Vertebra is the individual bone that makes up the spine. It is made up of several parts. The body is toward the front – this is the primary area of weight bearing and is where the disc rests. The lamina covers the spinal canal, which is the large hole in the center of the vertebra where the spinal cord comes through. The spinous process is the bump you feel when running your hands down your back. There is a transverse process on each side, this is where the back muscles attach.
Spinal Stenosis occurs when the spinal canal narrows and presses on the spinal cord and/or the exiting nerve roots. It can occur anywhere in the spine. Central canal stenosis is when the channel that the spinal cord passes through narrows. Foraminal stenosis is a narrowing of the channel on either side of the vertebra where the spinal nerve roots exit on their way to the body (ie. down the arms or legs). Cervical spinal stenosis can result in neck pain that may radiate into the shoulders, arms, wrists, and hands. Lumbar spinal stenosis results in low back pain that can radiate down the nerves into the hips, legs, thighs, feet or buttocks.
This describes the anterior (forward) displacement of a vertebra in relation to the vertebrae below. Spondylolithesis often contributes to spinal stenosis. Most commonly, its severity is graded using a lateral x-ray. The measurements of the distance from the posterior (back) edge of the superior (above) vertebral body to the posterior edge of the adjacent inferior (below) vertebral body is reported as a percentage of the total superior vertebral body length: Grade I is 0-25%, Grade II is 25-50%, Grade III is 50-75%, Grade IV is 75-100% . Fredrickson, et al. demonstrated that the spondylolytic defect is usually acquired between the ages of 6 and 16 years, and that the slip often occurs shortly thereafter. Once the slip has occurred it rarely continues to progress. It may or may not be symptomatic, but it is significant because abnormal biomechanical stresses cause a greater likelihood of disc degeneration and associated osteoarthritic changes at this level.
Degenerative Disc Disease
Degenerative Disc Disease (DDD) is not really a “disease,” but rather a term used to describe a condition that develops gradually and worsens over time. DDD indicates that the discs in the spine are the primary cause of the symptoms, and that the degenerative changes are advanced. To some degree intervertebral discs lose their flexibility, elasticity, and shock absorbing characteristics as we age. Abnormal or excessive mechanical stresses/injuries of the past coupled with hereditary, developmental, and metabolic influences can rapidly accelerate this process.
As the involved disc dries out and loses height, it causes the vertebra to become closer together which narrows the holes through which the nerve roots pass. A dry, hard disc can absorb less shock and is more easily torn. This results in a greater likelihood of herniation or bulge which further compresses or pinches the nerves.
Degenerative Joint Disease / Osteoarthritis (OA)
Osteoarthritis (OA) is also known as degenerative arthritis or Degenerative Joint Disease (DJD). In the spine, it usually means that multiple osteoarthritic changes are found in several areas. Any joint in the body can be exposed to abnormal or excessive mechanical stress or injury, however, the weight bearing joints of the spine, hip, and knee are the most common.
Factors that can contribute to the development of OA are: old injuries, poor health habits, a weakened immune system, and/or hereditary factors. Osteoarthritis is not a disease in the sense that a patient can “catch it”, but is the body’s natural response to abnormal or excessive mechanical stress over time coupled with hereditary, developmental, and metabolic influences. It is not necessarily a disease of the old because many younger people can have abnormal or excessive mechanical stress too, and not all older people do.
Osteoarthritis is the most common form of arthritis and the leading cause of chronic disability in the United States. As the stress continues and accelerates the joints may lose normal contour and abnormal amounts of fluid may build up inside the joint along with pieces of floating debris. Early on, a patient may only experience joint aches after physical work or exercise, which fades and then returns as the affected joint is used or overused. As the cartilage between the bones gradually thins, the patient increasingly experiences pain upon weight bearing, including walking, standing, and sitting as well as many other movements in between.
As a result of the patients attempt to avoid certain movements because of the pain, regional muscles may atrophy and ligaments may become more lax while other muscles may spasm in an attempt to limit the abnormal motion and reduce the pain, all resulting in further stress to the involved joints thereby accelerating and worsening the process. Now, the joint pain and stiffness occurs after periods of inactivity such as while sitting for long car rides or watching a long movie. Later, the pain often becomes substantial even at complete rest or with very little movement. This is the degenerative cycle in action – where everything makes everything else worse in an accelerating downward spiral of pain and disability.
An Osteophyte is often called a bone spur. This describes osteoarthritic changes that are a projection of bone that grows along the edges of joints at the attachment points for ligaments and tendons. The evidence of bone spurs can be found on an x-ray. These are frequently found on the edges of vertebral bodies where the spinal disc attaches to the bone (end plate of the vertebra). The body produces osteophytes to try to stop the motion of the arthritic joint and deal with the degenerative process. It never completely works. Hips, knees, and the joints of the fingers are other common locations in which to find these bone spurs.
Spondylosis is referring to the osteoarthritic changes of multiple spinal vertebra at the level of the discs. If severe, it may cause pressure on nerve roots which then causes pain, parasthesia, or muscle weakness in the limbs. Use of this term indicates that the facet joints at the back of the vertebrae are not necessarily involved.
