What is sciatica?

Sciatica is nerve pain felt due to irritation or damage to your sciatic nerve. The sciatic nerve is the largest nerve in your body, supplying sensation to the skin and controlling muscles in the back of the legs. Sciatica is typically felt as shooting pain travelling down the leg, or as a burning pain in your buttock. 

Causes

What is the sciatic nerve?

The sciatic nerve is a major nerve that originates in your spinal cord then travels deep within your pelvis to emerge through a muscle in your buttocks (piriformis muscle). It then passes down the back of your legs, branching towards your feet. It is the longest and widest nerve in your body. It controls function and sensation in areas of your legs and feet, and supplies supply sensation to areas of the buttocks.

The sciatic nerve is irritated by spasms in the piriformis muscle, causing pain in the buttocks and legs.The sciatic nerve is irritated by spasms in the piriformis muscle, causing pain in the buttocks and legs.  

A range of conditions can cause sciatica, by either compressing, irritating or pinching the sciatic nerve. Causes of sciatica include:

Prolapsed disc

Otherwise known as a 'herniated' disc or having a 'slipped disc', it refers to damage to a disc in your spine, which causes it to protrude and potentially put pressure on the spinal cord and nerves. The spine is made up of vertebrae (the bones) and discs that are stacked on each other. They help protect the spinal cord and nerves, while providing flexibility to the spine. The discs are fibrous capsules filled with a gel-like substance. If you damage a disc, the gel leaks out and can put pressure on the nearby nerves, potentially causing sciatica.

The lumbar (lower back) vertebrae have to handle a great deal of stress during your daily activities. The discs that support your lumbar region are vulnerable to degeneration and becoming less flexible as you age. This makes them more susceptible to injury and, once injured, may result in long-term sciatica or back pain.

Slipped disc, disc herniation, prolapsed disc.A herniated disc presses on the spinal nerve, resulting in pain. 

Spinal stenosis

This is when the spinal canal becomes narrower. This can place pressure on the spinal cord, which gives rise to pain in nerves such as the sciatic nerve. It can have numerous causes, including prolapsed discs, bony overgrowths, thickened ligaments, tumours and spinal injuries.

Cauda equina syndrome

Cauda equina syndrome is a rare condition in which the nerves that come out of the end of your spinal cord become damaged and compressed, leading to a lack of bladder and bowel control, numbness in the 'saddle' buttock area, and weakness or paralysis of the lower limbs. This is a medical emergency that can lead to paralysis, if not immediately treated.

Muscle spasm - piriformis syndrome

Your sciatic nerve can become irritated by muscle spasms in the tissues surrounding it, in particular your piriformis muscle. Your piriformis muscles are found deep within your buttock and connect the top of your thighbone (femur) to your lower spine (sacrum). These muscles stabilise your hip when you move from one foot to another and are responsible for rotating your thigh away from your body. Activities such as going up stairs, sitting for long periods and long-distance running can irritate this muscle, causing it to tighten or go into spasm and compress your sciatic nerve. Pain and numbness is felt in your buttock region and can travel down your leg. Stretching prior to running and avoiding being seated for long periods, in addition to visiting a physiotherapist to assess your condition, are often recommended. 

Other causes

Other reasons for sciatica include infections, a tumour growing near the nerve and injury or bleeding in the tissue surrounding the nerve.

Warning signs needing further investigation

There are some more serious conditions of which sciatica can be a warning sign. If you experience any of these symptoms, seek immediate medical attention;

Potential cauda equina syndrome signs:

  • Loss of bladder/bowel control;
  • Continued weakness in your leg and foot, and;
  • Numbness in your leg, foot or buttock.

Potential signs of infection or cancer:

  • Fever and chills;
  • Unexplained weight loss;
  • Being over 50 years of age and not having had back pain before;
  • Having a history of cancer;
  • Recent bacterial infection, such as a urinary tract infection (UTI);
  • If you intravenously inject recreation drugs, and;
  • If you have a weakened immune system.

Bladder

An organ in the lower abdomen that stores urine for excretion.

Cancer

A large group of diseases whose common feature is that they are caused by an uncontrolled growth of the body's cells.

Cauda equina syndrome

A rare and serious condition in which the nerve roots at the end of the spinal cord are compressed.

Disc

Intervertebral discs - layers of cartilaginous material that act as cushions between the vertebrae and the joints in the spine, enabling the spine to bend and twist.

Fever

An increase in body temperature above the normal temperature range. Fever is often caused by the body's immune reaction to infection.

