Delirium: Phenomenologic and Etiologic Subtypes

Abstract

While all delirious patients have clouding of consciousness (alteration of attention) and cognitive dysfunction, the level of alertness of different patients may range from stuporous to hyperalert. We, therefore, developed an analog scale to rate the alertness of delirious patients, and a separate scale to rate the severity of their clouding of consciousness. Based on these scales, patients were categorized overall as relatively "activated" (relatively alert despite clouding of consciousness), or "somnolent" (relatively stuporous along with clouding of consciousness). Cognitive function was estimated using the Mini-Mental Status Exam. Separate ratings were made of hallucinations, delusions, illusions, and agitated behavior. Activated and somnolent patients had similar ages, overall severity of delirium, and MiniMental Status Exam scores. Activated patients, however, were more likely to have hallucinations, delusions, and illusions than somnolent patients, and were more likely to have agitated behavior. Patients with hepatic encephalopathy were more likely to have somnolent delirium, while patients with alcohol withdrawal appeared more likely to have activated delirium. Thcse data indicate that phenomenologic subtypes of delirium can be defined on the basis of level of alertness. These subtypes arc validated in part by their differing associations with symptoms unrelated to alertness. These subtypes may havc different pathophysiology, and thus, potentially different treatments.

Clinical significance of delirium subtypes in older people

“…Our study population was highly selected, comprising patients selected for admission to an acute geriatric unit because of physical or mental frailty. Nevertheless, these results are in accordance with the findings of surveys in general hospital wards [18,19]. In contrast, agitated delirium predominates in studies of admissions to psychiatric hospitals or of psychiatric referrals [20,21].…”

“…There was no clear link between infection, the commonest aetiological factor, and any particular subtype. Ross and colleagues reported similar findings in a study of 58 delirious inpatients [19].…”

“…Ross and colleagues used analogue scales of alertness and of related symptoms together with a global classification of patients as 'somnolent' or 'activated' [19]. Liptzin and Levkoff defined specific symptoms from their delirium symptom interview as 'hypoactive' or 'hyperactive': patients with four or more hypoactive symptoms at any time during their hospital stay were said to have hypoactive delirium while patients with three or more hyperactive symptoms were defined as having hyperactive delirium [18].…”

Altered Mental Status in Older Emergency Department Patients

“…Delirium caused by an infection or metabolic derangement is more likely to be the hypoactive subtype, whereas delirium caused by alcohol or benzodiazepine withdrawal is more likely to be the hyperactive subtype. 31 The psychomotor subtypes of delirium may also have a differential effect on clinical course and outcomes. 32 In 225 older patients admitted to a post acute care facility, Kiely at al.…”

The panorama of opioid‐related cognitive dysfunction in patients with cancer

“…60 Furthermore, there is a suggestion that the outcome of delirium is more favorable in the "agitated" as opposed to the "somnolent" subtype. 61 In the case of delirium associated with initiating opioid therapy, clinical experience suggests the hypoactive subtype is probably more common, in keeping with the early sedative effects of opioids. However, in the case of toxicity associated with chronic opioid use in cancer patients, the literature reports suggest a predominance of the hyperactive subtype or agitated delirium.…”