Sciatica is a widespread and often debilitating problem that can cause complete misery and put your life on hold for weeks or months at a time, but what exactly is sciatica? In this article, I will share with you some of the most common causes of sciatica as well as what is going on beneath your skin and in your bones, discs, muscles and nerves when you have this condition.
As many as 3-5% of men and 1-3% of women in the UK will suffer from sciatica at some point in their life.1 Back pain and sciatica are also one of the most common causes of long-term disability worldwide.2 The lifetime incidence of low back pain is 58-84%, and 11% of men and 16% of women have chronic low back pain.3 Back pain accounts for 7% of GP consultations and results in the loss of 4.1 million working days a year.4 More than 30% of people still have clinically significant symptoms after a year after the onset of sciatica.5 To make matters more challenging, many of the surgical approaches to sciatica treatment have been shown not to be any more effective than waiting or doing conservative treatments.6
Underlying all of these statistics is the truth that sciatica can be a very complicated condition to treat, with many possible causes and a dizzying array of treatment options, ranging from chiropractic care, surgery, injections, home stretching and strengthening exercises. The right treatment choice always comes down to getting the correct diagnosis first. I’ll also clear up some of the most common causes of sciatica and show you when you when you may need to seek medical help and advice. There is also a big difference between treating the symptoms and correcting the underlying biomechanical cause, understanding this key point could make all the difference to your long-term outlook with this condition.
[clickToTweet tweet=”Many of the surgical approaches to sciatica treatment, including spinal fusion techniques, disc replacement and intradiscal electrothermal therapy, have no evidence to show that they ‘are superior to natural history or nonoperative treatment’ ” quote=”Many of the surgical approaches to sciatica treatment, including spinal fusion techniques, disc replacement and intradiscal electrothermal therapy, have no evidence to show that they ‘are superior to natural history or nonoperative treatment’ “]
Contrary to conventional theory, the underlying cause to the most common form of sciatica may not just be located in the lower back discs, but may well be the result of whole body mechanical distortion that builds up over many years.
What Is Sciatica?
Sciatica is the name given to pain that radiates down the sciatic nerve from the base of your spine to the back of your thigh, leg and foot. Sciatic pain often begins in the lower back with a relatively sudden onset, and over days to weeks spreads into the leg. Often the pain will develop to become worse in the leg and ease off in the lower back.
The pain is often associated with pins and needles in the foot, alongside numbness and muscle weakness. A drop foot, whereby your trip and scuff your foot as you walk is a sign of a more progressed condition where the motor nerves have been affected, and the muscles become unable to control the foot correctly.
Sciatica is often over-diagnosed and used as a label for anyone with back and leg pain, but true sciatica involves pain below the knee into the leg and foot and is accompanied by loss of sensation (to light touch, sharp touch, vibration and joint position sense) and muscle strength.
There are many reasons for why the sciatic nerve can become trapped/irritated, and there are also many other common causes of back, leg and thigh pain that have nothing to do with the sciatic nerve but can present with similar symptoms.
What Does Sciatic Pain Feel Like?
Sciatic pain is a characteristic “nervey” type of pain, most often presenting as a deep, dull ache, not dissimilar to a toothache in the leg. The pain can sometimes be felt as a burning, or electric shock type pain, particularly upon certain movements like bending, twisting or when coughing and sneezing (if the cause of the sciatica is due to a disc herniation in the lower back).
One of the classic signs of sciatica is that the pain gets worse when you stretch the nerve. If you find that putting your shoes and socks on in the morning is agony, or even looking down and flexing your neck when seated there is a good chance that there is pressure on your sciatic nerve.
What Causes Sciatica?
I will give you a brief outline of some of the more common causes. Please remember that there can potentially be more serious underlying causes to your pain, like a tumour growth or spinal infection. Please never take risks with your health by assuming anything. With any pain condition, you should seek professional help for a diagnosis and possible treatment from a chiropractor, medical doctor, orthopaedic surgeon or another qualified practitioner.
- Disc herniations
- Degenerative disc and joint disease
- Spinal stenosis
- Piriformis syndrome
- Serious conditions (cancer, infection, fracture)
1. Disc Herniations
The spinal discs, known as intervertebral discs, act as shock absorbers between the vertebrae of your back. They are made of two parts, an outer annular portion that is tough connective tissue, and a soft, gelatinous interior part called the nucleus pulposis.
