Piriformis and its role in sciatica

 

The effectiveness of treating trigger points in the buttock area is well known. In this short article, I wish to remind you of a biomechanical and muscular problem associated with the hip, and in the process prescribe an effective exercise treatment for the common problem of the piriformis syndrome as identified by Travell and Simons in their excellent Myofascial pain and dysfunction: the trigger point manual (here, volume 2, p. 186 ff.,1992).

Piriformis spasm and sciatica

Piriformis is an external hip rotator, acting with the adductors to facilitate walking and running, stabilising the femur in the sagittal plane so that the prime movers (gluteus maximus, quadriceps and the hamstring group) can propel the body over the legs. Less known about piriformis is that in about a fifth of the general population, one or both branches of the sciatic nerve pass directly through this muscle instead of passing between it and the one inferior to it, gemellus. Accordingly, this muscle can place sufficient pressure on the sciatic nerve to cause the familiar sciatica if it is in spasm. The unfortunate aspect of this for patients with sciatica is that if they demonstrate disc pathology the sciatica they suffer will normally be attributed to it­ and the possibility of misdiagnosis and ineffective treatment is high. This argument is developed in detail in my book Overcome Neck & Back Pain, 4th edition, Simon & Schuster, 2006, in the Causes of neck and back pain chapter, p. 225 ff.).

The oriental connection

From the oriental medical perspective, both the lung and large intestine meridien pass through piriformis as they run deeply through the body here and the small intestine and kidney meridiens pass above it (following Masunaga). We have found that deep elbow pressure (whether by shiatsu or deep tissue massage techniques) can be effective, if held statically for considerable periods (15-30 seconds). Static pressure is tolerated better by patients with this problem. Occasionally, patients can assist in the penetration of this pressure, by applying a gentle lifting pressure themselves to the leg being treated (for ten seconds or so), then being asked to relax and take a breath in; and you re-apply the shiatsu as they breath out, in a clinical use of the familiar Contract–Relax (C–R) technique. Be careful not to apply too much pressure; the piriformis syndrome when present renders this treatment area extremely sensitive to pressure, and the pain in the buttock can best be described as excruciating.

Necessity of stretching

Pressure alone is rarely effective in my experience. I have used the standard physiotherapy stretches (both solo and partner versions), but felt that they did not get into the area sufficiently deeply. The version presented by Travell and Simons is ineffective (the pressure the patient can apply to the iliac crest is insufficient to isolate the hip against the rotation applied to the knee for length of lever reasons; see vol. 2, p. 211, fig. 10.11). After much experimenting, I devised exercise 16 in my book, which is effective in most cases, and is offered in practitioner-applied and solo versions. If the patient lacks sufficient hip flexor suppleness to get into the starting position, then exercises 6–8 will also be effective. Note that either sciatica or simple hamstring tightness can make even the easiest of the floor versions difficult to use, in which case the table version (where the straight leg is folded at the knee over the edge of the table) can be used. One or a combination of these two exercises has proved effective.

Retest SLRT after stretching

And as I detail in the book, if your patient has been diagnosed with sciatica using the straight leg-lifting test, I suggest that you repeat the test for both legs, noting the point at which either the sciatica or the referred pain is elicited. Perform the partner version of either exercise 9 or 26 as appropriate, and re-test the straight leg-lifting test. In many cases the leg will pass straight though the previous stopping point, often testing 15 or 20 degrees better flexion at the hip­ without having stretched the hamstrings. If this is the case, suspect piriformis syndrome (this has proved to be the case in over 50 per cent of participants at the workshops I’ve been running around the country this year).

Consider context

Of course, the piriformis syndrome is not the only cause of sciatica, but you must suspect it if the sciatica has not responded to conventional treatment. Patients with this syndrome will often complain of pain after extended sitting, both in the buttocks and radiating down the affected leg. This problem is commonly associated with an actual leg-length difference (55% of the population have an actual leg-length difference of 5 mm or more; references to five studies provided in chapter eleven of my book), and following lifting accidents. It is often associated with pain in quadratus lumborum.

I hope this brief introduction can be used by you in the clinic, and I shall develop this and other themes in much greater detail in my practitioner workshops.

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