Piriformis syndrome

Written by Sam Tan

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What is piriformis syndrome?

Let’s start by defining what each word means; the “piriformis” refers to a muscle deep in your buttock which is about the size of your thumb. It attaches onto your sacrum, which is a triangular bone at the base of your spine, and inserts onto the tip of your thigh bone (femur). Judging from its name, the “piriform” also means pear-shaped. The piriformis muscles main function is to rotate your hips outward and is one of the six deep hip rotators which also do similar actions. On the other hand, the syndrome simply refers to a group of symptoms. So if the piriformis is only one part of the six deep hip rotators, why does it get so much attention?

Due to its exceedingly close relationship with the sciatic nerve, the piriformis tends to be the one that causes irritation to it. Almost everyone is aware of the term “sciatica”, which is a condition that is a result of irritation to this sciatic nerve. The sciatic nerve is the biggest nerve in your body (Davis et al., 2021) and extends from your lower back all the way down to your feet, so any irritation to this nerve would mean you would get pain, pins and needles, and/or numbness in those regions. The most common cause of sciatica is from a herniated, or bulging disc (Davis et al., 2021). However, other structures can also cause sciatica, which we refer to as non-discogenic, as the source of pain is not caused by the disc. It just so happens that 67.8% of non-discogenic sciatica is caused by the piriformis muscle (Filler et al., 2005). What about the other 32.2%? Well, other structures that are deep within your buttock can also irritate the sciatic nerve, such as scar tissue, the gemelli-obturator complex (the other deep hip rotators) (Cox and Bakkum, 2005), and sacroiliac joint irritation.

For the reasons above it is more inclusive to name this non-discogenic sciatica as deep gluteal syndrome (DGS), and is now being considered the preferred term as opposed to piriformis syndrome (Martin et al., 2015). This is because in the clinical setting, it can be difficult to be absolutely certain to diagnose someone with piriformis syndrome, and because conservative management would likely be similar, labelling it as deep gluteal syndrome would be more accurate.

It can definitely get confusing between the terms sciatica, deep gluteal syndrome, and piriformis syndrome, mainly because the literature is constantly evolving. But as it stands, sciatica that is caused by structures other than the disc should be referred to as deep gluteal syndrome. Piriformis syndrome is simply a subset of deep gluteal syndrome, because there are so many other structures that can irritate the sciatic nerve within this deep gluteal region. Consequently, there is debate whether labelling such pain has any benefit at all. There’s so much uncertainty when it comes to lower back pain and sciatica; even with imaging, a clinician diagnosing someone with back or buttock pain is not entirely reliable. However, I digress and that’s probably a topic for another blog.

What are the signs & symptoms of piriformis syndrome/deep gluteal syndrome?

The following are the main signs and symptoms of deep gluteal syndrome:

  • Buttock pain
  • Tender to touch of the buttock
  • Shooting, burning, or aching down the back of the leg
  • Numbness and/or pins and needles down the back of the leg
  • Aggravation of pain from prolonged sitting
  • Aggravation of pain by stretching or contraction the deep hip rotators

What are the common causes of piriformis syndrome/deep gluteal syndrome?

As you can see, these symptoms closely resemble sciatica, predominantly because of the sciatic nerve irritation. This emphasises the importance of identifying the root cause of what is stressing the sciatic nerve. As mentioned before, bulging discs are the most common cause of sciatica, other serious causes would be a tumour compressing the nerve, lumbar cysts, or even an aneurysm (when an artery bulges due to the wall weakness), however these causes are less common.

If the sciatic nerve is being irritated by the piriformis muscle, there is speculation that it might be linked with anatomical abnormalities (Hicks et al., 2021). Normally, the sciatic nerve splits near the knee into two branches, namely the tibial and the common peroneal nerves. However, in about 12% of people, the sciatic nerve can separate early at the level of the piriformis (Kirshner et al., 2009), so in their buttock region. As a result, one of the two branches can actually pierce through the piriformis which makes it easier for it to be irritated causing sciatica.

Additional causes which can irritate the sciatic nerve and other structures in the deep buttock region include trauma to the hip area, sitting for prolonged periods, and hypertrophy of the piriformis muscle (enlargement).

How is piriformis/deep gluteal syndrome diagnosed?

Piriformis syndrome, or deep gluteal syndrome, is primarily diagnosed in the clinic room by a physical therapist. As described above, it is paramount to rule out the more common (and more sinister!) causes of the sciatica, such as a disc herniation or lumbar stenosis as the management would be different.

Deep gluteal syndrome is normally a diagnosis of exclusion, meaning if everything else has been ruled out, we can be fairly certain it’ll be due to structures within the deep buttock that is causing the sciatic-like symptoms. At this stage, we can be rest assured that the sciatic-like pain is not going to be life-threatening and unlikely to get worse, so this is where the beauty of physical therapy can get creative in resolving the issue. But before we treat the issue, it can be useful to differentiate which specific structures in the deep buttock are causing the pain as best we can. We do this by a variety of tests, and the most popular ones are:

  • FADIR test – this test aims to isolate and stretch the piriformis muscle. The “F” stands for flexion, “AD” is adduction, and “IR” is internal rotation of the hip, which are movements that do the opposite of the piriformis. A positive test would be reproduction of symptoms.
  • Active muscle testing – by combining different muscle movements, it can help paint the symptom picture.
  • Palpation of the location of pain – this is fundamental as it can help identify the structures involved, as it is not always going to be the piriformis.

