Piriformis syndrome is a pain in the butt — literally. This condition is caused by compression of the sciatic nerve, which leads to pain and numbness in the buttocks and backs of the legs. The pain may be made worse by walking.
What Is the Piriformis?
The piriformis is a small muscle that runs from your sacrum at the bottom of your spine to the top of your femur bone in your thigh. It's a very important muscle that helps externally rotate your hip, and it's crucial for the activity of walking by providing stability to the sacrum and sacroiliac joint as you move.
What Is Piriformis Syndrome?
Piriformis syndrome occurs when your piriformis muscle compresses the sciatic nerve, which runs beneath it. The sciatic nerves — you have two — are the longest and largest nerves in the body, traveling from your lower spine through your buttocks and down your legs to your feet. The function of the sciatic nerve is to deliver signals between the muscles and skin of the legs and feet.
Just like any muscle, the piriformis can become shortened and tight, which can cause it to squeeze or pinch the sciatic nerve. This causes the nerve to become irritated and inflamed.
According to MedlinePlus, piriformis syndrome is not common in the general population, and it affects more women than men.
Piriformis Syndrome vs. Sciatica
Piriformis syndrome is not the same thing as sciatica, although the terms are often used interchangeably, according to Spine-Health. Sciatica is not a medical diagnosis in itself; rather it is a collection of symptoms — similar to those of piriformis syndrome — caused by another problem, such as a lumbar herniated disc, that affects the sciatic nerve. Sciatica, or lumbar radiculopathy, originates from the lumbar spine, whereas piriformis syndrome originates in the buttocks.
Placement of the Sciatic Nerve
In most people, the sciatic nerve passes underneath the piriformis muscle. However, in some people, the nerve passes through the muscle or over it.
After examining the lower limbs of 102 cadavers, researchers of a 2016 study in Translational Research in Anatomy found that 89 percent had normal anatomical placement of the sciatic nerve and 8.8 percent exhibited the anatomical abnormality in which the nerve passes through the muscle. In the remaining 2.9 percent, the sciatic nerve passed over the piriformis.
Causes of Piriformis Syndrome
The sciatic nerve passing through the piriformis muscle automatically increases the risk of nerve compression and piriformis syndrome, according to New York Dynamic Neuromuscular Rehabilitation & Physical Therapy.
Overworking is the main reason for the syndrome. The piriformis muscle is overworked when there is dysfunction, weakness or poor mechanics in another area of the body it connects to. For example:
- Dysfunction of the sacroiliac (SI) or hip joint
- Weakness of the deep stabilizing hip muscles
- Overpronation, or collapsing arch, of the feet
The muscle can also become overworked from extended bouts of physical activity, such as marathon running.
Other causes of piriformis syndrome include:
- Muscle spasms caused by irritation to the piriformis muscle or to a neighboring structure, such as the SI joint or hip
- Injury to the piriformis muscle
- Bleeding in the vicinity of the piriformis muscle that causes irritation
- Assuming positions that externally rotate your legs for long periods of time
- Hyperlordosis, or an exaggerated lumbar curve
According to bestselling author, physician and surgeon Dr. Joseph Mercola, piriformis syndrome affects more women than men because of the difference in body mechanics from a wider quadriceps muscle angle at the hip, which causes the joint angle to be wider.
Piriformis Syndrome Symptoms
Pain in the buttocks is the primary symptom of piriformis syndrome. You may also have pain that extends down the back of the thigh and into the calf and foot. This may be accompanied by tingling and numbness in the buttocks.
Any movement that involves hip activity can aggravate the pain, which is why walking can be challenging and uncomfortable when you have piriformis syndrome. Piriformis pain while walking may be worse when you're walking up stairs or up an incline.
Other signs and symptoms include:
- Difficulty putting weight on the affected buttock
- Piriformis muscle spasms
- Shooting pain in the buttock and down the back of your leg when rotating the hip outward against resistance
- Pain that worsens with sitting
Piriformis Syndrome Diagnosis
A direct cause can't always be pinpointed, and there is no piriformis syndrome test. Your doctor will take a history, asking questions about any injuries that may have led to the symptoms or the intensity and duration of your exercise activities.
Your doctor will also conduct a physical exam, assessing the pain elicited by certain movements. Radiologic tests, such as MRIs, may be performed to rule out other causes of the symptoms.
Exercises for Piriformis Syndrome
The first line of treatment for piriformis syndrome is a physical therapy program, including targeted exercises and stretches. These exercises should help reduce the pain of walking.
Because the causes of piriformis syndrome differ from person to person, the exercises that your doctor or a physical therapist recommends will be specific to you. However, some common examples include:
Piriformis stretch: Lie on your back with your knees bent and your feet flat on the floor. Draw your right knee in and clasp your hands around the top of the shin bone. Pull the knee toward your shoulder and hold for 30 seconds. Release and switch sides.
Hamstring stretch: Lie on your back with both legs extended. Lift one leg and wrap a towel or strap around the bottom of the foot. Keeping the leg extended, pull it in until you feel a gentle stretch on the back of the leg. Hold for 30 seconds; then switch sides.
Plank: Lie on your stomach with your forearms on the ground parallel to each other. Tuck your toes and lift your hips so your body is in one straight line. Hold for 15 seconds, working up to 60 seconds. Repeat three times.
Side plank: Lie on one side propped up on your elbow. Stack your feet on top of each other and lift your hips up so your body forms a straight line. Hold for 15 seconds, working up to 60 seconds. Switch sides. Repeat three times.
Other Treatment Options
In addition to the exercises, applying ice to the inflamed muscle can help reduce swelling and piriformis pain when walking. Place an ice pack on the area for 20 minutes every two to four hours.
You can also alternate heat therapy with cold therapy. Lie on your stomach and place a heating pad on the piriformis muscle for 20 minutes at a time.
Your doctor may also recommend taking over-the-counter anti-inflammatory medications. These may be particularly helpful if you know you'll be doing more walking on a certain day.
Read more: How to Release the Piriformis Muscle
Is This an Emergency?
- Innerbody: Sciatic Nerve
- MedlinePlus: Piriformis Syndrome
- Spine-Health: Is Piriformis Syndrome the Same Thing as Sciatica?
- Translational Research in Anatomy: Anatomical Variations of the Sciatic Nerve, in Relation to the Piriformis Muscle
- New York Dynamic Neuromuscular Rehabilitation & Physical Therapy: Difference Between Piriformis Syndrome and Sciatica
- PhysioWorks: Piriformis Syndrome
- Peak Fitness: Pain in the Butt: Piriformis Syndrome
- Harvard Health Publishing: Ask Dr. Rob About Piriformis Syndrome
- WebMD: Piriformis Syndrome
- Spine-Health: Piriformis Muscle Stretch and Physical Therapy
- Summit Medical Group: Piriformis Syndrome Exercises
- Spine-Health: Piriformis Syndrome Treatment