What is Sciatica?
The term sciatica is ever-evolving. Typically, it includes a variety of conditions that all relate to the sciatic nerve. Generally speaking, sciatica is associated with pain or other symptoms that radiate down the leg along the sciatic nerve. While this is pretty much correct, there are many fine details that could be worth knowing, particularly if you are concerned whether or not you have sciatica.
In this article, we would like to highlight some of the conditions that are included in the term sciatica, as well as some common misconceptions about this condition. However, given these types of conditions vary greatly across individuals, it is always best to have an examination performed by your doctor or physiotherapist before jumping to any self-diagnosis. Nevertheless, we hope this information provides you with some useful education and a good starting point.
The Sciatic Nerve
The sciatic nerve is the biggest nerve in the body. Believe me, it's shockingly big. Having seen and actually held an intact sciatic nerve on a cadaver, I was surprised even with prior information about its structure. The sciatic nerve is a combination of 5 nerve roots that exit from the spine in the lower back region. These nerve roots are L4, L5, S1, S2, an S3, and they combine to form the massive sciatic nerve, which emerges from under the piriformis, which is a small, but highly functional muscle deep in the gluteal region (a.k.a. the butt).
The sciatic nerve then goes on to travel down the back of the leg sending off branches as it goes. It travels all the way down across the knee joint, and as it continues down the leg, it gradually branches out more and more, thinning along the way. For example, the large nerves in the calf region, which include the tibial nerve and the common peroneal nerve, are both branches of the even larger sciatic nerve. The sciatic nerve can actually be about as thick as an index finger, and it really is incredible.
Given the sciatic nerve is the source of supply for so many muscles, including all the hamstring muscles (biceps femoris, semitendinosus, semimemranosus, and adductor magnus), as well as all the muscles in the calf area and many in the foot, one can start to understand why any compromise to this nerve can have major consequences. Below are a list of muscles supplied by the sciatic nerve and it's main two branches.
Muscles Supplied by the Sciatic Nerve, Tibial Nerve, and Common Peroneal Nerve
NOTE: Sometimes people interchange the word "peroneal" with "fibular". The tibia and fibula are the two bones of your shin. The tibia is the big one you can feel along the front of your shin, and the fibula is the smaller one that sits just to the outside of the tibia.
Common Peroneal Nerve
(superficial and deep peroneal nerves)
Peroneus longus (superficial)
Peroneus brevis (superficial)
Tibialis anterior (deep)
Extensor digitorum longus (deep)
Flexor digitorum longus
Extensor hallucis lingus (deep)
Flexor hallucis longus
The sciatic nerve and its associated branches also go along to supply sensation to specific areas of the skin, but this is much more variable across individuals, and there is also some overlap. However, the same principle holds in that if the sciatic nerve is compromised, you may notice symptoms such as numbness, tingling, or burning going down specific areas of the leg.
Difference Between Referred Pain, Radicular Pain, and Radiculopathy
This may seem irrelevant, but it's actually a crucial part in understanding sciatica, as well as discriminating it from other conditions.
Many people have heard the term "referred pain" before, but may not have received much explanation about it. Basically, referred pain is the sensation of pain somewhere other than the source of the pain. For example, if you have an injury to an anatomical structure in your lower back, you may notice pain extending into the buttock or hip region. Similarly with the neck, injury to structures in the neck can cause pain to be referred across to the shoulder, down the back, or up to the head.
Depending on the context, referred pain can actually be an overarching term for all type of pain that occurs away from the source of the injury or condition, but in some situations, some healthcare professionals will separate this from radicular pain, and radicular pain even further from radiculopathy.
Radicular pain is pain associated with irritation of a nerve root. For more information about nerve roots specifically, as well as associated conditions, please refer to our detailed articles on myotomes and dermatomes. In the case of the lower back, if the nerve roots that exit the spine in the lower back region become irritated, this can have a whole cascade of effects downstream.
Remember, the sciatic nerve itself is composed of 5 different nerve roots, so irritation to even one of those nerve roots can elucidate symptoms. There doesn't have to be any traumatic injury, and in fact, most nerve root conditions are due to posture or chronic patterns of movement, for example, repetitive movement at work that requires awkward positions of the lower back. Often times, people will complain of severe pain down the leg, but the lower back actually feels ok, maybe just a little stiff. That said, a traumatic or acute injury can definitely lead to nerve root problems as well, they're just a bit less common.
So what does this have to do with sciatica. In a sense, radicular pain in the leg is sciatica, as long as it involves the sciatic nerve! The sciatic nerve has become compromised at the source, and radicular pain is the main symptom, and it is often accompanied by some form of sensation symptoms, such as numbness or tingling in the foot and ankle.
