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Undiagnosed medical illness in psychiatric patients is a major concern in clinical practice. Of patients who are referred for psychiatric treatment, 3.5% to 16% have an undetected medical illness (Dubin and Weiss, 1984). Of greater concern is the misdiagnosis of delirium as a psychiatric illness. Clinicians who focus predominantly on aberrant and often violent behavior might overlook medical illness as an underlying cause, with a resulting increase in patient morbidity and mortality. The mortality rate for delirium 3 months after diagnosis is 14 times greater than that for mood disorders (Weddington, 1982), and a hospitalized patient with delirium has a mortality rate 5.5 times greater than that of a patient diagnosed with dementia (Rabins and Folstein, 1982).
This chapter discusses the evaluation and differential diagnosis of acute organic mental disorder, emphasizing features of delirium that may superficially resemble functional psychiatric illness.
Delirium is a reversible disturbance of cerebral metabolism secondary to a cerebral insult, such as an infection or metabolic disturbance. Onset is acute, usually within 4 to 6 hours, although it may evolve over several days or weeks. Delirium is characterized by impaired thinking, memory, perception, concentration, and attention (Lipowski, 1967).
In its most florid manifestation, delirium can be mistaken for a manic or schizophrenic episode. The agitated patient paces and cannot sit still. Thoughts are fragmented and incoherent. The patient expresses intense emotions, such as fear or anxiety, in response to delusions. For instance, he may refuse to leave a room or an area of the emergency department because "they'll know I'm here." Clinical evaluation is confounded further by fluctuating symptoms: within 30 minutes, the patient may be lethargic and no longer delusional. Thus, you must become familiar with the entire range of symptoms that occur in delirious patients.
The Diagnostic and Statistical Manual of Mental Disorders, 3rd edition, revised (DSM-III-R, 1987) describes mental status findings common to patients with delirium.
Clouding of consciousness - the hallmark of delirium - can vary from loss of awareness of self and surroundings to stupor and coma. Most patients with delirium are lethargic or stuporous and tend to drowse or fall asleep while being interviewed. If this happens, try to arouse the patient by raising your voice or shaking him. In such situations, consider the patient delirious until proven otherwise.
You may be disconcerted by the patient's fluctuating symptoms. Lucid intervals, in which the patient is fully oriented and appears mentally intact, alternate with periods of significant cognitive impairment, in which the patient is suspicious, paranoid, and disoriented. Don't misinterpret fluctuating symptoms as willful attempts to deceive you.
Always consider visual hallucinations to be of organic etiology until all likely medical causes are ruled out. The hallucinations usually are colorful, vivid, and well defined. Visual hallucinations in younger patients should alert you to the possibility of drug or alcohol intoxication or withdrawal.
Illusions are misperceptions of an actual stimulus (for example. misinterpreting the sound of a dropped stethoscope for a gunshot or a crack in the wall for a snake). A significant correlation exists between illusions and an underlying medical illness.
The patient usually experiences disorientation to time and place but rarely, if ever, to person. The extent of the disorientation varies with the severity of the delirium.
A patient with delirium usually has abnormal vital signs (including tachycardia, sweating, fever, and dilated pupils) and impaired attention span. The patient is easily distracted by irrelevant stimuli and tends to shift from topic to topic in seemingly unrelated ways, his thoughts typically disjointed and incoherent. Memory impairment affects both short-term and long-term memory.
Sundowner's syndrome, a disturbance of the sleep-wake cycle is characterized by drowsiness or stupor during the day and aler ness and hypervigilance at night. The syndrome is most common in elderly patients with dementia (see Chapter 14, Geriatric Emergencies).
Rapidly changing delusions are another sign of delirium. The patient may initially say that "someone is out to get me" and then modify this to "someone is trying to poison my food" before affirming his belief that he is "dying of an incurable disease."
Agitation, another common sign, had been considered a requisite for a diagnosis of delirium. However, one can experience a "quiet" delirium, during which the patient appears calm and relaxed. Only through careful questioning can the clinician discover that the patient is disoriented, delusional, and hallucinatory.
