Is Perioperative delirium related to dementia? Progress Neuro Psy Biol. June.2013.

31.05.2013

Delirium is a neuropsychological syndrome characterized by disorganized thinking, lack of orientation and a fluctuating course. It is a  behavioral syndrome that is diagnosed by observing the patient.  It is associated with increased morbidity and mortality.

Jeffrey H. Silverstein and Stacie G. Deiner   review peri operative delirium and its relationship with further cognitive dysfunctions in this article.

Patients coming off anaesthesia show confusion and can be very difficult to manage and frequently require additional sedation. This is referred to as emergence delirium or emergence excitation. Patients emerge from this additional sedation in a calmer and more manageable manner. This behavior does not fluctuate. Emergence excitation is probably not a real subset of delirium. It occurs across all age groups and with rare exceptions is extremely limited in time.

Postoperative delirium (PD) is predominantly a diagnosis of older patients. Presentation is typically 24–72 h after the completion of a surgical procedure . (= interval delirium). This occurs in up to 80% of patients admitted to intensive care.  PD can be hypoactive, hyperactive or mixed. a category of sub-syndromal delirium is also described.

Some patients have notable cognitive problems following surgery and anesthesia  that are distinct and distant from delirium described as Post Operative Cognitive Decline (POCD). Approximately 10% of patients show significant deterioration at 3 months following surgery .The incidence appears to drop over time with most POCD appearing to be transient over the course of a year.POCD currently is a research finding and not a recognised disease or syndrome.

Risk factors for Post Operative delirium include : pre-existing cognitive impairments  (dementia), depression, abnormal serum sodium,  increasing age ,exposure to longer acting benzodiazepine, a previous history of delirium, alcohol abuse, and pre-operative use of narcotic analgesics.It is suggested that the depth of sedation can be an important factor in determining the incidence of postoperative delirium.

Many symptoms of post op delirium overlap with dementia.To date there is no clinical data suggesting that the prevention of delirium avoids or diminishes the risk for dementia. There is little convincing evidence that an incidence of postoperative delirium in an otherwise intact patient is commonly associated with rapidly progressive dementia though case reports indicate its existence.

Conclusions: Patients who develop delirium are at high risk for POCD. There is relatively little data at the moment to suggest that POCD is either permanent or progressive. Patients with Post operative delirium need  extended periods of cognitive monitoring.

Summary of the article:

Perioperative delirium and its relationship to dementia. Silverstein JH, Deiner SG. Prog Neuropsychopharmacol Biol Psychiatry. 2013 Jun 3;43:108-15

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