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Emergency medical services bring a 59-year-old man to the acute care bay for evaluation of rapidly progressive lower extremity weakness. For the past week, the patient has experienced dull, constant, mid-thoracic back pain and subjective fevers, which he initially attributed to a mechanical strain. Over the last 12 hours, he developed difficulty walking and urinary retention. His medical history is significant for end-stage renal disease on hemodialysis, type 2 diabetes mellitus, and sick sinus syndrome. He had a non-MRI-conditional dual-chamber permanent pacemaker placed 14 years ago. His temperature is 38.8°C (101.8°F), blood pressure is 112/74 mm Hg, and pulse is 95/min. Physical examination reveals exquisite tenderness to percussion over the T8 to T10 spinous processes. Neurologic examination shows 2/5 strength in bilateral hip flexors and knee extensors, hyperreflexia at the patellae, and a positive Babinski sign bilaterally. Sensation to pinprick is markedly decreased below the umbilicus. Anal sphincter tone is diminished. Laboratory studies show a leukocyte count of 18,500/mm³ and an erythrocyte sedimentation rate of 92 mm/h. Which of the following is the most appropriate next step in imaging for this patient?

  1. CT myelographyCevap
  2. B
    MRI of the thoracic and lumbar spine without contrast
  3. C
    CT of the thoracic and lumbar spine with intravenous contrast
  4. D
    Plain radiography of the thoracic and lumbar spine
  5. E
    Radionuclide bone scintigraphy

Cevap

CT myelography
This patient presents with classic features of a spinal epidural abscess (SEA) complicated by acute spinal cord compression. The diagnosis is strongly suggested by the classic triad of localized severe back pain, fever, and progressive neurologic deficits (paraparesis, sensory loss below a dermatomal level, and autonomic dysfunction causing urinary retention). This condition is a neurosurgical emergency. The gold standard for definitively diagnosing SEA and outlining the extent of cord compression is an MRI of the spine with and without intravenous contrast. However, this patient has an absolute contraindication to MRI due to his legacy, non-MRI-conditional permanent pacemaker. Subjecting him to an MRI risks catastrophic device malfunction, thermal injury to the myocardium, and lead displacement. When MRI is absolutely contraindicated, CT myelography is the alternative imaging modality of choice. It involves the intrathecal administration of iodinated contrast followed immediately by a CT scan, providing excellent visualization of the subarachnoid space and clearly delineating any extradural masses compressing the spinal cord.

Adım Adım Çözüm

1
Identify the clinical syndrome based on the patient's presentation.
The triad of fever, focal back pain, and rapidly progressive neurologic deficits (paraparesis, sensory level, bowel/bladder dysfunction) strongly suggests a spinal epidural abscess with acute spinal cord compression.
Recognizing acute cord compression dictates the need for emergent definitive imaging to guide surgical decompression.
2
Determine the gold standard imaging modality for the suspected diagnosis.
Magnetic resonance imaging (MRI) of the spine with and without intravenous contrast is the standard of care.
MRI provides the highest resolution for evaluating the spinal cord, epidural space, and surrounding soft tissues.
3
Evaluate the patient's medical history for specific imaging contraindications.
The patient has a legacy, non-MRI-conditional permanent pacemaker.
This is an absolute contraindication to placing the patient in an MRI scanner, regardless of whether contrast is used.
4
Select the most appropriate alternative imaging modality.
CT myelography is selected.
When MRI is contraindicated, CT myelography (involving intrathecal contrast injection) is the most sensitive alternative for visualizing the subarachnoid space and identifying extradural cord compression.

Anahtar Kavram

CT myelography is the preferred alternative imaging modality for evaluating suspected spinal epidural abscess and acute spinal cord compression in patients who have an absolute contraindication to magnetic resonance imaging (MRI).
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