Subtypes
The following subtypes of delirium are recognized:
1.
Hyperactive delirium
is characterized by restless agitation. While this
form of delirium is common in alcohol withdrawal, it
is rare in hos-
pital-acquired delirium
, accounting for
≤
2% of cases (6).
2.
Hypoactive delirium
is characterized by lethargy and somnolence.
This
is the most common form of hospital-acquired delirium
, and is
responsible for 45 – 64% of cases (6).
3.
Mixed delirium
is characterized by episodes of delirium that alternate
between hyperactive and hypoactive forms of the illness. This type
of delirium is reported in 6 – 55% of patients with hospital-acquired
delirium (6).
As indicated, the popular perception of delirium as a state of agitated
confusion does not apply to hospital-acquired delirium, where the most
802
Nervous System Disorders
*Most common form of delirium in ICU patients.
Hyperactive Form
Patient is agitated
Hypoactive Form*
Patient is agitated
(and)
(with)
Attention Deficits
Difficulty focusing
or maintaining attention
Disordered Thinking
Disorganized, illogical,
or incoherent responses
Fluctuating Changes in Behavior
Behavioral changes fluctuate
over a 24-hour period
DELIRIUM
FIGURE 44.2
The clinical features of delirium