It is important to note that one of the main discriminating factors doctors and physiotherapists use to separate radicular pain from referred pain is that in the case of radicular pain (what we are talking about now), this will extend below the knee. A lot of research suggests that if the pain is only found in the hip or thigh area, that this often isn't due to irritation of the nerve roots contributing to the sciatic nerve. So if you don't have any pain extending below the knee, then there's a decent chance that you don't have sciatica, but that's not a guarantee, so it's always a safe bet to get it checked out regardless.
The difference between radicular pain and radiculopathy is often difficult for people to grasp. To simplify it, it's best not to go into too much detail, but here are some key points. With radicular pain, you may have some weakness due to the pain, usually in the form of inability to sustain a muscle contraction for a long period of time. Otherwise, function is fairly normal, it just hurts and there may be some weird sensation issues.
On the other hand, radiculopathy actually refers to a decreased ability of the nerve to conduct signals all the way down it's length. Nerve roots are still a primary culprit, but weakness will be much more noticeable, as will sensation changes. Sometimes pain may not be present at all, which can make it an alarming experience for some people to lose function without knowing what's really going on. Radicular pain and radiculopathy are closely related, but in the case of all three topics that we just discussed here, it will take careful examination by your doctor or physiotherapist to figure out which one is at play.
How do I know if I have sciatica?
First and foremost, sciatica will need to be diagnosed by your doctor or physiotherapist, and in some cases, may require some sort of medical imaging to confirm. However, there are many tests that physicians can use to help narrow the focus of the diagnosis and pinpoint sciatica.
Straight Leg Raise Test
This test is fairly straightforward, but it actually provides some very important information. This test is usually performed with the patient laying on their back. The doctor or physiotherapist will lift your leg towards the ceiling keeping the knee straight, so only bending at the hip. Given the sciatic nerve runs down the back of the leg and cross the hip, knee, and ankle joints, this will place tension on the nerve, ultimately producing pain and reproducing any other symptoms.
Leg Pain Worse Than Back Pain
In most cases of sciatica, the leg pain will be worse than the back pain. In cases where a fairly traumatic injury has occurred, making sciatic nerve pain an outcome of this injury, the pain may be very comparable at each site. Nevertheless, in most cases, sciatica is characterized by leg-dominant pain. Additionally, this pain is typically constant, with very few strategies proving effective for pain relief. Generally speaking, the pain will not be relieved by changes in position of the leg, but may be temporarily relieved in certain positions of the spine.
The presence of neurological symptoms also points towards a condition like sciatica. These are symptoms other than pain, including the classically present numbness and/or tingling. Some patients also feel like they have dead spots in their leg or foot, or that they have generalized weakness. This may be very subtle, or it may be intense enough to affect your walking pattern.
Sciatica is Not Very Common
One other thing to keep in mind is that sciatica is not very common. Estimates range between 5-15% of low back pain cases, but is likely more towards the lower end. This doesn't necessarily mean that if you do have sciatica that it's a huge problem, but rather, chances are if you have low back pain with a little bit of referred pain, that probability says there's a better chance it isn't sciatica. We're not saying to ignore your symptoms, but rather, think about this objectively and seek examination from a healthcare professional for a more valid and reliable diagnosis.
Underlying Causes of Sciatica
There are many different things that can lead to sciatica. When you think of the very small spaces that nerve roots must exit from the spine, it's easy to imagine that any irritation, trauma, or inflammation in the area will somehow affect the nerve roots. The most common culprits include herniated intervertebral discs, lumbar spinal stenosis, degenerative disc disease (usually with age), poor posture, and sometimes pregnancy, among many other conditions and factors.
Treatment for Sciatica
Aside from pain medications, particularly non-steroidal anti-inflammatory drugs, as well as home remedies like ice and heat, the main non-surgical treatment for sciatica is exercise prescription. A lot of people find this counter-intuitive, which is totally understandable, but in reality, exercise prescription is one of the best ways to make sustainable changes in body position, particularly in relation to joints like those in the spine. This is why physiotherapy is a highly effective method of treating sciatica. In extreme cases, and depending on the cause, surgery may also be indicated. Overall, the vast majority of cases clear up within a 1-3 months after starting physiotherapy treatment, but this will vary by individual.
We hope this article helped you understand sciatica in a little more detail. While we can't provide you with an exact diagnosis of the pain you are experiencing, we hope this will help you understand the advice you receive more comprehensively, and that this will provide you with a good starting point for seeking care. There are many other reliable resources on the web as well, so by exploring those in addition to this article, you can become well educated in the area of low back pain. Good luck!