In this issue, I'd like to discuss piriformis syndrome, one of the more interesting conditions caused by spasm of a specific muscle. This syndrome is intriguing, not only from a functional standpoint, but also from an anatomical perspective. The piriformis muscle can cause pain when in spasm, like any other muscle. Things get complicated by its relationship to the sciatic nerve, which runs close to—or even through—the piriformis muscle and can be irritated or entrapped by muscle spasm.
Is it a herniated disc or piriformis syndrome?
Sciatic nerve entrapment can mimic lumbar disc herniation, complete with motor and sensory neurological deficits. The piriformis muscle should be examined in all cases of failed back surgery or, even better, before lumbar disc surgery is contemplated.
The piriformis muscle originates on the anterior aspect of the lower sacrum, crosses the sacroiliac joint and, through its tendon, attaches to the posterior aspect of the greater trochanter of the hip. Its mechanical importance arises from it being both an external rotator of the hip and a stabilizer of the sacroiliac joint.
The piriformis is particularly important during the gait cycle as it helps guide the lower sacrum through a complex rocking and rolling of the sacrum on moving axes between the innominate bones. The intricacy of pelvic ring mechanics is awe-inspiring (See Dr. Wolf Schamberger's excellent coverage of this topic in his book, The Malalignment Syndrome: Implications for Medicine and Sport.) It is therefore hardly surprising that things can go wrong with the piriformis.
Of all the muscles involved in moving the legs and stabilizing the pelvis, the piriformis seems to be one of the muscles that decompensates more commonly, perhaps because so much is asked of it.
The piriformis muscle is a "postural" muscle (according to Janda). It therefore tends to shorten when overloaded, becomes tighter, and develops trigger points. Piriformis muscle trigger points refer pain in specific patterns (See Travell and Simons' Myofascial Pain and Dysfunction:The Trigger Point Manual.)
How is piriformis muscle spasm treated?
There are a number of ways of treating piriformis muscle spasm: by manipulation, by digital massage of the muscle belly through the rectum, by spray and stretch technique or by various injection techniques. Piriformus muscle spasm generally responds well to treatment, leaving a gratified patient and a satisfied physician.
However, on occasion, the piriformis muscle can be unusually irritable and unresponsive to treatment. When this occurs, one must look beyond the muscle itself and ask why the muscle is behaving in this way.
Could an interference field be involved?
Other mechanical stresses on the pelvis, such as innominate or sacral shears, or on the lower extremity, such as fibular, ankle or feet somatic dysfunction, should be searched for and treated. However, if the tight piriformis persists, it may be that the sympathetic tone of the muscle, or even of the whole region, is increased. When this occurs, an interference field in the ipsilateral lumbar sympathetic ganglia is likely present.
Another clue pointing to an interference field "behind" the piriformis syndrome is a pain pattern extending beyond the referral pattern from piriformis trigger points and not explainable by sciatic nerve entrapment. Pain felt above the iliac crest should make one particularly suspicious.
Where does Neural Therapy come in?
Treatment of the interference field in the lumbar sympathetic ganglia is by injection of procaine as outlined on page 188 of my book, Neural Therapy: Applied Neurophysiology and Other Topics. Alternatively, treatment with a TensCam device (page 65 of the same book) is fast, safe and probably equally effective.
Interference fields in regional autonomic ganglia should always be considered when an interference field (or somatic dysfunction) is particularly painful or difficult to treat. Autonomic ganglion interference fields seem to develop when more than one interference field is present in the region the ganglion innervates or when the afferent neurological signals are particularly intense.
Robert F. Kidd, MD, CM
The Neural Therapy in Practice newsletter was intended as a complement to Dr. Kidd's book, Neural Therapy: Applied Neurophysiology and Other Topics, which is still available for sale through Amazon.