Immune system

The organs and cells involved in protecting the body against infection.

Infections

Entry into the body of microorganisms that can reproduce and cause disease.

Ligaments

Short, flexible fibrous tissue that connects the bones and cartilage of joints.

Paralysis

An inability to move or feel; a loss of muscle function or sensation.

Pelvis

The bony structure in the lower part of the body trunk that connects the base of the spine to the legs. The pelvis protects important organs, such as the bladder and bowel (and in women, the uterus), and anchors thigh and abdominal muscles.

Physiotherapist

A healthcare professional trained in treating injury or disability with physical remedies, such as massage or exercise.

Sacrum

A triangular bone at the base of the spine.

Spinal cord

A bundle of nerve tissue that runs from the brain through the spinal column and connects the brain to the body, transmitting sensory and motor signals.

Tumours

A growth caused by an abnormal and uncontrolled reproduction of cells.

Spinal canal

The cavity running through the middle of each vertabrae of the spine that contains the spinal cord.

Bowel

The part of the digestive tract that comprises the small and large intestines.

Risk factors

Risk factors for sciatica include:

  • Age - between 30-50 years of age;
  • History of prolapsed disc or other degenerative spinal conditions;
  • Being overweight, obese or pregnant, as these conditions put extra pressure on the nerve;
  • Diabetes - if you are diabetic, you are more prone to nerve damage;
  • Being sedentary - people who sit all day, such as drivers or computer users, are at greater risk, and;
  • Regular, strenuous walking or running, due to continued use of the piriformis muscle.

Diabetes

A metabolic disorder that is caused by problems with insulin secretion and regulation and which is characterised by high blood sugar levels. Also known as diabetes mellitus.

Disc

Intervertebral discs - layers of cartilaginous material that act as cushions between the vertebrae and the joints in the spine, enabling the spine to bend and twist.

Signs and symptoms

You may experience the following symptoms:

  • Shooting or aching pain, radiating down the back of your leg;
  • Burning pain in the buttock;
  • Pins and needles in the foot;
  • Weakness in your foot or leg muscles, and;
  • Pain that worsens when you cough or lift something heavy.

Warning signs

If you also experience any of these symptoms, seek medical attention immediately;

Bladder

An organ in the lower abdomen that stores urine for excretion.

Fever

An increase in body temperature above the normal temperature range. Fever is often caused by the body's immune reaction to infection.

Paralysis

An inability to move or feel; a loss of muscle function or sensation.

Bowel

The part of the digestive tract that comprises the small and large intestines.

Methods for diagnosis

Sciatica can be diagnosed from its typical pattern of symptoms. Imaging tests are usually not needed, unless your doctor is concerned about the cause of your pain, or if you have had symptoms for longer than six weeks without any change in the level of pain. 

Imaging tests

Depending on your age and symptoms, your doctor may recommend imaging tests such as an X-ray, magnetic resonance imaging (MRI) or a computerised tomography (CT) scan to confirm your diagnosis.

Blood tests

To rule out the possibility of a spinal infection, your doctor may also request a blood test.

Computerised tomography

A scan that uses X-rays to create a 3D image of the body. This can detect abnormalities more effectively than a simple X-ray can.

Infection

Entry into the body of microorganisms that can reproduce and cause disease.

Magnetic resonance imaging

A type of imaging that uses a magnetic field and low-energy radio waves, instead of X-rays, to obtain images of organs.

X-ray

A scan that uses ionising radiation beams to create an image of the body’s internal structures.

Types of treatment

Self care

There are several measures you can do to help to relieve sciatica, including the following:

  • Rest - when in bed, lying on a well-supported mattress usually helps and you may find sleeping on your side with a pillow between your knees helps to relieve pain;
  • Exercise - give yourself a few days to rest, then start gentle, stretching exercises to increase blood flow and circulation to your lower back and legs;
  • Posture - sit up straight, keeping your shoulders back and your head upright. Slouching puts pressure on your vertebrae and discs;
  • Ice or heat - applying an icepack or heat pack can help with inflammation. Put a towel on your skin first though, to avoid skin damage from cold or heat. You may find alternating between heat and cold brings relief. Warm baths are also good for relaxing muscles and relieving pain, and;
  • Avoid triggers - avoid bending, twisting or lifting heavy objects until your symptoms have resolved.

Treatment at home is always best discussed with your doctor or physiotherapist first to ensure it is appropriate for your specific circumstance.

