6 Tell-Tale Signs Your Patient Has Sciatica
Most patients with pain down the back of their leg probably don’t have radicular pain (the proper term for lumbar nerve root pain, or ‘sciatica’). Lots of things could cause pain down the back of the leg: hips, facet joints, discs, lumps and bumps, endometrial plaques, vascular disease—even, sometimes, on very rare occasions, our friend the piriformis. True lumbar radicular pain, caused by an injury to a lumbar nerve root, is just one among many.
So how can you know, next time you see a patient who has pain down the back of their leg, whether it’s sciatica? Here are a few tell-tale signs that will point you in the right direction.
I should say, these signs are not meant to make up an exhaustive checklist, and they’re certainly not a diagnostic criteria! They’re just a few things that might help you to see your patients’ symptoms in a better light. I hope you find them useful.
1. Their bum hurts
It’s under-appreciated that buttock pain is a symptom of a nerve root injury.
Lots of people who have buttock pain that goes down their leg get diagnosed with piriformis syndrome, and are prescribed hip stretching or strengthening exercises. I reckon a lot of those people actually have a nerve root problem.
Just as people with cervical radicular pain often feel a tight knot or a dull ache in their scapula, people with lumbar radicular pain often feel the same sort of thing in their buttock.
Here’s an excerpt from an incredible 1968 study in which two physicians looped nylon thread round the nerve roots of people with sciatica and tugged on them, just to see what would happen:
“[When we pulled on the nerve root] the effect was immediate. The patient jumped and exclaimed that a severe pain shot into the right buttock… at the second attempt the thread was very slowly drawn upon… [As the tension] mounted severe pain spread from the center of the right buttock down the center of the back of the right thigh, veered laterally to the region of the biceps tendon, skipped the side of the knee, and was felt intensely on the lateral side of the calf.”
Here’s another excerpt:
“On pulling the thread, an ache was felt at the medial and inferior aspect of the left buttock just at the fold. It was localized to an area about one inch in diameter and was of a mild nature.”
If your patient’s bum hurts, think nerve root!
2. It’s worse in the leg, and worst below the knee
Your patient’s back hurts, and it’s going down their leg, but is that pain referred (i.e. from somatic tissue like discs and joints) or radicular (i.e. from the neural tissue of the nerve root)?
There are no rules in musculoskeletal pain, but it’s a rule of thumb is that referred pain is worst closest to the area it’s referred from, and gets milder the further away it gets. For leg pain referred from the spine, that means the pain is at its worst in the back, and then it gets milder the further down the leg it goes. This means there’s a good chance the pain won’t get past the knee but if it does, it usually isn’t too bad down there.
A 2018 study found five predictors of sciatica: one was ‘leg pain worse than back pain’, another was ‘pain below the knee’.
3. It’s really, really painful
After I started practicing, it took me a while to tune in to just how much pain my patients with sciatica were experiencing. Maybe I wasn’t ready for it because my own experience of radiculopathy had been mercifully mild. But here’s a quote from a 2019 qualitative paper, from someone experiencing sciatica:
“I feel like people have got no understanding of just how painful it can be. I don’t think it’s taken seriously enough. I don’t think people realise how painful it is. It’s excruciating, constant”
Here’s another quote from the epidemiologist Jonathan Mayer, after an unsuccessful operation for his sciatica:
“I’ve heard patients ridiculed in team discussions if they report a level of seventeen on a ten-point pain scale, but I discovered what those patients must mean. They were communicating feelings of loss of self, of being a screaming animal reduced to the level of mere survival. They were trying to emphasise that the pain was not just as bad as they could possibly imagine but worse than they could possibly imagine”
If your patient’s pain is this bad, that’s a sign their pain is radicular. Referred pain is no picnic either, but it tends to be duller and aching and people usually don’t describe it as knocking their socks off like radicular pain can.
If your patient is in these dire straits, what can you do? Acknowledge their pain and bear witness. Explain that it’s not necessarily a sign that there’s a more serious problem. Encourage them that radicular pain is worst in the early days and usually improves substantially in the first few weeks. And, finally, consider talking to your injecting and prescribing colleagues to see if they can help.
