WHAT IS A SPINAL DISC?
The spine provides axis to the whole body and the anatomy of the spine includes strong bones, flexible ligaments and tendons, large muscles and sensitive nerves. The most notable feature of the spine is the vertebral column or the spinal column. It is made up of block-shaped bones called vertebrae that typically total 33 at birth but later become 26 bones because some of the lower vertebrae fuse to form the sacrum and the coccyx or the tailbone.
The spine is connected to the head, shoulders, ribs and the hips. Each vertebra, except the first and second cervical vertebrae, is separated by an inter-vertebral disc. These discs are made of a tough fibro- cartilaginous material with elastic capabilities. These discs act as shock absorbers between the vertebrae and protect the bones from the adverse impact of jumping from heights, tough sports and certain forms of exercise. The spine derives its stability and inherent mobility from these discs.
Each disc has 2 parts:
- The inner coreIt is the jelly like soft inner core (nucleus pulposus). Its sponge like quality is provided by the water which forms about 80% of its total content. This soft structure provides it the ability to absorb spinal stress.
- An outer layerThe inner core is enclosed by the tough fibrous covering (annulus fibrosis) of the disc.
WHAT IS INTER-VERTEBRAL DISC DISEASE?
Inter-Vertebral disc disease is not a disease pre se but a medical condition because one or more discs have slipped out in part or as a whole from their respective location in the spinal column. The portion of the disc extending out of the normal alignment impinges upon the nerve root and causes pain. The condition could be attributed to damage and wear and tear to the intervertebral disc due to old age or other causes.
Due to the degenerative changes, the spinal discs become anatomically altered after losing water content and become thinner. The outer layer of the spinal disc may tear, resulting in expulsion of the contents of the inner core of the disc through the outer covering, a condition known as a herniated disc. These protrusions may press on nerves, causing pain in the back and leg that can range from mild to excruciating.
Although patients with degenerative disc disease will find that their discs continue to degenerate over time, most do not experience a corresponding increase in pain.
HOW DOES A HERNIATED DISC CAUSE BACK PAIN?
Degenerative disc disease occurs when wear and tear on the inter-vertebral discs between the bones (vertebra) in the spinal column cause deterioration that eventually results in pain. It is caused by old age and is among the most common sources of back pain in people who are middle-aged or older.
As one grows older inter-vertebral discs or spinal discs suffer from damage. These discs stabilize spine by providing flexibility and provide cushioning effect by acting as shock absorbers.
Due to old age, usually the spinal discs slowly become flat, deteriorate, lose water content and acquire a thin and brittle texture. These deteriorative changes make the discs render them vulnerable to the condition called degenerative disc disease.
Generally the outer layer of the disc develops a tear. The contents of the inner core may burst / leak out through the tear. This condition of the disc is called herniated disc. The disc matter protruding out may, sometimes, press on the nerves emanating from the spine and cause pain. This pain could ne in the leg or the back and could range from mild to severely excruciating.
The symptoms of degenerative disc disease may appear over a long time in several phases spread over a decade or more. In initial stages the severity of the back pain may render normal movements very difficult. Subsequently, the area becomes inflamed and the pain may sometimes disappear completely and again come back. Eventually, the condition stabilizes since the disc loses the protein substances that initially caused the pain, inflammation and discomfort.
WHY DO THE DEGENERATIVE CHANGES OCCUR IN THE DISCS?
These changes are caused by aging. Everyday, right from morning, the spine supports the body weight of an individual. The effect of resultant daily stress and minor wear and tear and un-noticed injuries gets accumulated over time and brings about structural changes in the discs. The primary role of the discs is to absorb these very stresses and protect the bones from injury.
The annulus or the outer part of the disc is the first to get damaged. Tears may appear on the annulus due to excessive pressure or injury. The natural healing process of the body creates scar tissue formation to repair the tears. Repeated tears and scar tissues formation greatly reduces the original strength of the annulus, making it vulnerable. This may result in damage to the inner core or nucleus pulposus and water content of the core is lost. This weakens the disc further and the proteins contained in the inner core may leak out. This inflames the nerves and cause pain and other symptoms.
