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Difficulty: MediumDiagnostic Workup and Test Sequencing

A 58-year-old man is brought to the emergency department by his wife due to severe, worsening mid-back pain for the past 5 days. This morning, he developed difficulty walking and states he has been unable to urinate for the past 12 hours. His medical history is significant for poorly controlled type 2 diabetes mellitus and a recent hospitalization for a staphylococcal skin infection. His temperature is 38.8°C (101.8°F), blood pressure is 132/82 mm Hg, pulse is 108/min, and respirations are 18/min. Physical examination reveals exquisite tenderness to percussion over the T8-T10 vertebrae. Neurologic examination shows 3/5 motor strength in the bilateral lower extremities, diminished sensation to pinprick below the umbilicus, and a palpably distended bladder. Laboratory studies reveal a leukocyte count of 16,500/mm316,500/mm^3. Which of the following is the most appropriate next step in the diagnostic workup of this patient?

  1. A
    Computed tomography of the thoracic spine without contrast
  2. B
    Plain radiography of the thoracic spine
  3. C
    Measurement of erythrocyte sedimentation rate and C-reactive protein
  4. D
    Lumbar puncture with cerebrospinal fluid analysis
  5. Magnetic resonance imaging of the entire spineAnswer

Answer

Magnetic resonance imaging of the entire spine
The correct answer is magnetic resonance imaging (MRI) of the entire spine. This patient's presentation of fever, focal spinal tenderness, and acute neurologic deficits (lower extremity weakness, sensory level, urinary retention) in the setting of a recent staphylococcal infection is highly suspicious for a spinal epidural abscess (SEA). When a patient presents with 'red flag' symptoms indicating acute spinal cord compression, the most appropriate next step in the diagnostic workup is urgent MRI. MRI is the most sensitive and specific imaging modality for diagnosing SEA and determining the exact location and extent of the infection, which is crucial for guiding emergent neurosurgical decompression.

Step-by-Step Solution

1
Identify the clinical syndrome based on the patient's presentation.
The patient has the classic triad of spinal epidural abscess: fever, focal back pain, and acute neurologic deficits (paraparesis, sensory level, and urinary retention indicating cauda equina/spinal cord compression).
Recognizing the pattern of acute spinal cord compression in the setting of infection dictates the urgency of the evaluation.
2
Determine the necessary diagnostic sequence based on the presence of neurologic deficits.
Because acute neurologic deficits are present, screening tests (labs, X-rays) must be bypassed in favor of immediate definitive imaging.
Delaying definitive imaging increases the risk of irreversible paralysis.
3
Select the optimal imaging modality.
Magnetic resonance imaging (MRI) of the spine is selected.
MRI provides the best visualization of the spinal cord, epidural space, and extent of the abscess, which is required for surgical planning.

Key Concept

Urgent magnetic resonance imaging of the spine is the initial diagnostic test of choice for patients presenting with suspected spinal epidural abscess who already exhibit neurologic deficits.
Estimated Time:1m 15s
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Diagnostic Workup and Test Sequencing

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