Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Piriformis Syndrome ?
    ### Response:
    Piriformis syndrome is a rare neuromuscular disorder that occurs when the piriformis muscle compresses or irritates the sciatic nerve-the largest nerve in the body. The piriformis muscle is a narrow muscle located in the buttocks. Compression of the sciatic nerve causes pain-frequently described as tingling or numbness-in the buttocks and along the nerve, often down to the leg.
    