The Piriformis Syndrome

Not all pain and paraesthesia along the sciatic nerve ( sciatica ) are due to lumbar disc hernation. Sciatica is a symptom not a diagnosis, just like fever, can be due to different causes. Piriformis syndrome is among the common causes of sciatica. There were patients with their sciatica not improved with surgery at the lumbar spine, only found to have piriformis syndrome after detail examination.

The pirifromis muscle is located deep in the buttock, running across and covering the sciatic nerve. When it is repeatedly irritated or traumatized, the piriformis muscle could become hypertrophic and spastic, thus compressing on the sciatic nerve. 

In the clinical examination of patients with sciatica, orthopaedic surgeon will need to perform a detail test to locate the exact site of sciatic nerve irritation, and if necessary a MRI scan of the nerve, nerve conduction study, Electromyogram or local needle stimulation of the nerve and muscle to confirm the diagnosis.

Most patients with piriformis syndrome would respond to conservative treatment with a course of anti-inflammatory medications, physiotherapy (passive stretching exercise of the piriformis muscle and strengthening exercise of the deep spinal muscles) and intramuscular injection of corticosteroids locally to control inflammation of the nerve. Only a minority who after a protracted course of conservative therapy, still has significant symptoms affecting daily activities, would require surgery to relieve the sciatic nerve from compression by the thickened piriformis muscle.


Dr. SUN, Lun-kit