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]Pratik Bahekar, MBBS [3]
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.
Delirium, like mental confusion, is a very general and nonspecific symptom of organ dysfunction, where the organ in question is the brain. In addition to many organic causes relating to a structural defect or a metabolic problem in the brain (analogous to hardware problems in a computer), there are also some psychiatric causes, which may also include a component of mental or emotional stress, mental disease, or other "programming" problems (analogous to software problems in a computer).
Too many to list by specific pathology, general categories of cause of delirium include:
Gross structural brain disorders
- Head trauma (i.e., concussion, traumatic bleeding, penetrating injury, etc.)
- Gross structural damage from brain disease (stroke, spontaneous bleeding, tumor, etc.)
Neurological disorders
- Various neurological disorders
- Lack of sleep
Circulatory
Lack of essential metabolic fuels, nutrients, etc.
- Hypoxia,
- Hypoglycemia
- Electrolyte imbalance (dehydration, water intoxication)
Toxication
- Intoxication various drugs, alcohol, anesthetics
- Sudden withdrawal of chronic drug use ("de-tox") in a person with certain types of drug addiction (e.g. alcohol, see delirium tremens, and many other sedating drugs)
- Poisons (including carbon monoxide and metabolic blockade)
- Medications including psychotropic medications
Mental illness per se is not a cause, as a matter of definition
Some mental illnesses, such as mania, or some types of acute psychosis, may cause a rapidly fluctuating impairment of cognitive function and ability to focus. However, they are not technically causes of delirium, since any fluctuating cognitive symptoms that occur as a result of these mental disorders areconsideredby definition to be due to the mental disorder itself, and to be a part of it. Thus, physical disorders can be said to produce delirium as a mental side-effect or symptom; however primary mental disorders which produce the symptom cannot be put into this category, once identified. However, such symptoms may be impossible to distinguish clinically from delirium resulting from physical disorders, if a diagnosis of an underlying mental disorder has yet to be made.
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)
- Heavy metals
- Toxins/drugs (prescribed - Tramadol, recreational)
List of commonly prescribed medicines which may attribute to delirium
- Antiarrhythmic
- Antihistamine
- Antiparkinsonian drugs such as benzatropine
- Antispasmodic
- Benzodiazepine
- Diuretic Furosemide
- Incontinence Oxybutynin
- Opioid Analgesics
- Tricyclic antidepressant[1]
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.[2] 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
References
- ↑ "Delirium in older people". Text " BMJ " ignored (help)
- ↑ Inouye, SK (Mar 4, 1999). "A multicomponent intervention to prevent delirium in hospitalized older patients". The New England Journal of Medicine. 340 (9): 669–76. doi:10.1056/NEJM199903043400901. PMID 10053175. Unknown parameter
|coauthors=ignored (help)