Sciatica is defined as pain or discomfort associated with the sciatic nerve which runs from the lower back, down the back of the legs to the feet. It most commonly occurs in adults in the 20 – 60 year age group. It is estimated that up to 40% of the New Zealand population will experience sciatica at some point in their lives.
In older age groups sciatica most commonly occurs as the result of conditions caused by spinal degeneration, such as spinal stenosis. This is where the pathways through which the sciatic nerve travels are narrowed. Again, this causes compression and/or irritation of the sciatic nerve.
The sciatic nerve is the largest and longest nerve in the body. It originates in the lower spine, branches into the pelvis, then travels through the buttocks, down the back of the legs and branches into the lower legs and feet. Sciatic pain occurs when there is pressure on, or damage to, the sciatic nerve.
The most common cause of sciatica is disc prolapse (also known as disc herniation or slipped disc). This occurs when one of the soft, gel-filled discs between the vertebrae of the spine bulges or ruptures, compressing and/or irritating the sciatic nerve.
Muscle spasms can also cause sciatica by compressing the sciatic nerve as it travels through the muscles. One such condition is piriformis syndrome, where the piriformis muscle irritates the sciatic nerve. Other less common causes of sciatica include:
Factors that increase the likelihood of developing sciatica include:
- Being overweight
Essentially, any injury or process which causes compression of the sciatic nerve can cause sciatic pain. In many cases however, no specific cause for the sciatic pain can be identified.
Signs and symptoms
The pain caused by sciatica can range from being mild to being very severe. It can occur suddenly or have a gradual onset. Sciatic pain is commonly described as a cramp-like pain that can be burning or sharp in nature. It may be associated with sensations such as pins and needles, tingling, numbness and weakness.
Sciatic pain is typically felt in the lower back and hip and radiates down the back of one leg. The characteristic that distinguishes it from other types of back pain is that the pain travels below the knee. The pain may be aggravated by specific actions, such as sneezing, coughing, lifting or sitting.
Pain and symptoms are usually most severe in the early stages of the condition, when compression and inflammation of the sciatic nerve are at their greatest. It is common for the pain to gradually reduce after this time until it resolves completely - usually within four to eight weeks.
In rare cases compression of the sciatic nerve can be so severe that there is progressive weakness in the legs and/or loss of bowel and bladder function. If these symptoms are experienced, medical attention should be sought immediately as they can signal severe nerve damage.
In order to make an accurate diagnosis the doctor will take a detailed medical history, including the nature and duration of the symptoms, and what action or event lead to the onset of the pain. They will assess neurological function by checking the strength, sensation and reflexes in the legs. If loss of bowel or bladder control has been experienced, the doctor may perform a rectal examination to check for loss of sensation and muscle tone.
If the sciatic pain persists for a number of weeks, x-rays may be taken to assess any changes to the bones of the spine and pelvis and to rule out other causes for the pain such as tumours and infection. A CT scan (computerised tomography) scan or MRI scan (magnetic resonance imaging) may be recommended in some cases in order to assess the nerves, discs and spine in more detail.
Pain relief and treatment
The primary goal of initial treatment is the relief of pain. Treatment and relief options for sciatica include:
Bed rest had traditionally been recommended in the treatment of sciatica but this is no longer the case. Research has indicated that bed rest does not tend to speed recovery, and may in fact hinder it. It is now recommended that heavy physical activity should be avoided, but moderate activity should be maintained. It is thought that maintaining activity assists with overall recovery by helping to reduce inflammation.
Pain relieving medications such as paracetamol and non-steroidal anti-inflammatory medications (NSAIDs) are commonly used to treat sciatic pain. In cases where muscle spasms are thought to be the cause, muscle relaxant medications may be recommended. When pain is severe the use of opioids (eg: pethidine, morphine) may be necessary. Other medications that may be used are low dose anti-depressants (these reduce nerve stimulation) and epidural cortisone injections.
Manipulation, the use of heat and/or cold and specific exercises may be helpful in the treatment of the condition.
Some people may find relief of symptoms through osteopathy, chiropractic, massage or acupuncture.
While most cases of sciatica resolve within four to eight weeks, surgery may need to be considered in severe, prolonged cases where non-surgical treatment has been unsuccessful. Surgery aims to relieve the pressure on the sciatic nerve. This may involve removal of part of one of the intervertebral discs (discectomy) or removing the cause of pressure on the nerve (decompression). Only about five percent of people with sciatica need surgery. All other forms of treatment should be exhausted before surgery is considered.
While back pain due to sciatica, and other causes, is common, there are a number of measures that can help to prevent it occurring or recurring:
- Maintain correct posture when standing, walking and sitting.
- Undertake exercise that maintains aerobic fitness and strength and flexibility in the abdominal and spinal muscles.
- Practice safe lifting techniques. When lifting bend the knees and keep the back straight. By doing this, the strain is taken by the hips and legs, not the back. Hold the object close to the body. The further away from the body the object is, the more stress is put onto the lower back.
- Ensure that your back is well supported when seated. Use chairs that provide good back support and are designed to provide a good seating posture. A lumber roll or contoured cushion can help to provide lower back support.
- Don’t smoke.
- Maintain a healthy body weight.
American Academy of Orthopaedic Surgeons (2000) Sciatica. Illinios. AmericanAcademy of Orthopaedic Surgeons
Anderson, K.N., Anderson, L.E. & Glanze, W.D. (eds.) (2006) Mosby’s medical, nursing, & allied health dictionary (6th ed.) St. Louis: Mosby-Year Book, Inc
Pubmed Health (2012) Sciatica. A>D>A>M> Medical Encyclopedia. www.ncbi.nlm.nih.govpubmedhealth/PMH0001706/
Barrett. J. (2006) Sciatica. The Gale Encyclopaedia of Medicine. Third Edition. Jacqueline L. Longe, Editor. Farmington Hills, MI. Thompson Gale.
Last Reviewed – 16 November 2012