Prolonged activation EEG differentiates dementia with and without delirium in frail elderly patients

OBJECTIVE

Delirium in the elderly results in increased morbidity, mortality and functional decline. Delirium is underdiagnosed, particularly in dementia. To increase diagnostic accuracy, we investigated whether maintenance of activation assessed by EEG discriminates delirium in association with dementia (D+D) from dementia without delirium (DP) and cognitively unimpaired elderly subjects (CU).

METHOD

Routine and quantitative EEG (rEEG/qEEG) with additional prolonged activation (3 min eyes open period) were evaluated in hospitalised elderly patients with acute geriatric disease. Patients were assigned post hoc to three comparable groups (D+D/DP/CU) by expert consensus based on DSM-IV criteria. Dementia diagnosis was confirmed using cognitive and functional tests and caregiver rating (IQCODE, Informed Questionnaire of Cognitive Decline in the Elderly).

RESULTS

While rEEG at rest showed low accuracy for a diagnosis of delirium, qEEG in DP and CU revealed a specific activation pattern of high significance found to be absent in the D+D group. Stepwise logistic regression confirmed that differentiation of D+D from DP was best resolved using activated upper alpha and delta power density which, compared with rEEG, enabled an 11% increase in diagnostic correctness to 83%, resulting in 67% sensitivity and 91% specificity. Among frail CU and D+D subjects, almost 90% were correctly classified.

CONCLUSION

Dementia associated with delirium can be discriminated reliably from dementia alone in a meaningful clinical setting. Thus EEG evaluation in chronic encephalopathy should be optimised by a simple activation task and spectral analysis, particularly in the elderly with dementia.

["FRAGILE"-Old people and surgery]

As life expectancy and modern surgical and intensive care techniques develop, the number of old patients in surgery is rising. Associated are problems with the indication for surgical intervention and rising incidence of "typical" peri- and postoperative complications such as postoperative delirium. Geriatric assessment serves to identify patients at risk of developing complications, to describe the postoperative course of functional and cognitive abilities, and to adjust therapeutic strategies to the individual needs of these patients. The most important instruments of geriatric assessment are described. Postoperative delirium, the most prevalent complication in surgical geriatric patients, is discussed in detail with regard to risk factors, prevalence, diagnosis, and therapeutic options.