| |
Hyperactive,
Hypoactive, and Mixed Delirium
Patients with
delirium generally fall into one of three categories depending
on the clinical features that are present:
- Hyperactive
Delirium: These patients most commonly present with psychomotor
agitation, increased arousal and delusions. The degree of cognitive
impairment may be variable and even minimal in some instances
(e.g. in some cases of corticosteroid induced delirium) (Stiefel
et al., 1989).
- Hypoactive
Delirium: Features of this type of delirium include withdrawal,
lethargy and reduced arousal.
- Mixed
Delirium: Presentation with features of both hyperactive
and hypoactive delirium is not unusual and requires a combined
approach to management.
Etiology
of Delirium
In a 1995
critique of instruments and methods to detect, diagnose, and rate
delirium, Smith and colleagues (Smith
et al., 1995) discuss theories on the pathophysiological basis
of delirium. Some authors have suggested that various subtypes
of delirium are associated with specific pathophysiological
changes, which are in turn associated with various etiologies.
For example:
- Some types
of hyperactive delirium are characterized by elevated or normal
cerebral metabolism, such as delirium associated with benzodiazepine
withdrawal.
- On the
other hand, hypoactive delirium associated with benzodiazepine
intoxication is characterized by decreased global cerebral function
(Ross,
1991).
Another approach
for looking at the pathophysiology of delirium is to consider
the extent of underlying brain dysfunction; either global
and non-specific, or more limited and specific. Delirium may be
a heterogenous group of disorders caused by different pathophysiological
mechanisms that result in different symptom complexes.
With improved
understanding of the pathophysiology of delirium, treatment targeted
at specific underlying neurotransmitter abnormalities will hopefully
improve management of this condition.
As is the
case with many symptoms in advanced cancer patients, delirium
has many potential underlying causes. These may vary in specific
groups of patients as discussed in the section on patient
population. Lawlor
et al., (2000a), in
their prospective study of delirium in advanced cancer patients
in a tertiary palliative care center, found a median (range) of
3 (1-6) precipitating factors for each episode of delirium.
Common causes
of delirium in cancer patients are summarized in Table 1f.
| Table
1f: Common causes of delirium in cancer patients
|
|---|
- Sepsis
- Metabolic
Problems (renal failure, hapatic failure, hypercalcemia,
hyponatremia)
- CNS
Involvement (brain metastases, leptomeningeal disease)
- Opioid
Medication
- Other
Drugs (e.g. tricyclic antidepressants, anticholinergics,
benzodiazepines, corticosteroids, antiemetics)
- Withdrawal
syndromes (opioids, benzodiazepines, alcohol)
- Chemotherapeutic
agents (e.g. ifosfamide)
- Dehydration
- Hypoxia
- Paraneoplastic
Syndromes
- Nutritional
deficiencies (vitamins)
- Endocrine
Problems (e.g. thyroid or adrenal dysfunction)
|
|
|