Sciatica can occur when this strong outer annulus gets torn allowing the soft jelly-like interior to protrude out into the adjacent space where spinal nerves exit your spinal cord. The pain is caused either by a direct mechanical pressure that this places upon the nerve or by irritation set up by the inflammatory process which occurs as the body attempts to heal the injury.
Discs are often injured during a heavy lifting movement, usually when there is a rotation through the trunk, such as lifting a heavy box into the car boot. Equally, they can occur in the gym through heavy back squats or traumatic impact injuries. Sometimes discs can become ruptured during simple daily movements, such as stepping off of a curve or bending over to pick up a pencil.
These type of injuries may feel like they happen ‘out of the blue’, but the underlying joint and disc health was likely declining for many months to years before the injury happening. It’s a bit like placing the final straw on the camels back that causes it to sink under the weight because it built up incrementally over time it appears sudden in onset. In these sorts of cases, there will usually have been many ‘warning’ signs over the years with intermittent episodes of lower back pain.
Disc herniations are commonly diagnosed with an MRI scan which can reveal the injured disc tissue. However, many people have a less severe form of disc problem known as a disc bulge. This is where there is some bulging of the discs towards the nerves, but there is no evidence of nerve pressure seen on MRI. There are a few things to consider in cases like this. Most MRI’s are performed with the patient lying on their back in what is known as the ‘supine’ position. When we are flat, there is significantly less mechanical pressure placed upon the spinal structures, and there may not be enough intradiscal pressure to reveal the true extent of the disc injury and herniation.
Thankfully there are upright functional MRI scanners that can be used to scan the patient in the seated position, which studies have shown that there is the most amount more pressure placed upon the disc, even more than when you are standing. Sometimes this will demonstrate what is going on beneath the surface.
Not many people realise but chiropractors can refer for private MRI scans, and there is a standing functional MRI scanning centre in London.
Another issue on using MRI scans to diagnose the cause of sciatica has to do with the possibility of false negatives. This means that you may show up as having a disc bulge, but it might not be the cause of your pain. Pain is a notoriously tricky beast to tie down. You may have a perfect looking spine on x-ray and MRI scans yet have chronic severe pain. Equally, you could be shown to have multiple degenerated and herniated discs on an MRI scan and have no pain at all. This happens and has been shown in studies. Once again there are many reasons why these sort of inconsistencies exist because the sensation of pain has as much to do with two other factors as it does with the local tissue problems:
a) Biomechanics – which is how all of your joints and muscles work together as an integrated and functional whole system. This is a huge topic and a crucial one to understand because many adverse mechanical conditions can be created in the feet, neck or jaw, for example, that place undue mechanical burden on the lower back leading eventually to disc problems.
If the diagnosis and treatment are limited to just the lower back disc in question, then symptoms may fail to go away, or problems could only be ‘shunted’ elsewhere. In the biomechanics section below I will share how new understandings in biomechanics have aided the development of more advanced manipulative techniques that consider the balance throughout the whole body structure, including the soft tissues which can impact the nerves and discs of your lower back.
b) Central Processing – which is how your brain perceives pain through the way that processes pain signals known as ‘nociception’. Many chronic pain sufferers have an increased sensitivity to these pain signals and suffer more because of it since it does not take many extra stimuli to cause of the perception of pain in the brain. There are also many factors that affect the central processing of pain, from emotional stress, work stress, lifestyle stress, nutrition and exercise factors to name just a few.
2. Degenerative Disc And Joint Disease
Nerves can get irritated through direct or dynamic intermittent pressure placed on them from degenerative bone spurs coming off the side of the vertebrae themselves. This degenerative process is prevalent as people age, especially into their 50’s and beyond, but it is not necessarily normal or to be expected in a healthy spine.
These degenerative bone spurs are called osteophytes, and their impact can be amplified if the discs degenerate as well, because as the disc shrinks and bulges the space through which the nerves pass becomes smaller, and there is more likelihood of impinging the nerve upon these bony osteophytes.
