A 68-year-old man is brought to the emergency department by his daughter due to a change in mental status. Over the past 2 days, the patient has reported seeing strangers sneaking around the house when only he and his daughter were at home. He has also been intermittently confused, difficult to rouse, and distractible. The patient has had no headaches or focal weakness. He has no chronic medical or psychiatric problems other than seasonal allergies, which his daughter says have flared up since he moved in with her 2 weeks ago. Temperature is 36.7 C (98 F), blood pressure is 140/85 mm Hg, pulse is 88/min, and respirations are 12/min. On physical examination, the patient is somnolent but arousable to voice. He is not oriented to place or time. Pupils are bilaterally equal and reactive to light. Bilateral upper and lower extremity muscle strength, deep tendon reflexes, and pain sensation are normal. Blood cell counts and serum chemistry studies are within normal limits. Which of the following is the most likely cause of his current condition?

Question

A 68-year-old man is brought to the emergency department by his daughter due to a change in mental status.  Over the past 2 days, the patient has reported seeing strangers sneaking around the house when only he and his daughter were at home.  He has also been intermittently confused, difficult to rouse, and distractible.  The patient has had no headaches or focal weakness.  He has no chronic medical or psychiatric problems other than seasonal allergies, which his daughter says have flared up since he moved in with her 2 weeks ago.  Temperature is 36.7 C (98 F), blood pressure is 140/85 mm Hg, pulse is 88/min, and respirations are 12/min.  On physical examination, the patient is somnolent but arousable to voice.  He is not oriented to place or time.  Pupils are bilaterally equal and reactive to light.  Bilateral upper and lower extremity muscle strength, deep tendon reflexes, and pain sensation are normal.  Blood cell counts and serum chemistry studies are within normal limits.  Which of the following is the most likely cause of his current condition?

Quizplus · Accepted Answer

This patient has altered mental status (eg, impaired consciousness, disorientation, hallucinations) consistent with delirium. The key characteristics of acute onset (hours to days) and fluctuation distinguish delirium from other disorders with similar symptoms (eg, dementia, psychosis). Delirium is frequently multifactorial, most often caused by an acute medical condition, drug intoxication/withdrawal, or adverse medication effect. Underlying illness and intoxication/withdrawal are unlikely given this patient's stable vital signs, nonfocal exam, and normal laboratory values. Therefore, medication-induced delirium, which is common with over-the-counter remedies for seasonal allergies, should be suspected. Drug reactions frequently cause delirium, and psychoactive agents (eg, anticholinergics, antihistamines, benzodiazepines, sedative-hypnotics, opioids) carry the highest risk. Comprehensive medication review (including over-the-counter agents and other family members' prescriptions) is essential to every delirium workup. The definitive treatment for delirium must address the underlying cause (eg, treat the medical illness, remove the offending medication). Dementia (often previously unrecognized) is among the most common risk factors for delirium, and cognitive assessment should follow delirium resolution. (Choice A) Brief psychotic disorder may be diagnosed in patients with ≥1 day but <1 month of psychotic symptoms not better explained by a medical illness/medication effect. Patients with brief psychotic disorder are typically alert without altered consciousness. (Choice B) Like delirium, dementia with Lewy bodies can cause visual hallucinations and cognitive fluctuations. However, it is marked by early executive dysfunction (eg, driving difficulty, job impairment), follows a progressive course, and has other neurologic findings (eg, parkinsonism, REM sleep behavior disorder). (Choice C) Frontotemporal dementias are a group of several neurodegenerative diseases. They can present with behavioral disturbance (eg, impulsivity, disinhibition, apathy) or language impairment (eg, aphasia). Unlike delirium, they have a gradual onset with a progressive course, and hallucinations are atypical. (Choice D) Hypothyroidism presenting as delirium is rare, but would be possible if severe (ie, myxedema coma); however, progressive lethargy with hypothermia, hypotension, and bradycardia is typically present. Delirium is a more common manifestation of acute thyrotoxicosis. Educational objective: Delirium involves the acute onset of fluctuating disturbances in attention (eg, altered consciousness) and cognition (eg, disorientation, hallucinations). When no clear medical illness is apparent, medication-induced delirium should be suspected. Psychoactive drugs (eg, anticholinergics, antihistamines, benzodiazepines, sedative-hypnotics, opioids) are common causes, and over-the-counter agents and unauthorized prescriptions should not be overlooked. __________ References: Delirium in older persons: advances in diagnosis and treatment. (http://www.ncbi.nlm.nih.gov/pubmed/28973626)

A 68-Year-Old Man Is Brought to the Emergency Department by His