In our last two blogs, we went over models that help explain how Dry Needling works. These two were the Radiculopathy and the Trigger Point Models. The topic of this blog will involve the third model, or the Spinal Segmental Sensitization and Pentad Model. As we have with the last two discussions, we will try to explain any difficult terminology or ideas.
Spinal Segmental Sensitization and Pentad Model
The Spinal Segmental Sensitization (SSS) and Pentad Model was proposed by the late Andrew Fischer, M.D. (Physiatrist…pain management and rehabilitation medical doctor). This is a good time to discuss this model as it really incorporates both of the first two models. Dr. Fischer proposed that the SSS is a ‘hyperactive’ state of the dorsal horn of the spinal cord that is caused by damaged tissue sending nociceptive (pain) input into the spinal cord. This information then causes the over-sensitivity of the associated spinal level dermatome (skin), pain sensitivity of the associated spinal level sclerotome (bone, ligaments, joints), and Myofascial Trigger Points (MTrPs) in the associated spinal level muscles. All this occurs because the nerve coming from the spine is over sensitized, and by being in this pathological state, it stimulates these changes listed above. In effect, we have a pretty vicious cycle of pain and dysfunction.
It is important to note that MTrPs in the spinal level associated musculature and tender spots in the supraspinous and interspinous ligaments of the spine of the associated level can lead to SSS due to their nociceptive bombardment. What matters most here is that the damaged tissue is bombarding the spinal cord (dorsal horn, in particular) with pain input. All of this pain and neurological irritation eventually trigger a response at the anterior horn of the spinal cord. The anterior horn is responsible for muscle function along the spinal level and when the anterior horn is sending out improper information to the muscle(s), MTrPs can form. (Think of it this way…information from the body goes into the dorsal horn of the spinal cord…it is then processed and information from the spinal cord out goes through the anterior horn) All of this leads to dysfunction and pain. With this model, like Gunn’s Radiculopathy Model, the spinal level problem affects the distal associated skin, muscles, and ligaments/joints.
So, what does this mean for treatment? Well, it means that treatment must be applied to the spinal area to shut off the stimuli from the supraspinous and interspinous ligaments so that the dorsal horn is not activated. There is no better way to get to spinal ligaments than with Dry Needling. If the dorsal horn gets activated, then there will be carryover to the anterior horn, and the body will be affected. With the SSS treatment approach, it is also okay to treat the MTrPs so that their afferent (going towards the spinal cord) stimuli is shut off. In effect, the entire vicious cycle must be stopped. This model is very big into identifying the spinal region of dysfunction as addressing the proximal problem should clear out the distal one(s).
It is clear to see that Dr. Fischer balanced the information from the Gunn and Travell models. He values the treatment of the peripheral problems, but treating the spinal location is of utmost importance. Dry Needling allows the trained practitioner to treat the spinal level of a problem as well as the distal problem. One of the main objectives of Dry Needling is to identify and destroy MTrPs. In addition, as per the SSS model, unless you administer a technique such as Dry Needling, it is virtually impossible to address the interspinous and supraspinous ligaments.
Fischer’s Pentad Model is really a set of 5 signs that go together to support the SSS. They are:
1. Supraspinous ligament sprain
2. Radicular involvement from the spinal level problem
3. Segmental paraspinal muscle spasm
4. Narrowed space between the spinous processes (the bumps that run up and down your spine from top to bottom…in-between each spinous process is where the interspinous and supraspinous ligaments reside)
5. Narrowed disc and IVF spaces that lead to additional stress that injures, or sprains, the interspinous and supraspinous ligaments
So, there you have it…the SSS and Pentad Model. Next time we’ll visit the fourth and final model that addresses how Dry Needling positively affects your body: the Central Model.