What is a Herniated Disc (Slipped Disc)?
The spinal cord is a soft, cylindrical column of tightly bundled nerve cells (neurons and glia), nerve fibers that transmit nerve signals (called axons) and blood vessels. It sends and receives information between the brain and the rest of the body. Millions of nerve cells situated in the spinal cord itself also coordinate complex patterns of movements such as rhythmic breathing and walking.
The spinal cord extends from the brain to the lower back through a canal in the center of the bones of the spine. Like the brain, the spinal cord is protected by three layers of tissue and is surrounded by the cerebrospinal fluid (CSF) that acts as a cushion against shock or injury.
Inside the spinal cord are:
- A collection of neurons and their projections that connect with other nerve cells to transmit and receive information (gray matter)
- Bundles of axons, some of which are coated with a whitish mixture of proteins and fat-like substances (white matter)
Other types of nerve cells sit just outside the spinal cord and relay information to the brain. Thirty-one pairs of nerves, each of which contains thousands of axons, are divided into four regions with individual segments that link the spinal cord to muscles and other parts of the body:
- Cervical spinal nerves (C1 to C8) emerge from the spinal cord in the neck and control signals to the back of the head, the neck and shoulders, the arms and hands, and the diaphragm.
- Thoracic spinal nerves (T1 to T12) emerge from the spinal cord in the upper- to mid-back and control signals to the chest muscles, some muscles of the back, and many organ systems, including parts of the abdomen.
- Lumbar spinal nerves (L1 to L5) emerge from the spinal cord in the low back and control signals to the lower parts of the abdomen and the back, the buttocks, some parts of the external genital organs, and parts of the leg.
- Sacral spinal nerves (S1 to S5) emerge from the spinal cord in the low back and control signals to the thighs and lower parts of the legs, the feet, most of the external genital organs, and the area around the anus.
The spinal column, which surrounds and protects the spinal cord, is made up of 33 rings of bone (vertebrae), pads of semi-rigid cartilage (discs), and narrow spaces called foramen that act as passages for spinal nerves to travel to and from the rest of the body. The spinal cord is particularly vulnerable to direct injury within these areas. In the spine, a disc or a nucleus pulposus is localized between vertebral bodies. It supports the spine by acting as a shock-absorbing cushion.
A herniated disc in the spine is a condition during which a disc (or nucleus pulposus) is displaced from its proper space in the spine and is a common cause of back pain. Patients who experience pain related to a herniated disc often remember an inciting event that caused their pain. Symptoms are usually described as burning or stinging, and may radiate into the lower extremity, with more severe cases patients may experience weakness or sensation changes. In some cases, a herniated disc injury can compress the nerve or the spinal cord that causes pain consistent with nerve compression or spinal cord dysfunction, also known as myelopathy.
Types of Herniated Disc (Slipped Disc)
Herniated or slipped discs are categorized by severity which determines the course of treatment. These conditions can occur in the cervical, thoracic or lumbar sections of the spine.
- Disc Protrusion: Not a fully herniated disc, a protrusion is the least severe form of a herniated disc which typically results in the outer layer of the disc to weaken. This results in mild pain and numbness in the back.
- Disc Extrusion: The outermost layer of the spinal disc has a tear which results in disc tissue spilling out, though it is still connected to the disc.
- Disc Sequestration: Similar to an extrusion, sequestration occurs when the spinal disc tissue is spilling into the spinal canal, but it is no longer attached to the disc.
- Disc Prolapse: A disc is bulging out between the vertebrae with the outermost layer is still intact.
Causes of Herniated Disc (Slipped Disc)
Aside from incidence of injury, the most common factors that can lead to a herniated or slipped disc include poor posture, lifestyle choices and age. The most common cause of a herniated or slipped disc is normal, age-related wear and tear. Over the lifespan, spinal discs naturally lose their elasticity, resulting in fluid leaking out and the discs becoming brittle or cracked. Since the spinal discs act as shock absorbers between the vertebrae in the spine, a weakened spinal disc can no longer bear normal strain, resulting in a slipped disc. Pain results from part of the spinal disc pushed against a nerve in the spinal cord.
Many individuals experience sciatica pain which radiates down one leg and into the foot. The nerves that run through the spinal canal connect to the sciatic nerve at the pelvis, then run down the legs. Herniated disc tissue may irritate a nerve root in the lumbar spine (lower back) causing sciatic pain. As well as being painful, an irritated sciatic nerve can also cause pins and needles and numbness.
