What is sciatica?
The term “sciatica” is often used incorrectly in reference to any pain felt in the area running from the back, down into the leg. Back-related nerve pain is more correctly referred to as radicular pain. Radicular pain is pain related to an irritation of the nerve roots as they exit the spine.
Nerve roots leave the spinal cord via the intervertebral foramina (holes or spaces between the vertebrae) and join together from various levels of the spine to travel as cord-like structures, called nerves, to their destinations (Figure 1). It is these nerves that travel outside the spinal cord that are referred to as “peripheral nerves”. Along their journey these peripheral nerves run between and through muscles and fibrous tunnels. While radicular pain arises from a problem as the nerve root exits the spine, nerve-related pain may develop due to a problem along the pathway of a peripheral nerve, outside the spine. Pain related to a nerve is called “Neuralgia” – which simply means nerve-pain.
Sciatica should be used to refer to neuralgia of the sciatic nerve. Here we will discuss hip related sciatica associated with irritation of the nerve as it runs through the buttock, across the back of the hip, including piriformis syndrome and deep gluteal syndrome.
What are the usual symptoms of hip related sciatica?
- Hip-related sciatica often presents as deep buttock pain, which may extend down the back of the thigh and even further into the lower leg and foot.
- Even if the irritation of the nerve is in the buttock, pain can also be felt into the lower back as well, which often results in delayed or misdiagnosis.
- There may be odd zings or zaps of pain
- Tingly sensations or numbness sometimes accompany the pain
- Pain is usually aggravated in positions where the hip is bent – such as in sitting, even more so if the knee is straighter. Driving can therefore be problematic.
- Pain may also be aggravated by any strong contraction of the buttock muscles such as walking upstairs or uphill or exercises that target the buttock muscles.
- Pain is often worse at night and is eased somewhat in the morning by standing and walking.
- In more severe cases, walking may be accompanied by a painful limp.
What causes hip related sciatica?
The sciatic nerve does not exit the spine as a single nerve. Nerve roots from the lower levels of the lower back (lumbar spine) and tailbone (sacrum) join together in the pelvis. Here they form a thick, cord-like structure, called “the sciatic nerve”. This large nerve exits the inner pelvis via the greater sciatic notch and runs through the buttock and down the back of the thigh (Figure 2).
The sciatic nerve can sometimes be compressed, irritated or entrapped as it runs through the soft tissues of the buttock. Traditionally, sciatica (sciatic neuralgia) generated from issues within the buttock has been termed “Piriformis Syndrome” (see Figure 2 to view the piriformis muscle and the sciatic nerve). This was based on a finding that in about 20% of the population, all or part of the sciatic nerve runs through the piriformis muscle. Compression of the nerve within the piriformis muscle was thought to be the problem in all cases of nerve related buttock and leg pain that could not be associated with a problem in the back. It is now thought that this is the case in only a relatively small number of cases.
In most people the sciatic nerve runs under the piriformis muscle to emerge into the “deep gluteal space” – the deep buttock area beneath the gluteus maximus (large, superficial buttock muscle). It is thought that the nerve may still be compressed under the piriformis muscle, particularly if the piriformis is particularly bulky, tight or excessively active1. It remains unclear how commonly this occurs, but it should be considered as one of a number of causes of hip-related sciatica.
Deep Gluteal Syndrome
The term “Deep Gluteal Syndrome” has been suggested recently to describe all causes of irritation of the sciatic nerve in the deep gluteal space, the space beneath the gluteus maximus (buttock) muscle2. In this space, the sciatic nerve may be compressed or irritated as it runs under the piriformis (piriformis syndrome), or as it runs over the deep external rotator muscles or by fibrous bands anywhere along its path through the buttock. The nerve can also be irritated as it leaves the pelvis to head down into the thigh. Here it runs through a tunnel (ischial tunnel), between the outer side of the sitting bone (ischial tuberosity) and the upper thigh bone (femur) (Figure 2). In this tunnel it may be squeezed between the bones or irritated by unhealthy hamstring tendons1. These tendons join the hamstring muscles in the back of the thigh, onto the sitting bones (Figure 2).
Tight (fibrous) bands may develop after trauma such as a hard fall onto the buttock or due to inflammation related to muscle or tendon injury or overuse1. These bands or tight/overactive muscles may bind down the nerve, causing restricted movement of the nerve and reduction in normal healthy blood flow. Altered strength or function in other muscles that control pelvic position (gluteus medius and minimus (Figure 2) may have secondary effects on muscles of the deep gluteal space. Postural and movement habits (e.g. pattern of walking, running, standing on one leg) that result in reduced space in the ischial tunnel (Figure 2), may also contribute to the development of symptoms.
Make sure you check out our next blog next on getting help with hip related sciatic pain – learn what treatment options are out.
And over the next few weeks we will continue to explore different ways in which you can help yourself.
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- Harris-Hayes, M. and Royer, N. (2011). Relationship of Acetabular Dysplasia and Femoroacetabular Impingement to Hip Osteoarthritis: A Focused Review. PM&R, 3(11), pp.1055-1067.e1.
- Martin, H., Reddy, M. and Gomez-Hoyos, J. (2015). Deep gluteal syndrome. Journal of Hip Preservation Surgery, 2(2), pp.99-107.
Check Out More You Can Read on this Area at HipPainHelp:
- Hip Pain Explained: Peripheral nerve pain. Learn about all the nerves aroudn the hip and pelvis that may be involved with hip, pelvic and upper thigh pain
- Is My Hip Pain Nerve Pain (Radicular or Neuralgia)? Read this blog to understand what nerve pain is and in what forms it can exist.
- Top Tips for Hip Pain Relief Sitting, when Socialising or Travelling. If your nerve pain is exacerbated when sitting this blog may be extremely useful in suggesting ideas to help relieve this.
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