There is reference in the literature regarding this problem. I seem to recall that this was addressed in an article in Spine Journal way back in the 1980's. One explanation is that it is a reflex response to the disc herniation and whether it is medial or lateral to the nerve root. In the old days..articles on the topic referred to this as "sciatic list". I believe that H. Duane Saunders covers the topic in his book on back pain. There was also an article on contralateral symptomatic SLR, the disc herniation being on one side of the body and painful SLR on the opposite side, and there was a biomechanical speculation re the behaviour of the dura. So that is the answer in haste.
Now, with respect to what I call a pelvic side-glide pattern. This can occur in the absence of dural and nerve root signs, with normal neural screen, normal tests etc. The pelvis is in a pattern of side glide which might be subtle but is easily detected with client supine and the clinician takes up the slack by pushing on the lateral portion of the pelvis with both open palms, goiing to the point of taking up the slack and then performing an additonal force to eval how it moves and recoils back to the first resistance point. It should move and recoil when approximately the same amount of force used to take up the slack is imparted again. I call this a "spring test". If restricted it can mimic several patterns of so-called sacroiliac joint dysfunction. I resolve it easily by passive stretch for 5 minutes at a time in side-lying over folded pillows-typically 2. If the motion restriction was to the left, the client lies with the left side on top. It typically resolves within 3 days performing the exercise 1 or 2x daily. You must make sure that the hip does not go into any flexion, slight extension is ideal. Pillow under the head is ideal. The bottom hip and knee can be flexed for comfort. I do not find the wall-stretch to be as effective (the iliotibial band stretch)One client had resolution of headache as the compensation was side bending at the occipito-atlantal region. Muscle testing before and after indicate inhibition of abductors on shortened side, release of that inhibition with stretch. Over time other inhibitions and compensations ads symptoms can manifest.
This is one of those patterns that is very rewarding to treat as results are rather quick and dramatic. It amazes me that this is not described in the literature except as a disc phenomenon (McKenzie method). I always evaluate for this pattern in my clients with axial pain.
Jerry Hesch, MHS, PT
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