Without careful assessment, delirium can easily be confused with a number of primary psychiatric disorders because many of the signs and symptoms of delirium are also present in conditions such as dementia, depression, and psychosis. Some characteristic signs and symptoms of delirium are described in this article. All of these symptoms may not be present in every patient. The presentation of a patient with delirium will fluctuate during the course of the condition and even during the course of a day. The diagnostic criteria for delirium are listed in Table 1.¹

Acute Onset/Fluctuating Levels of Consciousness

Delirium is characterized by an acute change (usually over hours to days) in mental status. Patients demonstrate fluctuating levels of consciousness that they often manifest by periodically falling asleep during an interview. This fluctuation in consciousness can result in conflicting reports from various caregivers about the patient’s mental state. Fluctuations in cognitive skills, including memory, language, and organization, are also common.

ATTENTION IMPAIRMENT

Patients with delirium demonstrate attention difficulties. They may not remember instructions and may ask that directions and questions be repeated. Useful screening methods to identify attention problems include asking patients to spell a word backwards or perform “serial 7s” (counting backward from 100 by sevens).

MEMORY IMPAIRMENT AND DISORIENTATION

Memory deficits, especially where recent events are concerned (e.g., the reason for hospitalization or for care being given by nursing staff), are also prominent in patients with delirium. Patients may report not being bathed or bedding not being changed when, in fact, these events occurred earlier in the day. Disorientation to date, place, and situation is common. However, the latter can go unrecognized if patients are not directly asked for the information. For example, hospital staff and family members may assume that a patient is fully oriented only to be surprised when the patient insists that he or she is at home and that the date is 10 years earlier.

AGITATION

Patients with delirium may become agitated as a result of the disorientation and confusion they are experiencing. For example, a patient who is disoriented may think he or she is at home instead of in a hospital, and nursing staff may be mistaken for intruders in the home. Consequently, this patient may not comply with bed or activity restrictions and may try to climb over the bedrails to get out of bed. Likewise, intravenous (IV) and oxygen tubing may not be recognized as such, and the patient may remove them.

APATHY AND WITHDRAWAL

Patients with delirium may present with apathy and withdrawal. They may appear to be depressed because of blunted affect, decreased appetite, decreased motivation, and disrupted sleep patterns.

SLEEP DISTURBANCE

Sleep disturbances are common in patients with delirium. They may periodically fall asleep during the day and then be awake for several hours during the night. This pattern, combined with confusion, disorientation, and decreased nighttime environmental cues, can create an especially hazardous situation in patients who are at risk for falling and pulling out an IV, Foley catheter, or nasogastric tubing.

EMOTIONAL LABILITY

Patients with delirium may display a wide range of emotions, including anxiety, sadness or tearfulness, and euphoria. They may have more than one of these emotions during the course of delirium.

PERCEPTUAL DISTURBANCES

Disturbances in reality testing manifested by visual and auditory hallucinations and delusions may be present. Delusions associated with delirium are likely to be related to disorientation and memory impairment, and fluctuate with these symptoms.

NEUROLOGIC SIGNS

Several neurologic signs and symptoms may be present in delirium regardless of cause. They include unsteady gait; tremor; asterixis; myoclonus, paratonia (e.g., gegenhalten) of the limbs and especially of the neck; difficulty reading and writing; and visuoconstruction problems, such as copying designs and finding words.

Subtypes of Delirium

The three subtypes of delirium are hyperactive, hypoactive, and mixed. Patients with the hyperactive subtype may be agitated, disoriented, and delusional, and may experience hallucinations. This presentation can be confused with that of schizophrenia, agitated dementia, or a psychotic disorder. Patients with the hypoactive subtype of delirium are subdued, quietly confused, disoriented, and apathetic. Delirium in these patients may go unrecognized or be confused with depression or dementia. The mixed subtype is characterized by fluctuations between the hyperactive and hypoactive subtypes.

Screening Tools

Several screening tools are available to aid in identifying delirium. The Folstein Mini-Mental State Examination (MMSE)² is familiar to most physicians. It screens for deficits in orientation, attention, memory, language, and visuoconstruction abilities. Administering the MMSE several times during the course of delirium can be a way to assess improvement. Comparison with an MMSE performed before the onset of the delirium is ideal.

