Causes Of Sciatica

Slipped (herniated) Disc

A slipped (or herniated) disc is the most common identified cause of sciatica.
Your spine is made up of vertebrae, discs and nerves. Vertebrae are the blocks of bone that make up the structure of your spine and protect the nerves.


The vertebrae are supported and cushioned by discs. The discs are made from a tough, fibrous case that contains a softer gel-like substance. A slipped disc occurs when the outer part of the disc ruptures (splits), allowing the gel inside to bulge and protrude outwards between the vertebrae. When this presses against the sciatic nerve, it can cause sciatica.
As a person gets older the discs start to become harder, tougher and more brittle. Repeated strain on the back means there is a greater chance of a hardened disc splitting and rupturing.

Spinal Stenosis

Spinal stenosis is the narrowing of nerve passages in the spine. It occurs when the bones, ligaments or discs of the spine squash the nerves of the spine (usually the sciatic nerve) causing pain, usually in the lower back and legs. It usually affects people in late middle age and older.

Causes Of Spinal Stenosis Include:

• Age-related changes in the spine
• Changes in the ligaments of the spine
• Diseases of the bone, such as Paget’s disease

Lumbar Decompressive Surgery - Who Needs It?

1. Healthy disc
2. Nerve root
3. Extruded disc protrusion
4. Disc bulge
5. Spinal nerves (cauda equina)

Conditions that may require lumbar decompressive surgery include:

Spinal Stenosis:

Spinal stenosis is the narrowing of the central spinal canal or side root canals of the spine. This narrowing causes pressure on the nerves in the canal, leading to pain, usually in the lower back and legs.

Causes Of Spinal Stenosis Include:

Age-related degeneration of the spine. The main cause of spinal stenosis is natural age-related degeneration. This is often linked to osteoarthritis. As the vertebrae (bones) of the spine begin to weaken and deteriorate, they rub against each other. This causes bony growths called bone spurs, which can cause the spinal canal to narrow.

Changes in the ligaments of the spine. Like the bones of your spine, the ligaments in your back degenerate over time and can become stiff and thick. This loss of elasticity can have the effect of narrowing your spinal canal.
Diseases of the bone. Diseases that affect bone growth, such as Paget’s disease and achondroplasia, can cause malformation of the bones of the spine and a narrowing of the spinal canal.

Slipped (herniated) Disc

A slipped or herniated disc is when the tough coating of a disc in your spine tears, causing the jelly-like filling to seep out. The torn disc can press on the surrounding nerves causing pain in your back and legs.
A slipped disc can happen at any age, but is more common in people between 20 and 40 years of age. It is usually caused by a combination of minor degeneration in the disc combined with trauma. The trauma can be minor, such as a cough or sneeze.
A slipped disc can press on the nerve sac in the spinal canal causing back pain, or on the surrounding nerves causing pain in the back and legs.

Spinal Tumours

Abnormal growths and tumours can form along your spine. These are usually benign (not cancerous), but growing tumours may compress your spinal cord and nerve roots causing pain.
Injury

Injury to your spine, such as dislocation and fractures, or the swelling of tissue after spinal surgery, can put pressure on your spinal cord or nerves.

When To Consider Surgery

Lumbar decompressive surgery is considered as a treatment for spinal stenosis when:
pain relief medication and other treatments have failed to help your symptoms,
the pain is so severe it is interfering with your quality of life, including work and sleep,
you have had an MRI scan that shows you have a disc, bony spur or thickened ligament pressing on a nerve, or
you have cauda equina syndrome, a rare and severe form of spinal stenosis. Pressure on the nerves in the lower back causes numbness in the buttocks and prevents you from urinating. In this case, emergency surgery is needed.