Incidence of neuropsychological deficits following cardiac surgery

Initially, the purpose of early research into cardiac surgery was to ascertain whether a neuropsychological problem existed after cardiac surgery. This work established that a significant proportion of patients undergoing cardiac surgery exhibit postoperative neuropsychological deficits, which may persist in a number of patients.2 The reported incidence, however, varies widely and this inconsistency has been attributed to a number of factors: the number, type, sensitivity, and timing of neuropsychological tests employed.3 Most studies assess patients before and at some time after surgery. Assessments in the few days after surgery appear to be contaminated by postoperative discomfort and anaesthetic residue. As a result they tend to yield a higher incidence of deficits. Later assessments, at about eight weeks after surgery, appear to be more stable and are considered to reflect an enduring neuropsychological problem.

The variation in the reported incidence of neuropsychological deficits following cardiac surgery is also likely to be associated with patient related variables such as age and extent of cardiac disease. There is evidence that a general association exists between age and neuropsychological outcome—that is, the older the patient the poorer the outcome.2 Centres using differing policies regarding the upper age limit for surgery may well report different neuropsychological outcomes. It has also been suggested that patients are now presenting with more chronic disease,3 and there …