Psychiatry - October 2008 - (Page 30)

TABLE 1. Core and common features of delirium are present in all DSM IV subtypes of delirium Core features of delirium are present in all DSM-IV subtypes of delirium. Common features of delirium may be present in all DSM-IV subtypes of delirium. THE CORE FEATURES INCLUDE: • disturbance of consciousness (that is, reduced clarity of awareness of the environment, with reduced ability to focus, sustain, or shift attention) • change in cognition (e.g., memory impairment) or a perceptual disturbance • onset of hours to days, and tendency to fluctuate. • evidence from the history, physical examination, or laboratory findings that the signs and/or symptoms are the direct physiological consequences of a medical condition or substance use. COMMON FEATURES INCLUDE: • hallucinations, delusions or inappropriate affective states. discontinue these agents. The exception to this rule is the patient who is delirious due to sedativehypnotic or alcohol withdrawal.2 NEUROPATHOGENESIS The list of illnesses, medications, and conditions that can cause delirium is extensive. Nonetheless, there is great controversy over how the brain becomes trapped in this altered state of consciousness. Both cortical and subcortical dysfunction have been implicated by regional cerebral blood flow studies, single photon emission computed tomography, positron-emission tomography, electroencephalogram, and evoked potentials.7 Among the neurotransmitters most strongly implicated in delirium pathogenesis are acetylcholine and dopamine. While decreased acetylcholine activity is presumed to play a role in delirium, hyperactivity in the dopamine system is also a strong etiologic candidate. Less certain is the role of serotonin and gamma-aminobutyric acid (GABA) in which an either increased or decreased activity of these neurotransmitters may be involved in delirium pathogenesis. Finally, excess glutamate activity or decreased histamine activity also may be etiologic factors in delirium (Figure 1).7 A complete list of all the possible causes of delirium would be very difficult and lengthy to compile due to the variety of causes potentially responsible for the condition. The most frequent causes of delirium include infectious disease, particularly of the central nervous system, cardiovascular compromise, endocrine abnormalities, trauma, and metabolic derangements from toxins, electrolyte imbalance, or withdrawal states. Some of the more common causes and etiologic factors are expanded upon and summarized in Table 2. inpatients can be delirious, and 30 to 50 percent of acutely ill geriatric patients are delirious at any given time in the hospital. Patients without delirium in the hospital have a twopercent mortality rate, with an additional three-percent mortality at three months after discharge. The mortality rate in delirious patients in the hospital has been found to be 11 percent, with 11 percent mortality at three months after discharge.1 Delirium reflects brain dysfunction that is almost always due to identifiable systemic or cerebral disease or to drug intoxication or withdrawal states. The disturbance is caused by the direct physiological consequences of a general medical condition.2,3 The onset of delirium is typically rapid and is characterized by a fluctuating course throughout the day with disturbances in consciousness and cognition (Table 1). Risk factors for delirium include greater severity of physical illness, older age, and baseline cognitive impairment.3 In particular, burn victims, postoperative and sensorydeprived patients, and patients with human immunodeficiency virus (HIV), head injury, seizures, renal failure, hepatic failure, or cardiac failure are at risk for delirium.4 Recognizing delirium, which may be subtle in less agitated forms, is particularly important as it may be the only evidence of a life-threatening 30 Psychiatry 2008 [ O C T O B E R ] condition.5 Differentiating delirium from dementia is of paramount importance and can be accomplished by noting the temporal pattern of the condition, as well as the attention span of the patient. Delirium differs from dementia in that delirium is characterized by fluctuations in the mental status of the patient (e.g., alertness, orientation), whereas dementia is characterized by a static mental status. Delirium is typically more acute in onset and may be rapidly fatal if not reversed, whereas dementia has a longer and more insidious course. It should be noted that it can be very difficult to distinguish delirium from dementia, especially when the condition is comorbid as is common in the elderly population. Prompt treatment of delirium is crucial as this syndrome has a significant mortality rate. As a first step, the physician should search for contributing causes, obtain a complete history, including a careful review of medication usage and illicit drug history, and perform full physical and neurological exams. Laboratory tests with neuroimaging studies and a lumbar puncture may be necessary. The most basic treatment principals begin with identifying and treating the causal or contributing medical conditions. If the patient is being treated with sedatives or other medications affecting the central nervous system, the physician should PHARMACOLOGIC TREATMENT OPTIONS With regard to the pharmacological management of

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Psychiatry - October 2008

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