Herniated disc, also known as slipped disc, is a condition in which the “cushion” (intervertebral disc) between vertebrae bulges or protrudes. It commonly occurs in the lower back (lumbar spine), causing low back pain and numbness in the legs. Treatments for herniated disc and low back pain are usually conservative and nonsurgical.
What is a Herniated Disc?
A human spinal column consists of 24 movable vertebrae stacked onto each other. In between each of the vertebrae, they are cushioned by intervertebral discs acting as shock absorbers and prevent the vertebrae from grinding together. These rubbery discs are made of a soft center (nucleus pulposus) surrounded by a tough outer layer (annulus fibrosis). These intervertebral discs dehydrate and compress with age, causing them to bulge into the spinal canal. When the outer layers of the bulging annulus remain intact, it is called a bulging disc.
Herniated disc is also known as prolapsed intervertebral disc, slipped disc or ruptured disc. It happens when the disc nucleus ruptures out of the annulus through a tear or crack in the annulus. Since the spinal canal has limited space, the herniated disc can irritate and put pressure on the spinal cord and nearby spinal nerves, causing severe pain and discomfort.
A herniated disc can occur in any part of the vertebral column, but it is more common in the lumbar spine (lower back) and cervical spine (neck). Thus, herniated disc is one of the most common causes of neuralgia (nerve pain) such as low back pain, cervical spondylosis and sciatica.
Causes of Herniated Disc
In children and young adults, the intervertebral discs contain high water content that makes the spine flexible to allow for motion but resist compression. Over time, the discs begin to dry out and become less flexible and more brittle. This process is called disc degeneration, which is a natural process of aging. The discs would then be more vulnerable to tearing or rupturing by body movements, for example twisting when lifting heavy objects. Sometimes, a traumatic injury, such as a fall, can also put pressure on the discs to cause herniation, too.
Risk factors of Herniated Disc
Although a herniated disc is most often age-related, the following factors may also play a role in inducing a higher risk of intervertebral disc herniation:
- Sex: Males are more likely to develop herniated discs than females.
- Weight: Obesity and Overweight may increase the stress on the lumbar vertebrae and hence the risk of herniated disc.
- Occupation: Physically demanding work increases the risk of backbone injury and intervertebral disc herniation, such as lifting, bending, or twisting.
- Smoking: Smoking increases the rate of discs degeneration by diminishing blood flow to the spine and vertebrae.
- Lack of exercise or sedentary lifestyle: Physical inactivity can weaken the low back muscles and make the spine and backbone more susceptible to injury.
- Family history: Some research found that there is a hereditary tendency for disc degeneration, which is associated with an increased risk of herniated disc.
Signs and Symptoms of Herniated Disc
Symptoms of herniated disc vary from person to person, greatly depending on where the disc herniated and which spinal nerve roots are affected. Sometimes, a herniated disc can be asymptomatic. In general, common signs and symptoms of herniated disc include:
- Low back pain. This is caused by herniated discs in the lumbar region. It can be continuous or intermittent. It can also be worsened by certain movements, such as coughing, sneezing, or moving.
- Sciatica: Pain that starts from the buttock or back of the thigh and radiates down the leg to the calf or foot. This usually affects one leg only.
- Buttock pain and hip pain
- Pain and/or numbness in the neck or between the shoulder blades: This is caused by herniated discs in the cervical spine. Coughing, sneezing, moving the shoulder or turning the neck around can cause severe pain.
- Pain and/or numbness that radiates down the arm to the hand: Herniated disc in the cervical spine compresses the cervical spinal nerve that innervates the upper limb, causing pain and numbness radiating along the corresponding area of the upper limb.
- Back muscle spasm
- Muscle weakness
- Numbness or tingling in affected areas
- Loss of bladder or bowel control: When the nerve is compressed severely in the lumbar spine, a rare condition called cauda equina syndrome can happen. If you experience changes in bladder or bowel function, you should seek medical attention immediately.
Complications of Herniated Disc
Occasionally, a herniated disc can cause damage to the spinal nerves when they are severely compressed. This complication is known as cauda equina syndrome.
Cauda equina is the sack of nerves located at the end of the spinal cord. These nerve roots are responsible for motor and sensory function to the legs and the bladder. A herniated disc at the lumbar region can possibly compress these nerve roots, impairing their corresponding functions. If the situation is being untreated, cauda equina would be significantly damaged and lead to long-term problems, such as permanent paralysis, nerve pain, impaired bladder control, impaired bowel control, sexual dysfunction, etc.
Cauda equina syndrome is often related to a symptom called saddle anesthesia. It refers to the altered sensation in the areas in contact with a saddle (e.g. anus, buttocks, the inner thighs, back of the legs). If you experience symptoms such as saddle anesthesia, bladder or bowel incontinence and weakness or paralysis in the lower extremities, you should seek medical attention right away as it would require emergent surgery.
Diagnosis of Herniated Disc
Herniated discs at different parts of the vertebral column require slightly different diagnostic methods. In general, diagnosis of a herniated disc can be made by physical examination together with imaging procedures. To confirm the diagnosis of herniated disc, the following measures are usually taken:
- Neurological examination: You may be asked to walk normally and on tiptoes to assess your muscle strength in the lower legs and check for a condition called foot drop, which is difficulty lifting the front part of the foot due to muscle weakness. Your reflexes at the knee and ankle may be tested as well. The sensation of the lower extremities may also be tested.
- Straight leg raise test (Lasegue test): During this test, you lie on your back and your doctor would raise your affected leg 30-70 degrees to see if you feel any pain radiating down the leg. If you have a lumbar disc herniation, it should press on the stretched nerve root as your leg is raised above 30 degrees.
