Updated: May 3
WHAT IS SCIATICA?
Sciatica is a term that tends to get thrown around quite a lot especially in reference to any nerve related pain in the lower extremity. Yet despite its common diagnosis, there are many misconceptions surrounding what it really is.
It is a vague term used to describe pain that is associated with the compression or irritation of a nerve root located in the lumbosacral region of the spine (lower back).
Now grasping that this pain originates from the lower back can be a touch more complicated, especially when factoring in that most symptoms are felt down the leg.
However, this begins to make more sense when looking into the major anatomical structures involved.
Sciatica derives its name from the condition’s involvement of the sciatic nerve which is the largest and longest nerve in the human body. Starting in the buttock and travelling down to the lower leg, this nerve is formed by a cluster of smaller nerve roots that can be traced back to the sacral plexus within the lower back.
If these nerve roots are irritated in any way it can manifest in referring pain down the nerves pathway which can include the buttock, thigh, calf, and foot.
HOW CAN THESE NERVE ROOTS BE IRRITATED?
To understand how the nerve roots can be irritated we need to look at where these nerve roots are and what structures can influence them. As can be seen in the image below, the nerve roots are the yellow cords exiting either side of the spinal cord.
These nerves send and receive information from the brain all the way down to the tips of the toes and are therefore a very important travel route for sensory (feeling) and motor (muscular) control. Another important structure to consider is the discs, depicted as the blue semi-circles.
When it comes to nerve root pain there are two primary types: mechanical pressure and chemical irritation.
The concept of mechanical pressure is relatively straightforward. It postulates that when a nerve root experiences compression, as can be seen in the image above on the right, this can limit the amount of blood flow to the nerve. Without the appropriate blood flow there is reduced oxygen being delivered meaning the nerve will not be able to perform its functions properly.
Furthermore, if this reduced blood supply is prolonged it can lead to nerve degeneration and the development of abnormal impulses within the nerve. This is what can often be experienced as the burning, pins and needles or electric shock type of sensations down the leg.
The chemical irritation system is slightly more complicated and has two additional schools of thought.
The first is that the discs contain powerful chemicals that when spilled onto the nerve can lead to inflammation making the nerve angry and dysfunctional.
Discs are very active tissues within the body. They are constantly laying down new cells and breaking down the old ones to ensure they are always healthy and functional. For the discs to be able to break down old cells they need to have powerful enzymes that can damage and discard them.
Therefore, if a disc herniates and some of the chemicals spill onto the nerve roots, they can irritate the nerve and start an inflammatory response from the body.
The second is that the disc can cause an autoimmune response which will often catch the nerve in the crossfire.
Whilst it is very rare that a tissue in the human body has no nerve or blood supply, this is the case for the discs after the first few months of life (like the inside of the eyeballs!). As a result, the discs are quite foreign to the body’s immune system, to the point where it is unrecognizable.
Therefore, when a disc herniates the immune system reacts to this as it would a foreign body, such as an infection or a virus. This means it attacks the disc tissue resulting in an inflammatory reaction which will end up affecting the nerve root given its proximity to the disc.
WHAT ARE THE SYMPTOMS OF SCIATICA, WHO DOES IT AFFECT AND FOR HOW LONG?
The most common symptoms associated with Sciatica is pain travelling down the back of the leg. Key areas include the buttocks, back of the thigh, calf, and foot.
Some people can experience a burning, electric shock or pins and needles type pain or in rare cases a sensation of cold water running down the leg that may be associated with numbness or muscle weakness.
The intensity of the symptoms can be quite broad ranging from mild, barely noticeable pain to severe pain, likened in some cases to childbirth. Sciatica can affect people of every age however it is mostly seen in the forties and fifties.
Expected timeframes for recovery from a sciatica diagnosis can vary greatly however the pain is generally the worst for the first 2-4 weeks.
At the 12-week mark 50% of those with sciatica will have nearly a complete resolution of initial symptoms. For a small group of people, pain may not improve at the rate normally expected however by the 12-month milestone over 75% of patients are asymptomatic.
HOW TO MANAGE SCIATICA?
When it comes to the management of Sciatica there are a range of treatment options available, including physiotherapy. The most important factor in most of these is allowing the appropriate amount of time for recovery.
Other common non-surgical treatments include adjusting lifestyle factors such as smoking cessation and weight loss as well as introducing general exercises or specific spinal/ nerve movements targeted at mobilising the sciatic nerve.
In extreme cases medications, specialist nerve injections or surgery may be used as a last resort however for most this is certainly avoidable!
If you are unsure about what may work best for you then book an appointment with your health professional who can provide you with an accurate diagnosis and a suitable treatment plan that is built around you and your lifestyle!
Dower, A., Davies, M., & Ghahreman, A. (2019). Pathologic Basis of Lumbar Radicular Pain. World Neurosurgery, 128, 114-121. doi: 10.1016/j.wneu.2019.04.147
Goldsmith, R., Williams, N., & Wood, F. (2019). Understanding sciatica: illness and treatment beliefs in a lumbar radicular pain population. A qualitative interview study. BJGP Open, 3(3), bjgpopen19X101654. doi: 10.3399/bjgpopen19x101654
Jesson, T., Runge, N., & Schmid, A. (2020). Physiotherapy for people with painful peripheral neuropathies: a narrative review of its efficacy and safety. PAIN Reports, 5(5), 1-e834. doi: 10.1097/pr9.0000000000000834
Schmid, A., Hailey, L., & Tampin, B. (2018). Entrapment Neuropathies: Challenging Common Beliefs With Novel Evidence. Journal Of Orthopaedic & Sports Physical Therapy, 48(2), 58-62. doi: 10.2519/jospt.2018.0603. <a href="https://www.freepik.com/photos/background">Background photo created by jcomp - www.freepik.com</a>