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3. Delirium
Keywords
DeliriumDiagnosisDifferential diagnosisMedical work-upTreatmentPreventionIntravenous haloperidolEssential Concepts
Delirium is the clinical expression of an acutely failing brain, leading to disturbances of alertness and attention (also known as confusion). Delirium is often accompanied by agitation and psychosis.
There is always at least one, sometimes several, medical causes for a delirium that need to be identified and treated.
The end stage of very severe psychiatric states can be a delirium (e.g., delirious mania).
The treatment of choice for managing the symptoms of delirium is antipsychotics, including for delirium tremens.
Non-pharmacological maneuvers (avoiding immobility, avoiding sleep deprivation, avoiding sensory deprivation) should be instituted routinely to prevent and help manage delirium in hospitalized patients. The prevention of a postoperative delirium on the other hand with prophylactic antipsychotics is not well established.
“If you can’t convince them, confuse them.” [1]
–Harry S. Truman, 33rd US President, 1884–1972
Clinical Presentation
When the brain as an organ fails acutely from a wide variety of insults, a fairly stereotyped clinical syndrome, delirium, is the result. Different terms for the same thing are used in other specialties (neurology uses the term toxic metabolic encephalopathy) or other countries (acute organic psychosyndrome). The onset of delirium is rather sudden, although an unspecific prodrome with anxiety and restlessness can predate the full-blown picture. One diagnostically useful hallmark of delirium is its fluctuation in severity over the course of the day.
Delirium is fundamentally a disturbance of consciousness, with both arousal and attention being affected. Patients are unable to pay attention, to shift attention, or to sustain attention. As attention is one of the basic brain functions that supports higher functions, other cognitive deficits are usually present. Patients are often unable to learn new information and appear puzzled, perplexed, and confused (hence the synonymous term “acute confusional state” for delirium). Patients are usually, but not obligatory, disoriented to time (often), place (sometimes), and person (only in severe cases); the key is the inability to attend. The level of consciousness can be altered in both directions, from hypervigilant to lethargic or stuporous. Some patients are anxious, labile, and agitated (hyperactive delirium); others are withdrawn (hypoactive delirium); most show a mixed pattern. Other patients might be rambling or be grossly incoherent. You should not expect to get a good history from a delirious patient. In addition, the sleep-wake cycle is disturbed, and patients are awake at night and sleepy during the day.
Differential diagnosis of delirium
Dementia | Chronic onset, symptoms stable. Usually alert and able to attend. Immediate memory OK. Establish premorbid function with help of family members. Dementia is a risk factor for delirium |
Psychosis | Patients are alert and oriented with intact memory and attention. However, this can be difficult to assess in acute psychosis when patients are disorganized and uncooperative. Onset of psychotic illness is very rarely days but usually weeks (or an even longer prodromal period). Psychosis can be part of delirium |
Depression | Can be confused with hypoactive delirium. Depressed patients can often participate in cognitive testing once you overcome their lack of motivation (persist when patient bemoans: “I can’t do that.”) |
Mania | Delirious mania (Bell’s mania) is a subtype of mania characterized by severe lack of sleep and constant moving about, among other manic symptoms that can lead to a state of dangerous physical exhaustion [3] and death [4]. Catatonic symptoms are common |
Diagnosis
Have a low threshold for suspecting a delirium in the right clinical setting. An elderly hospitalized patient with new-onset psychosis has a delirium until proven otherwise, not late-onset schizophrenia. Even seemingly benign medications (e.g., zolpidem added for insomnia) can cause a delirium when other delirium risk factors are present [5]. Any sudden change in mental status is a red flag for the presence of a delirium. However, patients with known psychiatric disorders can have a superimposed delirium: A delirium can develop in a manic patient who has not eaten or had anything to drink on his quest for the Holy Grail; a psychotic patient who is inadvertently overdosing on his benztropine because of disorganization can become delirious. “Bad behavior” can stem from subtly confused patients. While very severe psychiatric states might cause a “non-medical” delirium (e.g., Bell’s mania [3]), I suspect any delirium in these states is ultimately the result of some medical derangement.
Key Point
Etiologies of delirium
Withdrawal (alcohol, sedatives) |
Intoxication (illicit drugs, medications, toxins) |
Medical conditions Hypoxemia (from any cause, e.g., hypotension, anemia) Hypoglycemia Hypertensive encephalopathy Intracranial pathology (stroke, encephalitis, tumor, trauma, bleeding, seizures) Infections (UTI, pneumonia, cellulitis, SBE) Metabolic (Wernicke’s encephalopathy, hepatic encephalopathy, uremia, electrolyte abnormalities) Endocrine (thyroid, parathyroid, adrenal disease) |
Psychiatric conditions (leading to medical conditions associated with a delirium) |
Severe states of excitation or agitation (e.g., Bell’s mania) Severe disorganization Severe psychomotor withdrawal states (depression, catatonia) Severe eating disorders Severe drug use disorders |
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