3. Spinal Stenosis
The degenerative process described above can result in a narrowing of the vertebral canal, which is the hole through which the spinal cord itself passes. If this passageway gets narrowed too much, there can be restriction and pressure placed upon the spinal cord with resultant pain, numbness tingling of the torso, back and legs.
Spondylolisthesis is a condition whereby the vertebral body itself can move forwards over the disc, either as part of the long-term degenerative process or due to an athletic or accidental trauma in younger life. As the bone moves forwards, there is a change in the dimensions of the canal in which the spinal nerves exit and this can place mechanical pressure upon them, in a similar way to that which happens in degenerative discs and joints. Spondylolisthesis is often a complicating factor in sciatica, rather than the primary cause of sciatica itself.
5. Piriformis Syndrome
The sciatic nerve is a collection of multiple nerve roots that exit from the lower back and join together to form one big nerve. As this nerve descends into the buttock, it passes underneath the piriformis muscle (in some people the nerve can run through the piriformis muscle itself). If this muscle becomes tight, weak or dysfunctional it can lead to compression or irritation of the sciatic nerve leading to pain in the buttock and leg.
Characteristically there is usually a focus on pain in the buttock itself and a worsening of pain when walking up the stairs or when sitting for long periods. There is often restricted hip movement as well.
There are many reasons why piriformis syndrome can start:
- Myofascial trigger points within the muscle
- Injury to the muscle itself
- Dysfunction of the local sacroiliac joint
- Dysfunction of the local hip joint
- Lower back and pelvis alignment
6. Serious Conditions
As registered chiropractors, we are always screening our patients for the possibility of more serious causes to their sciatic pain. It is possible for tumours of bone, muscles, nerves and pelvic organs to place pressure on the sciatic nerve or lower back nerve roots resulting in pain. Equally is possible for a spinal infection or fracture to do the same thing. Ruling these conditions out is an essential part of the diagnostic process.
Some red flag symptoms that are a cause for concern (1):
- Unrelenting pain that never gives you a break
- Significant weight loss of 4.5kg or more over the past six months
- Pain that is worse at night and wakes you up (this is different to the pain that worsens when you change position at night)
- A traumatic injury preceded the pain (such as a car crash or a fall from a height)
- A recent infection or existing fever
If you have any of these conditions, there is no need to worry, but it is important to get checked and not simply wait it out and hope that some stretching will solve your pain.
Cauda Equina Syndrome
There are some other symptoms to be particularly vigilant of if you are suffering from sciatica, particularly if the cause is known to be a disc herniation. Very rarely the disc can bulge significantly in a central direction and place pressure on the descending spinal cord nerve known as the cauda equina. This is an emergency condition because it if is not treated quickly with decompressive surgery it can lead to permanent loss of bowel and bladder control.
Symptoms of a possible cauda equina syndrome include:
- Numbness around the anus and inner thighs
- loss or alteration of normal bowel or bladder control
- loss of normal sexual function or genital sensation
- one or both sided sciatic pain symptoms
- worsening lower back pain
If you have either of the first two symptoms or if your sciatic pain spreads into both legs then it is important to go to A&E as soon as possible to have it investigated.
Thankfully cases of Causa Equina Syndrome are rare, affecting only 1 in 33000 to 1 in 100000 people(2) but knowing what to look out for should you become a rare statistics yourself, is critical. At the same time, do not keep yourself up at night worrying about it, because it is, as I said, very rare.
(An MRI scan showing a larger disc protrusion at L4/5 resulting in CES)
The Pseudo-Sciaticas – Other Causes Of Lower Back And Leg Pain
Leg pain is often simply misdiagnosed by GPs or other practitioners as being sciatica. There are many other causes of leg pain that are more common. It is worth knowing that the sciatic nerve itself has no sensory innervation above the knee, which means that you cannot feel true sciatic pain between your buttocks and your knee. You can only feel sciatic nerve pain between your knee and down to your foot.
This means that if you are experiencing pain in your thigh or buttocks, it is likely to be something known as sclerogenous referred pain, which is pain that is being referred from muscles and ligaments of lower back, hips and pelvis.
Sclerotogenous Referred Pain
Sclerotegnous pain occurs in the areas where the tissue involved originated from embryologically as you developed from a fetus.
