What is the most appropriate diagnostic test for a patient presenting with lower limb weakness, urine incontinence, difficulty walking, and a T10 sensory level?

MRI of the Spinal Cord is the Most Appropriate Diagnostic Test

For a patient presenting with lower limb weakness, urinary incontinence, difficulty walking, and a T10 sensory level, MRI of the spinal cord without contrast is the definitive diagnostic test and should be obtained urgently. 1

Clinical Reasoning

This patient presents with classic features of spinal cord compression or cauda equina syndrome:

• Lower limb weakness
• Urinary incontinence (bladder dysfunction)
• Sensory level at T10
• Progressive neurologic deficit over 3 days

These symptoms represent a neurologic emergency requiring immediate imaging to identify the cause and guide urgent intervention. 1

Why MRI is Superior to CT

MRI is the imaging study of choice because it provides:

• Superior soft-tissue contrast to accurately depict the spinal cord parenchyma, nerve roots, and surrounding structures 1, 2
• Direct visualization of the spinal cord itself, which CT cannot adequately demonstrate 2, 3
• Ability to assess vertebral marrow, disc pathology, epidural space, and intraspinal lesions in a single examination 3
• Non-invasive evaluation of the entire spinal canal without radiation or contrast injection 2, 3
• Detection of multiple etiologies including disc herniation, epidural abscess, tumor, hematoma, myelitis, and cord infarction 2, 4

Evidence from Guidelines

The ACR Appropriateness Criteria explicitly states that MRI is the imaging study of choice for suspected cauda equina syndrome, multifocal deficits, or progressive neurologic deficits due to its ability to accurately depict soft-tissue pathology, assess vertebral marrow, and evaluate spinal canal patency. 1

While CT can identify whether compression is present, it is inferior to MRI for characterizing the etiology and evaluating the spinal cord itself. 1 CT should only be considered when MRI is contraindicated or unavailable. 1

Critical Clinical Pitfalls

• Time is critical: Delayed diagnosis in spinal cord compression leads to irreversible neurologic damage and poor outcomes 1, 2
• Do not wait for contrast: MRI without contrast is the initial study; contrast should only be added if infection, tumor, or inflammation is suspected after initial imaging 1
• CT is inadequate: CT cannot visualize the spinal cord parenchyma or detect intramedullary pathology, making it unsuitable as the primary diagnostic test 2, 3
• Urgent neurosurgical consultation should occur simultaneously with imaging, as surgical decompression may be required within hours 1