Excited (Agitated) Delirium

The understanding of delirium is as a complex neuropsychiatric syndrome that is characterized by disturbances in consciousness, orientation, memory, thought, perception and behavior resulting from or more structural and/or physiological abnormalities directly or indirectly affecting the brain. It is quite prevalent in medical and surgical settings and is associated with high rates of death and healthcare costs.[1] Delirium is defined as a unitary syndrome, whereby a range of different etiological causes produce a relatively consistent pattern of acute generalized cognitive disturbances. Delirium was introduced as an umbrella term encompassing all such disturbances and thus subsumed a range of synonyms that had previously been in use (acute confusion, ICU psychosis, acute brain failure, septic encephalopathy, etc.). However, despite these commonalities, the symptom profile, course, and outcome of delirium is highly heterogenous. Consequently, interest has focused on identifying clinically meaningful subtypes. Disturbances of motor behavior are an important and highly visible feature of delirium that physicians have recognized since ancient times with the terms 'phrenitis,' and 'lethargus' used to denote agitated/hyperactive vs. somnolent/hypoactive presentations respectively. To date, there have been many studies of motor defined clinical subtypes of delirium, which suggests that they differ significantly regarding frequency and severity of non-motoric symptoms, etiology, pathophysiology, detection rates and treatment experience.[2] Delirium characteristically demonstrates a cluster of symptoms of which the 'core' symptoms, which more frequently present include fluctuating levels of consciousness, inattention and disorientation, sleep-wake cycle disturbances, memory impairment, and motor activity changes. Other features that are more variable in their presentation are perceptual disturbances, thought process abnormalities, and affective disturbances.[3] The term "excited delirium" first appeared in 1985.[4] The term gained popularity in academic literature in the late 1980s as cocaine, and other sympathomimetic drugs gained popularity in the United States and a movement toward the de-institutionalization of the chronically mentally ill occurred.[5] Excited delirium syndrome is a disease state characterized by a constellation of delirium, agitation, and hyperadrenergic autonomic dysfunction. The cause of excited delirium is multifactorial and secondary to a complex interaction of co-morbid, and acute-on-chronic medical conditions, including psychiatric, neurologic, toxicologic, thermal, and metabolic derangement. In 1849, Dr. Luther Bell, the primary psychiatrist at McLane Asylum for the Insane, introduced the disease into medical literature under the name "Bell mania." It correlates with elevated morbidity and mortality that is at least in part independent of underlying medical morbidity and premorbid cognitive status.[6]