Diagnosis

During the physical exam, your doctor may check your muscle strength and reflexes. For example, you may be asked to walk on your toes or heels, rise from a squatting position and, while lying on your back, lift your legs one at a time. Pain that results from sciatica will usually worsen during these activities.

Imaging tests

Many people have herniated disks or bone spurs that will show up on X-rays and other imaging tests but have no symptoms. So doctors don't typically order these tests unless your pain is severe, or it doesn't improve within a few weeks.

• X-ray. An X-ray of your spine may reveal an overgrowth of bone (bone spur) that may be pressing on a nerve.
• MRI. This procedure uses a powerful magnet and radio waves to produce cross-sectional images of your back. An MRI produces detailed images of bone and soft tissues such as herniated disks. During the test, you lie on a table that moves into the MRI machine.
• CT scan. When a CT is used to image the spine, you may have a contrast dye injected into your spinal canal before the X-rays are taken — a procedure called a CT myelogram. The dye then circulates around your spinal cord and spinal nerves, which appear white on the scan.
• Electromyography (EMG). This test measures the electrical impulses produced by the nerves and the responses of your muscles. This test can confirm nerve compression caused by herniated disks or narrowing of your spinal canal (spinal stenosis).