4. And it’s not just the pain
People with sciatica say that the non-painful symptoms—the buzzing, the tingling, the pinpricks, the running water, the insects crawling, the itchiness, the hot legs, the cold legs—are just as bothersome as the painful ones. These weird symptoms might not be as agonising as the pain, but their unpredictability and mystery can make them a torment. Here’s another quote from that 2019 qualitative paper:
“When I think about my leg I can feel the pins and needles going down it and the pain, and I’m sure it’s all in the mind“
Where do these weird and wonderful extra symptoms come from? Broadly speaking, they’re caused when damaged neurons send all sorts of junk action potentials to the brain. Trying to interpret this mess of information, the brain wrongly decides something is happening in the leg. Exactly what it thinks is happening—ants crawling, electricity buzzing, water running—probably depends on what kind of neurons are sending the junk signals, and in what pattern.
These symptoms are a key sign of nerve injury, so they point to radicular pain.
Make sure you ask your patients about unusual symptoms, because I find a lot of patients are reluctant to bring them up first. Explain that they’re common and you hear about them all the time, and that they suggest a nerve is irritated so it’s firing off lots of wrong messages to the brain… “It’s not too different to when you sit on your leg too long and your foot starts to tingle… As your body gets to work it will help out the nerve and help it to repair, and these feelings are likely to ease. In the meantime, let’s work out which positions are making them worse and which ones make them better…”
5. Their strength and sensation are down (but not out)
If your patient has pain down the back of their leg that seems to be coming from their spine, and your neuro exam shows they’ve lost strength, sensation or reflex integrity, that points towards a conduction block in a nerve root.
To be fair, loss of just one of these things doesn’t point that hard to a nerve root problem. Lots of people lose their patellar reflex after a knee replacement. Lots of people lose sensation in a patch of skin after an accident they can hardly remember now. Lots of people have weaker muscles because their leg really hurts and they don’t want to move! Reflex testing is probably the most useful sign of the lot, but it’s still not that good by itself. You want to make sure you’re putting together a picture of a loss of nerve function, with a couple of signs or more. (Testing pinprick sensation can help you to do this.)
You have probably noticed that although people with peripheral neuropathies often have total paralysis of their muscles or total numbness in their skin, people with radicular pain usually have much milder loss of strength and sensation. One reason for this is that the neurons of the nerve roots all jumble together once they have left the spine, and share the work of any one task. So, moving any one muscle is the task of two or more nerve roots. Similarly, unlike most dermatome maps, much of the skin in the legs is innervated by two nerve roots, with only a few patches being served by just one. This means that if one nerve root is injured, another can shoulder some of motor and sensory load.
So your patient might have sciatica if their strength and sensation are down—but not out.
6. They hate stretching their nerves out
Here’s another sign that I wish I could tell you was a sure-fire thing, but isn’t! There’s lots of reasons why someone’s nerves might hurt when you stretch them out. Maybe they just have sensitive nerves! But, like the other things in this list, neural mechanosensitivity does point to sciatica.
The straight leg raise is a great test. It’s easy to do and it’s often just as enlightening for the patient as it is for the clinician. “Do you feel your pain when I point your foot up like this?” “Yes! I never noticed that…”. Once they realise that stretching this or that bit of their nervous system makes their pain worse, they can get more control over it in real life.
But is the straight leg raise necessary? It’s often not that nice for patients. They have to lie on a hard plinth while a stranger holds their leg and says “okay, just relax”, then pushes their leg up into exactly the most painful position it could be in.
All we really want to know is whether our patient’s nerves hurt when they’re stretched. A slump test is probably just as good a way to find out, and it’s a lot nicer for the patient, and it transitions nicely into teaching some neurodynamic exercises if that’s what you want to do.
There’s even a sort of ‘lazy man’s slump’: “Just while you’re sitting there, if you point your foot up to the ceiling, how does it feel?”. If it reproduces the pain down the back of their leg, then surely the straight leg raise is going to as well, so maybe there’s no need to do the more painful test! Something to think about…
I hope these 6 signs were interesting. I doubt any of them were new to you, but I hope that after reading this you can see them in a better light, and that it will be helpful to recall one or two next time you see a patient with pain down the back of their leg.
If you found this article interesting or useful, you might like to know that I am currently writing two books, one on radicular pain, the other, with my friend Rob Tyer, on cauda equina syndrome. If you want to get updates on how it’s going, and when they’re ready, please subscribe to my newsletter here.
Want to learn more about sciatica?
Tom Jesson has done a Masterclass lecture series for us on:
“Assessing and managing radicular pain”
You can watch it now with our 7-day free trial!
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