MRI of the Spine
This patient requires MRI of the lumbar spine now because he presents with classic neurogenic claudication from lumbar spinal stenosis—bilateral leg symptoms (tingling and numbness) that worsen with walking/standing and improve with sitting/flexion, accompanied by progressive symptoms and mild bilateral weakness. 1, 2, 3
Clinical Reasoning
Why This is Spinal Stenosis, Not Simple Low Back Pain
Neurogenic claudication pattern: The bilateral leg symptoms that worsen with walking/standing and improve with sitting/lying down are pathognomonic for spinal stenosis, not nonspecific low back pain. 1
Progressive neurologic deficits: The patient has mild symmetrical weakness in both lower extremities, which represents a progressive neurologic deficit requiring immediate imaging. 1, 2
Three-month duration with recent worsening: This is chronic low back pain (>3 months) with acute progression over the past week, indicating potential clinical deterioration. 2
Why Immediate MRI is Indicated
The American College of Physicians recommends immediate imaging for patients with severe or progressive neurologic deficits, which this patient demonstrates with bilateral weakness. 1, 2
The American College of Radiology specifies that patients with severe symptoms or significant neurological findings at initial presentation should not be delayed in receiving imaging, as this expedites definitive care. 3
MRI is the preferred imaging modality for evaluating spinal stenosis and nerve root compression, providing detailed visualization of the spinal canal, cauda equina, and nerve roots. 3, 4
Why Other Options Are Incorrect
Ibuprofen (Option B)
NSAIDs are appropriate for nonspecific low back pain without neurologic deficits, but this patient has already failed acetaminophen and presents with progressive bilateral weakness. 2
While NSAIDs can be initiated for pain control, they do not address the urgent need for diagnostic imaging in a patient with progressive neurologic deficits. 3
Radiography (Option C)
Plain radiography is not recommended for initial evaluation of suspected spinal stenosis because it cannot visualize the spinal canal, nerve roots, or soft tissue structures. 1, 2
The American College of Physicians states that routine plain radiography is not associated with improved patient outcomes and exposes patients to unnecessary radiation. 1
Plain films would only be appropriate for suspected vertebral compression fracture in high-risk patients (osteoporosis, steroid use), which is not the clinical picture here. 1
Outpatient Physical Therapy (Option D)
Physical therapy is appropriate for nonspecific low back pain without red flags, but this patient has progressive neurologic deficits (bilateral weakness) requiring urgent diagnostic evaluation before initiating conservative management. 2
Delaying imaging in favor of physical therapy could miss a surgical indication and potentially worsen outcomes in a patient with progressive spinal stenosis. 3
Clinical Pearls
Age is a risk factor: Patients older than 65 years have a positive likelihood ratio of 2.5 for spinal stenosis. 1
Bilateral symptoms are key: Unlike unilateral radiculopathy from disc herniation, spinal stenosis typically causes bilateral leg symptoms due to compression of multiple nerve roots in the cauda equina. 1
Relief with sitting/flexion is highly specific: Spinal flexion increases the anteroposterior diameter of the spinal canal, relieving compression—this positional relief strongly suggests stenosis over other pathologies. 1
Normal reflexes don't rule out stenosis: Unlike acute radiculopathy where reflexes are often diminished, spinal stenosis may present with preserved reflexes despite weakness. 1