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MYOFASCIAL TECHNIQUES AXIAL SCIATICA ALSO KNOWN AS... ENTRAPMENT SITE ENTRAPMENT MECHANISM LOW-BACK PAIN POSTERIOR THIGH AND/OR BUTTOCK PAIN PAIN DISTAL TO KNEE TYPE I, "TRUE SCIATICA" NERVE ROOTS BONE-TO-BONE OR DISC-TO-BONE COMPRESSION USUALLY PRESENT USUALLY PRESENT USUALLY ABSENT APPENDICULAR SCIATICA TYPE II, PSEUDOSCIATICA, PIRIFORMIS SYNDROME, ETC. DISTAL TO NERVE ROOTS MYOFASCIAL DENSITY OR NEUROFASCIAL TETHERING USUALLY ABSENT USUALLY PRESENT SOMETIMES PRESENT Table 1: Types of Sciatic Pain. In addition to the mechanisms of entrapment listed above, infection, tumors, and direct trauma either at the nerve roots or distally can also cause nerve entrapment and sciatic symptoms. • Postural or positional issues, including the postural strain of late pregnancy, sacral instability, or spondylolisthesis (instability and anterior shift of a vertebra on the one below it, narrowing their intervertebral foramen). • Articular disc degeneration, herniation, or bulging into the foraminal space. • Stenosis (boney deposits in the foramen or spinal canal). These mechanisms involve compression of the nerve roots between adjacent vertebrae (bone-to-bone compression), or between a disc and vertebra (disc-to-bone). There are also reports of small accessory muscles being found within the foramen parallel to the nerves,3 as well as dural tube adhesions at the nerve roots, either of which could conceivably cause axial sciatic pain. Infections, tumors, cancer, or trauma at the nerve roots (or elsewhere along the nerve) can also cause sciatic pain, and are reasons why referral to a specialist is prudent when sciatic pain is persistent, unresponsive, or severe. Axial sciatica will show one or more of these signs: • Pain in the low back along with buttock or thigh pain, usually without pain below the knee (unless there are also appendicular contributors).4 • Sciatic scoliosis: a reluctance to put weight on affected side, resulting in leaning away from affected side in order to minimize pain. • A positive (i.e., painful) result when performing the Straight Leg Test. STRAIGHT LEG TEST The Straight Leg Test (SLT), or the Lasègue Test, is a common and reliable assessment for identifying lumbar nerve root compression. With your client seated at the front edge of a chair, ask him or her to raise a straightened leg at the hip (with the knee extended straight). The straight leg test is positive (meaning that it indicates likely nerve root compression) if sciatic pain is reproduced with the motions listed in the caption of Image 3. Pain in the opposite (supporting) leg can be due to more severe disc herniation, and is clear cause for referral. Why does ankle dorsiflexion, slumping, or neck flexion increase the pain when a nerve root is compressed? All three of these movements stretch 112 massage & bodywork july/august 2011 the nerve tissues further, putting a little more tension on any entrapment. Slumping and neck flexion also pull upward (caudally) on the dural tube within the spinal canal. The dural tubes' projections surround the nerve roots and line each foramen (Image 2), so restrictions here can be a cause of axial sciatic pain. If this is the case, the slump test itself can be a helpful self-treatment, gently stretching the dural adhesions. However, clients should be instructed not to over- do the stretching, or do too many repetitions, so as to avoid aggravating the already inflamed nerve roots. When performed and interpreted correctly, the SLT has a high statistical sensitivity (91 percent of correct positive results), and a lower statistical specificity (26 percent of correct negative results).5 In other words, the SLT is quite reliable at assessing compression of sciatic nerve roots (on average, 9 out of 10 positive results will accurately indicate nerve root involvement). But the SLT is a less reliable at determining that there is not compression at the roots