A 79-year-old woman is brought to the emergency department from a memory care facility due… — USMLE Step 2 CK

A 79-year-old woman is brought to the emergency department from a memory care facility due to a 3-day history of extreme agitation and visual hallucinations. Staff report she has been picking at the air and describing "spiders on the ceiling." The patient has a 4-year history of Major Neurocognitive Disorder due to Alzheimer disease, with a baseline Mini-Mental State Examination score of $17/30$ . Five days ago, she was evaluated for new-onset urinary incontinence, and a new medication was prescribed.

Her current daily medications include donepezil and sertraline. Her son, who is visiting from out of state and is not her legally appointed healthcare proxy (her daughter holds this role), is highly distressed and demands the physician immediately administer heavy sedatives to "calm her down."

On examination, the patient's temperature is $37.8^\circ\text{C}$ ( $100.0^\circ\text{F}$ ), pulse is $110/\text{min}$ , and blood pressure is $142/86 \text{ mm Hg}$ . She is disoriented, continuously muttering, and unable to participate in cognitive testing. Pupils are $6 \text{ mm}$ bilaterally and minimally reactive to light. Mucous membranes are extremely dry. Abdominal examination reveals absent bowel sounds and a palpable, dull suprapubic mass.

Laboratory results show:
Thyroid-stimulating hormone (TSH): $0.2 \text{ \mu U/mL}$ (Normal: $0.5 - 5.0 \text{ \mu U/mL}$ )
Free T4: $1.3 \text{ ng/dL}$ (Normal: $0.9 - 1.7 \text{ ng/dL}$ )
Urinalysis: Negative for leukocyte esterase and nitrites.

Which of the following is the most appropriate next step in management?

Discontinue the recently added incontinence medication and perform bladder catheterizationAnswer
B
Initiate levothyroxine supplementation to address the underlying endocrine abnormality
C
Diagnose a primary psychotic disorder and initiate a long-term typical antipsychotic
D
Add a monoamine oxidase inhibitor to her regimen to target treatment-resistant behavioral symptoms
E
Obtain consent from the son to administer intravenous lorazepam for rapid behavioral control

Answer

Discontinue the recently added incontinence medication and perform bladder catheterization

This patient's clinical presentation is highly characteristic of acute delirium secondary to anticholinergic toxicity. She has a baseline major neurocognitive disorder (Alzheimer disease) which leaves her highly susceptible to iatrogenic delirium. Five days ago, she was started on a medication for urinary incontinence. Medications used for overactive bladder, such as oxybutynin or tolterodine, possess strong antimuscarinic (anticholinergic) properties. The classic anticholinergic toxidrome includes central nervous system effects (delirium, visual hallucinations, agitation) and peripheral autonomic effects (tachycardia, mydriasis, dry mucous membranes, decreased bowel sounds, and urinary retention, evidenced here by the palpable suprapubic mass). The most appropriate next step in management is to discontinue the offending medication and immediately decompress the bladder via catheterization, which will resolve both the pharmacologic toxicity and the severe discomfort contributing to her agitation.

Step-by-Step Solution

Identify the nature of the cognitive change.

The patient has a 3-day history of extreme agitation, fluctuating consciousness, and visual hallucinations superimposed on a baseline dementia diagnosis, defining an acute delirium.

Differentiating acute delirium from progressive neurocognitive decline is the critical first step in evaluating behavioral changes in the elderly.

Analyze the physical examination findings.

The patient has tachycardia, mydriasis, dry mucous membranes, absent bowel sounds, and a palpable suprapubic mass indicating urinary retention.

These specific signs constitute the classic anticholinergic toxidrome ('blind as a bat, dry as a bone, red as a beet, mad as a hatter, hot as a hare').

Determine the precipitating cause based on the recent medical history.

The medication started 5 days ago for urinary incontinence is identified as the trigger, highly likely to be an antimuscarinic/anticholinergic drug like oxybutynin.

Anticholinergics directly oppose the action of acetylcholinesterase inhibitors (like her donepezil) and are notorious for causing delirium and urinary retention in patients with baseline cognitive impairment.

Formulate the most appropriate management plan.

Discontinuation of the offending anticholinergic medication and immediate placement of a urinary catheter.

Stopping the toxic agent addresses the root cause of the delirium, and decompressing the distended bladder relieves the acute pain and agitation driving the behavioral symptoms.

Key Concept

Diagnosis and management of anticholinergic delirium superimposed on major neurocognitive disorder.

Estimated Time:2m 30s

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