was no associated improvement in general intellectual function. We found that hypoxia due to obstructive sleep apnea and CO poisoning resulted in neuropathological changes and neuropsychological impairments. The observed group differences provide insight into the relationship between etiology of injury, neuropathological changes, and clinical presentation.

Changes in Vascular Risk Factors from Midlife to Late Life and White Matter Lesions: A 20-Year Follow-Up Study

“…In some structural MRI studies, obstructive sleep apnea has been related to decreased hippocampal volumes [44,45,46], but results have been inconsistent especially with white matter changes [47]. However, in one diffusion tensor imaging study, the authors noticed multiple affected white matter regions suggesting decreased integrity of axons in obstructive sleep apnea subjects compared to controls [48].…”

Neurologic Changes during Critical Illness: Brain Imaging Findings and Neurobehavioral Outcomes

“…The most common abnormality was atrophy, followed by WMHs. Anoxia and ischemia have been implicated as causes of cerebral atrophy (Fukushima et al 1988;Walters et al 2003), resulting in focal and diffuse atrophic changes (Bachevalier and Meunier 1996;Caine and Watson 2000;Gale and Hopkins 2004;Hopkins et al 2005a) and hippocampal atrophy (Bayley et al 2005;Hopkins et al 2004a;Manns et al 2003). In a review of the anoxia or ischemia following cardiac arrest (N=90), 44% of patients have diffuse cerebral atrophy and 21% have hippocampal atrophy (Caine and Watson 2000).…”

“…Rapid cerebral atrophy occurs following hypoxemic encephalopathy and steroid use in preterm infants and anoxia and steroid use in adults (Belet et al 2004;Gordon 1980;Lagenstein et al 1979). The atrophy reported following anoxia is presumed to be ischemic in nature and is usually irreversible (Belet et al 2004;Gale and Hopkins 2004;Gordon 1980;Hopkins et al 2005a). Alternatively, atrophy observed following steroids is likely multifactorial and may be reversible following steroid withdrawal (Gordon 1980;Lagenstein et al 1979).…”

Sleep Apnea and Risk of Panic Disorder

“…22,23 Functional and structural neuroimaging studies show that sleep apnea alters brain structure with time, leading to a decrease in gray matter in the hippocampus, frontal lobe, and the anterior cingulate cortex. [24][25][26] Damage to similar regions are also seen in the patients with panic disorders. [27][28][29][30] Lastly, hypercapnia may play a role based on the evidence that panic attack can be provoked by inhalation of carbon dioxide.…”