Seated Piriformis Stretch Test for Deep Gluteal Syndrome Deep gluteal syndrome, abbreviated as DGS is defined as pain in the buttock area caused by a non-discogenic entrapment of the sciatic nerve in the subgluteal space. The structures that can be involved in sciatic nerve entrapment are the not only the piriformis, but also fibrous bands containing blood vessels, gluteal muscles, hamstring muscles, the gemelli-obturator internus complex, vascular abnormalities and space-occupying lesions. For