- X-rays: X-rays are used to show the structure of the vertebrae and the outline of the joints to rule out other causes of back pain (e.g. tumor, infection), but cannot show a herniated disc.
- CT scan: A CT scan uses X-rays and computer technology to show detailed images of your spinal column and the structures around it.
- MRI: MRI is the most commonly used imaging procedure for a herniated disc. It shows detailed images of bones, spinal cord, nerve roots, intervertebral discs and other soft tissues in a three-dimensional image. MRI imaging can be applied to confirm the diagnosis of a herniated disc.
- Myelogram: It involves injecting a contrast dye into the spinal canal, followed by x-rays or CT scans to show the size and location of a herniation.
- Electromyogram (EMG) and Nerve conduction study (NCS): These tests measure the electrical impulses along the nerve roots and muscles to pinpoint which spinal nerve root is affected. EMG measures the electrical activity of muscle at rest and during contraction, while NCS measures how fast an impulse moves through your nerve.
Treatments for Herniated Disc
For the majority of patients with a herniated disc, the condition requires long-term non-invasive treatments and rehabilitation. During rehabilitation, conservative treatments are usually applied to monitor the condition, while surgery would only be applied in severe cases with complications.
Treatments for herniated disc:
First-line treatments for herniated discs usually aim to relieve pain by medications and physical therapy, for example:
- Oral medications: Usually, mild-to-moderate pain caused by a herniated disc can be well-managed by nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen and naproxen. If you experience muscle spasms, you may be prescribed muscle relaxants such as baclofen.
- Physiotherapy: Your doctor may also recommend physiotherapy which is tailor-made based on your condition aiming to relieve pain and strengthen your muscles. The program may also train you on performing daily activities safely, such as lifting and walking.
- Epidural steroid injection (ESI): Unlike oral medications, ESI is a minimally invasive treatment option. In case oral medications and physiotherapy are ineffective, an injection of steroid medication and local anesthetic into the epidural space of the spine may be applied to provide short-term pain relief. Such injection needs to be performed by physicians under X-ray control professionally. It can reduce inflammation of the affected nerve and provide better recovery.
Surgeries for herniated disc:
Surgery may be recommended to treat herniated disc if the above-mentioned treatments fail to relieve symptoms effectively or the following conditions and complications are developed:
- Loss of bowel and/or bladder control (Cauda equina syndrome)
- No response after 6 weeks of non-invasive treatments and ESI
- Difficulty standing and/or walking
- Progressive neurological symptoms, such as worsening weakness, and/or numbness
Surgical operations mainly focus on removing the protruding portion of the herniated disc without damaging other parts of the spinal column. These surgical procedures often include:
- Microdiscectomy / Discectomy / Laminotomy: During microdiscectomy, the surgeon would make a small incision at the level of the disk herniation to remove a portion of the herniated disc (discectomy) with the aid of a microscope which allows a better sight of the herniated disc. Part of the lamina of the affected vertebral arch may also be removed if necessary (laminotomy).
- Endoscopic discectomy: Endoscopic discectomy is a minimally invasive surgery with an extremely tiny incision (even smaller than that of microdiscectomy). During an endoscopic discectomy, the herniated disc is removed with the aid of a tiny camera through a small surgical tube. Such surgery minimizes the damage to normal tissues and allows faster recovery.
Home remedies for Herniated Disc
In addition to conservative treatments, you can also try the following tips at home to relieve symptoms caused by a herniated disc:
- Ice or heat application: Applying cold packs on the affected area may be helpful to relieve pain and inflammation initially after symptoms start. A few days later, you can alter with gentle heat (e.g. heating pads, a hot compress) for pain relief.
- Minimum bed rest: Staying in bed can help relieve pain but it should be limited to 1-2 days only because prolonged bed rest may lead to joint stiffness and muscle weakness.
- Resuming activity slowly: After resting, try to resume some low-impact activities such as stretching and walking. Resuming exercises early can improve the outcome of recovery, but you should avoid doing strenuous activities or exercises that cause or worsen pain.
Prevention of Herniated Disc
Disc herniation can be prevented by paying attention to your daily activities, you can reduce the risk of disc herniation by:
- Regular exercising: Exercise that strengthens your back and abdomen muscles can help support your spine and hold the backbone in place.
- Quit smoking: Avoid smoking can reduce damages to the intervertebral discs.
- Maintaining a healthy weight: A healthy body weight can reduce pressure on the spine and the intervertebral discs. Reducing the risk of displacing the discs.
- Maintaining a good posture: Try to keep your back straight and aligned, and use proper techniques when lifting. Avoid lifting heavy objects.
Yes, a herniated disc generally recovers on its own in a few months. During recovery, conservative treatments are recommended to help relieve pain and strengthen your muscles. If these approaches are not effective or If your symptoms don’t get better, you may need surgery.
This article was medically reviewed by Dr. Eric Sze Tsun Yeung. Dr. Yeung is a specialist in Orthopaedics and Traumatology both in UK and HK who graduated from the University College London Medical School, University of London. Before his return to HK in 2011, Dr. Yeung was an Orthopaedic Consultant in a London teaching hospital. Dr. Yeung worked for the HK Hospital Authority at the Prince of Wales Hospital, Yan Chai Hospital and Queen Elizabeth Hospital. He is now the Honorary Clinical Associate Professor of the Department of Orthopaedics and Traumatology at both the University of Hong Kong and the Chinese University of Hong Kong. Dr. Yeung is actively practicing at the SINCERUS Orthopaedics & Rehabilitation Centre, Central, HK.
This article was independently written by Healthy Matters and is not sponsored. It is informative only and not intended to be a substitute for professional medical advice, diagnosis or treatment. It should not be relied upon for specific medical advice.