The Sciatic Scoop
Answers to all your questions
What is Sciatica?
The Information You Need
Sciatica, otherwise known as lumbar radiculopathy, is a loosely defined term that refers to pain that radiates down the leg due to irritation of the sciatic nerve or its roots, most often in the presence of low back pain. The sciatic nerve is the largest nerve in the body, composed of nerve roots stemming from 5 spinal levels (L4-S3) and runs down the back part of the hip and leg. This nerve sends signals to the muscles of the leg to cause them to move and carries sensory information (ex: touch, temperature, pain) from the leg, which is why irritation of the spinal roots or nerve may cause pain throughout some or all of the leg (Jensen et al., 2019). Because the term is somewhat loosely defined, it is difficult to find exact numbers on how common the condition is. Different reports show that anywhere from 1.6-43% of people will experience sciatica at some point in their lives (Konstantinou & Dunn, 2008), and estimate that 5-10% of those with low back pain will also have symptoms of sciatica (Koes, Tulder, & Peul, 2007).
Causes
Most often, this condition is caused by disc herniation in the lumbar spine. Contrary to previous beliefs, this is not a mechanical process but rather an inflammatory one. The spine contains intervertebral discs between the vertebrae which help absorb the forces placed on the back in daily life. As we age, it is common for these discs to bulge out beyond their normal boundaries. Previously, it was believed these bulged discs compressed the nerve roots of the sciatic nerve as they exited the spine. Now, it is much more accepted that the bulging disc results in inflammation, causing irritation to the nerve roots that send symptoms of pain and tingling into the leg (Valat et al., 2010). Other rarer causes of sciatica include a narrowing of the spinal canal and inflammation due to irritation of the muscles nearby (ex: piriformis syndrome). In rare circumstances, sciatica may indicate a more serious condition in which physician treatment would be advised (Jensen et al., 2019). For more information about these serious conditions, see the section on the home page titled Red Flags.
Symptoms
Pain radiating from lower back to buttock and possibly down the back of the leg
May be felt as a burning or electric shock sensation into leg
May be aggravated by coughing, sneezing, or prolonged sitting
Usually only on one side of the body
Possible numbness and tingling in the leg and/or foot
Possible weakness in the leg and/or foot
Diagnosis
There is no specific test that confirms a diagnosis of sciatica. Instead, a physician or physical therapist will use a series of tests and findings to build up the likelihood of sciatica (Jensen et al., 2019). They will look at things such as:
Sensation in the leg and back
Strength through the leg and foot
Reflexes in the knee and ankle
Straight Leg Raise and Slump Tests
What about imaging?
Imaging is generally not recommended for sciatica, as it can lead to increased costs and more unnecessary tests without any improvement in outcomes. While sciatica may be related to a disc issue, individuals with symptoms suggestive of sciatica only have a confirmed disc issue on MRI about half the time, and individuals without any symptoms may have MRI findings showing disc issues up to a third of the time. There appears to be only a weak relationship between disc issues and sciatic symptoms (Brinjikji et al., 2015). Imaging is only recommended if you have any red flag symptoms or have failed to improve after conservative treatment.
Prognosis
Outcomes for this condition are favorable. Exact percentages range in the research, but several studies have found that most pain and disability should resolve within 2 weeks. Remaining symptoms will resolve within 2-3 months for 60-80% of people and within 1 year for 70-95% with proper management (Valat et al., 2010).
Section References
Brinjikji, W., Diehn, F. E., Jarvik, J. G., Carr, C. M., Kallmes, D. F., Murad, M. H., & Luetmer, P. H. (2015). MRI Findings of Disc Degeneration are More Prevalent in Adults with Low Back Pain than in Asymptomatic Controls: A Systematic Review and Meta-Analysis. AJNR. American journal of neuroradiology, 36(12), 2394–2399. https://doi.org/10.3174/ajnr.A4498
Jensen, R. K., Kongsted, A., Kjaer, P., & Koes, B. (2019). Diagnosis and treatment of sciatica. BMJ (Clinical research ed.), 367, l6273. https://doi.org/10.1136/bmj.l6273
Koes, B. W., van Tulder, M. W., & Peul, W. C. (2007). Diagnosis and treatment of sciatica. BMJ (Clinical research ed.), 334(7607), 1313–1317. https://doi.org/10.1136/bmj.39223.428495.BE
Konstantinou, K., & Dunn, K. M. (2008). Sciatica: review of epidemiological studies and prevalence estimates. Spine, 33(22), 2464–2472. https://doi.org/10.1097/BRS.0b013e318183a4a2
Valat, J. P., Genevay, S., Marty, M., Rozenberg, S., & Koes, B. (2010). Sciatica. Best practice & research. Clinical rheumatology, 24(2), 241–252. https://doi.org/10.1016/j.berh.2009.11.005