Another screening tool is the Confusion Assessment Method.³ The Delirium Rating Scale (DRS)⁴ and the Memorial Delirium Assessment Scale (MDAS)⁵ measure the severity of delirium.

Indications of Underlying Medical Conditions

Recognizing delirium is important because it is an indication of an underlying medical condition that should be identified and treated. The underlying etiology should be aggressively sought after. Delirium can be caused by a medical emergency or a subacute, chronic medical condition (Table 2).⁶ Prescription drugs, illicit drugs, and toxic substances can also cause delirium. The underlying medical condition is not always readily identifiable, and more than one etiology is often responsible for delirium. In fact, in almost one half of elderly patients with delirium, two or more underlying conditions are responsible for the delirium.⁷

Differentiating Delirium from Primary Psychiatric Disorder

Certain signs and symptoms can help physicians distinguish between delirium and a preexisting psychiatric disorder. For example, visual hallucinations are an indicator of an underlying metabolic disturbance or adverse effect of medication or substance abuse. While visual hallucinations can occur in patients with primary psychiatric illnesses such as schizophrenia, they are much less common than auditory hallucinations. In primary psychiatric disorders, visual hallucinations would be associated with other, more characteristic signs and symptoms of the disorders. Visual hallucinations that occur in patients with delirium can be formed (e.g., people, animals) or unformed (e.g., spots, flashes of light).

Electroencephalography (EEG) can be useful in differentiating delirium from other conditions. In patients with delirium, the EEG shows a diffuse slowing of the background rhythm. An exception is patients with delirium tremens, where the EEG shows fast activity. EEGs are also useful in detecting ictal and postictal seizure activity, as well as nonconvulsive status epilepticus, all of which can present as delirium. Abnormal EEG readings would not be expected in patients with psychotic disorders or depression. However, slowing may occur in patients with dementia.

Finally, the acute onset and fluctuating nature of delirium are key features in distinguishing it from primary psychiatric disorders. Patients are often unable to provide an adequate history. It is important to interview family members and caregivers to determine the time of onset of symptoms and other pertinent medical and psychiatric information, including a review of medications and a history of substance abuse. It is equally important to know how patients are currently different from their normal cognitive state. Psychiatric symptoms that arise in persons 50 years and older without a prior psychiatric history or the development of new symptoms in patients with preexisting psychiatric illness should prompt a thorough medical work-up. Table 3 provides a list of indicators suggesting delirium. Table 4 lists some distinguishing characteristics of delirium, dementia, psychosis, and depression.

Risk Factors

Delirium affects 10 to 30 percent of hospitalized patients who are medically ill.⁸ The prevalence is even higher in certain subgroups. For example, 25 percent of hospitalized patients with cancer, 30 to 40 percent of hospitalized patients with human immunodeficiency virus (HIV) infection, and more than 50 percent of postoperative patients develop delirium during hospitalization.^9–11 Among nursing home residents older than 75, up to 60 percent may have delirium at any time.¹² Table 5 lists the characteristics of patients who are at increased risk for delirium and some medical conditions that increase a patient’s risk for developing delirium. Recognizing dementia as a risk factor for delirium can help physicians avoid attributing the confusion and agitation associated with delirium to preexisting dementia, which can lead to a failure to search for underlying medical conditions or to discontinue medications that may be causing the delirium.

Management

IDENTIFYING UNDERLYING MEDICAL CONDITIONS

The definitive treatment for delirium is to correct the underlying medical condition causing the disorder. The initial steps in managing patients with delirium are to conduct a careful review of the medical history, physical examination findings, laboratory evaluations, and any drugs the patient is using, including over-the-counter agents, illicit drugs, and alcohol. Information from patients’ current and past medical history, as well as the physical examination, should guide the initial work-up. Often the etiology will be fairly obvious from the history and basic laboratory tests.¹³ Table 6^6,14 outlines a plan for assessing patients with delirium.

SYMPTOMATIC TREATMENT

During the search for an underlying medical condition, symptomatic treatment for delirium may include the use of antipsychotic drugs to control agitation and hallucinations, and to clear the sensorium (i.e., improve attention abilities and level of orientation). Haloperidol (Haldol) has been studied most often in the symptomatic management of delirium,⁸ but risperidone (Risperdal)^15,16 and olanzapine (Zyprexa),¹⁷ which are newer, atypical antipsychotics, have been the subjects of a few case reports. Two small studies^18,19 with olanzapine suggested that this drug might be a useful alternative in the treatment of delirium.

