Thread by @thomas_jesson

Thread on differential diagnosis of lumbar radicular pain, aka

"I think my patient has sciatica, could it be anything else?" 🧵

Firstly, this isn't meant to be a 'do it like this' tweetorial, but it's how I think of this stuff and the goal is to help you think about it, too.

Disclaimer over.

The first main differential is that it's just spinally referred pain, which is much more common than true lumbar radicular pain.

https://twitter.com/thomas_jesson/status/1570107416678912000

@adamdobson123 has been trying to make the 'Stynes criteria' happen. These are the festures to look out for:

- pins and needles, numbness
- pain below knee
- leg pain worse than back pain
- positive SLR
- loss of function on neuro ax

make you think radicular over referred...

Then we can broadly split the differentials up into 'stuff to do with the hip' and 'stuff to do with nerves'. Crude but it works for me...

'Stuff to do with the hip' no 1: The hip joint.

The danger here is that people tend to think of hip joint pain as groin pain. In fact, some of the time the hip joint can cause buttock pain that radiates down past the knee - looks like sciatica

Pics: Poulsen 2016 and Lesher 2008

Also, seriois pathology of the hip causes a down-leg referral pattern and *severity* that can look radicular.

https://twitter.com/thomas_jesson/status/1413700676404846597

How to differentiate hip vs spine?

Well hip more likely involves
- pain on weighbearing
- pain getting in and out of car
- pain putting on shoes and socks
- C-sign (see pic)
- Sitting with hip in external rotation
- Clicking, popping

And is less likely to have 'nervey' sx.

In terms of 'special tests', the log roll and FADDIR tests might be useful. In this context, a positive test doesn't mean too much - we're looking for a negative test, which will help to 'rule out' the hip.

More here: ncbi.nlm.nih.gov/pmc/articles/P…

Next on our list of 'stuff to do with the hip' is greater trochanteric pain syndrome.

You might think that lateral hip pain and tenderness is difficult to mix up with lumbar radicular pain, but it does happen - in one spine clinic, 20% of the time!

Things that make you think GTPS:
- Overweight
- Female
- >40

Someone else can chip in with the non-PC mnemonic.

In terms of special tests, we are quite familiar with Grimaldi's tests and the most relevant ones are:

- Palpation aka 'jump sign'. If negative almost certainly not GTPS. How about a rhyme? 'It hurts to press on GTPS'
- Single leg standing. If negative, unlikely GTPS...

Next in 'things to do with the hip that might look like radicular pain'...

Piriformis syndrome aka deep gluteal syndrome 😬

The deep gluteal space is a meaty space with a sciatic nerve running through it!

If something's wrong in there, you can get buttock pain with sciatic nerve irritation - easy to see how this looks like radicular pain.

It's almost certain that piriformis syndrome is over-diagnosed. Most cases are surely a spinal, hip joint or SIJ problem.

https://twitter.com/thomas_jesson/status/1712499843304735117

IMO for deep gluteal syndrome to be the most likely diagnosis, I think you would want to see

- An 'un-spiney' presentation: history, aggs & eases don't point to the spine at all.
- Buttock trauma or prolonged sitting
- Features of sciatic neuropathy - distal, nonderm neural sx

Last on our list of 'stuff to do with the hip' is pelvis stuff, which we can further break down into
- SIJ
and
-Bad boney stuff

SIJ pain is rare, but can look very radicular. Supposedly it can travel down below the knee.

Things that make you think SIJ over radicular
- Fall onto bum
- No neural symptoms
- Can bend and touch floor normally

There are also of course Laslett's tests. For our purposes - I believe that unless three of these can provoke your patient's pain, you can be pretty sure it's not the SIJ.

Finally, by 'bad boney stuff' I mean things like osteosarcome, insufficiency fractures, pathological fractures.

Look out for
- A limp, especially if using crutches
- Load dependent pain
- Tenderness on bone
- Osteoporosis, steroid use, overtraining, trauma...

Again, it seems like the severity of the pain for these conditions means people often assume it's radicular.

To summarise so far, if you are saying "I think my patient might have radicular pain, what else might it be?" then the first 'bucket' of differentials you might want to think of is 'stuff to do with the hip'.

1) Hip joint
2) GTPS
3) DGS
4) Pelvic stuff: SIJ and bad boney stuff

Without wanting to sound complacent, it strikes me that a lot of this is less about special tests etc. and more of a 'knowing is half the battle' thing. Just stopping to consider.

Plus listening carefully and not jumping to conclusions.

The other 'bucket' of differentials I think about is 'stuff to do with the nerves'. But it's time to pick up the girls from school, so that will have to wait for another day!

In the meantime - critiques, disagreements?