Piriformis Syndrome: Not an Uncommon Source of Buttock and Leg Pain
Piriformis Syndrome: The Overlooked Cause of Sciatica-Like Pain
Piriformis syndrome (often grouped under deep gluteal syndrome) is a common-but-under-recognised cause of buttock pain and sciatica-like symptoms. It is frequently missed, sometimes mislabelled as “disc sciatica,” and in many cases not considered at all — even when spinal scans are normal.
Key messages
- Piriformis syndrome is a real, physical cause of myofascial pain and sciatic nerve irritation outside the spine.
- It can be triggered by overload, altered biomechanics, injury, and can occur after back surgery or hip replacement.
- Standard lumbar MRI can be normal or show incidental findings that do not explain symptoms.
- Accurate diagnosis and treatment often require a targeted clinical assessment and, when appropriate, ultrasound-guided injection.
What is piriformis syndrome?
Piriformis syndrome is a condition where the piriformis muscle (a small but powerful muscle deep in the buttock) irritates or compresses the sciatic nerve. If the piriformis becomes tight, overactive, inflamed, or spastic, it can contribute to one-sided buttock pain, sometimes with pain, tingling, or referral down the leg.
Anatomy: Why Piriformis syndrome can mimic sciatica
The sciatic nerve passes through the deep buttock region, generally under the piriformis muscle. In some people, the nerve runs very near, or even through, the piriformis muscle. This is one reason symptoms can feel exactly like “sciatica,” even when the lumbar spine is not the main driver.
What does piriformis syndrome feel like?
Symptoms vary, but many people describe deep buttock pain that may radiate down the back of the leg, sometimes with tingling or numbness. Discomfort often worsens with prolonged sitting, walking, or climbing stairs. Pain can range from a dull ache to sharp or stabbing sensations.
Why is piriformis syndrome missed or misdiagnosed?
Piriformis syndrome is commonly overlooked because symptoms can resemble disc-related sciatica. If a scan shows a disc bulge (even an incidental one), it can be tempting to assume the disc is the cause. However, many people have disc changes on MRI that do not match their symptoms. Piriformis syndrome should be considered especially when pain is buttock-dominant, sitting is difficult, and imaging does not clearly explain symptoms.
- A: Normal anatomy (most common): The sciatic nerve passes inferior to the piriformis muscle as a single trunk.
- B: Common variant: The sciatic nerve divides early, with one division passing through the piriformis muscle and the other inferior to it.
- C; Less common variant: The sciatic nerve divides early, with one division passing anterior to the piriformis and the other posterior to it.
- D: Rare variant: The undivided sciatic nerve passes through the piriformis muscle.
Common causes and triggers
Piriformis pain is often driven by overload and biomechanics. Typical contributors include prolonged sitting, repetitive lifting, running, gluteal weakness, hip stiffness, altered gait, and local trauma. Importantly, piriformis syndrome can appear after back surgery or after hip replacement because posture, gait pattern, muscle recruitment, and load sharing can change during recovery, placing unexpected strain through the deep gluteal muscles.
- Post-back surgery: altered movement patterns, guarding, reduced glute activation, and persistent protective tension can overload the deep buttock muscles.
- Post-hip replacement: changes in gait mechanics, hip rotation control, and gluteal strength can increase piriformis demand during walking and stair climbing.
- Other factors: leg length discrepancy, pelvic rotation, gluteal tendinopathy, and “deep gluteal space” irritation from multiple structures.
Disc sciatica vs piriformis syndrome
| Feature | Disc-related sciatica | Piriformis syndrome |
|---|---|---|
| Primary pain source | Lumbar disc bulge/herniation compressing a nerve root | Piriformis muscle irritating/compressing the sciatic nerve in the buttock |
| Where pain usually starts | Lower back | Deep buttock |
| Back pain | Common | Often minimal/absent |
| Pain pattern | Often dermatomal (nerve root distribution) | Often patchy/non-dermatomal deep aching or tightness |
| Pain with sitting | Variable | Frequently worse with prolonged sitting |
| Effect of walking/stairs | Often posture/distance-related | Often worse uphill or climbing stairs |
| Lumbar MRI | May show correlating disc pathology | Often normal or incidental changes only |
| Response to spinal injections | Often helpful | Usually limited |
| Response to piriformis injection | Usually no benefit | Often diagnostic and therapeutic |
First-line treatment: rehabilitation and targeted exercises
Rehabilitation is central to recovery. The piriformis is designed to work as part of a team with your gluteal muscles and hip stabilisers. When it becomes overloaded, it can start “doing too much” and tighten protectively. A well-structured plan aims to reduce overload, restore hip control, and rebuild confidence in movement.
