What Is Sciatica?
The sciatic nerve is the longest and thickest nerve in the body. Made up from nerve roots coming off the spinal cord in the low back and these nerve roots combine to form a thick nerve that is approximately 2cm wide, known as the sciatic nerve. From this point where these nerve roots combine the sciatic nerve runs down from the lower spine, through the buttocks all the way down the back of the leg to the foot. Each leg has its “own” sciatic nerve; therefore, it is possible to experience “sciatica” in either the right or left leg (and more rarely sciatica in both legs at the same time).
Statistically it is suggested that up to 40% of people will get sciatica, or experience sciatica symptoms at some point in their lifetime. Henceforth as a physiotherapist it is common to have someone seek your assistance to help them manage their sciatica. So, then what is sciatica? It may be news to you reading this that sciatica is not actually a diagnosis but is really just a term used to describe a set of symptoms. Anything that puts pressure on or irritates the sciatic nerve can potentially cause pain (or other neural symptoms, such as numbness or tingling) to shoot down the leg. It is these symptoms running down the leg from the irritation to the sciatic nerve which people refer to as sciatica. Nerve pain once present is often relentless and frequently causes significant discomfort to the individual suffering it. The nature of the pain with sciatica is that it can vary from being a dull ache, to a sharp, stabbing pain, or described as a burning sensation the latter of which is a common descriptor for nerve pain from many who suffer with it. Accompanying this pain as mentioned some may also experience other neural symptoms including tingling or numbness in the leg and foot, even weakness in any of the muscles the sciatic nerve innervates (supplies).
When someone comments that they are suffering with sciatica, what they are referring to is the sensation of pain, numbness, tingling, weakness… in one or both of their legs resulting from the compression, or irritation of the sciatic nerve. These symptoms will be experienced along the sciatic nerve pathway or in the muscles the nerve supplies.
Sciatica Is A Set Of Signs And Symptoms
As mentioned above sciatica is not actually a diagnosis in itself, rather a potential set of signs and symptoms indicating compression or irritation to the sciatic nerve. This irritation can come from several different origins. Meaning simply being told by a medical practitioner you have sciatica does not explain the actual underlying cause of the pain, it suggests nerve irritation but not what the actual origin of the nerve irritation or compression is, it simply highlights that they believe irritation is present. Technically sciatica simply refers to the pain caused by irritation or compression of one or more of the nerves exiting the lower spine that combine in making up the sciatic nerve, or to the irritation to nerve itself. There are several conditions which can cause this compression or irritation to the nerve roots contributing to the sciatic nerve or to the sciatic nerve as a whole.
What follows is a list of a few (but by no means is it an exhaustive list) of the common causes of “sciatica”:
- A Bulging or Herniated Disc: A bulging or herniated disc may in turn compress, nudge against or simply irritate nearby structures including the exiting lumbar or sacral nerve roots coming off the spinal cord. The very nerve roots that eventually join up to form the sciatic nerve. A disc bulge in one of these low back levels could cause compression or irritation to the adjacent nerve root and this may ultimately relay symptoms along the pathway that that specific nerve root supplies, giving the individual sciatic symptoms.
- Spinal Stenosis: Is a condition where there is narrowing of the spaces within the spine and with individuals suffering spinal stenosis of the lumbar spine the spinal nerve roots (and in more advanced conditions the spinal cord) in the lower back can become compressed (or choked). A situation which again can produce symptoms of sciatica.
- Spondylolisthesis: Isthmic spondylolisthesis can cause sciatica as one vertebral body slips forward over another and in turn may “pinch” on the nerve root. This is most common in the bottom couple of levels of the lower back due to the forces at these levels being the greatest. The nerve roots coming from these L4-5 and L5-S1 levels combine to make up part of the sciatic nerve and therefore spondylolisthesis at these levels in the back is another possible cause of sciatica.
- Sacroiliac Joint Dysfunction: Sciatica is generally defined as ‘pain in the lower back and hip, radiating in the distribution of the sciatic nerve’. Dysfunction or trauma to the sacroiliac joint (SIJ) can also give pain in a similar pattern to sciatica. Irritation or injury to the SIJ causing direct trauma or dysfunction, as well as inflammation, too much or too little movement at the SIJ can all potentially cause irritation to the portion of the sciatic nerve that travels directly in front of the sacroiliac joint.
- Piriformis Syndrome: Piriformis syndrome sometimes referred to as wallet sciatica is a condition whereby the piriformis, a muscle with its origins inside the pelvis irritates the sciatic nerve. The sciatic nerve runs under (and sometimes bisects through) the piriformis muscle on its way out of the pelvis. As a result, the relationship between the piriformis muscle and the sciatic nerve is such that the piriformis can potentially “squeeze” and irritate the sciatic nerve in this area leading to the individual experiencing sciatica.
In summary, when posing the question what is sciatica? Then sciatica itself isn’t the diagnosis and is simply an indication that irritation to the sciatic nerve exists. Said irritation may ultimately have one of several causes and physiotherapists are well positioned to help patients understand where their sciatica is coming from and advise on, as well as carry out many appropriate treatment approaches. If you suspect you have sciatica then seeing your physiotherapist is a good starting point. A physio can help in confirming the presence of irritation to components of the sciatic nerve and help ascertain the origin of any irritation and guide you on an appropriate management approach.
Disclaimer: This information is provided as an educational service and is not intended to serve as a substitute for personalized medical advice. Sydney Physio Clinic does not endorse any treatments, procedures, products mentioned in this post. Anyone seeking specific advice, or assistance regarding “What Is Sciatica?” should consult his, or her physiotherapist, orthopaedic surgeon, general practitioner, sports medicine specialist, or otherwise appropriately skilled medical practitioner.