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Zorluk: ZorOrdering Imaging Studies

A 68-year-old man is brought to the emergency department by his wife due to worsening mid-back pain, fever, and progressive weakness in his legs over the past 3 days. For the past 12 hours, he has been unable to urinate. His medical history is significant for type 2 diabetes mellitus, hypertension, and sick sinus syndrome, for which a dual-chamber permanent pacemaker was placed 15 years ago. His temperature is 38.8°C (101.8°F), blood pressure is 148/88 mm Hg, pulse is 76/min, and respirations are 16/min. Physical examination reveals exquisite tenderness to percussion over the T8-T10 spinous processes. Neurologic examination shows 3/5 motor strength in the bilateral lower extremities, decreased pain and temperature sensation below the umbilicus, and absent Achilles reflexes. Post-void residual bladder volume is measured at 650 mL. Laboratory studies show a leukocyte count of 16,500/mm³ and an erythrocyte sedimentation rate of 85 mm/h. Which of the following is the most appropriate next step in imaging for this patient?

  1. A
    Computed tomography angiography of the chest and abdomen
  2. Computed tomography myelography of the spineCevap
  3. C
    Magnetic resonance imaging of the spine with and without gadolinium
  4. D
    Non-contrast computed tomography of the spine
  5. E
    Technetium-99m bone scintigraphy

Cevap

Computed tomography myelography of the spine
The correct answer is computed tomography myelography of the spine. This patient's presentation of fever, focal back pain, progressive paraparesis, sensory deficits, and urinary retention strongly suggests acute spinal cord compression, most likely due to a spinal epidural abscess. Prompt imaging is required. The gold standard imaging modality is an MRI of the entire spine with and without contrast. However, this patient has a permanent pacemaker placed 15 years ago. Legacy pacemakers are absolute contraindications to MRI due to the risk of severe thermal injury, lead dislodgment, and complete device failure. In patients who require urgent evaluation of the spinal canal and epidural space but have a strict contraindication to MRI, CT myelography is the imaging modality of choice.

Adım Adım Çözüm

1
Identify the patient's primary clinical syndrome.
The triad of severe back pain, fever, and progressive neurologic deficits (paraparesis, sensory level, urinary retention) is highly indicative of acute spinal cord compression secondary to a spinal epidural abscess.
Recognizing this neurosurgical emergency is critical to initiating the correct diagnostic and therapeutic pathways.
2
Determine the gold standard diagnostic imaging for this condition.
Magnetic resonance imaging (MRI) of the spine with and without intravenous contrast is universally the initial imaging modality of choice for suspected spinal epidural abscess.
MRI provides the best soft-tissue resolution to visualize the epidural space, the extent of the abscess, and the degree of spinal cord compression.
3
Evaluate the patient's medical history for specific imaging contraindications.
The patient has a legacy permanent pacemaker placed 15 years ago, which is an absolute contraindication to undergoing an MRI.
Legacy pacemakers are not MRI-conditional. Exposure to the strong magnetic field can cause thermal injury to the myocardium, lead displacement, or catastrophic device failure.
4
Select the optimal alternative imaging modality.
Computed tomography (CT) myelography is the most appropriate next step.
When an MRI is strictly contraindicated, CT myelography (which involves injecting contrast into the thecal sac followed by a CT scan) provides the necessary delineation of the spinal canal and identifies the site and severity of cord compression.

Anahtar Kavram

In a patient presenting with signs of spinal cord compression (e.g., spinal epidural abscess), the standard of care is an urgent MRI of the spine. If the patient has an absolute contraindication to MRI, such as a legacy pacemaker, CT myelography is the preferred alternative imaging study.
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