To the Editor:
“Anybody can treat, but not anybody can diagnose.”1
In “Recommendations for the Nomenclature of Cognitive Change Associated with Anesthesia and Surgery-2018,” Evered et al.2 fail to acknowledge that perioperative neurocognitive disorder is a diagnosis by exclusion, i.e., “a diagnosis that remains after all other differential possibilities have been excluded.”1 In reports of perioperative neurocognitive disorder to the present, “differential possibilities” are not excluded. Investigators presume, but do not prove, that patients with perioperative neurocognitive disorder experience declines in tests of psychometric performance after surgery that do not arise from other neurologic and psychiatric diagnoses including stroke, epilepsy, trauma, infection, hydrocephalus, intoxication, psychosis, depression, posttraumatic stress disorder, and other progressive neurocognitive syndromes.3 These disorders prejudice cognitive test results in the elderly, and may first become manifest to the patient and clinician in the interval between surgery and neuropsychologic test administration 3 and 12 months later. None of the articles cited by the authors in their article or in its supplements that attest to the existence of perioperative neurocognitive disorder report evaluations at scheduled intervals before surgery, and at 3 and 12 months after surgery by specialists credentialed to perform comprehensive neurologic and mental examinations of the central nervous system.2–4 Patient self-report of interval medical history and physical status provides unreliable data in the differential diagnosis of conditions that weaken memory. Thorough review of medical records after surgery is clearly necessary (albeit often unreported) in perioperative neurocognitive disorder research but is not a sufficient substitute for neurologic and psychiatric examination at the time of neuropsychologic testing. Surgery and anesthesia may hasten expression of known conditions, and detection of subtle changes may point to modifiable steps in the perioperative care of an undetermined proportion of patients. Only by exclusion of known conditions may neurocognitive signs and symptoms that arise from anesthetic and surgical harms of unknown origin be identified. In supplement 1 to their article, Evered et al. observe, “Remarkably research into POCD [perioperative neurocognitive disorder] (anesthesia and surgery) and AD [Alzheimer disease] has occurred independently of each other.”4 In an accompanying editorial, Cole and Kharasch underscore the value of working collaboratively to achieve the aims of the Perioperative Brain Health Initiative.5 Participation of neurologists, psychiatrists, and geriatricians able to distinguish neurocognitive conditions of known and unknown origin one from the other at the time of psychometric testing remedies a flaw in published perioperative neurocognitive disorder experimental designs.
The author declares no competing interests.