Bilateral gluteal pain caused by piriformis muscle compartment syndrome in the greater sciatic foramen: a case report

Abstract

The piriformis syndrome is an entrapment neuropathy of the sciatic nerve, which before MRI was often misdiagnosed as lumbar radiculopathy. Using MR neurography, Filler et al. [1] showed that among patients with a diagnosis of sciatica in whom standard treatment failed to effect an improvement, up to 68% had the piriformis syndrome. The piriformis muscle arises from the anterior surface of the middle third of the sacrum, between and lateral to the anterior sacral foramina and inserts into the medial aspect of the greater trochanter. Contraction of the piriformis, externally rotates the extended lower limb at the hip joint, and abducts the flexed hip. The piriformis lies on the sciatic nerve as both structures exit the pelvis via the greater sciatic foramen, where it confines the sciatic nerve to a potentially tight compartment.A 63-year-old, well-built male (BMI = 27.58 kg/m 2 ), presented with severe and progressive, bilateral buttock pain radiating to the back of the thighs of 2 years duration. His pain was unbearable at the time of waking; movement reduced the pain, whilst prolonged sitting aggravated it. He had associated anal pain. He was fit and had engaged in contact sports in his youth. There was no history suggestive of either neuromuscular disease or trauma to the buttock or pelvic regions. Abdominal examination was unremarkable;and rectal examination revealed tenderness over the piriformis muscle, which also triggered his buttock pain. Flexible sigmoidoscopy was unremarkable. Pelvic CT showed hypertrophy and herniation of the piriformis muscle between the rectum and sacrum. Pelvic MRI showed evidence of hypertrophy with altered signals in and around the piriformis muscles on both sides, suggesting fluid accumulation; more on the left side ( Figs. 1 and 2). Overall, MRI was suggestive of inflammation of the piriformis muscles. MRI of the lumbo-sacral spine was normal.Oral prednisolone 10 mg 8-hourly, gave dramatic pain relief within 2 days. Symptoms improved for 14 days leaving only mild intermittent buttock pain but recurred after therapy was discontinued. After 1 month, a second Fig. 1 Pre-treatment magnetic resonance image showing altered signal intensity and herniation of both piriformis muscles (solid arrows)

Piriformis syndrome: implications of anatomical variations, diagnostic techniques, and treatment options

“…Ratnatunga et al [21] more specifically noted that in those sciatica patients who failed to improve with standard treatment, up to 68% had piriformis syndrome. Although piriformis syndrome is considered to be uncommon, it is often an undiagnosed cause of buttock and leg pain [4].…”

“…Prior to the use of magnetic resonance imaging (MRI), piriformis syndrome, otherwise referred to as entrapment neuropathy of the sciatic nerve, was often misdiagnosed as lumbar radiculopathy [21]. The use of computed tomography (CT) for viewing soft tissues of the pelvis in cases of piriformis syndrome may show an abnormal uptake by or enlargement of the piriformis muscle, whereas MRI may confirm an enlarged piriformis muscle, but with normal intensity [4].…”

Surgical Treatment of Piriformis Syndrome

“…PS commonly evokes the symptom of sciatica and is usually diagnosed only after excluding all other conditions originating from the back, buttocks or legs. Thus, it is likely that PS is often overlooked and probably represents the most common cause of extraspinal sciatica 12)…”