Motor abnormalities (such as tremor, myoclonus, asterixis, and reflex and muscle tone changes) are exhibited by many, but not all, delirious patients (Wise, 1987). Other neurologic signs are relatively uncommon unless the delirium is caused by a primary central nervous system disturbance.
The initial physical examination of an agitated, delirious patient need not be intrusive or time-consuming. At a minimum, you should evaluate the patient's general appearance, vital signs, head (for injuries), eyes (for pupil size and for nystagmus or exophthalmos), neck (for rigidity or thyroid enlargement), skin color and perspiration, hands (for tremor, asterixis, or chorea), and reflexes (for hyperactivity or asymmetry). Ultimately, thorough medical and neurologic examinations are necessary to help determine the cause of the delirium (see table below).
| DELIRIUM: Signs and Causes | |
| Signs and Symptoms | Possible Cause |
| Elevated blood pressure | Hypertensive encephatopathy |
| Low blood pressure | Myocardial infarction |
| Tachycardia | Hypoglycemia, hypoxia, anemia, hyperthyroidism |
| Tachypnea | Chronic obstructive lung disease |
| Headache and stiff neck | Meningitis or intracranial hemorrhage |
| Nystagmus, ophthalmoplegia, and ataxia | Thiamine deficiency secondary to alcohol intake (Wemicke's encephatopathy) |
| Dilated pupils, tachycardia, flushing, and dry skin | Anticholinergic toxicity |
| Stupor or coma | Hypoglycemia (response to 50 ml of 50% dextrose and water IV. will confirm diagnosis) |
| High fever, tachycardia, and hyperreflexia | Thyroid storm |
| Tachypnea, odor of acetone on breath, dehydration, and hypotension | Diabetic ketosis |
| Elevated autonomic signs, hyperreflexia, agitation, and visual hallucinations | Alcohol withdrawal syndrome |
| Fluctuating consciousness, history of head trauma, and dilated pupils (late sign) | Subdural hematoma |
| Ataxia, lethargy, and nystagmus | Phenytoin (Dilantin) toxicity |
| Memory disturbance, hallucinations, egocentricity, intense focusing of attention on some object, and automatisms | Complex partial seizures (temporal lobe epilepsy) |
| Source: Walter, 1983, p. 28. Adapted with permission from the publisher. | |
Order routine laboratory studies for any patient you suspect of having delirium to rule out life-threatening illnesses. These tests-complete blood count, glucose and electrolyte levels, blood urea nitrogen, chest X-ray, arterial blood gas levels, toxic drug screen, electrocardiogram, and serum drug levels (such as lithium and theophylline) - help detect problems that require immediate medical intervention.
A patient who exhibits acute behavioral changes or clouded consciousness that cannot be explained by laboratory evaluation may require a lumbar puncture. A computed tomography (CT) scan before the lumbar puncture helps rule out intracranial causes of delirium.
More extensive evaluation on an inpatient unit is necessary if the cause cannot be determined in the emergency setting. While the patient is hospitalized, additional laboratory testing may include a serial electroencephalogram; blood chemistries for heavy metals. thiamine, vitamin Bi;;, and folate levels; thyroid test; lupus erythematosus cell test; antinuclear antibody test; urine porphobilinogen; blood and urine cultures; and lumbar puncture and CT scan, if not performed earlier.
The clinician may avoid searching for a cause because the etiologies of delirium are so diverse (Wise, 1987). Be especially alert to the most common life-threatening causes of delirium (see Life-threatening causes of delirium, page 28). Prescription medications are one of the most overlooked causes of delirium. Delirium in an elderly patient may be related to polypharmacy: The patient takes five or more medications a day, many of which are not needed. Simply discontinuing some of the medications or reducing the dosages may resolve the delirium.