Hypertrophy means a thickening or overgrowth of the ligaments which help hold the spinal bones together. Tissue responds to biomechanical stress through hypertrophy (an increase in the size of cells) or hyperplasia (an increase in the number of cells). As an example, excessive or prolonged stress to the skin of the hands or feet results in a hypertrophy of the skin known as callous formation. Spinal ligaments, specially the ligamentum flavum along the posterior aspect of the spinal canal, respond to stress by thickening in the same way. The problem with this is that there is little ”extra” room along the spinal canal. If one tissue is thicker than it should be another is being compressed or pinched.
Sclerosis to describes areas of increased density or whiteness found on X-ray or MRI examination. This is indicative of a calcium buildup in areas of excessive stress to form osteoarthritic bone. This depicts an early stage of osteoarthritis and with continued stress will eventually become osteophytes (bone spurs).
A pinched nerve occurs when too much pressure is applied for too long to a nerve by surrounding tissues. Tissues that can cause the pressure can be bones, cartilage, muscles, tendons, ligaments, spinal discs or (rarely) tumor. The most common reasons for the direct physical pressure are as a result of the changes occurring with degenerative joint disease or degenerative disc disease. Nerve pain resulting from direct physical pressure is called an entrapment neuropathy because the nerve is trapped or pinched by some structure. This term helps to distinguish them from neuropathies resulting from infection or disease.
A good example of this concept is when you “bump your funny bone” (which is actually the ulnar nerve). This physical pressure disrupts the nerve’s function causing pain, tingling, numbness or weakness. Too much pressure applied for too long to a nerve along the spine results in much the same sensations.
Neuritis / Neuralgia
Neuritis describes nerve inflammation while neuralgia describes nerve pain. The most common cause of neuritis or neuralgia for those suffering from arm pain or leg pain is direct physical pressure as a result of the changes occurring with degenerative disc disease (DDD) and/or degenerative joint disease (DJD).
The pain may radiate anywhere along the course of the nerve and is most often described as a burning, stabbing, or shooting pain from the neck into the shoulder, arm, elbow, wrist, or hand. If the nerve originates in the lower back the pain radiates into the buttock, hip, thigh, leg, or foot.
Paresthesia is when there is involvement of the sensory nerves described as numbness or tingling, but not really pain, and with no motor or muscle weakness. In the medical community neuritis / neuralgia / paresthesia are often used interchangeably without clear distinction and simply mean that the nerve is irritated and causing symptoms. The symptoms often include actual pain, but may be limited to numbness, tingling, burning, stinging, prickling, pins and needles, skin crawling, or itching.
Radiculitis / Radiculopathy
These are not specific conditions, but describe a nerve that is being pinched at or very near the spinal cord at the beginning (root) of the nerve. The most common cause of radiculitis/radiculopathy is a herniated or protruding spinal disc that results in pain at that area of the neck or back. The most severe symptoms may be noticed along the course of the adjacent nerve root resulting in arm pain or leg pain through. This process is called referred pain or radicular pain.
Sciatica / Sciatic Neuritis / Sciatic Nerve Pain / Leg Pain
Sciatica (or Sciatic Neuritis) is caused by compression and/or irritation of one of five nerve roots that exit the lumbar spine that join together to form the sciatic nerve. This nerve runs through the buttock muscles, past the hip joint, into the thigh, past the knee, down into the calf, ankle, and foot to the toes. Sciatica is usually caused by the compression of lumbar nerve roots L4 or L5 or S1, but sometimes sacral nerve roots S2 or S3. The symptoms are felt in the lower back, buttock, hip and/or various parts of the leg and foot. In addition to pain, which is sometimes severe, there may be numbness, muscular weakness, tingling, and difficulty in supporting weight on the affected leg.
Sciatica is a set of symptoms, rather than a diagnosis, for what is irritating the root of the nerve causing the pain. The most common causes of sciatica are degenerative disc disease or degenerative joint disease. It may also be caused by pregnancy or nerve entrapment.
In approximately 15% of the population, the sciatic nerve runs through the piriformis muscle rather than beneath it. When the muscle shortens or spasms due to trauma or overuse, it can compress or pinch the sciatic nerve beneath the muscle. This can be referred to as entrapment neuropathy. Piriformis Syndrome is often the major cause of sciatica when the nerve root is normal.
Herniated discs occur when the spinal disc becomes less elastic. When the disc ruptures, a portion of the spinal disc pushes outside its normal boundary–this is called a herniated disc. When a herniated disc bulges out from between the vertebrae, the spinal nerves and spinal cord can become pinched. There is normally a little extra space around the spinal cord and spinal nerves, but if enough of the herniated disc is pushed out of place, then these structures may be compressed. Symptoms are due to the irritation of the nerve from the herniated disc. Because of the nerve irritation, signals from the brain may be interrupted causing muscle weakness. Nerve irritation can also be tested by examining reflexes. Bowel or Bladder Problems are very important symptoms because it may be a sign of cauda equina syndrome, which is a possible condition that can result from a herniated disc. (*This is a medical emergency, and your should see your doctor immediately if you have problems urinating, having bowel movements, or if you have numbness around your genitals).
Inflammation is characterized by redness and heat due to increased blood flow to the inflamed site; swelling caused by accumulation of fluid; and pain due to release of chemicals involved in the repair process that irritate nerve endings. If your body did not produce inflammation when injured, the damaged cells would never heal and progressive destruction of the tissue would continue.