Thread by @thomas_jesson

If you want to start a fight in a bar full of physios, mention piriformis syndrome.

'Piriformis syndrome' is practically a household name now, and yet plenty of clinicians will tell you it doesn't even exist.

What's going on?
🧵

Well, the first thing to know is it's changed it's name!

It's called 'deep gluteal syndrome' now...

After all, the piriformis is only really one of many structures in the bum that could entrap the sciatic nerve...

There are also the gluteal muscles, vascular abnormalities, space occupying lesions, fibrous bands, and all those little hip muscles

(Pic from Martin et al., 2015)

In any case, the idea behind the diagnosis is the same: deep gluteal syndrome is when something bad happens in the bum that traps the sciatic nerve.

So yes, it could be piriformis 'tightness' but it also could be fibrous bands, like the ones in these pictures. (Caro et al., 2016)

What does DGS look like? According to a systematic review, it's:

- Buttock pain
- Tenderness on deep palpation of the buttock
- Aggravation of pain on prolonged sitting
- Positive passive stretching or resisted contraction tests

Which also sounds a lot like a description of...

Lumbar nerve root pain!

Non-severe nerve root pain often looks like what people think piriformis syndrome looks like.

Let me explain by starting in the neck. It's well known that cervical pain, especially cervical nerve root pain, often causes pain in the scapula that can then travel down.

We don't think that just because pain starts in the shoulder, the person has 'deep rhomboid syndrome'.

Yes, there's thoracic outlet syndrome, but we accept that this is very rare, and most 'nervey shoulder stuff' is probably coming from the spine and nerve roots.

You can see where I'm going with this - I think that when someone has buttock pain, especially if it's 'nervey' or radiating down the leg, the most likely culprit is the spine, not the pirformis or the deep gluteal muscles.

For example, here's what happens if you stimulate injured lumbar nerve roots: buttock pain!

(Quotes are from Smyth and Wright, '58)

In another similar study - spinal stimulation in awake, symptomatic patients - Kuslich found that buttock pain was caused by "the application of pressure on the nerve root and outer annulus simultaneously".

More evidence that buttock = ?root.

This study found that of 286 patients with a disc herniation, 168 had buttock pain.

(Almost all of those 168 had a herniation at L4/5, so perhaps that is the level that most frequently refers pain to the buttock.)

Or how about this little case study?

But that only accounts for the pain. As we saw earlier, deep gluteal syndrome supposedly also has other symptoms.

But I think these too are also pretty much expected with nerve root pain!

'Tenderness on deep palpation of the buttock' has long been recognised as a symptom of nerve root pain!

From 1943: "in many cases, tenderness along the course of the sciatic nerve is present. It is frequently most severe over some area such as the buttock..."

From 1948:

"In a few of our cases of [nerve root pain] tender spots which could be described as "nodules" were observed in the muscles of the buttock and calf... we always found an associated disc prolapse."

A more recent study attempted to quantify this phenomenon, and found that 71% of 271 patients diagnosed with radicular pain had sore spots in their bums, compared to only 2% of control volunteers.

Radicular pain makes your bum sore!

As for the other symptoms of deep gluteal syndrome - pain on sitting and pain on passive stretching tests - these too are common, in fact expected, with nerve root pain. They're symptoms of nerve sensitivity!

Basically:

Just because someone has radiating/nervey pain and a sore buttock, doesn't mean their sciatic nerve is being compressed in their buttock

In fact, that's also a classic presentation of a much more established and known-to-be-common condition: lumbar nerve root pain!

To put it another way, I think piriformis syndrome is much less common than the rate of its diagnosis suggests, and many people with buttock pain that travels down their leg probably have good old fashioned spinal pain.

Or...

Something I haven't even mentioned, good old fashioned hip pain!

There's much more to say on piriformis syndrome. Does it actually exist? (Probably, it's just rare). What *does* distinguish it from spinal/hip pain? And when does all this matter, if indeed it does? But I'll leave that for another time...

tl;dr 🤷‍♀️