At first glance, the symptoms of delirium may superficially resemble those of schizophrenia or mania. Too often the differential diagnosis is based on a single piece of data, a single symptom, a single item of past history, or a previous diagnosis (Leeman, 1975). An inexperienced clinician can easily be misled into a premature diagnosis of psychiatric illness (Dubin and Weiss, 1984). The pitfalls to diagnosis include:
| Life-Threatening Causes of Delirium | |
| Cause | Clinical Findings |
| Wernicke's encephalopathy or alcohol withdrawal syndrome | Ataxia, ophthalmoptegia, alcohol or drug history, elevated blood pressure or pulse rate, sweating, hyperreflexia |
| Hypertensive encephalopathy | Elevated blood pressure, papiltedema |
| Hypoglycemia | History of insulin-dependent diabetes, decreased blood glucose |
| Hypoperfusion of the central nervous system | Decreased blood pressure, decreased cardiac output (for example, myocardial infarction, arrhythmia, cardiac failure), decreased hematocrit |
| Hypoxemia | History of pulmonary disease, decreased PO2 |
| Intracranial bleeding | History of unconsciousness Of head trauma, focal neurologic signs |
| Meningitis or encephalitis | Meningeal signs, elevated white blood cell count, fever |
| Poisons or medications | Pupillary abnormality, nystagmus, ataxia |
| Source: Anderson, 1987, p. 425. Adapted with permission of the publisher. | |
Although interpersonal techniques alone cannot treat delirium, supportive therapy can help minimize a patient's agitation. Try to provide a quiet, reassuring atmosphere, and don't subject the patient to multiple interviews with medical students, interns, or residents. Keep your instructions direct and concise. To prevent an agitated or confused patient from harming himself or others, make sure that you, another staff member, or the patient's family or friends remain with him at all times.
Familiarity is a key to maintaining the patient's orientation. Reorient the patient periodically and tactfully, introducing yourself again and describing what you are doing and why (Tomb, 1988). A calm and sympathetic manner and the ability to anticipate the patient's anxiety by offering frequent reassurance helps reduce the patient's agitation (Tomb, 1988). Additionally, soft music from a radio or tape may help attenuate hypervigilance and agitation, particularly in a patient with sundowner's syndrome (Murray, 1987).
When a delirious patient becomes belligerent or assaultive, many clinicians erroneously withhold neuroleptic medication for fear that the drug will either obscure symptoms or place the patient in further medical jeopardy. As a result, menial status examinations, physical examinations, and diagnostic studies are sometimes performed on patients who are either mechanically restrained or held down by staff members. An examination performed in this manner is of questionable value, and the restraints themselves involve medical risks and complications. A patient with a cardiac illness or orthopedic problem, for example, may worsen his condition by struggling to free himself from the restraints. The argument that neuroleptic agents will obscure symptoms and delay diagnosis is specious because the definitive diagnosis is never made on a single mental status evaluation. Tranquilization of the patient is humane and clinically effective in ensuring behavioral control and reduces the risks of violence and self-injury.
Rapid tranquilization (RT) is a reliable procedure in which standard doses of a neuroleptic drug are administered at 30- to 60-minute intervals, with the dose titrated according to the patients symptoms (Dubin et al., 1986). Target symptoms include excitement, anxiety. tension, hyperactivity, and agitation. At its best, RT can control hyperactivity and combativeness without restraints or isolation techniques. Core psychiatric symptoms, such as hallucinations and delusions, usually do not subside with short-term use of neuroleptics. RT is contraindicated in patients with an anticholinergic intoxication, as evidenced by dilated, unreactive pupils.
High-potency neuroleptic drugs are the preferred treatment: most patients usually respond to standard doses (see Doses for rapid tranquilization). Administer a test dose, noting the patient's behavioral response and any side effects. Avoid low-potency neuroleptic drugs, such as chlorpromazine (Thorazine) or thioridazine (Mellaril), because their strong anticholinergic side effects might exacerbate the delirium. Administer the medication in an oral concentrate form, if possible, rather than by intramuscular injection. which may agitate a patient or require the use of temporary restraints.
