The piriformis syndrome appears to be more common because it is often underdiagnosed and undertreated. This syndrome is caused by compression or irritation of the sciatic nerve by the piriformis muscle as it passes through the sciatic notch. This entrapment neuropathy presents as pain, numbness, paresthesias, and associated weakness in the distribution of the sciatic nerve. In this article. we present the clinical symptoms, anatomy of the piriformis muscle, and the technique and result of the injection therapy with local anesthetics and steroid.

A 72-year-old woman presented with 7 days history of severe pain in the right buttock, hip, numbness of the right thigh. Previous management had included non-steroidal anti-inflammatory drug and physical therapy in local orthopedic clinic. Her past medical history was unremarkable. Her right side buttock was tender and discomfort was increased by right hip flexion, adduction and internal rotation with pain radiating to the anterior thigh. The her leg lenghts were equal, the strenght of right hip abductors and abduction was normal. Also low back range of motion and neurological examination were normal. Radiographs of the lumbosacral spine, pelvis and the hip joint were unremarkable. The she didn't respond to conservative treatment including physcal theraphy combined with the use antiimflammatory drugs, analgesics and muscle relaxants.

One week later she received an injection of 0.5% mepibacaine HCI 8cc and methyl-predanisolone(Depomedrol) 40mg into the medal right piriformis muscle. She reported that the 3 days after the injection, her right buttock pain had resolved and 7 days after the injection the pain resolved completely and she resumed normal activities and continued pain free.

We reviewed the literature on piriformis syndrome and its signs, symptoms and treat-ments. In an isolated piriforms syndrome, the major finding include buttock tenderness from the sacrum to the greater trochanter, piriformis tenderness on rectal or vaginal examination. The patient with piriformis syndrome usually does not have neurologic deficits Through complete history, physical and neurologic examinations, the other causes of low back pain and sciatica should be eliminated. Patients who do not respond to conservative therapy are candidates for local anesthetics and steroid injection. We injected methyl prednisolone 40mg and 0.5% mepibacaine HCl 8cc into the medial right piriformis muscle. 3 days after injection, her pains of right buttock and trochanter had resolved and 7 days after the injection, she resumed normal activites and consumed free. In order to improve the reliability of proper needle placement and allow for definite and treatment, EMG-assisted or MRI guidance may utilize.