What is sciatica?

Sciatica has become a bit of a buzz word among my patients when they speak about lower back pain. They use it for anything from localised pain in their lower backs to pain down their legs. But what is sciatica and why is it called that?

What is sciatica?

Simply put: Sciatica is pain that you feel in your leg due to irritation of the sciatic nerve or any of the nerve roots in the spine that form part of the sciatic nerve. The sciatic nerve is a thick nerve that runs down the back of your leg.

The Sciatic Nerve

Sciatica is defined as:

• pain in a person’s leg

• that is well defined (The person can normally tell you that it runs down the back of their leg and often into their foot or toes.)

• usually follows the dermatomal distribution of the sciatic nerve (see picture 4)

• is often accompanied by changes in sensation e.g. pins and needles or numbness

Sciatica can come in a variety of intensities. It can sometimes cause constant, severe pain with patients struggling to get comfortable in any position. Sitting and standing can be very aggravating and cause immediate pain. They often struggle to sleep due to pain. In milder forms of the condition people only suffer with intermittent pain down their leg e.g. if they sit or stand for a certain period of time or drive their car.

To fully understand this condition one has to have a basic knowledge of the anatomy of the lower back.

 The anatomy of the lower back

Our spines consist of several vertebrae (bones) that are stacked on top of each other. There are 7 in the neck, 12 in the mid back (where the ribs attach), 5 in the lower back (lumbar spine) and it terminates with the sacrum and the coccyx at the bottom.

Picture 2: The lumbar vertebrae. (Blausen.com staff. "Blausen gallery 2014". Wikiversity Journal of Medicine. DOI:10.15347/wjm/2014.010. ISSN 20018762)

The vertebrae in the lower back sit on top of each other, resting on two facet joints (one on each side) and a disc between them. The discs consists of a thick fibrous cartilage layer on the outside and a softer inside.

By Debivort: Anatomy of the spine - https://commons.wikimedia.org/wiki/File:ACDF_oblique_blank.png#/media/File:ACDF_oblique_blank.png

Each vertebra has a hole in it and together these holes form the spinal canal. Your spinal cord runs in the spinal canal. The spinal cord gives off little branches known as spinal nerve roots at each vertebra and these nerve roots exit the spinal canal through openings near the facet joints.

Each nerve root provides sensation to specific areas of the skin (known as dermatomes) and also control specific muscles in the body. That's why you can make a pretty accurate "guess" as to which nerve you have injured depending on where you feel your pain/numbness or which muscles are weak. This is the reason why the physio or doctor tests the sensation and muscle strength in different parts of your body.

If, for instance, you are unable to lift your toes up and walk on your heels, it tells us that you have likely injured your L5 nerve root.

Once the nerve roots exit the spine, they combine to form the different nerves that travel down your limbs. The sciatic nerve is formed by the L4 to S3 nerve roots.

The dermatomes of the body

What can cause sciatica?

It was traditionally believed that sciatica is mainly caused by prolapsed discs in the lumbar spine pressing on the nerve roots. People like talking about "slipped discs", but the disc can’t actually slip. What happens is that their fibrous outer layer tears and the soft inner filling then pushes out (prolapses). It then causes swelling and inflammation in the nerve if this ‘leaked’ inner layer presses (pinches) on the nerve root.

Osteoarthritis in the facet joints can cause little bony spurs which can also directly press on the nerve root or just narrow the canal so that it is easier to irritate the nerve root.

We now know that direct pressure on the nerve is, however, not needed for you to develop sciatica. Inflammation in structures close to the nerve root e.g. in the disc can also cause swelling and inflammation in the nerve root, even if it is not pressing on it.

Will I need surgery to relieve sciatica?

Not very likely. Most cases of sciatica can be treated successfully via conservative treatment. Surgery will/should only be considered if you still have severe pain after a year of conservative treatment, unless you have severe loss of muscle function and strength.

Why wait so long? Because surgery is no guarantee for success and most cases of sciatica do resolve within 12 months.