For delirious patients who do not respond to standard doses of neuroleptic agents during RT, Adams (1988) has proposed using a combination of haloperidol (Haldol) and lorazepam (Ativan). Side effects are usually few, mild, and reversible. The most common extrapyramidal symptoms are dystonia and akathisia.
| Doses for Rapid Tranquilization | ||||
| Drug | Dose in Patients Younger than 65 | Dose in Patients 65 and older | ||
| Concentrate | I.M. | Concentrate | I.M. | |
| thiothixene (Navane) | 20 mg | 10 mg | 10 mg | 5 mg |
| trifluoperazine (Stelazine) | 20 mg | 10 mg | 10 mg | 5 mg |
| haloperidol (Haldd) | 10 mg | 5 mg | 5 mg | 2.5 mg |
| loxapine (Loxitane) | 25 mg | 10 mg | 15 mg | 5 mg |
| Source: Dubin et al., 1986, p. 5. Adapted with permission of the publisher. | ||||
Intravenous RT, although not widely practiced by clinicians, may be of value in medical intensive care units when the patients medical condition precludes the use of oral or intramuscular medication (Dubin et al., 1986). Several reports have documented the safety and efficacy of I.V. medication in medically ill and debilitated patients. I.V. administration may be useful in patients with lowered cardiac output who cannot absorb I.M. medication, those who are incapable of taking oral medication, and those with extensive tissue damage, such as burn patients.
I.V. antipsychotic medication can be safe and effective. Although onset of action varies, incidence of side effects from I.V. administration appears to be no greater than that from other routes. Some patients who receive I.V. neuroleptic drugs may actually have a lower incidence of extrapyramidal side effects than those receiving oral medication (Menza et al., 1987).
Treatment for dystonia and akathisia is 2 mg of benztropine (Co-gentin) or 50 mg ofdiphenhydramine (Benadryl) I.M. or I.V. Repeat the dose every 5 minutes for up to three doses. Relief usually occurs within 3 minutes of administration, although some patients, especially those with akathisia, may not respond. In these cases. 5 mg of diazepam (Valium) I.V. or 10 mg orally or 2 mg of lorazepam I.V. or I.M. may be helpful. (See Chapter 6, Schizophrenia and Mania. for a more detailed discussion of RT and its side effects.)
Patient education cannot be attempted during a delirious episode. even in lucid intervals. And because a delirious patient will probably be transferred to an inpatiem setting, you will not have much time to provide family members or friends with such information. When possible, briefly explain the problem (for instance, drug withdrawal. drug toxicity, suspected medical illness), and reassure them that the condition usually is short-lived. If the delirium was caused by drug use or dehydration, give them suggestions for preventing future episodes, such as closely monitoring all drugs purchased and periodically checking the house for medications or keeping a weekly weight chart and closely monitoring the patient's food and fluid intake.
Most patients with delirium should be hospitalized. Their high risk of mortality necessitates comprehensive medical, neurologic, and psychiatric evaluations to ensure that all treatable causes are discovered. If you are certain that a patient's delirium results from an overuse of drugs or mild dehydration—and if a caring family member or friend is willing to stay with him overnight-you can discharge the patient and schedule him for a follow-up evaluation the next day. However, given the potentially grave prognosis for delirium, you may prefer to admit him to confirm the diagnosis and initiate appropriate treatment for the underlying cause.
Failure to diagnose delirium will expose the patient to an excessive risk of morbidity and mortality. Although the common conception of delirium is a state of wildly disorganized behavior, it can be less dramatic. An elderly person with a delirium superimposed on dementia may exhibit only diminished verbal and motor behavior, as is commonly seen with infections. Cavalierly dismissing a confused patient as senile or demented rather than making an appropriate evaluation constitutes negligent care. Thus, for risk management purposes, document delirium as a possible diagnosis for any patient with disturbed consciousness.
Delirium is a medical emergency in which the patient is incompetent to participate in treatment decisions. With the family's knowledge and consent, you can begin treatment without a civil commitment decision. If a family member is unavailable and the delirium exposes the patient to an increased risk of morbidity or mortality, you can begin treatment without the family's consent.