Herniated Disc (Herniated Disk)
A herniated disc is a condition that affects one or more discs that make up the spine. It most commonly affects the low back (lumbar region), although it can also occur in the neck (cervical) or even less commonly the upper back (thoracic region). A disc (or disk) herniation happens when the soft inner part of a spinal disc (nucleus pulposus) pushes out through its tough outer layer (annulus fibrosus), irritating nearby nerves (Figure 1). A disk herniation can cause marked pain in the back that often radiates down the leg (sciatica). If spinal nerves are compressed numbness or weakness in the lower legs may occur. The exact location of numbness or weakness will depend on which nerve, or nerves, are compressed.
The disc is a shock absorber and cushions the spinal bones (vertebral bodies). The disk provides flexibility and allows movement of the spine. A herniated disk is relatively common in middle-aged patients (45-65 years) but can occur at any age. As a person ages, the center of the disc (nucleus pulposus) begins to lose water and becomes stiffer and less flexible. These changes make it harder for the disc to absorb shock. As a person ages, the outer layer (annulus fibrosus) becomes weakened, developing cracks and tears. These changes make it more likely a patient will experience a disk herniation.
Herniated Disc Symptoms and Physical Exam Findings
A herniated disc can cause several symptoms, including lower back pain, leg pain (sciatica), numbness, tingling, and muscle weakness in the lower leg. These symptoms occur because the disk presses on nearby nerves, causing irritation and inflammation. The symptoms can vary depending on the part of the spine affected. If the nerve is compressed for a long time, it may lead to permanent nerve damage. To check for a herniated disc, a doctor will perform certain physical exam maneuvers. They will look at how well you can move your lower back and may do specific tests, such as a straight leg raise test (Figure 2). Doctors also check for changes in sensation, muscle strength, and reflexes. These exams help identify which part of the spine is affected since different nerves control specific muscles and areas of sensation in the body.
Herniated Disk Imaging Studies
X-rays of the spine are often performed initially to assess the alignment of the spine and identify any obvious arthritis or other abnormal findings. However, the most common imaging tool used to diagnose disc herniation is a magnetic resonance imaging (MRI) scan (Figure 3). An MRI provides excellent visualization of soft tissue structures in the back -including the intervertebral disks. An MRI can show nerve compression, disk degeneration, and disk protrusion. A CT scan is useful for patients who cannot undergo the MRI examination. It provides better resolution of the bones than an MRI, although soft-tissues such as the disk space may not been seen quite as clearly.
Conservative Treatment of a Herniated Disc
When a patient is diagnosed with a herniated disc, non-surgical treatments are usually the first option. These treatments often include physical therapy, medication, and steroid injections. Physical therapy focuses on strengthening and stabilizing muscles, which can improve movement and reduce pain. Medications like nonsteroidal anti-inflammatory drugs (NSAIDs) and corticosteroids help reduce pain and inflammation. In some cases, doctors may prescribe muscle relaxants or recommend steroid injections for short-term pain relief, especially for patients with severe discomfort. This pain relief allows patients to participate in physical therapy and return to their daily activities. Educating patients about their condition is also important, as it helps them better manage symptoms and maintain their recovery.
Sample Conservative Treatment Plan for Low-Back Pain (pdf version)
Surgical Treatment of a Herniated Disc
If the disc herniation is large and there is evidence of a progressive neurological deficit (increasing weakness, increasing weakness) or appropriate nonsurgical management has failed to to provide relief for the patient, then surgical treatment may be indicated. Surgery usually entails a discectomy or microdiscectomy where the herniated disk is removed. If there is evidence of spinal instability or notable arthritis in the spine a spinal fusion may need to be added.
Edited by Nadia Hackett and Stephen Pinney MD July 27th, 2025