It is important to recognise that both sclerotogenous referred pain in the thigh and nerve root entrapment causing pain in the lower leg and foot can occur together. One scenario that we commonly see as chiropractors is an injury to the ligaments of the lower back setting up abnormal movement mechanics into the L5 disc which ultimately results in an S1 nerve root entrapment and sciatica. In cases like this correcting the ligament injury and lower back alignment allows the disc pressure to lift and the sciatic pain to resolve.
Often patients will present with lower back and leg pain which looks for all the world to be sciatica. Upon further testing and a careful diagnostic workup is found to be something far more simple and straightforward. Here are some of the other key conditions which can refer pain into the leg and look a lot like sciatica.
Facet Joint Syndrome
The small joints of your spine are known as facet joints; these are the ones that make your back flexible and allow it to move. Healthy facet joints have cartilage between them which would enable your vertebrae to move smoothly without grinding or catching. These small joints have many nerve receptors in them, and if they get inflamed or irritated by faulty spinal alignment or movement, then they can refer pain into the buttocks or thighs.
Myofascial Trigger Points
Muscle knots are known as “trigger points” and are a very common cause of back and leg pain. They are highly sensitive ‘knotted” regions within a muscle can refer pain to distant places in the body and cause confusion as to the exact cause of the pain. A knowledge of the pain referral patterns of trigger points is crucial to the accurate diagnosis of lower back and leg pain. In chiropractic practice, the use of functional muscle testing is a handy tool that allows these trigger points to be discovered and treated where appropriate.
Sacroiliac Joint Syndrome
This joint is the main pelvic joint that sits either side of the large sacrum bone at the base of your spine. There is minimal movement at this joint but it can become unstable, misaligned or inflamed and significant pain into the buttock and outside of the thigh area. Often this sort of pain feels worse when you go from sitting to standing, or with prolonged standing. Often patients will note that their pelvis clicks a lot on certain leg movements or when exercising. Sacroiliac joint problems are often found together with a lower back disc, facet and muscular problems, so it is important to remember that you can more than one problem at once.
There are many other potential causes to the lower back and leg pain that you may be experiencing. The discussion above is merely addressing the more common causes of the condition.
Treatment Options For Sciatica
If you are suffering from sciatica, the good news is that you have a lot of treatment options available to you. With conditions related to spinal pain, it is vital to get an accurate diagnosis, this is something that a registered chiropractor can do, or a GP or orthopaedic surgeon.
The diagnosis of sciatica in a chiropractic office includes:
- Detailed history taking
- Orthopaedic and neurological examination
- Referral for possible MRI or X-Ray imaging if required
An individual treatment plan will then be put together for you, would involve gentle spinal manipulation in some cases, soft tissue treatments along with home lifestyle modifications and recommendations for proper resting, sleeping and exercising to optimise healing and prevent recurrence.
Chiropractic care has been shown to be more effective in the management of sciatica than surgery and corticosteroid injections, both of which carry significantly increased risks compared with gentle, biomechanically specific spinal manipulation.1
In fact, many of the surgical approaches to sciatica treatment, including spinal fusion techniques, disc replacement and intradiscal electrothermal therapy, have no evidence to show that they “are superior to natural history or nonoperative treatment” .6
Surgery for sciatica should likely only be considered after more conservative approaches have failed to provide lasting relief for at six months, and only when the patient is fully aware of the potential benefits and drawbacks of surgery, the results of which, cannot be undone.
In future articles, I will address all of the other treatment options available to sciatic sufferers, because in some cases, surgery or injections may well be the best choice.
The Bigger Biomechanical Picture In Sciatica
Chiropractors are well known to think holistically and beyond just the area that is hurting. I believe that it is crucial to look at the body from both the micro and macro, to maintain a 30,000ft view as you also take a careful look down at ground level. While there may be a disc protrusion applying pressure to the S1 nerve root causing sciatica, the question should always be, “why did that happen?”
That question is what drives the search for the underlying mechanism of “why do spinal discs and joints become unhealthy in the first place?” It cannot be a simple matter of statistics and genetics, there must be a process involved, just as there is in tooth decay, for example.
