Delirium differential diagnosis
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Pratik Bahekar, MBBS [2]; Vishal Khurana, M.B.B.S., M.D. [3]
Overview
Delirium is differentiated from other causes cognitive dysfunction: psychiatric Disorders, dementia, other neurological disorders etc.
Differential Diagnosis
Psychiatric Disorders
- Psychotic disorders: Delirium may be distinguished from psychosis, in which consciousness and cognition may not be impaired (however, there may be overlap, in acute psychosis, especially with mania, is capable of producing delirium-like states). Delirium must be differentiated from following psychiatric disorders which have psychotic features.
- Brief psychotic disorder
- Schizophrenia
- Schizophreniform disorder, and other psychotic disorders
- Bipolar and depressive disorders with psychotic features. Mania should be differentiated from hyperactive delirium. Previous history of bipolar disorder is useful in distinguishing delirium from mania.
- Acute stress disorder: Delirium accompanied by fear, anxiety, and dissociative symptoms must be differentiated from acute stress disorders.
- Malingering and factitious disorder.
- Confusional states: Delirium is distinguished by time-course from the confusion and lack of attention which result from long term learning disorders and varieties of congenital brain dysfunction. Delirium has also been referred to as 'acute confusional state' or 'acute brain syndrome'. The key word in both of these descriptions is "acute" (meaning: of recent onset), since delirium may share many of the clinical (i.e., symptomatic) features of dementia, developmental disability, or attention-deficit hyperactivity disorder, with the important exception of symptom duration.
- Delirium is not the same as confusion, although the two syndromes may overlap and be present at the same time. However, a confused patient may not be delirious (an example would be a stable, demented person who is disoriented to time and place), and a delirious person may not be confused (for example, a person in severe pain may not be able to focus because of the pain, and thus be by definition delirious, but may be completely oriented and not at all confused).
- Other neurocognitive disorders: Sometimes delirium is superimposed on underling neuro cognitive disorders such as dementia. [1]
(see below)
Dementia
- Delirium is distinguished from dementia (chronic organic brain syndrome) which describes an "acquired" (non-congenital) and usually irreversible cognitive and psychosocial decline in function. Dementia usually results from an identifiable degenerative brain disease (for example Alzheimer disease or Huntington's disease). Dementia is usually not associated with a change in level of consciousness, and a diagnosis of dementia requires a chronic impairment.
- Sundowning: Typically observed in patients suffering from dementia. It's an impairment in behavioral patterns in the evening hours. Similar symptomology can be observed in the patients suffering from other ailments such as impaired circardial rhythm. New onset in change in behavioral patterns should always be assessed carefully and diagnosis of delirium should be considered.[2]
| Attributes | Delirium | Alzheimer's disease | Depression | Psychotic Disorders |
|---|---|---|---|---|
| Onset | Sudden/acute/subacute | Gradual | Gradual | Acute or gradual |
| Progression | Shifts in severity, likely to resolve in days to weeks. | Worsens over period of time | Acute or chronic with acute exacerbation | Chronic with acute exacerbation |
| Hallucinations | May be present, mostly visual | Mostly absent (exceptions: Lewi body dementia, etc.) | May be present if associated with psychotic features | Present |
| Delusions | Fleeting | Mostly not present | May be present | Present |
| Psychomotar activity | Increased or decreased, may shift from increased to decreased states. | May or may not change | Change | Change |
| Attention | Poor attention span and impaired short term memory. | Progressive worsening short term memory. Attention span is likely to be affected in severe cases | May be altered | May be altered |
| Consciousness | Altered, rapidly shifts | Mostly intact until severe stages | Normal | Normal |
| Attention | Altered, rapidly shifts | Mostly intact until severe stages | May be altered | May be altered |
| Orientation | Altered, rapidly shifts | Mostly intact until severe stages | Not altered | Not altered |
| Speech | Not coherent | Errors | Slow | Normal or pressured |
| Thought | Disorganized | Impoverished | Normal | Disorganized |
| Perceptions | Altered, rapidly shifts | Mostly intact until severe stages | Normal | May be altered |
| EEG | Moderate to severe background slowing | Normal or mild diffuse slowing | Normal | Normal |
| Reversibility | Mostly | Very rarely | Yes | Rarely |
Other Neurological Disorders
- Frontal lobe disorders such as tumor can produce deficits in memory, distorted emotional responses, impaired judgment, etc. Imaging studies and focal neurological symptoms may be helpful to differentiate from delirium.
- Temporal lobe disorders may lead to memory deficits, cortical deafness, visual agnosia, etc. Imaging studies and focal neurological symptoms may be helpful to differentiate from delirium.
- Occipital lobe disorders can demonstrate various symptoms such as confabulation, cortical blindness, etc. Imaging studies and focal neurological symptoms may be helpful to differentiate from delirium.
- Parital lobe disorders like Wernicke's aphasia can hinder patient's ability to follow examiner's instructions which is often misinterpreted as a state of confusion.
- Nonconvulsive epileptic episodes should also be considered as a differential diagnosis of delirium.
Delirium represents an organically caused decline from a previously attained level of cognitive functioning. It is a corollary of these differential criteria that a diagnosis of delirium cannot be made without a previous assessment, or knowledge, of the affected person's baseline level of cognitive function. In other words, a mentally disabled or demented person who is operating at their own baseline level of mental ability might appear to be delirious without a baseline functional status against which to compare.
Common Usage of the Term v/s Standard Medical Usage
In common usage, delirium is often used to refer to drowsiness and disorientation. In broader medical terminology, however, a number of other symptoms, including sudden inability of focus attention, and even (occasionally) sleeplessness and severe agitation and irritability, are also defined as "delirium."