Medication

Depending on the level of pain you are experiencing, you may find medication will relieve the majority of your symptoms along with rest or stretching, including the following:

  • Pain-relief medications, such as paracetamol and ibuprofen;
  • Corticosteroids, such as prednisolone, can be taken orally for a short period of time to reduce inflammation;
  • Nerve block - local anaesthetic and/or corticosteroids can be injected directly around the affected sciatic nerve to reduce pain and inflammation;
  • Epidural injection - this involves injecting local anaesthetic and/or steroids directly into the epidural space within your spinal canal. This is used to reduce the pain and inflammation that is putting pressure on your nerve roots. This is only used in severe cases and there are mixed views on the long-term efficacy of this treatment, and;
  • Antibiotics - these are likely to be prescribed if you have an infection.

Physiotherapy

A physiotherapist is an expert in how your muscles work and, in particular, how to rehabilitate them after an injury or sprain. They can assess the condition of your muscles, tendons and ligaments, then design exercise programs to strengthen them. Your physiotherapist can teach you exercises and stretching techniques that you can then use at home.

Surgery

Surgery is only considered as a last resort if all other treatments have failed. All forms of surgery carry risks and these can be discussed with your surgeon before a decision is made:

  • Laminectomy - trimming off parts of the vertebra that place pressure on the spinal cord or sciatic nerve;
  • Discectomy - removal of part of a damaged disc that is putting pressure on the sciatic nerve, and;
  • Fusion surgery - surgery to fuse the vertebrae together. 

Acupuncture

Acupuncture may help to relieve pain and relax tight muscles.

Acupuncture

A form of complementary therapy that involves fine sterilised needles being inserted into the skin at specific points to treat medical conditions.

Antibiotics

Chemical substances that kill or suppress the growth of bacteria.

Corticosteroids

A medication that resembles the cortisol hormone produced in the brain. It is used as an anti-inflammatory medication.

discs

Intervertebral discs - layers of cartilaginous material that act as cushions between the vertebrae and the joints in the spine, enabling the spine to bend and twist.

Epidural

An anaesthetic injected into the epidural space of the spinal cord, especially used in childbirth.

Infection

Entry into the body of microorganisms that can reproduce and cause disease.

Inflammation

A body’s protective immune response to injury or infection. The accumulation of fluid, cells and proteins at the site of an infection or physical injury, resulting in swelling, heat, redness, pain and loss of function.

Ligaments

Short, flexible fibrous tissue that connects the bones and cartilage of joints.

Local anaesthetic

A type of medication that, when administered to an area, creates a localised loss of sensation by blocking nerve activity.

Physiotherapist

A healthcare professional trained in treating injury or disability with physical remedies, such as massage or exercise.

Spinal cord

A bundle of nerve tissue that runs from the brain through the spinal column and connects the brain to the body, transmitting sensory and motor signals.

Steroids

A class of chemical substances that have a certain complex of carbon particles. The body produces several types of steroids naturally and artificially-produced steroids are used as medications.

Tendons

Dense bands of connective tissue that attach muscles to bones.

Vertebrae

The bones that make up the spinal column.

Spinal canal

The cavity running through the middle of each vertabrae of the spine that contains the spinal cord.

Potential complications

Most cases of sciatica are uncomplicated, but if your symptoms are chronic (prolonged) or if there is significant nerve compression, you may need medical or surgical intervention. Serious conditions such as cauda equina syndrome, infection or cancer will need urgent medical intervention.

Cancer

A large group of diseases whose common feature is that they are caused by an uncontrolled growth of the body's cells.

Cauda equina syndrome

A rare and serious condition in which the nerve roots at the end of the spinal cord are compressed.

Infection

Entry into the body of microorganisms that can reproduce and cause disease.

Prognosis

The outlook for most cases of sciatica is good. Self care, exercise and pain relief tend to be sufficient in managing symptoms. Avoiding injury, along with staying fit and healthy, are often enough to manage symptoms.

Prevention

It may not be possible to avoid developing sciatica, but you can avoid activities that can lead you to injuring your back, including the following:

  • Learn how to lift properly - bend your knees and keep the load close to your waist;
  • Do not twist when lifting - keep your knees in line with your shoulders;
  • Push objects instead of pulling them;
  • Try not to sit all day - this puts pressure on your sciatic nerve. Get up at least once an hour and walk around;
  • Regular, gentle exercise can give flexibility and strength to your back;
  • Maintain a healthy weight, and;
  • Be aware of your posture and learn what triggers your symptoms.