Risk Factors for Herniated Disc (Slipped Disc)
Slipped discs are more common in people over the age of 30, and are about twice as common in men as they are in women. The most common risk factors for a herniated disc include genetics, sedentary lifestyle, excess body weight and occupation. Physically demanding jobs that require repeated lifting, pulling, twisting and pushing increase the risk of injury, as can poor lifting technique or posture.
Screening for & Preventing Herniated Disc (Slipped Disc)
Preventing a herniated or slipped disc typically requires lifestyle modifications. Those with a sedentary lifestyle should add moderate exercise and maintain a healthy weight. Cessation of smoking also leads to overall better health. Focusing on proper posture and spine alignment throughout the day also improves spine health; avoid slouching, and try to create a healthy sleep position. Studies show that side and back sleepers have healthier backs than those who sleep on their stomach. Additional tips include using a pillow under or between the knees, choosing a firm mattress, and replacing an old mattress.
Doctors will use a series of screening questions and methods to determine if you have a herniated disc, beginning with a thorough medical history, family history and genetics to help establish risk factors. Additionally, a physical exam to determine cause and location of pain will be performed followed by an X-ray, MRI scan, Elegromyogram and/or a CT scan.
Signs & Symptoms of Herniated Disc (Slipped Disc)
A slipped disc can result in anything from minor discomfort to extreme, acute pain. The good news is that symptoms typically go away on their own within less than six weeks in most cases–and not every slipped disc is painful.
A slipped disc typically results in sudden and severe shooting pain. When it occurs in the neck area, you might experience pain that radiates into the arms. Slipped discs in the lumbar (lower back) region are the main cause of sciatica, which is pain that radiates down one leg and into the foot.
Some patients may experience numbness in the buttocks or signs of paralysis, which may indicate a more serious problem, like nerve damage. Any injury or spinal issues that affect the function of the bladder or bowels requre immediate treatment, as it may be "cauda equina syndrome" (CES) which is a medical emergency.
Diagnosing Herniated Disc (Slipped Disc)
Your doctor can typically determine what is causing acute back pain by conducting a brief case history and performing a physical examination. X-rays may be used to reveal spinal disc damage and cause of symptoms. Other imaging techniques such as magnetic resonance imaging (MRI) are needed if any of the following occur:
- Numbness or paralysis in one or both legs
- Impaired function of the bladder or bowel
- Unbearable pain despite treatment
- Severe symptoms remain for many weeks despite treatment
- Another condition is thought to be causing the pain, for example a tumor
Doctors won’t always suggest performing a complex diagnostic examination at first if you have back pain: Imaging techniques may show a supposed cause of back pain that actually has nothing to do with the symptoms. This kind of misdiagnosis can then result in unnecessary treatment that may itself be harmful.
Treating Herniated Disc (Slipped Disc)
Often even the most extreme sciatic pain can go away on its own after a while. In all cases of slipped or herniated discs, a range of pain relief treatments can help relieve symptoms. The primary goal for recovery is to stay as active as possible, often by working with a physical therapist to incorporate gentle exercise and stretching techniques. Rehab can improve symptoms while strengthening muscles in the torso which supports spine stability.
If severe sciatic pain caused by a slipped disc lasts longer than six weeks, surgery may be an option to try to relieve the pressure on the affected nerve. Surgery is performed in rare cases when the nerves are severely affected such that the bladder or the bowel is no longer functioning properly or certain muscles have become very weak.
In other rare cases, a discectomy may be performed to relieve the pressure resulting from a herniated, slipped, ruptured, prolapsed or bulging disc. Known as “microdiscectomy,” this minimally invasive spine surgery requiring a small incision at the site of injury.
Living with Herniated Disc (Slipped Disc)
Often even the most extreme sciatic pain can go away on its own after a while. In all cases of slipped or herniated discs, a range of pain relief treatments can help relieve symptoms. The primary goal for recovery is to stay as active as possible, often by working with a physical therapist to incorporate gentle exercise and stretching techniques. Rehab can improve symptoms while strengthening muscles in the torso which supports spine stability.
If symptoms last longer than six weeks, it is unlikely that they will go away on their own, and your doctor may suggest surgery.