Delirium Health Article

Definition

Delirium is a state of mental confusion that develops quickly and usually fluctuates in intensity.

Description

Delirium is a syndrome, or group of symptoms, caused by a disturbance in the normal functioning of the brain. The delirious patient has a reduced awareness of and responsiveness to the environment, which may be manifested as disorientation, incoherence, and memory disturbance. Delirium is often marked by hallucinations, delusions, and a dream-like state.

Delirium affects at least one in 10 hospitalized patients, and is a common part of many terminal illnesses. Delirium is more common in the elderly than in the general population. While it is not a specific disease itself, patients with delirium usually fare worse than those with the same illness who do not have delirium.

Causes

There are a large number of possible causes of delirium. Metabolic disorders are the single most common cause, accounting for 20–40% of all cases. This type of delirium, termed "metabolic encephalopathy," may result from organ failure, including liver or kidney failure. Other metabolic causes include diabetes mellitus, hyperthyroidism and hypothyroidism, vitamin deficiencies, and imbalances of fluids and electrolytes in the blood. Severe dehydration can also cause delirium.

Drug intoxication ("intoxication confusional state") is responsible for up to 20% of delirium cases, either from side effects, overdose, or deliberate ingestion of a mind-altering substance. Medicinal drugs with delirium as a possible side effect or result of overdose include:

• anticholinergics, including atropine, scopolamine, chlorpromazine (an antipsychotic), and diphenhydramine (an antihistamine)
• sedatives, including barbiturates, benzodiazepines, and ethanol (drinking alcohol)
• antidepressant drugs
• anticonvulsant drugs
• nonsteroidal anti-inflammatory drugs (NSAIDs), including ibuprofen and acetaminophen
• corticosteroids, including prednisone
• anticancer drugs, including methotrexate and procarbazine
• lithium
• cimetidine
• antibiotics
• L-dopa

Delirium may result from ingestion of legal or illegal psychoactive drugs, including:

• ethanol (drinking alcohol)
• marijuana
• LSD (lysergic acid diethylamide) and other hallucinogens
• amphetamines
• cocaine
• opiates, including heroin and morphine
• PCP (phencyclidine)
• inhalants

Drug withdrawal may also cause delirium. Delirium tremens, or "DTs," may occur during alcohol withdrawal after prolonged or intense consumption. Withdrawal symptoms are also possible from many of the psychoactive prescription drugs.

Poisons may cause delirium ("toxic encephalopathy"), including:

• solvents, such as gasoline, kerosene, turpentine, benzene, and alcohols
• carbon monoxide
• refrigerants (Freon)
• heavy metals, such as lead, mercury, and arsenic
• insecticides, such as Parathion and Sevin
• mushrooms, such as Amanita species
• plants such as jimsonweed (Datura stramonium) and morning glory (Ipomoea spp.)
• animal venoms

Other causes of delirium include:

• infection
• fever
• head trauma
• epilepsy
• brain hemorrhage or infarction
• brain tumor
• low blood oxygen (hypoxemia)
• high blood carbon dioxide (hypercapnia)
• post-surgical complication.