What is a Herniated Disc?
The spinal discs are the shock absorbers or the cushions in between the vertebrae, or the bones of the spine. A herniated disc comes in a variety of flavors, but simply it means that part of the disc material is no longer where it should be and is either bulging out towards the nerves in the spinal canal or a fragment of disc has been pushed out completely into the spinal canal. The spinal discs are present at every level of the spine from C2-3 (cervical spine or neck) down to L5-S1 (lumbar spine or lower back). Thus, herniated discs can occur at any level of the spine but are most common in the cervical spine (neck) and in the lumbar spine (lower back), and less common in the thoracic spine (mid back).
What causes a disc herniation?
The cause of most disc herniations is unknown, in that most patients cannot recall a specific traumatic event such as a fall or an injury that resulted in a disc herniation. As discs begin to age the central soft portion of the disc (nucleus pulposus) begins to lose its water content and the tough outer portion of the disc (annulus fibrosis) begins to degenerate and can develop fissures. This leads to disc bulging which is a normal part of aging, but in certain cases the fissures in the annulus can allow the nucelus pulposus to herniate out resulting in a true disc herniation. Factors that accelerate the degenerative process also can increase the likelihood of a disc herniation such as smoking (nicotine itself and cigarette smoke are toxic to the spinal discs), being overweight (increases the stress on the spinal discs), or occupations with long amounts of sustained vibration (e.g. truck driving), among other causes. However, in most cases the cause of a herniated disc is multifactorial. Regardless of the precise cause, the end result is that the disc becomes injured by a force placed on it that the disc is not healthy enough to tolerate and absorb.
Herniated disc symptoms
Bulging discs or protruding discs themselves are very common and this naturally happens as the spine ages and these do not typically cause symptoms. Patients often associate their neck or back pain with their bulging discs but many patients with no pain at all would have bulging discs on an MRI. A new herniated disc, however, can indeed cause neck and back pain. Exactly how a new herniated disc causes pain is not fully understood, but it is believed that the pain symptoms of a herniated disc come from the injured disc itself and the pressure from the herniated disc pushing against the posterior longitudinal ligament (a ligament which separates the disc from the spinal canal where the spinal cord and nerves are). When a herniated disc goes into the spinal canal, it can cause compression and narrowing of the spinal canal or the channels for the nerves (spinal stenosis). The symptoms of a herniated disc in this situation often involves pain, numbness, or tingling running down the arm (disc herniation in the neck) or leg (disc herniation in the lower back). If the spinal cord is compressed by the herniated disc it can cause symptoms of myelopathy, which is difficulty with hand dexterity and coordination, and difficulty with balance and walking.
The other common symptoms associated with cervical disc herniation include:
- Increased pain with movement
- Burning, tingling or numbness
- Stiffness in hand or arm
- Improper balance and gait
- In rare cases, bowel and bladder dysfunction
How is a herniated disc diagnosed?
Herniated discs are initially suspected and diagnosed by a thorough history and physician exam with your primary care doctor, non-surgical spine specialist (physiatrist or pain management doctor), or with a spine surgeon. Patients that present with new onset radicular pain (pain traveling down the arm or down the leg in the distribution of a nerve root) are suspected of having a herniated disc, although these symptoms can also be caused by degenerative disc disease and spondylosis (age-related wear of the spine). X-rays of the spine are often obtained which can distinguish between these two entities, and can also reveal other structural abnormalities of the spine (fractures, kyphosis, scoliosis, etc). If symptoms have been present for more than 4-6 weeks and are not improving with conservative treatment or are associated with severe neurological symptoms (numbness, weakness), then an MRI scan is obtained for further workup and confirmation of the diagnosis.
The workup for a cervical disc herniation consists of the following steps:
- Medical history of the patient
- Physical and neurological examinations
- Testing of reflexes to evaluate muscle weakness, sensitivity, and other signs of neurological injury.
- Diagnostic imaging techniques such as X-rays, CT scan, and MRI scans are employed to confirm the location of the damaged cervical disc.
The simple X-ray helps in identifying the collapsed disc space, while CT and MRI scan helps to visualize the bone, disc, spinal cord, nerves, and other soft tissues.
How to treat a herniated disc?
Herniated disc treatment is entirely dependent on the symptoms the patient is having. Thankfully, most symptoms of a new disc herniation resolve with conservative treatment within 6-12 weeks. If the symptoms are primarily neck or back pain, with minimal or no arm or leg pain and no severe weakness or numbness attributable to the disc herniation, then the treatment is entirely non-surgical as surgery does not provide reliable neck or back pain relief. The initial treatments which helps ease herniated disc symptoms include physical therapy, anti-inflammatory medications (NSAIDS), and a regular low-impact exercise program. Non-traditional treatments such as yoga, acupuncture, and mindfulness exercises can also be very helpful. For patients that smoke, smoking cessation is critical to the treating the symptoms of a herniated disc as people that smoke are more likely to have a painful herniated disc than those patients that don’t smoke.
The common non-surgical treatment options include:
- Activity modification
- Medications such as anti-inflammatories and muscle relaxants
- Spinal injections
- Use of neck braces to support the cervical spine and relieve pain
- Physical therapy
Surgical treatment is recommended for patients who fail to respond to non-surgical treatment and in patients with associated spinal instability and neurological dysfunction. Sometimes spinal stabilization and fusion are employed to prevent further deterioration of the condition. Anterior cervical discectomy and fusion (ACDF), cervical disc replacement, or posterior cervical foraminotomy are the common procedures used to treat cervical disc herniations when they cause radiculopathy.
Surgical treatment is reserved for herniated discs that are causing severe arm or leg pain from a pinched nerve, or causing numbness, weakness, or other neurological symptoms because of spinal stenosis. Surgery for a herniated disc can often be performed in a minimally-invasive fashion. Lower back or lumbar disc herniations are typically treated with a microdiscectomy. Neck or cervical disc herniations are typically treated with a cervical disc replacement, anterior cervical discectomy and fusion, or a posterior cervical foraminotomy. The specific operation that may be recommended is dependent on many factors and is tailored to each individual patient’s needs.