Sciatica is the name given to any pain stemming from the irritation of the sciatic nerve. Anything that irritates this nerve can cause pain that ranges from mild to severe; usually, from a compressed nerve root in the lumbar (lower) spine. Often, the term "sciatica" is confused with general back pain. However, sciatica is not just limited to the back.
The sciatic nerve is the longest and widest nerve in the human body. It runs from the lower back, through the buttocks, and down the legs, ending just below the knee. This nerve controls several muscles in the lower legs and allows that area to be sensitive to touch.
Sciatica is not, in fact, a condition, but rather a symptom of another problem involving the sciatic nerve.
According to MediLexicon's medical dictionary, sciatica means "Pain in the lower back and hip radiating down the back of the thigh into the leg, initially attributed to sciatic nerve dysfunction (hence the term), but now known to usually be due to herniated lumbar disk compressing a nerve root, most commonly the [5th lumbar vertebra] or [1st sacral vertebra] root."
Types of sciatica
There are two types of sciatica. These are:
The sciatic nerve branches from the lower back, through the buttocks, and down the legs, ending just below the knee.
Acute sciatica (short-term)
Acute sciatica does not typically require professional treatment; symptoms can be significantly reduced with the use of accessible over-the-counter (OTC) painkillers combined with hot and cold packs and exercise.
Chronic sciatica (long-term)
Chronic sciatica, on the other hand may require physical therapy (UK: physiotherapy), which may include exercise, applied heat, and other techniques. In rare cases surgery may be required.
Acute sciatica may last between four to eight weeks, while chronic sciatica persists for longer.
Causes of sciatica
Sciatica is a common symptom of several different medical conditions, the most pervasive being a herniated (slipped) disc.
The spinal column is made up of three parts:
- Vertebrae (individual bones in the spine that protect underlying nerves)
A herniated disc occurs when some of the nucleus (pink) pushes through the annulus (yellow). This can put pressure on the sciatic nerve, causing pain.
A disc is made of a strong and resilient type of tissue (cartilage), and acts as a cushion between each vertebrae and allows the spine to be flexible. A herniated disc occurs when a disc is temporarily pushed out of place and puts pressure on the sciatic nerve.
Other causes of sciatica include:
- Lumbar spinal stenosis - a narrowing of the spinal cord (a channel within the vertebrae that contains the nerves) in the lower back that may compress the sciatic nerve.
- Spondylolisthesis - a condition in which a disc may slip forward over the vertebra below it, pinching the sciatic nerve.
- Tumors within the spine may compress the root of the sciatic nerve.
- Infection within the spine.
- Injury within the spine.
- Cauda equina syndrome - a rare, but serious condition that affects the nerves on the lower part of the spinal cord; it requires immediate medical attention. Cauda equina syndrome may permanently damage the nervous system and even lead to paralysis.
In many cases of sciatica there is no single obvious cause. Anything that irritates the sciatic nerve can produce sciatic pain. However, it is thought that a combination of muscle, joint and bone strain may lead to sciatica, which is why it is more common in people over 40.
Risk factors for sciatica
A risk factor is something that increases the likelihood of developing a disease or condition. For example, smoking raises the risk of developing many cancers - therefore, smoking is a risk factor for cancer.
Common risk factors for sciatica include:
- Age - due to the deterioration of discs, people in their 30s and 40s have a higher risk of developing sciatica.
- Profession - jobs that require lifting heavy loads for long periods.
- Sedentary lifestyle - people who sit for long periods and are physically inactive are more likely to develop sciatica, compared to physically active individuals.
Symptoms of sciatica
The main symptom of sciatica is a shooting pain anywhere along the sciatic nerve; from the lower back, through the buttock, and down the back of either leg (usually only one leg is affected). This pain can range from mild soreness to a sharp pain or severe discomfort, and may be aggravated if you sit for long periods.
Other common symptoms of sciatica include:
- Numbness in the leg along the nerve; occasionally, this numbness in one part of the leg may be accompanied by pain in a different part of the leg.
- Tingling sensation (pins and needles) in the feet and toes.
On the next page we look at the diagnosis of sciatica, the treatments for the condition and some of the exercises you can do at home to help with sciatica.