Abstract
For adults age 65 and older, the brain shows acute functional connectivity decreases after total knee arthroplasty with the severity of change predicted by preoperative cognitive function and brain disease burden. The extent of acute structural microstructural brain changes acutely after surgery remains unknown within the literature. For the current study, we report on the severity of acute post-surgery microstructural brain changes as measured by diffusion imaging and free-water analysis. Participants who underwent total knee arthroplasty under general anesthesia and non-surgery peers were part of a federally funded prospective cohort investigation involving participants. Recruitment occurred between 2013 and 2017. Data were collected in outpatient and inpatient settings within a university-affiliated medical center. A total of 232 TKA patients were referred by the study surgeon and contacted for study inclusion. Of these, 78 met inclusion and exclusion criteria and completed assessment. Five participants were excluded due to anesthetic protocol changes (spinal instead of general) with an additional 12 excluded for imaging-related complications. The total included sample size was 61. A total of 127 non-surgery participants were screened with 66 enrolled. One non-surgery participant was excluded for an imaging-related complication. Total knee arthroplasty and general anesthetic protocols were standardized. Participants received preoperative neurocognitive assessment and brain magnetic resonance imaging, with repeat imaging 48 h after surgery or pseudo surgery. Free-water analyses were performed using diffusion weighted images and tract-based spatial statistics with baseline cognitive data used to predict free-water changes. Surgery participants had widespread increases in white matter free-water. Surgery participants with higher cognitive functions as measured by immediate memory and less evidence of brain atrophy and disease (i.e., brain integrity) had greater free-water increase. Non-surgery peers had no free-water change. We interpret the surgery group’s free-water change as indicating widespread brain white matter glial response, with greater change indicative of better brain response to the acute surgery/anesthesia experience.
Highlights
Coupled with the exponential growth of older adults is an increased need or desire for operative interventions that include anesthesia
Four surgery participants were identified with delirium lasting less than one day no participants had evidence of delirium at the time of the post-surgery MRI; all participants were included in analyses
One surgery participant had an acute, focal right inferior parietal white matter stroke that appeared on the post-surgery MRI
Summary
Coupled with the exponential growth of older adults is an increased need or desire for operative interventions that include anesthesia. The purpose of the present investigation was to examine if free-water brain white matter microstructural changes in a study group occur after the same major surgery with the same anesthesia protocol and if observed changes could be predicted by preoperative brain and cognitive integrity. Ventricular volume was used as a marker of global white and gray matter atrophy (Apostolova et al, 2013) and entorhinal thickness as a sensitive marker of neurodegenerative processes (Devanand et al, 2007) Neurodegeneration, such as in Alzheimer’s disease, is associated with chronic neuroinflammatory processes and glial activation (for a review see Griffin et al, 1998), which in turn might explain increases seen in brain white matter in older adults with amnestic mild cognitive impairment and Alzheimer’s disease (Ji et al, 2019). Given the dominance of executive/frontal-subcortical functions and memory declines after non-cardiac surgery (Price et al, 2008), aspects of behavioral frontal-subcortical system functions and memory were examined as potential predictors of microstructural changes
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