Piriformis syndrome occurs when tightnes or spasms of the piriformis muscle result in the compression of the sciatic nerve, resulting in sciatic symptoms.
Sciatica generally results in pain in the lower back, with radiating symptoms down the back of the thigh. Depending on where the sciatic nerve is affected, the pain may also radiate to the foot or toes. Sciatica can occur from pressure on the sciatic nerve from a herniated disc (also referred to as a ruptured disc, pinched nerve, slipped disc, etc.), or secondary to entrapment of the peripheral nerve fibers.