What is Delirium?
Delirium, or acute confusional state, is a sudden, severe and serious disturbance in brain function that results in confusion, decreased awareness of one’s environment, and impaired focus. Although delirium can occur in any age group, it is most common in the elderly. It is not a disease per se, but a syndrome of similar symptoms that can be caused by various ailments. These symptoms associated with delirium typically fluctuate during the course of illness. Delirium is very common in the ICU and during palliative care and can be fatal if not picked up early, so prompt diagnosis and management is of utmost importance.
Types of DeliriumDelirium is typically classified into 3 subtypes: hyperactive, hypoactive and mixed. Some special scenarios also exist, such as delirium tremens, excited delirium, post-operative delirium etc.
HyperactiveIn this type of delirium, patients are agitated, aggressive and frequently hallucinate; Up to 22% of patients with delirium have the hyperactive type.
HypoactiveUp to 50% of delirium cases may be hypoactive. This type of delirium is characterized by a state of reduced awareness of surroundings, decreased muscle movements, lethargy, indifference and neglect of things happening around, which can often be mistaken for depression. It is necessary to properly diagnose this state, because it has a higher rate of mortality than hyperactive delirium.
MixedThe mixed form of delirium exhibits features of both of the above states, often in a fluctuating manner.
Excited DeliriumExcited delirium is a unique form of acute delirium that usually occurs in drug abusers. It manifests as sudden onset of bizarre behaviour, fear, paranoia, aggression and sudden death. Patients in excited delirium often feel the urge to indulge in violent activities, resulting in being apprehended by the law. Excited delirium is still under investigation and the molecular reasons behind it are being studied.
ICU DeliriumUp to 80% of patients admitted in the ICU may have delirium. ICU delirium occurs due to various causes, as most patients in the ICU already have severe medical and/or surgical conditions. It may manifest as any of the three forms of delirium.
Delirium TremensDelirium tremens (alcohol withdrawal delirium) is caused because of withdrawal of alcohol in people who have become dependent on it. It can also be caused by concurrent infection or illness in alcoholics. It commonly manifests as tremors, agitation and confusion.
Operation Related DeliriumThere are many reasons for delirium occurring before, during or after an operation. These include:
- Before operation: Pre anaesthetic medications, electrolyte imbalance
- During operation: Sedatives, opioids, anticholinergics
- After the operation: Low BP, low oxygen levels, withdrawal effect of medications
- Post-operative psychosis:
Depression, hallucination, mania, impulsivity, loss of understanding of reality may occur in people following surgery, collectively called post-operative psychosis. This is a major cause of hospitalization, but the reasons and pathology behind it are poorly identified till date.
Causes of DeliriumDelirium can be caused by substance abuse or withdrawal, or due to general medical conditions.
The common causes of delirium include:
- Infections such as meningitis, encephalitis, septicaemia etc
- Metabolic problems
- Medication related:
- Anticholinergic such as atropine, commonly used to treat organophosphorus poisoning
- Centrally acting anti-hypertensives
- Anti-allergy medication
- Anti Parkinson’s treatment such as levodopa
- Post operative state
- Deficiency of glucose in the blood
- Hypoxia or deficiency of oxygen in the blood
- Substance abuse, such as alcohol, cannabis, heroin etc.
- Alcohol withdrawal delirium – also called delirium tremens
- Sleep deprivation
- Structural problems in the brain
- Severe vitamin deficiencies
- Heart, liver, kidney or thyroid failure
- After seizures
- Metabolic disturbances
- Anticholinergic medication
- Alcohol withdrawal
- Drug intoxication
- Medication related
Risk Factors of Delirium include:
- Use of physical restraints
- Catheterization of the bladder
- Any treatment-related event
- Use of 3 or more medications
- Related psychiatric disorder
- Old age
Signs and Symptoms of DeliriumThe signs and symptoms of delirium are many and may vary with the type of delirium, but they can generally be said to be as they are listed below:
- Change of the level of consciousness – Consciousness level may be highest during the morning and may worsen during the night – called the “sundowning” phenomenon
- Difficulty in maintaining attention
- Changes in feeling and perception
- Disorientation to time, place and person
- Altered behaviour
- Changes in movement – depending on the subtype of delirium
- Incoherent, irrelevant speech
- Tremors (particularly in delirium tremens)
- Cloth picking behaviour
- Emotional changes – patients with delirium may go through the whole gamut of emotions in a short time
- An inner feeling of restlessness, manifested outside as restless movements of the body
Diagnosis of DeliriumThe diagnosis of delirium is purely clinical. Many clinical scoring systems are available to aid in the diagnosis. It is important to differentiate delirium from dementia.
The diagnosis of delirium is purely clinical. It is not detected by any laboratory test or radiological investigation. A thorough clinical examination focussing on the central nervous system, which includes testing for movements, sensations and higher functions, is imperative to arrive at the diagnosis. There are a few tools which make it easier to diagnose delirium, such as:
- Confusion Assessment Method
- Delirium Symptom Interview
- Delirium rating scale
- Memorial Delirium Assessment Scale
- DSM 5 criteria
- Disturbance of consciousness
- Change in cognition that is not due to dementia.
- Sudden onset, fluctuating disturbance
- Evidence from the clinical examination or laboratory testing that it is caused by a direct consequence of a general medical condition, an intoxicating substance, medication use, or more than one cause.
- Complete metabolic profile
- Blood ammonia level
- ABG (arterial blood gas)
- Toxicology screening for alcohol and recreational drugs
- Liver function tests
- Kidney function tests
- Thyroid function tests
- Magnesium and other electrolytes
- Vitamin levels in the blood
- Chest X ray
- CT scan of the brain
- MRI scan of the brain
- EEG (Electro Encephalogram)
- Lumbar Puncture and CSF analysis
- Mental Status Tests
- Urine analysis
- Alzheimer’s disease
- Vascular dementia (multi-infarct dementia)
- Lewy body dementia
- Fronto temporal dementia, and others
Treatment for DeliriumThe treatment of delirium involves both supportive therapy and pharmacological therapy.
The treatment of delirium basically depends on identifying the cause of delirium and treating it. Treatment may be broadly categorized into two complementing methods of care:
- Monitoring of the patient’s fluid and nutrition status and treating accordingly
- Reorientation methods
- Avoiding Physical Restraints correction of sensory deficits
- Behaviour modification
- Psychiatric consultation
- Neuroleptics (Also called antipsychotics)
- Olanzapine etc
- Sedatives (short acting)
- Cholinesterase inhibitors
- Thiamine, which is mostly prescribed for alcohol withdrawal delirium
- Vitamin B 12, if its deficiency is identified
- Specific therapy for the underlying cause