I hear this a lot. A sudden bout of crippling low back pain can be frightening, and there’s some kind of comfort in having a name for what’s going on. If we can name it, maybe we can control it. And yes, perhaps it is sciatica… but perhaps not. The majority of people who come for treatment with a very painful, acute low back problem don’t have sciatica. And even if they do, “sciatica” is really just a symptom of what’s happening in your back – it’s not the cause. It’s a bit like having a cough. The cough is caused by something – whether that’s an upper respiratory tract infection, an allergy, or something you’ve eaten that’s “gone down the wrong way”; the cough is the body’s response to the problem. It’s the same with sciatica – it’s your body telling you there’s a problem.
So what is “sciatica”?
The term “sciatica” comes from the name of the nerves that get affected and give you all that pain – the sciatic nerves; which are the two largest nerves in the body. They’re formed from five “nerve roots” that leave the your lower spine through little spaces between the vertebrae. These then combine to form each sciatic nerve which runs through your buttocks, down the back of each thigh, and branches into the lower legs and feet. At their largest, they are around two centimetres wide – the width of your thumb! These nerves control most of the muscles in your legs, and carry most of the feeling from your legs back to your brain.
What causes sciatica?
Anything that interferes with normal nerve function can cause pain and other neurological symptoms, such as tingling, numbness and weakness (just like when you bang your “funny bone” in your elbow (where the “ulnar nerve” is) and get tingling in your hand). So, if any part of the sciatic nerve gets a bit squashed, you can feel pain – and not just where the compression is happening, but anywhere along the nerve’s length. That’s why a problem in your back (such as a herniated (or “slipped”) disc) which compresses the nerve roots that combine to form the sciatic nerve, can cause pain right down your leg and into your foot. In fact, in many cases like this, you can suffer worse pain in your leg than you do in your back, where the actual problem is. Commonly, the pain is accompanied by tingling in the thigh, leg or foot, and sometimes weakness, such as a difficulty bending your foot upwards at the ankle. The cause of sciatica is most often in the spine – anything that narrows that little gap between the vertebrae where the nerve roots exit can trigger symptoms. Causes include:
- “slipped” or herniated disc – the disc between the vertebrae is tough and squashy, but if it gets damaged it can bulge and press on the nerve roots as they exit the spine. If it’s really damaged, the gel-like centre of the disc can squeeze out, and that actually irritates the nerve root as well – so a bit of a double-whammy!
- arthritis in the spine – just as it does in the knees, arthritis can cause the little joints of the spine to enlarge, and they’re right next to those all-important nerve-root spaces!
- “wear-and-tear” of the discs – these tend to thin as we age, allowing the vertebrae to sit closer together. This means the ligaments in the spinal canal, usually held taut, are able to buckle – again pressing into that nerve-root space.
- a tumour in the spine – tumours grow and take up space, sometimes pressing on those nerve roots. Thankfully these are extremely rare.
There are sometimes causes of sciatic pain outside the spine, too. For instance, the sciatic nerve runs right by a small muscle deep in the buttock, so if this muscle gets really tight, damaged or inflamed, it can irritate the sciatic nerve as it passes by.
Here you can see the nerve roots exiting the spine through the small gaps between the vertebrae. This shows how a bulging disc can impinge on the nerve root as it passes through.
Do I have sciatica?
Symptoms of sciatica tend to be like this:
- sharp, stabbing, shooting pain in the back or side of the thigh, lower leg, or into the foot.
- you may also have pain in your low back, or you may have been aware of a niggly back before the leg pain showed up, but the leg pain is usually worse.
- sometimes the pain is there no matter what you do or what position you’re in, but most often it gets worse when you spend some time sitting or standing, or when you cough, sneeze or “squeeze” (when you’re on the loo, for instance), and sometimes when you bend backwards.
- tingling in your leg or foot, or a sense of numbness, and sometimes weakness.
There are other back problems that can seem like sciatica – these are more common. The symptom pattern is more like this:
- low back pain, which may be severe, and may be accompanied by a sense that you can’t take your weight on your legs – that your back might “give out”. This is different to neurological weakness as seen in sciatica.
- pain that radiates into your buttocks and maybe your upper thighs – this often feels like a strong, deep ache.
- sometimes you can get pain that goes all the way down your leg to your ankle or foot; this can happen with irritation of the “sacro-iliac joint”. This is at the very base of your back, out at the side a little. The bumps at the sides of your low back (where you often see dimples) mark the top of these joints. Problems here can imitate sciatica.
What can I do about it?
- take some painkillers – try paracetamol or ibuprofen (read the leaflets to make sure you can take them ok)
- ice-packs can be really helpful; a gel-pack with a cover or some frozen peas wrapped in a tea-towel applied at the base of your back for 15-20 mins at a time
- get assessed by a therapist to determine whether you have sciatica or another problem – and if it is sciatica, what the underlying cause is.
- some people find acupuncture helpful to control the pain.
- in the early stages, try to find a comfortable position to rest in. This could be “foetal position”, laying on your back with your knees bent and your feet flat on the bed, or on your side with the painful leg uppermost – lay close to the edge and let your lower legs rest over the edge of the bed. This can help to take the pressure off the pinched nerve roots.
It’s an emergency if….
- you develop problems with your bowel or bladder (loss of control, difficulty emptying)
- you have numbness in the “saddle” area (for instance, when you use toilet paper)
- you develop weakness in your legs or feet
Collectively, these symptoms are known as “cauda equina syndrome”, a rare but serious complication. It indicates pressure on the lower spinal nerves which needs to be dealt with quickly to avoid permanent damage. If you’re worried about this, go to A&E or seek urgent advice from your GP.