Repeated wear and tear may accumulate to the point that the discs begin to deteriorate. Over time, spinal discs usually begin to flatten, lose water content, thin out and become more brittle. In addition, injuries and wear and tear suffered during sports or other strenuous activities can sometimes lead to disc damage.
WHAT SIGNS AND SYMPTOMS APPEAR FOR DEGENERATIVE DISC DISEASE?
Pain is the main symptom associated with degenerative disc disease. This pain tends to be concentrated in the lower buttocks and upper back. Pain that radiates down into the leg or foot is usually minimal. Depending on the location of the injured disc, neck pain may also occur.
The pain begins slowly and gradually but increases with prolonged sitting or standing. The pressure load on the inter-vertebral discs is around 3 times while sitting as compared to standing. The pain, thus, is more severe while sitting and relief may be felt while standing upright, moving about, walking or lying in fetal position. Any movement with bending, twisting or lifting makes the pain worse.
Pain caused by degenerative disc disease may range from mild to severe. Also, the pain may not be felt always but may come and go. The pain may disappear for sometime and reappear for a few days to a few months. Damage to nerves caused by the damaged discs may result in weakness in the leg muscles or foot.
HOW IS DEGENERATIVE DISC DISEASE DIAGNOSED?
As with any other disease the physician starts the diagnostic process by recording the medical history of the patient with specific details about back pain being sought. The patient may be asked:
- The period since the pain is felt- days / months etc.
- What circumstances cause the pain to increase?
- Any family history of back pain?
- Any other disease that the patient is suffering from or taking medication for?
- Physical Examination-A physical examination follows and the extent of limb movement and the resultant pain is noted and pain assessment is carried out.
- Imaging tests- the condition of the discs is also assessed by some imaging tests like:
- X-rayThe radioactive rays are used to record the images of the spine. The images help in assessing any decrease in the space between the bones (veetebrae), bone spurs, hardening (sclerosis) of the nerve bundles, hypertrophy (enlargement) of the vertebral facets or articulating joints between vertebrae and any instability during flexion / bending or extension / straightening of the limbs.
- DiscographyIt is an x-ray examination after a contrast media (dye) has been injected in to the disc with a small needle under guidance with fluoroscopy (a real time x-ray technique). The pressure of the contrast medium injected in to the disc will reproduce the pain if the same was due to a damaged disc.
- CAT Scan (computed axial tomography) Multiple images taken from different angles to create 3 dimensional images of the disc to assess the damage to the discs, identify tumors, herniated discs or any other condition pressing on the nerves.
- MyelogramContrast media is injected into the spinal canal prior to the CAT scan to identify the precise spinal anatomy and dysfunction.
- MRI (magnetic resonance imaging)Magnetic waves are used in this non-invasive test to create computer generated images to identify any abnormalities in the soft tissues (nerves or ligaments) surrounding the spine. MRI images also help in identifying any loss of water in a disc, facet joint hypertrophy, stenosis or narrowing of the spinal canal or a herniated disc.
WHAT TREATMENT OPTIONS ARE AVAILABLE FOR DEGENERATIVE DISC DISEASE?
Degenerative disc condition can be treated without any surgery in most cases. Non-surgical techniques available are:
- PhysiotherapyIt has many benefits in improving posture, strengthening muscles of the back and abdomen – muscles supporting the back- and improving flexibility. The increased strength of the spinal muscles reduces pressure on the inter-vertebral discs.
- Regular physical activityRegular exercise strengthens the muscles of the back, reduces strain on the back by strengthening muscles of the abdomen, arms and legs and reduces the risk of muscle spasms. Weight-bearing exercises help in preventing the loss of bone mass due to osteoporosis and reduce the risk of compression fractures. Release of endorphins, a natural chemical in the body for combating pain is enhanced by aerobic exercise.
- Use of physical agentsThermotherapy, hydrotherapy, cryotherapy or electrical therapy uses certain agents for relieving pain and inflammation. These also improve the body range of motion and function. It is necessary to consult a physician before trying these.
