History: Diagnosis is based on criteria listed in the DSM-IV-TR. History is usually given by the family or caregiver, as the individual is often too confused to give a reliable history. Symptoms develop over a period of a few hours to a few days, with symptoms that fluctuate throughout the day and are generally worse at night (sundowning), when there are fewer environmental cues and less stimulation available. The individual may alternate between decreased states of alertness and consciousness (lethargy), with sluggishness and apathy, and hyperactive states. During periods of heightened arousal, there may be episodes of seeing or hearing things that aren't there (visual or auditory hallucinations), misinterpreting perceptions (illusions), false but persistent beliefs (delusions), or agitation. Visual hallucinations are most common, but there may also be hallucinations involving the sense of hearing (auditory), touch (tactile), taste (gustatory), or smell (olfactory). Illusions may cause the individual to misinterpret environmental stimuli, such as mistaking a banging door as a gunshot.
The individual is often unaware of his or her own altered state of consciousness, and may be confused and disoriented to person, place, or time. He or she may be unable to identify caregivers or family members, and may not know his or her location or the day, date, time, or year. Fear may cause the individual to attack caregivers because of perceived threats, or because of a delusion, such as, "They're trying to poison my food." Other emotional states may include anxiety, irritability, or euphoria. History may reveal a possible cause of delirium, such as a general medical condition such as low blood sugar (hypoglycemia) or other disturbance in blood chemistry, fever, infection, liver or kidney failure, head injury, alcohol withdrawal syndrome, terminal illness, AIDS, or recent use of a medication or drug (corticosteroids, pain medications, anti-asthma drugs, hallucinogens, cocaine).
Physical exam: In response to hallucinations or illusions, the individual may startle easily, talk to imagined voices, or pick at the air or bedclothes. They may be sleepy (lethargic) or overly alert and fearful (hypervigilant). They may be unable to focus on a conversational topic, be easily distracted, or continue to answer a previous question rather than shifting focus to a new topic (perseveration). Language may be disturbed, with slurred speech (dysarthria), inability to name objects (dysnomia), inability to write (dysgraphia), or exhibit rambling, irrelevant, or incoherent speech. General physical examination may reveal jaundice or enlarged liver (hepatomegaly) suggesting liver failure, bluish discoloration (cyanosis) or shortness of breath (dyspnea) suggesting lack of oxygen (hypoxia), fever suggesting infection, or other underlying cause of delirium. Neurological examination may reveal abnormal reflexes (frontal lobe release signs) suggesting diffuse brain involvement, or focal weakness suggesting dysfunction in a specific brain location, as might be seen with head trauma.
Tests: Verbal tests can be given to determine the individual's level of orientation, such as asking the names of family members or the time of day. Simple memory tests, such as asking the individual to recall items or count backwards, might be helpful. The Folstein Mini-Mental State Examination (MMSE), administered by the evaluating clinician, assesses for deficits in orientation, attention, memory, language, and visuoconstruction performance. Other screening strategies include the Confusion Assessment Method, the Delirium Rating Scale (DRS) and the Memorial Delirium Assessment Scale (MDAS). Caution should be used when using verbal or memory tests to ascertain levels of orientation, since education level and cultural background and differences could affect an individual's answers.
There are no specific diagnostic lab tests except those that might better define an underlying general medical condition or intoxication. An electroencephalogram (EEG) typically shows abnormal, generalized slowing or, occasionally, fast activity (alcohol withdrawal delirium). Blood work is needed to determine specific imbalances in blood chemistry that might be contributing to delirium. Arterial blood gas tests, as well as a chest x-ray, and electrocardiogram, might be utilized if disease of the lungs or heart is suspected as the underlying cause. Cultures of blood and body fluids should be performed if systemic infection is suspected. Urine and blood drug screens or levels of specific medications are helpful is delirium is related to a specific substance.