What is Piriformis Syndrome?
Piriformis syndrome is a condition where the piriformis muscle in your buttock compresses or irritates the sciatic nerve, causing pain in your buttock that can radiate down the back of your leg, mimicking sciatica. 1, 2
Understanding the Anatomy
The piriformis is a small muscle located deep in your buttock, running from your lower spine to the top of your thigh bone. The sciatic nerve—the largest nerve in your body that runs from your lower back down each leg—typically passes underneath this muscle, though in about 16% of people, the nerve actually pierces through the muscle itself. 2
What Causes It
The syndrome develops when the piriformis muscle becomes tight, inflamed, or goes into spasm, squeezing the sciatic nerve. 1, 2 This commonly happens after:
- Minor trauma to the buttock or pelvic region 3
- Prolonged sitting 4, 5
- Repetitive activities that stress the muscle 3
What It Feels Like
You'll typically experience pain in your buttock that may shoot down the back of your leg, similar to sciatica from a herniated disc. 1, 4 The pain can be:
- Dull and aching, sharp, or electrical in character 6
- Worse when sitting for long periods 4, 5
- Aggravated by climbing stairs or walking 5
- Tender when pressing on the buttock area over the muscle 4, 5
Unlike true sciatica from a herniated disc, piriformis syndrome usually doesn't cause specific numbness in distinct areas of your leg or significant weakness in specific muscle groups. 6
How It's Different from Other Conditions
Piriformis syndrome is frequently confused with sciatica from a herniated disc because the symptoms overlap significantly. 6, 1 The key differences are:
- You typically won't have the specific patterns of numbness or weakness that occur with nerve root compression from a disc 6
- Your symptoms are more focused in the buttock and may not extend all the way to your foot 1
- Pain is particularly worse with sitting rather than standing or walking 4, 5
How Common Is It
Estimates suggest piriformis syndrome accounts for 5-6% of all cases of low back, buttock, and leg pain, and up to 17% of patients with chronic low back pain. 2, 5 However, it's often underdiagnosed because many healthcare providers don't consider it or mistake it for disc-related sciatica. 5
The Bottom Line
Think of piriformis syndrome as a "pinched nerve in your buttock" rather than in your spine. The piriformis muscle acts like a clamp on the sciatic nerve, creating leg pain that mimics the more commonly known sciatica from disc problems, but the source is muscular rather than spinal. 1, 2