**3. Mechanism and causes**

The genesis of delirium is multifactorial. In general, all conditions that can induce a neuroinflammatory process are potential causes of delirium. Through the action of cytokines, chemokines, tumor necrosis factor-alpha, and other inflammatory agents (e.g., interleukin (IL)-1, and IL-6), a cascade of events is activated; it culminates in endothelial and microvascular damage and alterations of the blood– brain barrier. Again, disorders of neurotransmitter pathways such as the dopamine and acetylcholine systems, involving respectively dopamine excess or acetylcholine depletion, have a key role in the pathophysiology of delirium [9]. Further, in clinically ill patients, the impairment of cerebral oxidative metabolism is another potential mechanism to be considered [10].

Although drugs such as opioids, anticholinergic drugs, steroids, chemotherapies and metabolic disorders such as metabolic encephalopathy, nutritional deficiencies, electrolyte disturbances, dehydration are the main inducers of delirium, many conditions can provoke delirium. These causes include constipation, infections, hematological changes, paraneoplastic syndromes, brain neoplasms, central nervous system (CNS) secondarisms, seizure disorders, hypoxia, hypo/hypercarbia, and environmental factors. Several acronyms are commonly used to memorize and recognize potential causes. Sometimes the cause of the delirium cannot be found (**Table 1**).


**5**

*Introductory Chapter: Delirium in Palliative Care DOI: http://dx.doi.org/10.5772/intechopen.98654*

form and the hyperkinetic form.

defined delirium based on four criteria, namely:

dent on a pre-existing condition of dementia.

maintain or shift attention.

tion, or withdrawal.

According to the type of psychomotor activity, there are three subtypes of

• Hypokinetic form. It is improperly referred to as "quiet delirium" or "acute encephalopathy". This type is featured by apathy, declined responsiveness, reduced psychomotor function, withdrawn attitude, lethargy, and drowsiness.

• Mixed form. The person may exhibit a fluctuation between the hypoactive and hyperactive subtypes where there is an alternation between the hypokinetic

In palliative care, the hypoactive and mixed are the most frequent subtypes of delirium. The lack of tangible agitation and the erroneous belief that the patient is drowsy because of illness, drugs administered, or an underlying depressed habitus, make this subtype very often misunderstood. This is a serious care gap as hypoactive delirium is frequently associated with perceptual disturbances and

According to the recently updated guidelines of the National Institute for Health and Clinical Excellence (NICE), the assessment of delirium should be performed in all hospitalized patients who are at risk of experiencing it, including oncological and terminally ill patients (respectively up to 88% and 50% incidence) [12]. Despite this and other recommendations, the lack of a systematic assessment for delirium is

The Diagnostic and Statistical Manual of Mental Disorders (DSM-V, 2013) [2]

• An alteration of consciousness characterized by a reduced ability to focus,

• A cognitive change (such as memory deficit), language alteration, and the development of a perceptual disorder (such as delusion) that are not depen-

• Evidence collected from the medical history, physical examination and laboratory investigations that show that the disorder is caused by physical conditions resulting from a serious pathology, problems of alcohol abuse or drug intoxica-

Of note, despite DSM-V is the gold standard for the diagnosis of delirium, it cannot be easily administered by non-psychiatrist personnel including nurses. This is a great limitation as nurses have constant contact with the patient throughout the day, and they could efficiently evaluate modifications in the patient's attention and

• A development of the disorder in a short time with daily fluctuations.

• Hyperkinetic form. It features agitation, restlessness, with or without

**4. Clinical features**

hallucinations.

delirium:

distress [11].

**5. Diagnosis**

a serious issue.

#### **Table 1.**

*Acronyms used to memorize possible causes of delirium in palliative care.*
