Pinched nerves, slipped discs and sciatic-AH!

Oct 31, 2024

6 min read

We’ve all heard the terms before, either in relation to ourselves or someone we know. But whether you’ve had an MRI, seen the doctor or self-diagnosed online, do you actually know what these terms mean, and what is going on in your body when you experience these things?

Let’s start with sciatica. Whilst a lot of people use this term, in my experience sciatica is not a very helpful diagnosis. ‘Sciatica’ translates from its Greek origin to ‘hip pain’ [1], and I have heard patients use it describe pain in their back, hip, thigh or legs. The National Institute of Clinical Excellence (NICE) who produce guidance for healthcare professionals describe sciatica as ‘lumbar radiculopathy’, which is ‘radiating leg pain caused by inflammation or compression of the lumbosacral nerve roots…forming the sciatic nerve’ [2] – basically, pain in the leg coming from an injury to a nerve at the spine. So is sciatica the same as a pinched nerve?

It really depends on your definition of ‘pinched’. The term ‘radiculopathy’ technically does not describe pain but rather describes a reduction in sensation, strength or reflexes as a result of nerve compression or ‘conduction block’ [3]. It’s important to understand that the role of a nerve is to communicate messages between the body and the brain or spinal cord. An appropriate analogy could be a poor phone signal: you might still be able to communicate with the person at the other end of the call, but there would be interference on the line and you may struggle to hear everything clearly – therefore bits of conversation might get missed or information misinterpreted. For example, if the nerve around your L5 vertebrae is compressed, you may find that you struggle to lift your foot up enough to clear steps and stairs because you have weakness in your ability to bend the ankle upwards (dorsiflexion). This is not because the muscle is damaged but because the signals cannot get from your brain and spinal cord to the muscles that do the movement. Radiculopathy describes this loss of conduction, however these symptoms may not be accompanied by pain. So a pinched nerve isn’t sciatica?

Many people with a radiculopathy will also have pain. This may be in the back, but commonly they will experience leg pain. This is because the nerve that is affected supplies a certain part of the leg, and the brain gets confused about where the problem is – remember, the nerves job is to communicate. Take the telephone analogy again. If your call is cutting out or there is interference the issue could be with your phone, the other persons phone, or anywhere in between – the interference just tells you there is a problem but not where it is. And nerve pain has a particular name – radicular pain. If you have ever had radicular pain, you will know it is very distinct and often severe. People describe it as ‘shooting’, ‘shocking’, ‘electric’ or ‘lancinating’, and this is usually what most people are referring to when they say ‘sciatica’. The key distinction between radicular pain and radiculopathy is that radicular pain does not affect the ability of the nerves to send messages [3]. Imagine someone keeps tapping on your nose with their finger. After a few hours, your nose will start to get quite uncomfortable, but your ability to breathe wouldn’t be affected. Now imagine instead somebody squeezed your nose together – there may not be much pain but it will certainly make getting oxygen into your lungs a lot more difficult. Likewise radicular pain is uncomfortable but does not affect the ability of the nerves to do their job, however a radiculopathy may not be painful but affects the signals getting to and from the brain. And you could experience just radicular pain, just radiculopathy, or both together. So am I just being a bit pedantic with terminology here?

Maybe, but distinguishing between the two diagnoses is quite important from a management perspective. The most common cause of radiculopathy is a bulging disc [3] but there are other more concerning things that could cause a radiculopathy [4]. If a patient presents with back and leg pain, they should always be assessed for a radiculopathy. If there is a mild radiculopathy (i.e. the patient still has some strength, sensation or reflex), we may be quite happy to monitor them, however if they a complete loss of strength or sensation, or their symptoms are worsening, that may mean they need urgent assessment and management [5]. If we refer someone on because of ‘sciatica’, that doesn’t really tell us whether they have radicular pain or radiculopathy, nor help us to quantify the extent of the symptoms. Diagnosing a ‘right sided L5 radiculopathy’ or ‘left sided radicular pain’ tell us far more about the severity and extent of the problem that just saying ‘left sided sciatica’. So now we understand this terminology, how worried should you be about these diagnoses?

NICE estimate around 13-40% of people will experience ‘sciatica’ at some point in their lives [6]. This is quite a wide range, and NICE themselves cite inconsistencies with terminology as one of the challenges to accurate reporting – another reason why clearer terminology is useful. It’s important to note however that around 50% of radiculopathies will resolve in 6 weeks, and most have got better after a few months [7]. Current guidelines recommend that patients trial at least 6 weeks of physiotherapy and medical management prior to MRI or other investigations [8], and so whilst these problems can be very painful and early assessment is important, in most cases they are nothing to be concerned about in the long term.

Disc bulges are a common finding on MRI, and whilst we may assume that they are associated with severe injury, they are found very often in asymptomatic patients. Around 30% of people aged only 20 years old will have disc bulges found on MRI and be completely asymptomatic [10], and so whilst some do cause more problems than others, having a disc bulge is not usually a serious, long term condition that will cause permanent damage or dysfunction. Whilst there may be some genetic factors that increase the likelihood of developing disc bulges, some key modifiable risk factors for disc bulges include smoking, activity levels and obesity [10], and therefore by staying healthy we can give ourselves the best possible chance of having a healthy spine.

So if you have any symptoms of ‘sciatica’, whether it seems like radicular pain or radiculopathy, it’s always worth getting an assessment with a health professional. Most of the time your symptoms will improve on their own, but you may benefit from some pain relief (certain medications are more effective than others for nerve pain) and some physiotherapy to help you keep functioning and potentially speed up your recovery or maximise your function. Most cases are not concerning, however a thorough assessment should be able to give you peace of mind and ensure that if there is a need for more investigation this can be done in a timely manner. By keeping healthy and staying active, you can also reduce your risk of developing sciatica.

If you have any back pain or other symptoms please check the NHS guidance at the following links and follow the advice relevant to your symptoms: Health A to Z - NHS (www.nhs.uk) ; Back pain - NHS (www.nhs.uk)