Sciatica or piriformis syndrome? How to tell the difference

What is sciatica?

Sciatica is pain from an irritated or compressed sciatic nerve. It usually affects the buttock and the back of one leg, and often travels down into the foot and toes. The most common cause is a slipped (herniated) disc in the lower back, with narrowing of the spinal canal, a slipped vertebra and back injuries among the other causes (NHS, 2024).

You may see wildly different figures for how common it is, from 1.2% to 43% of people. That range exists because studies define sciatica in very different ways, and only 2 of the 23 studies in one review confirmed it with a proper clinical examination (Konstantinou and Dunn, 2008).

What is piriformis syndrome?

The piriformis is a small muscle deep in the buttock that runs from the base of the spine to the top of the thigh bone. The sciatic nerve passes right beside it, and in about 16% of people it runs straight through it (Lo and Robinson, 2024). Piriformis syndrome describes sciatic type pain caused by this muscle pressing on the nerve.

It has been described for more than 70 years and is still debated (Hopayian et al., 2010). There is no agreed definition and no test that confirms it (Lo and Robinson, 2024). Because other structures in the buttock can also trap the nerve, many specialists now use the wider term deep gluteal syndrome (Martin, Reddy and Gómez-Hoyos, 2015).

One review estimates piriformis syndrome accounts for 5% to 6% of low back, buttock and leg pain, although that figure depends heavily on which diagnostic criteria are used (Lo and Robinson, 2024). Having the nerve run through the muscle is no more common in people with the syndrome than in people without it, so that piece of anatomy doesn't explain it on its own (Lo and Robinson, 2024).

Sciatica or piriformis syndrome: the main differences

No single symptom settles it. The clues we look at in clinic are the pattern of symptoms, a handful of physical tests and how your pain behaves from day to day.

A systematic review pulling together 55 studies found the most consistent features of piriformis syndrome were buttock pain, tenderness near the sciatic notch, pain made worse by sitting, and pain when the piriformis is stretched or tightened (Hopayian et al., 2010). An update narrowed these to four core symptoms and confirmed that a normal straight leg raise doesn't rule it out (Hopayian and Danielyan, 2018).

The tests we use

Straight leg raise. You lie on your back and we lift your straight leg. If that reproduces your leg pain, it points towards irritation of a nerve root in the back. In a Cochrane review, mostly of surgical patients, a positive test picked up 92% of disc problems but was also often positive in people without one. Lifting the other leg and getting pain in your sore leg was rarely positive without a disc problem, but missed most of them (van der Windt et al., 2010).

FAIR test. With you lying on your side, we bend the hip and turn it inwards to put the piriformis on stretch. A large single centre study reported good accuracy for this test (Fishman et al., 2002), but it had no comparison group, so we treat it as one clue among several rather than a yes or no answer.

Nerve checks. We test feeling, reflexes and strength in your legs. Changes here point more towards a nerve root problem in the spine.

The same review that looked at single tests found most of them perform poorly on their own (van der Windt et al., 2010).

Do I need a scan?

Usually not, at least not straight away. NICE advises against routine imaging for back pain and sciatica outside specialist settings, and only recommends it when the result is likely to change your treatment (NICE, 2016). Scans also find a lot of things that aren't causing pain. Disc bulges show up in 30% of 20 year olds and 84% of 80 year olds who have no back pain at all (Brinjikji et al., 2015).

For piriformis syndrome, ultrasound may show a thickened muscle and specialist MRI may help in future, but neither is yet a standard diagnostic test (Lo and Robinson, 2024).

Will it get better?

There is good reason to be hopeful. In a large UK study of 609 people with back related leg pain seen in GP practices, 55% had improved at 12 months, and the rate was the same in those with confirmed sciatica (Konstantinou et al., 2018). People whose leg pain had already lasted a long time, or who believed it would last a long time, were less likely to recover (Konstantinou et al., 2018), which is one reason good early advice matters.

Disc herniations can also shrink on their own. A review estimated this happens in 96% of the largest type (where a fragment of disc breaks off) and in 41% of smaller protrusions (Chiu et al., 2015). The bigger, more dramatic looking discs on a scan are often the most likely to settle.

What helps sciatica?

NICE guidance recommends staying as active as you can and returning to normal activities and work, and suggests considering a group exercise programme. Hands on manual therapy is only recommended as part of a package that includes exercise. NICE advises against traction and acupuncture (NICE, 2016).

On medication, NICE advises against gabapentinoids such as gabapentin and pregabalin, other epilepsy drugs, oral steroids and benzodiazepines for sciatica, and against opioids for long term sciatica (NICE, 2016). If you were prescribed any of these, don't stop suddenly. Speak to your GP or pharmacist first.

For severe sciatica that isn't settling, an epidural injection or, where scan findings match your symptoms, surgery may be considered through a specialist (NICE, 2016).

What helps piriformis syndrome?

The research is thinner. A 2022 review of 13 treatment studies rated the evidence as low quality, found no injection that clearly beat another, and recommended physiotherapy as the first line approach, with surgery an option for long standing cases (Hopayian et al., 2022). In the large FAIR test study, 79% of people improved by at least half with a combination of injection and physiotherapy (Fishman et al., 2002).

In practice, our treatment focuses on reducing the things that aggravate it (long spells of sitting are a common one), easing pressure on the nerve with gentle nerve and hip mobility work, and then building strength through the hip so it copes with daily life again.