Neuropsychological Tests in Post-operative Cognitive Dysfunction: Methods and Applications

Abstract

Post-operative cognitive dysfunction (POCD) is a neurological complication that relatively frequently occurs in older people after anesthesia/surgery, with varying durations and significant differences in the severity of cognitive impairment. POCD is mainly characterized by memory loss mostly without consciousness disorders, accompanied by abnormal emotions, behaviors, and language, mostly without consciousness disorder. The clinical performance of POCD lacks specificity but can reflect the severity of cognitive impairment in patients. The diagnosis of POCD cannot be separated from the evaluation of perioperative cognitive function of patients, and the more popular and accepted method is neuropsychological tests (NPTs).

Perioperative neurocognitive disorders: A narrative review focusing on diagnosis, prevention, and treatment

“…The objective evidence for NCD is “modest (mild NCD) or significant (major NCD) cognitive decline from the previous level of performance in one or more cognitive domains (complex attention, executive function, learning, and memory, language, perceptual‐motor, or social cognition).” 97 Traditionally, a battery of neurocognitive tests is used to evaluate the function of different cognitive domains. Among the individual neurocognitive tests, the digit span test (including forward and backward subtests), the trail‐making test part A, and the digit symbol substitution test are the most commonly used 116,117 . However, accomplishing a battery of tests is time‐consuming.…”

An Update on Postoperative Cognitive Dysfunction Following Cardiac Surgery

“…Post-operatively, patients are recovering from surgical trauma, the effects of anaesthesia or medications, and complications are, therefore, unlikely to be able to cooperate with clinicians [25]. Secondly, given the limited number of neuropsychologists available, clinicians often assess cognition using quick bedside tests such as the MMSE or MoCA [36].…”

“…The individual Z score is calculated by subtracting the mean score change between the pre-operative and post-operative tests in the control group from the difference in performance in the same tests in the surgical group. Then, this result is subsequently divided by the standard deviation of the mean score change in the control group[36,42,43]. Thirdly, the percentile change criteria identify patients with POCD based on a specific…”

An Update on Postoperative Cognitive Dysfunction Following Cardiac Surgery

“…Post-operatively, patients are recovering from surgical trauma, the effects of anaesthesia or medications, and complications are, therefore, unlikely to be able to cooperate with clinicians ( 25 ). Secondly, given the limited number of neuropsychologists available, clinicians often assess cognition using quick bedside tests such as the MMSE or MoCA ( 36 ). Whilst the use of these tests is acceptable, they should be complemented by other validated neuropsychological tests.…”

“…The individual Z score is calculated by subtracting the mean score change between the pre-operative and post-operative tests in the control group from the difference in performance in the same tests in the surgical group. Then, this result is subsequently divided by the standard deviation of the mean score change in the control group ( 36 , 42 , 43 ). Thirdly, the percentile change criteria identify patients with POCD based on a specific decrease in the patients’ pre-operative and post-operative neuropsychological test scores.…”