Confusion

Perspective

The term confusion connotes an alteration in higher cerebral functions, such as memory, attention, or awareness. In addition, the ability to sustain and focus attention is impaired. Confusion is a symptom, not a diagnosis. The degree of confusion may fluctuate, as may the patient’s level of consciousness. Clinical jargon includes the phrases “altered mental status,” “delta MS” (change in mental status), “altered mentation,” and “change from baseline.” Implicit in the definition is a recent change in behavior. Chronic mental status changes such as dementia typically have a different clinical chronology. Other forms of altered mentation include states of diminished alertness on the coma spectrum; these presentations may result from some of the same pathophysiologic processes causing confusion and are discussed in Chapter 16. Confusion may range in severity from a mild disturbance of short-term memory to a global inability to relate to the environment and process sensory input. This extreme state is termed delirium. Delirium has two subtypes: hyperactive and hypoactive.¹ Hyperactive delirium is characterized as an acute confusional state associated with increased alertness, increased psychomotor activity, and disorientation and is often accompanied by hallucinations. In hypoactive delirium (sometimes referred to as quiet delirium), the confusional state is present but the patient has a reduction in alertness and behavior. Hypoactive delirium may be the more common type in emergency department (ED) patients.² Confusion has many causes, and an orderly approach is necessary to discover the causative diagnosis. The assessment of mental status and cognitive impairment in elderly ED patients has been proposed as a key quality indicator in the care of elderly patients by the Society for Academic Emergency Medicine Geriatric Emergency Medicine Task Force.³

Physicians underestimate the incidence of confusion in patients.4,5 Often, confusion is accepted as an incidental or secondary component of another condition. A patient with injuries from a motor vehicle crash or with dyspnea may be confused, but the primary condition overshadows the underlying abnormal mental status. When confusion exists as an isolated or unexplained finding, it is more likely to receive full and immediate consideration by the clinician. Confusion is estimated to occur in 2% of ED patients, 10% of all hospitalized patients, and 50% of elderly hospitalized patients.^4,6 Delirium in older ED patients was found to be an independent predictor of increased mortality within 6 months in one study.⁷

Pathophysiology

Conceptually, consciousness may be divided into elements of alertness or arousal and elements constituting content of consciousness. Confusion is largely a problem of the content portion of consciousness. Many different clinical processes may disrupt optimal cortical functioning and result in confusion. The pathophysiology is not straightforward. Widespread cortical dysfunction is thought to result from substrate deficiencies (hypoglycemia or hypoxemia), neurotransmitter dysfunction, or circulatory dysfunction. Compounding this problem is the concept that the reserve of central nervous system (CNS) function varies from individual to individual; individuals with a preexisting impairment may become confused after even minor changes in their normal physiologic state.

Diagnostic Approach

Differential Considerations

The observation of acute confusion prompts a search for an underlying cause. Four groups of disorders encompass most causes of diffuse cortical dysfunction: (1) systemic diseases secondarily affecting the CNS, (2) primary intracranial disease, (3) exogenous toxins, and (4) drug withdrawal states (Box 17-1).¹ Focal cortical dysfunction, such as from tumor or stroke, typically does not cause confusion, although occasionally, receptive or expressive dysphasia may be mistaken for confusion. Likewise, subcortical or brainstem dysfunction most frequently results in a diminished level of alertness and consciousness, not confusion.

BOX 17-1 Major Categories

Differential Considerations

Primary intracranial disease

Systemic diseases secondarily affecting the central nervous system

Exogenous toxins

Drug withdrawal

Rapid Assessment and Stabilization

Most patients with acute confusion do not require immediate interventions. Three crucial exceptions are hypoglycemia, hypoxemia, and shock. A complete set of vital signs, including temperature and oxyhemoglobin saturation, and a bedside blood glucose level should be determined promptly for all confused patients. Oral or intravenous glucose therapy is indicated if low blood glucose is discovered. Supplemental oxygen and intravenous fluid are administered as necessary. In a patient with abnormal or unstable vital signs, initial diagnostic and management efforts are directed toward treatment of the systemic condition. A confused patient with acute pulmonary edema, hypoxia, and confusion obviously requires evaluation and treatment of the pulmonary edema, not a screening test for cognitive functioning.

Confused patients should be protected from harming themselves or others. Close observation may need to be supplemented by medications or physical restraint. Family members may offer valuable assistance in observing and comforting the patient.

In general, in patients with schizophrenia and other psychiatric disorders, results of tests of cognition, orientation, and attention are normal unless the condition is severe. The term psychosis implies a disorder of reality testing and thought organization severe enough to interfere with normal daily functioning. Psychosis is a nonspecific syndrome, and careful evaluation is required to differentiate between psychiatric and organic origins (e.g., drug intoxication or other systemic process) (Box 17-2).

BOX 17-2 Findings That May Help Differentiate between Organic and Functional Causes of Confusion

Organic	Functional (Psychiatric)
History	History
Acute onset	Onset over weeks to months
Any age	Onset ages 12 to 40 years
Mental status examination	Mental status examination
Fluctuating level of consciousness	Alert
Disoriented	Oriented
Attention disturbances	Agitated, anxious
Poor recent memory	Poor immediate memory
Hallucinations: visual, tactile, auditory	Hallucinations: most commonly auditory
Cognitive changes	Delusions, illusions
Physical examination	Physical examination
Abnormal vital signs	Normal vital signs
Nystagmus	No nystagmus
Focal neurologic signs	Purposeful movement
Signs of trauma	No signs of trauma