What are the diagnostic tests for lumbar (lower back) spinal stenosis?

From the Guidelines

Lumbar spine stenosis can be diagnosed through a combination of clinical examination and imaging studies, with magnetic resonance imaging (MRI) being the preferred method for evaluating patients with persistent back and leg pain who are potential candidates for invasive interventions, as recommended by the American College of Physicians and the American Pain Society 1.

Key Diagnostic Tests

• Magnetic Resonance Imaging (MRI): The gold standard for visualizing soft tissues, neural structures, and the degree of stenosis.
• Computed Tomography (CT) scans: Useful alternatives, especially when MRI is contraindicated, and can be enhanced with myelography for better visualization of the spinal canal.
• X-rays: Less detailed, but can identify structural abnormalities like bone spurs or degenerative changes.

Clinical Examination

• Specific provocative tests such as the extension test, which typically reproduces or worsens symptoms in stenosis patients.
• The bicycle test: Patients with neurogenic claudication from stenosis can often pedal a stationary bicycle in a flexed position without pain, unlike those with vascular claudication.
• Electrodiagnostic studies like EMG: May help rule out other conditions that mimic stenosis symptoms.
• A thorough neurological examination: Should assess muscle strength, reflexes, and sensation in the lower extremities.

Recommendations

• Clinicians should evaluate patients with persistent low back pain and signs or symptoms of radiculopathy or spinal stenosis with MRI (preferred) or CT only if they are potential candidates for surgery or epidural steroid injection (for suspected radiculopathy) 1.
• Clinicians should provide patients with evidence-based information on low back pain with regard to their expected course, advise patients to remain active, and provide information about effective self-care options 1.

From the Research

Diagnosis of Lumbar Spine Stenosis

• The diagnosis of lumbar spinal stenosis can be made based on a clinical history of back and lower extremity pain that is provoked by lumbar extension, relieved by lumbar flexion, and confirmed with cross-sectional imaging, such as computed tomography or magnetic resonance imaging (MRI) 2.
• Magnetic resonance imaging is the recommended diagnostic test because it allows cross-sectional measurement of the spinal canal 3.
• A systematic review concluded that there is insufficient evidence to recommend any specific type of non-surgical treatment, and clinical decision making should be based on a collection of data, including the history and physical findings, functional status, imaging and electrodiagnostic studies, and other adjunctive studies 4, 5.

Imaging Studies

• MRI is a more reliable tool than CT for assessing lumbar spinal stenosis, but neither correlates with functional status 6.
• CT overestimates the degree of stenosis 20-35% of the time, while MRI overestimates the degree of stenosis 2-11% of the time 6.
• The experience of the reader and the standardization of a qualitative assessment are influential to the reliability of imaging studies 6.

Clinical Presentation

• Lumbar spinal stenosis is a clinical syndrome of pain in the buttocks or lower extremities, with or without back pain, associated with reduced space available for the neural and vascular elements of the lumbar spine 4.
• The condition is often exacerbated by standing, walking, or lumbar extension and relieved by forward flexion, sitting, or recumbency 4, 2, 3.
• The pain is typically burning or cramping, which worsens with standing and walking and improves with bending forward or sitting 3.