Postoperative cognitive dysfunction (POCD) is a decline in

cognitive function Cognitive skills are skills of the mind, as opposed to other types of skills such as motor skills, social skills or life skills. Some examples of cognitive skills are literacy, self-reflection, logical reasoning, abstract thinking, critical th ...

(especially in

memory Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembe ...

and

executive functions In cognitive science and neuropsychology, executive functions (collectively referred to as executive function and cognitive control) are a set of cognitive processes that support goal-directed behavior, by regulating thoughts and actions thro ...

) that may last from 1–12 months after surgery, or longer. In some cases, this disorder may persist for several years after major surgery. POCD is distinct from emergence delirium. Its causes are under investigation and occurs commonly in older patients and those with pre-existing cognitive impairment. The causes of POCD are not understood. It does not appear to be caused by lack of oxygen or impaired blood flow to the brain and is equally likely under regional and general anesthesia. The cause of postoperative cognitive dysfunction are not clear. It is thought that it may be caused by the body's

inflammatory response Inflammation (from ) is part of the biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. The five cardinal signs are heat, pain, redness, swelling, and loss of function (Latin ''calor'', '' ...

to surgery, stress hormone release during surgery,

ischemia Ischemia or ischaemia is a restriction in blood supply to any tissue, muscle group, or organ of the body, causing a shortage of oxygen that is needed for cellular metabolism (to keep tissue alive). Ischemia is generally caused by problems ...

, or hypoxaemia. Post-operative cognitive dysfunction can complicate a person's recovery from surgery, delay discharge from hospital, delay returning to work following surgery, and reduce a person's quality of life.

Causes

The body's

to surgery likely plays an important role, at least in elderly patients. Various research initiatives during recent years have evaluated whether actions taken before, during and after surgery can lessen the possible deleterious effects of inflammation. For example, anti-inflammatory agents can be given before surgery. During surgery, inflammation can be modulated by temperature control, use of regional rather than general anesthesia or the use of

beta blocker Beta blockers, also spelled β-blockers, are a class of medications that are predominantly used to manage abnormal heart rhythms ( arrhythmia), and to protect the heart from a second heart attack after a first heart attack ( secondary prevention ...

s. After surgery, optimal pain management and infection control is important. Several studies have shown variable-significance positive effects when a multidisciplinary, multifactorial approach to elderly patient is followed during pre, peri and post-operative care. The release of stress hormones during surgery, ischemia, or hypoxemia may also play a role in causing postoperative cognitive dysfunction. The role of anesthetics in causing postoperative cognitive dysfunction is not clear. A comparison between inhalation anesthetics and intravenous anesthetics to determine which were more likely to cause postoperative cognitive dysfunction when used in the elderly for non-cardiac surgery found that fewer people experienced POCD with total intravenous

anesthesia Anesthesia (American English) or anaesthesia (British English) is a state of controlled, temporary loss of sensation or awareness that is induced for medical or veterinary purposes. It may include some or all of analgesia (relief from or prev ...

(TIVA) compared to inhalational anesthesia, however, these conclusions are of low quality and further research is necessary to determine differences between the two approaches to anesthesia.

Prevention

Approaches to prevent postoperative cognitive dysfunction include monitoring of anesthetic during surgery and ensuring that the person is in the optimal range to ensure that they are not aware of their surroundings and do not feel pain. An

electroencephalograph Electroencephalography (EEG) is a method to record an electrogram of the spontaneous electrical activity of the brain. The bio signals detected by EEG have been shown to represent the postsynaptic potentials of pyramidal neurons in the neoc ...

(EEG) may help guide the surgical team to determine the optimum depth of anesthesia and prevent high or low doses during the surgical procedure. This approach may reduce the risk of a neuroinflammatory response and/or neurological disturbances including cognitive dysfunction.

Assessment

Cognitive tests are given prior to operations to establish a baseline. The same tests are again given post-operatively to determine the extent and duration of the decline for POCD. "A project examining adults 55 and older who have major non-cardiac surgeries is finding that 'upward of 30 percent of patients is testing significantly worse than their baseline 3 months later.

Epidemiology

POCD is common after cardiac surgery, and recent studies have now verified that POCD also exists after major non-cardiac surgery, although at a lower incidence. The risk of POCD increases with age, and the type of surgery is also important because there is a very low incidence associated with minor surgery. POCD is common in adult patients of all ages at hospital discharge after major noncardiac surgery, but only the elderly (aged 60 years or older) are at significant risk for long-term cognitive problems. Patients with POCD are at an increased risk of death in the first year after surgery. Research interest has increased since early 2000, especially as more elderly patients are able to undergo successful minor and major surgeries. POCD has been studied through various institutions since the inception of the IPOCDS-I study centred in Eindhoven, Netherlands and Copenhagen, Denmark. This study found no causal relationship between

cerebral hypoxia Cerebral hypoxia is a form of Hypoxia (medical), hypoxia (reduced supply of oxygen), specifically involving the human brain, brain; when the brain is completely deprived of oxygen, it is called ''cerebral anoxia''. There are four categories of c ...

and low blood pressure and POCD. Age, duration of anaesthesia, introperative complications, and postoperative infections were found to be associated with POCD. * POCD is just as likely to occur after operations under regional anesthesia as under general anesthesia. * More likely after major operations than minor operations. * More likely after heart operations than other types of surgery. * More likely in aged than in younger patients. * More likely in older patients with high alcohol intake. * People with higher preoperative ASA physical status scores are more likely to develop POCD. * People with lower educational level are more likely to develop POCD than those with a higher educational level. * People with prior history of a

stroke Stroke is a medical condition in which poor cerebral circulation, blood flow to a part of the brain causes cell death. There are two main types of stroke: brain ischemia, ischemic, due to lack of blood flow, and intracranial hemorrhage, hemor ...

, even though there is complete functional recovery, are more likely to develop POCD. * More likely in the elderly with pre-existing declining mental functions, termed

mild cognitive impairment Mild cognitive impairment (MCI) is a diagnosis that reflects an intermediate stage of cognitive impairment that is often, but not always, a transitional phase from cognitive changes in normal aging to those typically found in dementia, especially ...

(MCI). MCI is a transitional zone between normal mental function and evident

Alzheimer's disease Alzheimer's disease (AD) is a neurodegenerative disease and the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in remembering recent events. As the disease advances, symptoms can include problems wit ...

or other forms of

dementia Dementia is a syndrome associated with many neurodegenerative diseases, characterized by a general decline in cognitive abilities that affects a person's ability to perform activities of daily living, everyday activities. This typically invo ...

. It is insidious, and seldom recognized, except in retrospect after affected persons are evidently demented. *

Delirium Delirium (formerly acute confusional state, an ambiguous term that is now discouraged) is a specific state of acute confusion attributable to the direct physiological consequence of a medical condition, effects of a psychoactive substance, or ...

and severe worsening of mental function is very likely in those with clinically evident Alzheimer's disease or other forms of dementia, as well as those with a history of delirium after previous operations.

Causes

Prevention

Assessment

Epidemiology

Footnotes

Further reading