Delirium

Delirium is a disturbed mental state caused by somatic illness characterised by lack of the attention and awareness of the environment, and disordered stream of thought. It is characterized by disorientation, confusion, amnesia, agitation, and hallucinations (most commonly visual). It usually worsens at night, and develops over a short period of time.

Delirium mostly affects elderly (> 65 years), due to their reduced physiological reserves. It's a very common condition, affecting almost 30% of elderly patients at some point during hospitalisation; in addition to this, it's probably underdiagnosed.

It's one of the neurocognitive or organic mental disorders, disorders characterising reduced brain function due to non-psychiatric illness.

Etiology

Delirium can be caused by many disorders, the most common of which are:

Infections (even a small UTI)
Medications
Drug withdrawal (alcohol, benzodiazepines)
Drug intoxication (illicit drugs, anticholinergics)
Metabolic (acidosis, electrolyte disturbance, liver failure, kidney failure)
Trauma (especially to the head)
CNS disease (stroke, tumour, seizures, hypoxia)
Endocrine disorders

Clinical features

Delirium develops over a short period of time and fluctuates during the course of a day, usually worsening during the night. Characteristic for delirium is:

Disturbed attention (e.g. unable to name months of the year backwards)
Disturbed awareness (e.g. not oriented to time and space)
Disturbed memory, language, perception, or visuospatial ability

Delirium may manifest as psychosis, with hallucinations, delusions, or thought disorder.

We distinguish two major types of delirium based on the clinical presentation, hyperactive delirium and hypoactive delirium.

Hyperactive delirium

The hyperactive delirium is the most commonly diagnosed form, characterised by restlessness, agitation, trembling,

Hypoactive delirium

Hypoactive delirium is probably under-diagnosed as it's easier to miss than the hyperactive form. It's characterised by increased drowsiness, lethargy, and inactivity.

Hypoactive delirium likely has a worse prognosis than the hyperactive form.

Diagnosis and evaluation

The diagnosis is clinical, and should be suspected in all elderly with an altered mental status. Determining and treating the underlying cause is essential. Labs, medication review, and medical history may provide clues to the etiology.

Management

There is no causative treatment for delirium; treating the underlying cause is the aim.

Environmental and interpersonal measures are essential in symptomatically managing delirium. The hospital environment itself, with all its noises and busy personell, worsens the confusion. One must try to avoid these worsening factors. Frequent reassurance, verbal orientation, pain management, maintainance of hydration, and mobilisation are all helpful in improving the symptoms of delirium.

Agitated patients

In some cases of hyperactive delirium, patient behaviour may interfere with patient care or safety. Physical restraint should be avoided if possible, but may sometimes be necessary.

If all else fails, low-dose antipsychotics can be used to treat severe agitation in delirium. Haloperidol is often used. It can be administered intramuscularly if necessary. Benzodiazepines should be avoided as they may worsen the condition.