Wednesday, June 18, 2008

Blogging on Peer-Reviewed Research

Degenerative Disc Disease. For many of those that get an unnecessary MRI and get this diagnosis, it's often taken as a death sentence for a back instead of what it is - a normal process related to aging. Although pain can be associated with DDD, it is more often just a radiologic finding. Something that was most likely present before onset of spinal pain and will remain unchanged once the spinal pain recedes.

June's issue of the Journal of Orthopedic & Sports Physical Therapy (JOSPT) includes and excellent commentary on what we know and don't know regarding intervertebral disc degeneration. I would like to summarize some critical points I found in the article.

  • Although environmental factors play a role in the incidence and progression of DDD, the strongest predictors are genetically related. It is estimated that 74% of what causes DDD appears related to genetics.
  • Smoking and heavy labor have not been supported as etiologic factors in developing DDD. In fact, competitive weight lifters w/o trauma have a lower than expected rate of DDD.
  • Primary factor in DDD is reduction of the Intervertebral Disc's (IVD) nutritional capacity.
  • "...age-related changes that occur in the composition of the IVD are similar to those observed in articular cartilage and are not necessarily related to pain."
  • Vertebral endplate disruptions are being shown to have a strong relationship with DDD.
  • Although similar in appearance, there are measurable differences in the diffusion capacity at the vertebral endplate of those IVD's with age-related disc degeneration and symptomatic degnerative discs. This may suggest that aging and degeneration are 2 separate processes.
  • "High-Intensity Zones" represented by high intensity T2 signals near the outer margins of the annulus are correlated to pain production with discography (IMO, discography is often painful regardless of pathology) but also commonly found in asymptomatic individuals. This leads to poor specificity and the authors suggest it should not be used in isolation to make clinical decisions.
  • The body's attempt to heal annular tears may lead to increasing the area of the disc that is innervated which is further increased by inflammatory byproducts which can lower the threshold needed to trigger pain. The result could be increased sensitivity to otherwise innocuous stimuli. This includes those from just standing and/or walking.
  • Even if MRI shows a dramatic disc bulge, this finding is very often not associated with symptoms.
  • When nuclear material breaks free and migrates into the vertebral foramen, ipsilateral pain and parasthesia may occur. This results from the chemical response to the nuclear material touching the dorsal root ganglion and not from "pinching" the nerve.
The authors then make some comments on clinical relevance. Here are a few that will lead to a change in the way I treat on Monday:
  • Patients with later stage DDD - decreased disc height and hydrostatic nucleus lost - care should be taken during loading progressions, avoiding sustained loading at end range trunk motions.
  • Symptoms often occur several hours after trauma to the degenerated disc (DD). Thus, exercise in the gym may go well but in the morning the patient may be too painful to even get out of bed.
  • Studies have found favorable outcome in treating DDD with lumbar stabilization exercises.
  • It was found that patients with DD who avoided early morning lumbar flexion had significantly less pain and disability then did those who performed lumbar flexibility exercises early in the morning.
  • Patients with DD should be encouraged to avoid prolonged flexed compressive forces such as sitting in flexed position.
  • Hip ROM limitation can have large effects on loads acting on the lumbar spine.
  • The authors make it a point to illustrate the important role the psychological effect that the diagnosis of "degenerative disc disease" has on the patient. they state:
    • " is important that clinicians carefully communicate with patients to reassure them that DD is a normal aging process; while it certainly can be associated with episodes of pain, only in rare exceptions do these symptoms represent serious disease, and they should not, therefore, prevent one from performing reasonable activities."
It's important to remember the fact DD is related to normal aging. And, thus, it's main treatment should most likely be non-invasive conservative care. And, as I always say, PT's are the experts in this area and well positioned to give the more efficacious care.

Jason L. Harris

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