Disc protrusions can be reabsorbed by the body over time. Do not believe any therapist that tells you that they can push discs back into place – the body does not work that way. Also, do not allow anyone to manipulate your back if you have a disc injury – it will very likely aggravate it further.

 What does conservative treatment for sciatica consist of?

I tend to split my patients with sciatica into 2 groups: 1) those with severe, constant pain or funny sensations (pins & needles etc.) and 2) those with more dull and intermittent symptoms.

1. Treatment in cases with severe, constant symptoms

• Pain medication – consult your GP so that they can prescribe adequate pain relief. This is a very painful condition and you will feel worse if you cannot sleep due to pain. Anti-inflammatory drugs may also help to decrease swelling and pressure around the nerve.

• Activity modification – Stop doing the activity that is aggravating your back.

• Physiotherapy: It will be money well spent to consult an experienced physiotherapist for advice. They will be able to tell you the likely cause for your sciatica and be able to advise you on daily activities that can help or hinder your recovery. I do not find hands-on techniques of any use during the acute stage of sciatica. Acupuncture or dry needling can however provide some pain relief. Hands-on techniques and exercises become more effective once the symptoms have started to calm down a bit.

• Consult a back specialist doctor e.g. orthopaedic consultant if your pain has not decreased over a period of 6 weeks. They will request further investigation and likely offer you one of 2 types of injections: a) an epidural if a disc is causing your problem or b) a facet joint injection if the facet joints are deemed to be the problem, consisting of a corticosteroid and a local anaesthetic.

2. Mild, intermittent symptoms

• Your first port of call should be your physiotherapist. I find that these type of patients respond extremely well to treatment consisting of soft tissue release, dry needling, gentle exercises and advice regarding their activites of daily living. Your physio will also refer you on for further investigation if they feel it is needed.

Should I avoid surgery at all cost?

No, surgery can be effective when it is absolutely needed. Research has shown that it can be very effective in relieving leg pain and improving quality of life. There is also research that shows that elite athletes can successfully return to sport after micro-discectomy surgery, but this will depend on the type of sport they do.

Need more help with your injury? You’re welcome to consult one of the team at SIP online via video call for an assessment of your injury and a tailored treatment plan.

About the Author

Maryke Louw is a chartered physiotherapist with more than 15 years' experience and a Masters Degree in Sports Injury Management. Follow her on LinkedIn or ReasearchGate.

References:

1. Arden, N. K., Price, C., Reading, I., Stubbing, J., Hazelgrove, J., Dunne, C., et al. (2005). A multicentre randomized controlled trial of epidural corticosteroid injections for sciatica: the WEST study. Rheumatology, 44(11), 1399-1406.

2. Atlas, S. J., Keller, R. B., Wu, Y. A., Deyo, R. A., & Singer, D. E. (2005). Long-term outcomes of surgical and nonsurgical management of sciatica secondary to a lumbar disc herniation: 10 year results from the maine lumbar spine study. Spine, 30(8), 927-935.

3. Bicket, M.C., Horowitz, J. M., Benzon, H. T., & Cohen, S. P. (2015). Epidural injections in prevention of surgery for spinal pain: systematic review and meta-analysis of randomized controlled trials. The Spine Journal, 15  (2), 348-362.

4. Bush, K., Cowan, N., Katz, D. E., & Gishen, P. (1992). The Natural History of Sciatica Associated with Disc Pathology: A Prospective Study with Clinical and Independent Radiologic Follow-Up. Spine, 17(10), 1205-1212.

5. Dodwad, S.-N. M., Dodwad, S.-J. M., & Savage, J. W. (2015). Lumbar Discectomy Review. Operative Techniques in Orthopaedics, Published Online: June 09, 2015: http://www.optechorthopaedics.com/article/S1048-6666%2815%2900033-6/abstract.

6. Manchikanti, L., Nampiaparampil, D. E., Manchikanti, K. N., Falco, F. J., Singh, V., Benyamin, R. M., et al. (2015). Comparison of the efficacy of saline, local anesthetics, and steroids in epidural and facet joint injections for the management of spinal pain: A systematic review of randomized controlled trials. Surg Neurol Int, 6(Suppl 4), 2152-7806.