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Friday, November 8, 2013

Patient Information: Lumbar (low back) Degenerative Disc Disease with Color X-Ray and MRI Images - Part I

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            What is Lumbar (low back) Degenerative Disc Disease?


Degenerative Disc Disease (DDD) is the result of wear and tear on the spine over time. Gravity, motion and weight-bearing combine to take a toll on the spine. While the development of DDD is normal and expected, some patients will develop this process earlier in life or to an extent beyond what would be expected.
 
 
This illustration shows how spinal discs undergo degeneration. A healthy spine is shown on the left. The discs are tall. The center image shows early inflammation of the discs. The image of the right shows severely degenerated discs where the spine is fusing. Bone is actually replacing the discs and the motion is lost.
 
 
At what age do patients get Lumbar Degenerative Disc Disease?
 
Some patients have signs of DDD as early as their 20’s whereas it would usually not be expected until they reach their 30’s or 40’s. Similarly, some patients have 3 degenerated discs in their 40’s, whereas widespread DDD like this would not be expected until their 70’s.
 
 Do all patients with Lumbar Degenerative Disc Disease have pain? 
It is important to know that just because someone has signs of DDD on an X-Ray, does not mean they have to have pain. Studies have shown that up to 1/3rd of patients in their 40’s will have some signs of DDD on an MRI, yet only a small fraction of them will complain of any symptoms. Overall, 25% of the population under the age of 40 who do not have symptoms, have evidence of degenerative disc disease on an MRI scan. 60% of the population over the age of 40 who do not have symptoms, have findings of degenerative disc disease on an MRI scan.
 How does a Lumbar Disc Degenerate?
At birth our disc contains 80% water. The water content of the disc can be a measure of its ability to function appropriately as a shock absorber. Starting in our 3rd decade of life, we begin to lose some of this water content. Also, some of the important proteins which make up the core of the disc (nucleus) diminish. They are often replaced by collagen (a tough fiber) which does not attract much water to the disc. As a result, the disc gets progressively harder in nature, and subsequently loses its function as a shock absorber. Another consequence of this process is the loss of the height of the disc. This is one of the reasons why we lose height as we age.
At the same time, the disc’s outer ring (annulus fibrosus) becomes more brittle and less elastic. It can develop cracks and begin to bulge outward potentially causing spinal stenosis.

                               Do Degenerated Discs Cause Bone Spurs?
 
                                                                            Copyright Medical Media Images
                              
This image is a MRI scan of the low-back (lumbar spine) which shows the spine from the side. The front of the spine is to the left. A disc has undergone the process of severe disc degeneration. Bone spurs can be seen at the front and the back of this disc.

When a disc degenerates and gets harder, the top and bottom sides (endplates) of the respective vertebrae above and below the diseased disc encounter more resistance. Rather than pushing against a soft shock absorber they begin to grind against a harder material. Eventually this can lead to bone spurs which develop as a result of bone coming into contact with hard material. This stimulates bone growth, which grows bone spurs. Depending on their location, these bone spurs can cause irritation or compression of spinal nerves or the spinal cord.


 
Does Lumbar Disc Degeneration cause joint pain as well?
When a disc loses its height and function, the facet joints in the back of the spine are often also affected.
Each spinal segment consists of two vertebrae with a disc in between them and two facet joints in the back of the spine. Since the disc has motion, it can be thought of as a joint as well. In essence then, the disc and the two facet joints form a triangle, each representing a mobile joint.
As a consequence, degeneration and loss of height at the “disc joint” will have an effect on the facet joints. Specifically, as the disc loses height, more and more weight is transferred from the “disc joint” to the facet joints. This causes significant stress over time and often results in degeneration of the facet joints.
 
 

 
Who is at risk for developing Lumbar Degenerative Disc Disease?
The following are people at risk for developing DDD:
1.     Smokers
2.     People exposed to significant vibration such as driving a vehicle for a living.
3.     Genetics. DDD tends to run in families through genes passed from one generation to the next.
4.     Patients with a history of spine trauma.
5.     Patients of advanced age.
6.     Patients with obesity.


   What symptoms do patients with Lumbar Degenerative Disc Disease have?
Symptoms from DDD can vary depending on the degree of DDD and which other structures are affected by it. Classically, DDD is felt as pain the center of the spine. It often radiates to the sides of the spine. This pain is often worse with physical activities and while remaining in one position for longer periods of time. It may also be accompanied by a sensation of stiffness in the spine. Resting the spine often improves the symptoms. Symptoms of DDD typically slowly worsen over time, but can also level off at some point.
When a disc loses height during the process of degeneration, the spinal nerve can be compressed causing leg pain.
Here again are the common symptoms of Lumbar Degenerative Disc Disease:
                                                                                                                                                  i.            Low-back pain
                                                                                                                                                ii.            Low-back muscle spasms
                                                                                                                                              iii.            Loss of spine mobility
                                                                                                                                             iv.            Low-back stiffness
 
 
 
Our next Blog will Discuss the Diagnosis and Treatment of Lumbar Degenerative Disc Disease. So, stay tuned!
 




 
 
 

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