Of course, these tests only form a part of a full comprehensive consultation, which will involve extensive case history taking, neurological examination, and other tests to fully ensure the symptoms are non-discogenic or non-sinister. A consultation with a physical therapist, such as an osteopath or physiotherapist, is an opportunity for you to work with them to unravel the mystery behind your symptoms.

What are the treatment options for piriformis/deep gluteal syndrome?

The first line of intervention would always have to be conservative, for example, physical therapy, rest, or non-steroidal anti-inflammatories. Most of the time, effective physical therapy would eradicate the pain within 3 weeks (Hicks et al., 2021). However, reinjuries of the area are common if preventative measures are not taken.

On the rare occasion that conservative treatment doesn’t resolve the piriformis/deep gluteal pain, then more invasive treatment would be the next step. This normally involves a steroid injection which is a powerful anti-inflammatory that helps reduce pain and inflammation. It’s important to note that even if the steroid injection provides relief, strengthening the tissues is paramount in making sure no re injury occurs.

Another type of injection is botulinum toxin, AKA Botox, has been shown to offer pain relief, but only in the short term (Hicks et al., 2021; Fishman et al., 2002), and apparently can cause more scar tissue around the sciatic nerve (Martin et al., 2015).

As a last resort, surgery can be considered if all other interventions fail. This usually involves manipulating the tissues to decompress the sciatic nerve, or to remove scar tissue/adhesions that are impinging on the nerve. We know that pain is always going to be multifactorial, so results post-surgery may not always have full resolution of symptoms. This is why surgery is always going to be the last resort as it’s the point of no return.

What are the best exercises for piriformis/deep gluteal syndrome?

Once your sciatica has been confirmed to be non-discogenic and non-sinister, and it is indeed originating from the deep gluteal region, we can finally be creative in how to approach this symptom picture.

The goals of physical therapy is to provide space for the structures in the buttock, to desensitise the irritated tissues, to build resilience of the tissues by strengthening them, and to provide appropriate education for long term care.

My favourite exercises that can help with these goals are:

  • Providing more space:
    • Figure of 4 stretch (piriformis stretch) – this is the equivalent of the pigeon pose but you’re lying on your back.
    • Lumbar rotation stretch AKA world’s greatest stretch – an effective way in relieving the tissues in the buttock and lower back at the same time
    • Hamstring stretch – also helps builds resilience to your sciatic nerve
  • Desensitise the pain:
    • Massage ball on the gluteal region – literally “mashing” a massage ball to those areas that feel “glued up” can help desensitise them.
    • Sciatic nerve glide
  • Build resilience:
    • Banded glute raise
    • Squats
    • Lunges
  • Note that with the stretches, it is essential to exaggerate the breathing to encourage change. If you’re straining too much, you’re making it harder for your tissues to relax. Breathe out as you stretch!
  • As with all rehabilitation exercises, it’s also important to not push yourself too much by aggravating the pain.

In conclusion, it is important for a physical therapist to rule out anything sinister with sciatica and to hypothesise which specific structures in the deep gluteal region are affected to maximise effectiveness of care. Seeing an osteopath or physiotherapist will guide you to your recovery journey.

*It is recommended to get the go-ahead from your GP, osteopath or physiotherapist before carrying out any of these exercises.

References

Cox, J. M., & Bakkum, B. W. (2005). Possible Generators of Retrotrochanteric Gluteal and Thigh Pain: The Gemelli–Obturator Internus Complex. Journal of Manipulative & Physiological Therapeutics, 28(7), 534–538.

Davis D, Maini K, Vasudevan A. Sciatica. [Updated 2021 Feb 26]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK507908/

Filler AG, Haynes J, Jordan SE, Prager J, Villablanca JP, Farahani K, McBride DQ, Tsuruda JS, Morisoli B, Batzdorf U, Johnson JP. Sciatica of nondisc origin and piriformis syndrome: diagnosis by magnetic resonance neurography and interventional magnetic resonance imaging with outcome study of resulting treatment. J Neurosurg Spine. 2005 Feb;2(2):99-115.

Fishman LM, Anderson C, Rosner B. BOTOX and physical therapy in the treatment of piriformis syndrome. Am J Phys Med Rehabil. 2002 Dec;81(12):936-42.

Hal David Martin, Manoj Reddy, Juan Gómez-Hoyos, Deep gluteal syndrome, Journal of Hip Preservation Surgery, Volume 2, Issue 2, July 2015, Pages 99–107,

Hicks BL, Lam JC, Varacallo M. Piriformis Syndrome. [Updated 2021 Apr 22]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK448172/

Kirschner JS, Foye PM, Cole JL. Piriformis syndrome, diagnosis and treatment. Muscle Nerve. 2009 Jul;40(1):10-8.

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