Why is the diagnosis of delirium important? Because delirium may be the only sign of significant medical illness such as:
- Abdominal infection
- Intra-cerebral event
When these words are heard during your practice they should trigger the thought of delirium as a symptom.
- “Not feeling/acting right“
- “Just not him/herself“
- “Poor historian“
- “Pleasantly confused“
- “Vague complaints“
- “Little old lady in no apparent distress“
- “Well, she looks okay to me…“
Today’s vague historian may be tomorrow’s ICU patient.
Why do we not notice delirium?
- We don’t think about the time course (“What has changed?”)
- We assume (incorrectly) that most older people have baseline cognitive impairment and don’t look for changes.
- We usually have a static snapshot of a condition that is by definition fluctuating
- We under-estimate the severity of the condition and its consequences
- We believe delirium always means agitation whereas hypoactive form is most common
- The diagnosis overlaps with dementia and depression
- The presentations are almost always atypical
- We rarely use formal assessment methods
We know that the elderly have atypical presentations of common diseases. The following are just a few examples of potential atypical presentations in the older person presenting in the ED. Each of these may result in delirium.
Frequently does not present with fever (because of altered thermoregulation) or with tachypnea (because a resting tachypnea can be normal) or cough (because of decreased strength of respiratory musculature) or even dyspnea (because of sensory impairment).
Acute Coronary Syndrome
Frequently doesn’t have chest pain (sensory impairment) or tachycardia (decreased adrenergic response or beta-blocked) or ECG changes (already have a LBBB).
Diverticulitis/cholecystitis – complaints of pain and findings of tenderness/guarding/rigidity are often not present. A change in mental status may be the only symptom.
Important Take Home Message
Often, the only way to establish the diagnosis is to investigate its symptom – but in this case the symptom is the delirium.