Contents
Introduction
Altered mental status (AMS) is broad term with many causes and manifestations. Delirium is one serious cause of AMS.
Delirium is an acute, fluctuating change in cognition, accompanied by impaired attention and consciousness. (1)
Definitions
The above definition of delirium makes reference to the main components of "altered mental status."
- Level of consiousness, or arousal and attention is the first component. The spectrum of level of consiousness includes hyperalert > alert and attentive > lethargic > stuporous > comatose.
- Content of consiousness or cognition, incudes memory, orientation, and language.
- In geriatric population three major subtypes of delirium are identified: hypoactive, hyperactive/agitated, and mixed.
Pathphysiology
Hypotheses include dopamine excess, cholinergic deficiency, inflammation, and chronic stress; an important subset of delirium also involves toxic-metabolic encephalopathy.
- The cholinergic deficiency hypothesis originated in observations that delirium occurred with consumption of toxins and drugs that impair cholinergic function. Some structural and functional neuroimaging of delirium patients have suggested abnormalities that coincide with areas involved in cholinergic pathways.
Treatment of Pediatric Delirium
A literature review of pediatric delirium (2) proposed that,
- Hyperactive, agitated delirium may respond preferentially to haloperidol, due to its strong D2 blockade, necessary for apparent dopamine excess state.
- Use of risperidone is effective for patients with hypoactive delirium due its broader receptor effects. Specifically 5HT-2a modulation attenuates EPS effects, and indirect 5HT1a activation increases dopamine in the medial prefrontal cortex (mesocortical tract). (This effect of atypicals is believed to be responsible for cognitive enhancement and improvement in the negative symptoms of schizophrenia.)
- Risperdone may exacerbate agitation in hyperactive delirium due to dopamine increase as outlined above.
Depakote and buspirone may have a role in treatment of delirium.
References
1. Wilber ST. Altered Mental Status in Older ED Patients. Emerg Med Clin N Amer.24(2006) 299-316
2. Karnik et.al. Subtypes of Pediatric Delirium: A Treatment Algorithm, Psychosomatics 2007; 48:253–257