The answer comes where the field of biomechanics and neurology meet. Which in simple terms means the interplay between the way your joints align and move and the way that your brain perceives the signals that these joints are sending them. These two aspects of your health are very much interrelated and cannot be separated from each other.
The characteristic structural fault that occurs in spinal and extremity bones when they get injured in certain ways is that they can misalign in directions that the body cannot correct because it doesn’t have the muscles or combination of muscles required to do so.
Now that statement is a mouthful, but it is accurate and hugely impactful on the understanding of biomechanics. When spinal bones get misaligned they fall forwards and they also twist. This is why you see so many people with their heads stuck forwards and their shoulders rounded and uneven. You would see the same imbalance in the hips if you looked for it.
The consequence of this, as the neurosurgeons Breig7 and Yamada8 discovered, was that these forwards postures can place a mechanical stretch or tension upon the spinal cord, effectively pulling it tight. The consequence is that adhesions form within the spinal meninges effectively anchoring, or tethering this posture in place. Once there is a long axis traction placed on the spinal cord it can get pulled up against disc bulges or osteophytes leading to nerve pressure and sciatica. This mechanism may well explain why some patients with disc bulges seen on MRI are asymptomatic. They don’t yet have enough stretch placed upon their spinal cord.
The forward twisting can happen at any spinal vertebrae, so a rounded upper back and forward head could place just as much mechanical tension upon the spinal cord as a misalignment in the lower back. It could, therefore, for some patients, be important to consider the mechanical movement and alignment of the entire spine when treating cases of sciatica.
What To Do If You Are Suffering From Sciatica
If you are suffering from this challenging condition, then the first step is to get asessed by your chiropractor or GP and find out the cause. From there the solution becomes self-evident, and you could be on your way to living pain-free before you know it. Many cases of sciatica appear to be self-limiting, meaning that if you take painkillers and wait a few weeks the pain subsides.
However more often than not it will recur again in the future and may come back worse the next time around. If you would like to know more about living pain-free, then subscribe to my newsletter and keep an eye out for the following articles in this series on sciatica. I will be diving deeper into how to look after yourself at home, how to fix your biomechanics and posture and how to pursue natural, safe forms of pain relief.
Now I’d like to hear from you. Are you suffering from Sciatica? What has or hasn’t worked from you in your pursuit of a cure? Tell me in the comments below.
1. Lewis R, Williams N, Matar HE, et al.The Clinical Effectiveness and Cost-Effectiveness of Management Strategies for Sciatica: Systematic Review and Economic Model. Southampton (UK): NIHR Journals Library; 2011 Nov.
2. Disease and Injury Incidence and Prevalence Collaborators. Global, regional, and national incidence, prevalence, and years lived with disability for 310 diseases and injuries, 1990-2015: a systematic analysis for the Global Burden of Disease Study 2015. Lancet2016;356:1545-602.
3. Parson S, Ingram M, Clarke-Cornwell AM, Symmons DPM. A Heavy Burden The occurrence and impact of musculoskeletal conditions in the United Kingdom today.Arthritis Research UK Epidemiology Unit, 2011
4. Bridges S. Chronic pain. In: Craig R, Mindell J, eds. Health Survey for England 2011 Health, social care and lifestyles.356. Health and Social Care Information Centre, 2012: 1-33,
5. Weber H, Holme I, Amlie E. The natural course of acute sciatica with nerve root symptoms in a double-blind placebo-controlled trial evaluating the effect of piroxicam. Spine (Phila Pa 1976)1993;356:1433-8.
6. An H, Boden S, Kang J, et al. Spine2003: 28(15S):S24-S25
7. A Breig. Adverse Mechanical Tension in the Central Nervous System.
8. Yamada, Shokei; Lonser, Russell R. Adult Tethered Cord Syndrome. Journal of Spinal Disorders: 2000, Volume 3, Issue 4, 319-323.
9. A Garnder et al. Cauda equina syndrome: a review of the current clinical and medico-legal position. Eur Spine J. 2011 May; 20(5): 690–697.
10. F Fuso, et al. Epidemiological study of cauda equina syndrome. Acta Ortop Bras. 2013 May-Jun; 21(3): 159–162.