Low Pre-Existing Gray Matter Volume in the Medial Temporal Lobe and White Matter Lesions Are Associated with Postoperative Cognitive Dysfunction after Cardiac Surgery

Abstract

ObjectivesPostoperative cognitive dysfunction (POCD) is recognized as a complication in the elderly after cardiac surgery. Imaging of the brain provides evidence of neurodegeneration in elderly patients; however, abnormalities in brain structure and their relation to POCD are uncertain. This pilot study investigated whether loss of gray matter in the bilateral medial temporal lobe (MTL), seen in preoperative MRI, was associated with POCD.MethodsData were collected prospectively on 28 elderly patients scheduled for elective cardiac surgery. MRI of the brains of all patients were assessed for prior cerebral infarctions, and carotid and intracranial arterial stenosis. Patients also completed six neuropsychological tests of memory, attention and executive function before and after surgery. POCD was defined as an individual decrease in more than two tests of at least 1 standard deviation from the group baseline mean for that test. The degree of gray matter loss in the MTL of each patient was calculated using voxel-based morphometry with three-dimensional, T1-weighted MRI. This represented the degree of gray matter change as a Z score.ResultsPostoperative cognitive dysfunction was identified in 8 of the 28 patients (29%). Patients with POCD had significantly more white matter lesions on MRI, and greater loss of gray matter in the bilateral MTL (average Z score 2.0±0.9) than patients without POCD. An analysis by stepwise logistic regression identified gray matter loss in the MTL and cerebral infarctions on MRI as independent predictors of POCD.ConclusionsThese preliminary findings suggested that reduced gray matter in the bilateral MTL and white matter lesions existed in brains of elderly cardiac surgery patients who experienced POCD. Additional studies with larger sample sizes are needed to confirm these findings.

Neurocognitive Changes Associated With Surgical Resection of Left and Right Temporal Lobe Glioma

“…The criterion for at least mild postsurgical decline (i.e., z-score change ≤ −1.0) is a commonly used heuristic for describing NCF change in clinical neuropsychological practice and neurosurgical research. 35,36 …”

Management of cognition as reported in Japanese historical documents and modern anesthesiology research papers

“…He also reported that postoperative pain management and intensive early rehabilitation seem to be important for the prevention of POCD in elderly patients. Kengo Maekawa showed that assessment of magnetic resonance images of the brain revealed reduced gray matter bilaterally in the medial temporal lobe, together with white matter lesions in the brains of elderly cardiac surgery patients who developed POCD [30,31]. Kazuyoshi Ishida reviewed >100 previous studies and pointed out that many patients undergoing major vascular surgery under deep circulatory arrest or retrograde cerebral perfusion, and an equal or even larger number of patients undergoing surgery with selective cerebral perfusion, seem to develop POCD when compared with patients after coronary artery bypass grafting [32].…”

Postoperative Cognitive Dysfunction: An Updated Review

“…This suggests that other factors are involved in the pathogenesis of POCD such as the patient's own pathological state and subsequent systemic inflammatory conditions. For example, a Japanese prospective study [29], showed that preoperative existence of low grey matter volume and white matter lesions on MRI were associated with higher incidence of POCD after elective cardiac surgery. In a study using standardized assessment tools and good statistical design, Evered et al compared the occurrence of POCD after CABG [on-pump; general anesthesia], coronary angiography [sedation only], and total hip arthroplasty [spinal and light general anesthesia]; the incidence of POCD after 3 months was 16%, 21% and 16% respectively.…”