Post-operative Neurobehavioral Disturbance

Some form of Post-operative Neurobehavioral Disturbance (POND) is a common condition. It is reported to occur in 10-20% of all hospital admissions but figures vary. One study reported incidence rates that ranged from 16 to 62%. It is most likely to occur in elderly patients, particularly in those patients who already have some impairment of cognitive ability. Postoperative psychosis, which may also be described as delirium, acute confusional state, acute brain failure or acute organic reaction, is a less common subset of all conditions that fall within the POND classification.

Risk factors for all POND conditions:
  • Age, especially if more than 65 years old
  • Male Sex
  • Pre-existing cognitive impairment e.g. dementia, stroke
  • Drug use and therapy and dependence e.g. benzodiazepines
  • Regular alcohol use
  • Stress
  • Visual or hearing problems
  • Poor mobility
  • Terminally ill
  • ICU admission

Co-morbidity and a previous similar history are predictive factors for the development of an acute confusional state. Patients with one or more risk factors should be closely observed for the first indications of confusion and treatment started at an early stage. A period of normality does not indicate that this condition will not occur. Delay in treatment may result in a poorer outcome.

What is Postoperative Psychosis or delirium?

POND describes a number of conditions where a patient experiences a neurobehavioral disturbance. A subset of POND is described as postoperative delirium or psychosis. It is characterized by various symptoms including hallucinations, delusions, paranoia, disturbed consciousness and reduced clarity of awareness of the environment. Patients may also manifest uncharacteristic aggressive behavior and extraordinary physical strength. It may follow a period of normal lucidity. For patients who have had surgery the immediate postoperative period appears to be a crucial phase during which the brain is most vulnerable to provocations that give rise to delirium.

General causes, incidence, and risk factors for psychosis

Psychosis is a severe mental condition characterized by a loss of contact with reality. A lack of contact with reality gives rise to two phenomena. The first is the presence of hallucinations – hearing, seeing or feeling things that are not there. The second is the presence of delusions, which means holding unusual beliefs not shared by other people that can be shown to be incorrect. Psychosis is a symptom of psychiatric illness; it is not itself the name of a mental disorder. Psychosis may occur in a number of other mental conditions including the following examples taken from a full list available from Chapter V of the International Statistical Classification of Diseases and Related Health Problems, 10th Revision:

  • Postnatal psychosis (a severe form of postnatal depression in some mothers with newborns)
  • Substance-induced psychosis (including alcohol, certain illegal drugs and some prescription drugs, such as steroids and stimulants)
  • Some personality disorders.
  • Bipolar disorder (manic depression)
  • Brain tumors
  • Epilepsy
  • Psychotic depression
  • Schizophrenia
  • Dementia (Alzheimer’s and other degenerative brain disorders)
  • Stroke
  • HIV AIDS

Post-operative psychosis or delirium (or acute confusional state) occurs in both community and hospital settings. It manifests itself as a period of reversible confusion of sudden onset. It may occur in association with concurrent illness or during a period of post-operative convalescence, and is often found in a setting of unfamiliar surroundings. Psychosis may require prolonged periods of hospitalization and is associated with an increased morbidity.


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