In most adult patients with delirium of moderate severity, haloperidol therapy can be initiated at 1 to 2 mg twice daily, repeated every four hours as needed, and can be administered via IV, oral, or intramuscular routes. The IV route has been shown to produce a lower incidence of extrapyramidal side effects²⁰; however, it does carry a risk for the development of torsades de pointes.^21,22 Preferably, patients receiving IV haloperidol should be on a cardiac monitor. QTc prolongation greater than 450 msec or more than 25 percent above baseline should prompt the physician to consider discontinuing haloperidol therapy, or a cardiology consultation should be obtained.⁸

Elderly patients should be started at lower drug dosages. In these patients, haloperidol therapy can be started at 0.25 to 1.0 mg twice daily and repeated every four hours, as needed.⁸ Risperidone therapy can be initiated at a dosage of 0.5 mg twice daily and increased gradually if necessary. In all patients, response to antipsychotics and the amount of as-needed medication used should be monitored at least every 24 hours.

If as-needed medication is necessary on a regular basis, the amount of scheduled antipsychotic should be increased. When patients’ cognitive states stabilize, antipsychotics should be continued over the next few days, then tapered and discontinued. Physicians should not automatically discontinue antipsychotics on the first day the patient’s mental status shows improvement, because the improvement may just be a normal fluctuation in the delirium. Gradual tapering that ends in discontinuation allows time to assess patients, to ensure that the delirium has resolved and avoid rapid rebound of symptoms.

ENVIRONMENTAL INTERVENTIONS

Environmental interventions that can help in managing patients with delirium are listed in Table 7.²³ Assigning patients to a room near the nursing station will allow for closer monitoring. The presence of a family member or close friend can also be helpful. In more severe cases, the use of 24-hour, one-on-one supervision may be necessary to monitor the patient and assist in controlling agitation. Frequent reorientation by nursing staff and family members is important. Patients should be reminded of the month, year, day of the week, time of day, and reason for hospitalization. Patients should also be reminded of the name of the hospital, city, and state. A calendar, clock, and family pictures displayed within patients’ view can be beneficial.

Understimulation resulting from absence of cues about the time of day and the situation should be avoided, but overstimulation should also be avoided. The activity, light, and noise (including that from beepers) in and around the patients’ rooms should be monitored. Frequent checking of vital signs during the night should be avoided unless the necessity is clearly indicated, because frequent waking can lead to sleep deprivation, which may worsen delirium.²⁴

The use of physical restraints should be avoided, if possible. Physical restraint can increase agitation and the risk for injury in patients who are cognitively impaired. However, if other measures to control a patient’s behavior are ineffective and it seems likely that the patient, if unrestrained, may cause personal injury or injure others, restraints can be used with caution. Patients who are restrained should be monitored closely, and restraints should be discontinued as soon as possible. Physicians should be aware of hospital policies and other regulations regarding the use of physical restraints.²⁵

Delirium can be a frightening experience for patients and family members. Patients may fear that they are losing their minds. Educating patients and family members about delirium and its association with underlying medical conditions is important. Unless there is reason to believe that a patient has experienced permanent loss of cognitive function, the patient and family members should be reassured that the symptoms are temporary and should resolve. Neurologic consultation can help establish a differential diagnosis in patients with delirium. Psychiatric consultation can aid in distinguishing delirium from a primary psychiatric disorder and in managing the behavior disturbances associated with delirium.

COURSE AND PROGNOSIS

Considerable morbidity and mortality are associated with delirium. Patients with delirium have longer hospital stays and more medical complications, such as pneumonia and pressure ulcers. Mortality is also higher in patients with delirium, probably as a result of more severe underlying medical pathology. The mortality rate among elderly hospitalized patients with delirium is estimated to range from 22 to 76 percent.⁸

The course of delirium can last from several hours to several months. Through appropriate identification and correction of the underlying etiology, most patients experience complete resolution of delirium, although full recovery of mental function may lag behind corrected laboratory values by several days. Without treatment, however, progression to stupor, coma, or death can occur. Patients who are elderly and those who have HIV infection are less likely to fully recover.^26,27