When rehabilitation falls short: ultrasound-guided injections
While physiotherapy, stretching, and activity modification are the foundation of treatment, some people continue to experience persistent sciatic-type pain despite conservative measures. In these situations, targeted interventions such as piriformis injections can be valuable — both to clarify the diagnosis and to create a window to progress rehabilitation.
Ultrasound-guided local anaesthetic + steroid injection
A piriformis injection using a combination of local anaesthetic and corticosteroid can serve both diagnostic and therapeutic purposes. If the piriformis is the main pain generator, the local anaesthetic can provide a temporary reduction in symptoms, helping confirm the diagnosis, while the steroid may reduce inflammation and irritation around the sciatic nerve.
Ultrasound-guided Botox injection (for sustained relief)
For patients who do not achieve sustained benefit from steroid injections, or where significant piriformis spasm is contributing to sciatic nerve irritation, botulinum toxin (Botox) injection may be an effective option. Botox works by temporarily reducing overactivity in the piriformis muscle, allowing it to relax and reducing nerve irritation. Onset of benefit is typically within days to a few weeks, and effects can last several months.
Why ultrasound guidance matters
The piriformis sits deep in the buttock near important structures, including the sciatic nerve. Ultrasound guidance allows real-time visualisation of the piriformis muscle and surrounding anatomy, supporting accurate needle placement and reducing risk. This is particularly important when symptoms are complex, when there is previous surgery, or when anatomy is altered by posture, pelvic tilt, or muscle guarding.
Expertise at Pain Spa
Dr Krishna has substantial expertise in performing both corticosteroid and botulinum toxin injections for piriformis syndrome using high-resolution ultrasound guidance. His experience in interventional pain management and musculoskeletal ultrasound supports accurate targeting, safer delivery, and better outcomes — particularly in patients with persistent symptoms, previous back surgery, or post–hip replacement biomechanics.
GP & Referrer Summary
Piriformis syndrome (deep gluteal syndrome) is an under-recognised cause of extraspinal sciatic pain and should be considered where symptoms are buttock-dominant, sitting intolerance is prominent, and lumbar MRI is normal or non-correlating. It is particularly relevant in patients with persistent symptoms after spinal surgery or hip surgery. Ultrasound-guided piriformis injection with local anaesthetic ± steroid can be diagnostic and therapeutic; Botox may be appropriate in refractory cases with muscle hypertonicity.
FAQ
Is piriformis syndrome real?
Yes. Piriformis syndrome (often grouped as deep gluteal syndrome) is a recognised cause of sciatic nerve irritation outside the spine. While less common than disc sciatica, it is well described and frequently under-diagnosed.
Can scans miss it?
Yes. Standard lumbar MRI focuses on discs and nerve roots and may not visualise the piriformis region in detail. Symptoms can persist even when spinal imaging looks “normal” or shows changes that do not match the pain pattern.
Can piriformis syndrome happen after back surgery or hip replacement?
Yes. Changes in gait, posture, muscle activation, and load-sharing after surgery can overload the deep gluteal muscles. Piriformis-related pain can develop even when the operation itself has been successful.
Next steps
If you suspect piriformis syndrome — especially if your symptoms have persisted despite physiotherapy, if lumbar imaging does not explain your pain, or if symptoms began after back surgery or hip replacement — a targeted assessment can help clarify the main driver. Where appropriate, ultrasound-guided diagnostic injection (local anaesthetic ± steroid) and Botox can be considered as part of a broader rehabilitation plan.
Please contact Pain Spa at clinic@painspa.co.uk or via our website www.painspa.co.uk. to arrange a consultation or if you have any further questions.