Delirium is a highly prevalent disease in the elderly and
postoperative, cancer, and AIDS patients. However it is often misdiagnosed
and mistreated. This may be partly due to the inconsistencies of the
diagnosis itself. Delirium is best defined currently by an association of
cognitive impairment and arousal disturbance. Three subtypes (hyperactive,
hypoactive, mixed) receive a definition in the literature, but those
definitions may vary from author to author according to the importance
they give either to the motoric presentation of the delirium or to the
arousal disturbance. Our aim is to point out the inconsistencies we found
in the literature, but also to identify different paths that have been
explored to solve them, that is, the suggestion to emphasize the arousal
disturbances in defining the subtypes instead of the motoric
presentations, which seem to be more fluctuating, and because of the
fluctuating course of the disease to extend the observation over a period
of time, which may improve the accuracy of the diagnosis. This is not
without importance from a clinical standpoint. Subtypes of delirium may be
explained by different pathophysiologic mechanisms, which remain partly
unexplained, and may respond to specific treatments. There is a trend to
isolate core symptoms (disorientation, cognitive deficits,
sleep–wake cycle disturbance, disorganized thinking, and language
abnormalities) so as to distinguish them from secondary symptoms that may
be correlated with the different etiologies. Our contribution is also to
challenge, with new data, the accepted belief that psychotic features are
quite rare in the hypoactive type of delirium. We demonstrate that
delusions and perceptual disturbances, although less frequent, are present
in more than half of the patients with hypoactive delirium. The psychotic
features are clearly correlated with a highly prevalent rate of
patients', spouses', and caregivers' distress. The mixed
subtype of delirium seems to have the worst prognosis, the hyperactive
showing the best prognosis. The treatment of the agitated delirious
patient is also more consensual. Haloperidol remains the gold standard in
the treatment of delirium regardless of the clinical presentation, but the
literature provides several alternatives that may prove more specific and
have less adverse effects (atypical antipsychotics, psychostimulants,
anesthetics).