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Difficulty: HardDiagnostic Workup and Test Sequencing

A 74-year-old woman is brought to the clinic by her son for a progressive decline in her memory over the past 12 months. The son notes that she frequently repeats questions, forgets recently discussed topics, and recently became disoriented while walking in her own neighborhood. She previously managed her own finances but now struggles to pay bills on time. She has a history of essential hypertension, osteoarthritis, and occasional urinary incontinence over the past 2 years. Her current medications include lisinopril and acetaminophen. Vital signs are Temp 36.8°C (98.2°F), BP 132/82 mmHg, HR 72/min, and RR 14/min. Neurological examination shows normal cranial nerves, normal motor strength and sensation, and a normal, steady gait. She scores 21/30 on the Montreal Cognitive Assessment (MoCA), losing points primarily on delayed recall, orientation, and visuospatial tasks. Which of the following are indicated as the most appropriate concurrent steps in the initial diagnostic workup of this patient? (Select 2)

  1. Serum vitamin B12 and thyroid-stimulating hormone assaysAnswer
  2. Noncontrast magnetic resonance imaging of the brainAnswer
  3. C
    Lumbar puncture for cerebrospinal fluid biomarker analysis
  4. D
    Fluorodeoxyglucose-positron emission tomography scan of the brain
  5. E
    Apolipoprotein E genetic testing

Answer

The most appropriate concurrent steps are serum vitamin B12 and thyroid-stimulating hormone assays, along with noncontrast magnetic resonance imaging of the brain.
The correct sequence for evaluating progressive cognitive decline begins with a thorough clinical assessment, followed concurrently by laboratory testing to rule out reversible metabolic causes (such as hypothyroidism and vitamin B12 deficiency) and structural neuroimaging (such as an MRI of the brain) to rule out vascular disease, tumors, or hydrocephalus. The patient presents with a classic insidious onset of memory loss and functional decline, making this standard initial evaluation the most appropriate next step.

Step-by-Step Solution

1
Identify the primary clinical syndrome.
The patient has progressive cognitive decline affecting memory, orientation, and executive function, indicative of a major neurocognitive disorder (dementia).
Establishing the clinical syndrome directs the subsequent diagnostic workup.
2
Evaluate for red flags or atypical features.
The presentation is consistent with typical Alzheimer disease. Although she has urinary incontinence, her normal gait significantly lowers the probability of normal pressure hydrocephalus (NPH).
Atypical features might alter the sequence of testing, but their absence supports a standard diagnostic pathway.
3
Select the guideline-recommended initial diagnostic tests.
Standard guidelines require screening for reversible causes (vitamin B12, TSH) and structural neuroimaging (MRI or CT) to rule out covert cerebrovascular disease or masses.
These tests form the mandatory baseline workup for any patient presenting with new-onset, progressive dementia.

Key Concept

The initial evaluation of a patient with suspected dementia requires ruling out reversible systemic causes with basic laboratory tests (B12, TSH) and ruling out structural intracranial pathology with neuroimaging (MRI or CT).
Estimated Time:1m 30s
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Diagnostic Workup and Test Sequencing

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