It is caused by the compression or irritation of the sciatic nerve in the piriformis muscle. Sciatic neve is a nerve that originates from your lower back and helps with sensation and muscle contraction in your legs. Piriformis is a flat muscle that originates from the sacrum and attaches to the upper end of thigh bone. It is one of the lateral rotator of your hip joint that means the outward rotation of hip joint.
Common causes are over use of piriformis muscle in long distance running or walking, direct compression due to repetitive trauma, direct trauma in the gluteal or sacroiliac region.
If you have piriformis syndrome you may have radiating low back pain, numbness, difficulty with walking, sitting, squatting, standing and pain with bowel movements. There will be tenderness over the muscle belly. The low back pain can radiate in to hip, back of the thigh and lower leg. There may increase in pain bring the leg inwards which causes tension in the muscle. There will not be any weakness to the muscles supplied by the nerve.
Your Physiotherapist will be able to an assessment to confirm the Piriformis syndrome using various tests. Ultrasound therapy, heat and cryotherapy are used to reduce the pain. Stretching of piriformis muscle, postural correction, strengthening of weak hip muscles, soft tissue release and manual therapy techniques to the lower lumbar spine are the other treatment which helps to release the stress on the sciatic nerve.
Make sure that you do not sit for longer periods of time, stand and stretch or walk in between. Daily stretching of the muscle is recommended to avoid recurrence.