Course of Delirium
Often, but not always, patients exhibit some prodromal symptoms prior to the onset of delirium. These prodromal symptoms include:
★There are two main features of delirium:
Consequently, there is often a waxing and waning of symptoms with periods of relative lucidity and periods of more severe impairment. During the so-called lucid periods, there is usually cognitive impairment.
There are many cognitive impairments that occur during delirium. For example, patients have difficulty sustaining attention and are very distractible. They exhibit short term memory deficits and have distinct difficulty in visuoconstructional tasks, such as clock drawing, etc. Delirious patients are typically not oriented to time and place. In addition, delirious patients commonly exhibit disorganized thought patterns that range from tangentiality and circumstantiality to loose associations.
Delirious patients also exhibit perceptual disturbances characterized by auditory or visual illusions or hallucinations, although visual hallucinations tend to be more common.
The psychomotor disturbances associated with delirium are varied and patients can be either hypoactive or hyperactive, or even alternate between the two states. One concern, of course, is that hypoactive cases of delirium are not as easily detected as hyperactive cases. The most common form of delirium seems to be 'mixed' with respect to psychomotor disturbances and exhibit alterations of agitation and apathy.
The sleep-wake cycle is often reversed in delirious patients. Initially, patients will present with increasing insomnia accompanied by fragmentation of sleep, and daytime sleepiness, until the rhythm is reversed.
Delusions occur in 20-40% of the cases of delirium and are often persecutory. Occasionally, the delusions persist after the resolution of the delirium.
Delirium is often accompanied by affective disturbances that are characterized by dysphoria and affective lability.
The neurological correlates of delirium are varied and inconsistent, but can include ataxia, cranial nerve palsy, and dysarthria.
The course of delirium can be tracked with the Delirium Rating Scale.
Prognosis
There are five possible outcomes of delirium:
Fortunately, complete remission is the most common outcome. The average length of an episode of delirium is usually 10-12 days; though some patients may recover in 5-7 days, full recovery may take somewhat longer.
Less fortunately, patients who are delirious on admission have mortality rates of 30-40%. Those who become delirious in the hospital have a lower mortality rate of 1.5%.