The sciatic nerve is the longest and largest nerve in the body. At its widest point, it has the width of a thumb! It has five nerve roots that converge together to create the whole nerve. These roots exit at the base of the spine at levels L4,5,S1,2,3. The nerve then extends through the pelvis and down the back of the leg where it branches off into smaller nerves that travel to the lower leg and foot.
What is sciatica?
True sciatica is an irritation or a compression of the sciatic nerve. Because its role is to provide both motor and sensory information to various parts of the leg and foot, when it becomes irritated or compressed, this can prevent nerve messages from travelling down the sciatic nerve properly. When a nerve becomes disrupted in this way, symptoms such as pain, burning sensations, pins and needles or numbness can occur, usually following the route of the affected nerve. This is why the main symptom of sciatica is pain travelling down the back of the leg. Some people find the sensation only goes as far as the back of the knee whilst for some it may travel all the way to the foot. Some people may find they can still move around with the pain and for others, the pain may be so debilitating that even walking is too painful to do.
Other symptoms of sciatica
The main symptom of sciatica is pain and this usually occurs either in the buttock, back of the leg, feet or toes. Sometimes the pain may occur in all of these places or it may occur in only one or two.
Other symptoms include:
Pins and needles or a ‘tingling’ sensation in the leg
Numbness in the leg
The affected leg may feel weaker than normal
Sometimes back pain can occur with sciatica but this is typically not as bad as the pain in the leg and if you only have back pain with no leg pain, it is unlikely to be sciatica
Causes of sciatica
Disc prolapse/bulge – this is one of the most common causes of sciatica. A disc prolapse is when the soft material inside the disc leaks out through the outer layers and irritates a nerve root near the spine. A disc bulge is slightly different. This is where the disc outer layer starts to bulge due to the pressure building up inside the disc. The soft material inside hasn’t leaked out but the pressure inside the disc is forcing it to bulge backwards and it’s the bulge that can press onto a nerve root.
Degeneration in the spine – as we age, the spine and other areas of the body start to show signs of ‘wear and tear’. In the spine, bony spurs may develop which can press onto the sciatic nerve roots.
Spondylolisthesis – this is a condition that results in one vertebral body slipping forward on the one below it. This condition normally occurs as a consequence of the ageing process whereby the ligaments and joints in the spine become weaker and are less able to support the spine properly. Spondylolisthesis can also be caused by a small stress fracture in the spine which then allows a vertebral body to slip over the one below it. The slipping forward can pinch the sciatic nerve.
Lumbar spinal stenosis – stenosis refers to a narrowing of the spinal canal. Lumbar canal stenosis is common with natural ageing, particularly over the age of 60.
Piriformis syndrome – the piriformis muscle is located in the buttock and is responsible for turning the hip outwards (external rotation). The sciatic nerve runs right underneath the piriformis muscle so if the muscle becomes irritated or too tight, it can irritate or pinch the sciatic nerve. Piriformis syndrome is not classed as a true lumbar radiculopathy as the irritation of the nerve is not happening at the nerve roots. However, because piriformis syndrome can cause the same symptoms of leg pain, it is sometimes also referred to as sciatica.
Sacroiliac joint dysfunction – this refers to irritation of the sacroiliac joint located at the base of the spine where the spine and pelvis meet. Sacroiliac joint dysfunction can irritate the L5 nerve which can cause sciatic-type pain. Again, like piriformis syndrome, the nerve roots are not affected so it is not classed as true lumbar radiculopathy but may still be diagnosed as sciatica.
Muscle strain – in some cases, muscles surrounding the sciatic nerve that become strained or spasm can put pressure on the sciatic nerve and cause sciatic type symptoms.
Spinal tumour – this is rare but if present, it can pinch some of the nerve roots in the lower back and cause sciatica.
Pregnancy – particularly during the later stages of pregnancy as the bump grows and the body gains weight can cause sciatica during pregnancy.
Fracture – if a fracture occurs within the lumbar spine, it can cause sciatica if it pinches the nerve roots. Most fractures in the lumbar spine occur due to serious trauma such as a car accident or fall but they can also occur if the bone weakens due to conditions such as osteoporosis.
How to treat sciatica
For most people, sciatica usually gets better on its own but this does depend on the cause so it’s important to always get your symptoms checked. Ways to treat sciatica include:
Painkillers and anti-inflammatories – these should only be taken if prescribed by your GP or other health care professional.
Ice/heat – in the first couple of days, only apply ice. Ice should be applied to the painful site for between 5-10 minutes and repeated 3-5 times a day. After the first couple of days, switch to heat.
It’s important to try to keep moving as normally as possible but try to avoid any high impact activities such as running and jumping.
Avoid heavy lifting and if you do have to lift something, make sure it’s light, bend your knees and brace your core. Try to avoid bending over as this will stretch the sciatic nerve and cause pain.
When returning to exercise, start gently and focus on building up core strength.
Physical therapy such as osteopathy is proven to help people suffering with the symptoms of sciatica.
If physical therapy is unsuccessful, it may be necessary to have an MRI scan to determine how severely the sciatic nerve is being pinched. Results of an MRI may determine whether other treatment options may be needed such as injections or surgery to decompress the sciatic nerve.
If you or someone you know is suffering with sciatica, feel free to get in touch if you have any questions or would like to enquire about treatment. Remember, sciatica is a symptom, not a diagnosis. What causes one person’s sciatica may be different for someone else. Even if the cause is the same, your symptoms may be different. Factors such as age, lifestyle and overall health can determine how sciatica affects you. To find out how osteopathy can help you, get in touch!