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Piriformis syndrome has been described as an abnormal condition of the piriformis muscle characterized by signs and symptoms due to sciatic nerve entrapment at the greater sciatic notch. This syndrome is a rare and disputed entity; its valid diagnosis has become less common and generally is considered only after other causes of sciatica have been excluded.
It is well-known that there are anatomical variations in the relationship between the sciatic nerve and the piriformis muscle. Some authors have ascribed a causative factor in piriformis syndrome to these abnormal anatomical conditions with surgical exposure.1,2
This article reports a case of piriformis syndrome with an uncommon anomalous relationship between the sciatic nerve and piriformis muscle.
CASE REPORT
A 22-year-old woman presented in November 1994 with low back pain of 1 week's duration. The pain radiated down the right leg to the lateral aspect of the foot and was particularly aggravated by forward bending.
On examination, deep tendon reflexes were normal bilaterally. The patient reported muscle weakness in the right great toe extensors. There was no gross muscle atrophy of the lower extremities. Straight-leg-raising test was positive at 70°. Hypoesthesia and numbness were noted at the distribution of the Si nerve root
A myelogram revealed minimal anterior indentation of the dura mater at the L5-S1 level, and a diskogram showed mild posterior protrusion of the contrast material without pain provocation (Fig 1).
A right Sl nerve root block with betamethasone provided transient symptom relief. Based on the clinical findings and the patient's desire for a rapid recovery from her discomfort, in December 1 994, nucleotomy was carried out by hermTaminectomy of the right side of the L5 lamina, and a mild disk protrusion was found.
After surgery, her symptoms did not improve, except for the low back pain. This result made it more difficult to establish the cause of her symptoms. Over the next 9 months, the patient's symptoms progressed, and other characteristic clinical signs associated with piriformis syndrome developed; they were observed with further careful examination as follows.
There was sensory loss along the distribution of the posterior cutaneous nerve of the thigh. Distinct tenderness over the piriformis muscle was elicited. The patient's discomfort was increased by right hip flexion, abduction, and external rotation with pain,...