- Rest and recuperationActivities like twisting, jumping, prolonged sitting and rotating movement may worsen pain. Pain is severe initially and may improve after a few days rest. Prolonged rest on the other hand weakens back muscles and causes further deterioration of the conditions.
- OTC drugsOver the counter anti- inflammation drugs, non-steroidal anti-inflammatory drugs (NSAIDs) help in relieving both pain and inflammation. In more sever cases epidural steroid injection may be provided under x-ray guidance in to the epidural space. This involves injecting corticosteroids at an interval of 1 month for 3 months. The injections, administered in to the area around the spinal nerves quick relief from inflammation.
- Other medicationsDrugs that may help relieve pain brought on by degenerative disc disease include:
- AnticonvulsantsThese drugs generally used to treat seizures are also used for treating pain caused by herniated discs. Anticonvulsants are prescribed in combination with analgesics (pain relievers).
- AntidepressantsSome of these can relieve pain and assist with sleep.It is essential to consult a physician before taking any medicine. Medicines provide effective relief from pain and inflammation but can not stop the degenerative changes caused by this disease.
- SurgerySpinal surgery may also be advised in certain cases to treat degenerative disc disease. Spinal fusion is carried out by joining 2 or more vertebrae to improve stability, correct a deformity and treat pain. The affected disc may be removed and some extra pieces of bone may be fused to fill and gaps / space between the vertebrae.
Spinal fusion eliminates some spinal flexibility, which can be beneficial if movement between spinal segments is the source of a patient’s pain.
Other surgical options may include:
1. Disc replacement- An artificial inter-vertebral disc may be inserted to treat degenerative disc disease.
- Intra Discal Electro Thermal Therapy (IDET)The inter-vertebral disc is heated to make it stiff. The heat is provided through the medium of a wire inserted in to the are
- ForaminotomyThe foramen, or the bony hole in the spine, is enlarged to provide relief to the nerve root being pinched due to any condition.
WHAT PREVENTIVE STEPS CAN BE TAKEN TO PREVENT DEGENERATIVE DISEASE?
Disc disease is condition that is caused by old age and other factors. Many of the cause are controllable and some steps taken in time can prevent the onset of this disease or improve the condition. Some of thee could be:
- Proper posture and ergonomicsGood posture relieves pressure on the back. Reduced spinal curvature helps the spine in supporting body weight efficiently. Some steps for correct ergonomics could be:
- Regular exercisePressure on the back and inter-vertebral discs can be reduced to a great extent by strengthening the back and abdominal muscles. Stretching and strength training exercises planned to develop these muscles help in preventing degenerative changes in the discs. The exercise regimen should be planed in consultation with the physician.
- When standing for long periods of time, put one foot on a stool or box to relieve pressure on the back.
- When sitting for long periods of time, put feet on a stool so knees are higher than hips and get up and walk around periodically.
- Maintain proper body weight. Excessive body weight can increase the load on the lower back, and also increase the risk of a herniated disc.
- Do not wear high-heeled shoes.
- Do not sleep on the stomach.
- When lifting heavy weights, bend the knees and hips and keep the back straight.
- Hold objects close to the body while carrying them.
What is artificial disc replacement?
Degenerative disc disease may cause total or irreversible damage to a disc or the disc may be damaged due to trauma / injury. In such situations the disc needs to be removed. The options available after removal of the inter-vertebral disc are not many and fusion of the two vertebrae is carried out. Fusion, however, cause some amount of mobility and flexibility loss. Replacement of the damaged disc by an artificial disc is the other option available in such cases.
The procedure involves removing the damaged disc and the new artificial inserted. This artificial disc is made of metal and plastic and its size is about the size of a quarter coins.
It is believed that ideal candidates for this surgery have the following characteristics:
- Between 20 and 60 years old
- Have just one degenerating disc
- Do not have a systemic bone disease, such as osteoporosis
- Have tried other non-surgical treatments without success
So far, studies indicate that patients who have this surgery recover more quickly and have fewer complications than patients who have more traditional forms of surgery.
Other prostheses are also being developed, including some that replace only a disc’s inner core or the nucleus pulposus. Attempts towards tissue engineering and regeneration are also being made.