Delirium causes
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Vishal Khurana, M.B.B.S., M.D. [2]
Overview
Causes
Delirium may be caused by severe physical or mental illness, or any process which interferes with the normal metabolism or function of the brain. For example, fever, pain, poisons (including toxic drug reactions), brain injury, surgery, traumatic shock, severe lack of food or water or sleep, and even withdrawal symptoms of certain drug and alcohol dependent states, are all known to cause delirium.
In addition, there is an interaction between acute and chronic symptoms of brain dysfunction; delirious states are more easily produced in people already suffering with underlying chronic brain dysfunction.
A very common cause of delirium in elderly people is a urinary tract infection, which is easily treatable with antibiotics, reversing the delirium.
Common causes of Delirium
A mnemonic for the myriad causes of Delirium: IWATCHDEATH
- Infections (Pneumonia, Urinary Tract Infections)
- Withdrawal (Ethanol,opiate)
- Acute Metabolic (acidosis, renal failure, imbalances, alkalosis)
- Trauma (acute severe pain)
- Central nervous system pathology (epilepsy, cerebral haemorrhage)
- Hypoxia
- Deficiencies (vitamin B12, thiamine)
- Endocriopathies (thyroid, parathyroid, hypopituitarism, hyper/hypoglycemia, Cushing's)
- Acute vascular (Stroke, MI, PE, heart failure)
- Toxins/drugs (prescribed - Tramadol, recreational)
- Heavy metals
Causes by Organ System
| Cardiovascular | Malignant hypertension , Heart failure |
| Chemical/Poisoning | Withdrawal states from ethanol, benzodiazepines , Water hemlock poisoning , Toxic mushrooms -- Monomethylhydrazine , Toluene , Texas Mescalbean poisoning , Poison hemlock , Organic solvent , Methanol , Marijuana , Lead , Jimson weed, , Hyperbaric sickness , Hydrogen sulfide , Heroin , Hallucinogens , Ethylene glycol , Ethanol , Daphne poisoning , Cyanide , Carbon tetrachloride , Carbon monoxide toxicity , Alcohol withdrawal , Thallium Sulfate poisoning , Phencyclidine poisoning , Nickel Carbonyl poisoning |
| Dental | No underlying causes |
| Dermatologic | No underlying causes |
| Drug Side Effect | Valproic acid , Skeletal muscle relaxers , Serotonin syndrome , Quinolones , Lithium , Drug withdrawal , Drug overdose , Cabergoline , Antipsychotics, Antihistamines |
| Ear Nose Throat | No underlying causes |
| Endocrine | Pituitary apoplexy , Phaeochromocytoma , Hypothyroidism , Hypopituitarism , Hypoglycemia , Hyperthyroidism , Hyperosmolar non-ketotic diabetic coma , Hyperglycemia , Hyperthyroidism , Elevated or depressed pituitary function , Elevated or depressed adrenal function , Diabetic ketoacidosis , Diabetic hypoglycemia , Cushing syndrome , Adrenal cortex insufficiency |
| Environmental | Hypothermia , Hyperthermia , Heat stroke , Electric shock , Decompression sickness , Acute Altitude sickness |
| Gastroenterologic | Elevated or depressed pancreas function , Chronic Liver failure , Acute Liver failure |
| Genetic | No underlying causes |
| Hematologic | Thrombocytosis , Polycythemia , Leukemic blast cell crisis , Hypereosinophilia |
| Iatrogenic | Postoperative stress |
| Infectious Disease | Viral Hemorrhagic Fevers , Vancomycin resistant enterococcal bacteremia , Urinary tract infection , Typhoid fever , systemic inflammatory response syndrome , Systemic infections , Surgical wound infection , Subdural empyema , Sleeping sickness (West African) , Sleeping sickness (East African) , Sepsis , Rickettsiae , Rabies , Pyelonephritis, acute , Plague , Neurocysticercosis , Malaria , Intraspinal abscess / granuloma , Intracranial abscess / granuloma , Infections , Gangrene , Chest infection , Cerebral malaria , Brain or epidural abscess , Brain infection |
| Musculoskeletal/Orthopedic | No underlying causes |
| Neurologic | Venous sinus thrombosis , Raised intracranial pressure , Post-ictal states , Nonconvulsive status epilepticus , Meningoencephalitis , Meningitis , Intracranial bleeding , Hypertensive encephalopathy , Epileptic seizures , Epidural haemorrhage , Encephalitis , Encephalitis , Cerebrovascular accident , Cerebral oedema , Cerebral infarction , Brain tumor , Brain bleeding , Brain abscess |
| Nutritional/Metabolic | Wilson's disease , Wernicke's encephalopathy , Vitamin B12 deficiency , Thiamine (Vitamin B1) deficiency , Niacin deficiencies , |
| Obstetric/Gynecologic | No underlying causes |
| Oncologic | No underlying causes |
| Ophthalmologic | No underlying causes |
| Overdose/Toxicity | No underlying causes |
| Psychiatric | Schizoaffective disorder , Mental stress , Mental exhaustion |
| Pulmonary | Respiratory failure , Hypoxemia , Hypercarbia |
| Renal/Electrolyte | Hypophosphatemia , hypoosmolar states , Hyponatremia , Hypocalcemia , Hyperosmolar states , Hypernatremia ,
Hypermagnesemia , Hypercalcemia , Hypomagnesemia , Hyperphosphatemia , Chronic Renal failure , Acute Renal failure |
| Rheumatology/Immunology/Allergy | Vasculitis |
| Sexual | No underlying causes |
| Trauma | Trauma , Skull fracture , Head injury |
| Urologic | No underlying causes |
| Miscellaneous | Coproporphyria , Burns |
Causes in Alphabetical Order
Risk Factors
- Older age
- Cognitive impairment / dementia
- Physical comorbidity (biventricular failure, cancer, cerebrovascular disease)
- Psychiatric comorbidity (e.g. depression)
- Sensory impairment (vision, hearing)
- Functional dependence (e.g. requiring assistance for self-care and/or mobility)
- Dehydration / Malnutrition
- Drugs and drug-dependence.
- Alcohol dependence
Precipitating factors
Any acute factors that affect neurotransmitter, neuroendocrine or neuroinflammatory pathways can precipitate an episode of delirium in a vulnerable brain. Clinical environments can also precipitate delirium, and optimal nursing and medical care is a key component of delirium prevention.[1] Some of the most common precipitating factors are listed below:
- Metabolic
- Malnutrition
- Dehydration, electrolyte imbalance
- Anaemia
- Hypoxia
- Hypercapnoea
- Hypoglycaemia
- Endocrine disorders (e.g. SIADH, Addison’s disease, hyperthyroidism, hypercalcaemia)
- Infection
- Especially respiratory and urinary tract infections
- Medication
- Anticholinergics, dopaminergics, opioids, steroids, recent polypharmacy
- Vascular
- Stroke/Transient ischaemic attack
- Myocardial infarction, arrhythmias, decompensated heart failure
- Physical/psychological stress
- Pain
- Iatrogenic event, esp. post-operative, mechanical ventilation in ICU
- Chronic/terminal illness, esp. cancer
- Post-traumatic event, e.g. fall, fracture
- Immobilisation/restraint
- Other
- Substance withdrawal, esp. alcohol, benzodiazepines
- Substance intoxication
- Traumatic head injury