Presently, the direct pathophysiological mechanism of sciatica is not fully known, but pressure on the spinal nerve roots has been linked to pain and neural dysfunction in distribution of the nerve root. Pressure on the nerve root can hamper the transportation of nutrients to nerve tissues in a way that would affect its functioning. Substances leaking from worn or degenerated intervertebral discs can also affect nerve roots or root sleeves.
When we talk about Sciatica, (pain in hip and leg: pain and tenderness extending from the back of the hip down to the calf, usually caused by a protrusion of vertebral disk substance pressing on the roots of the sciatic nerve) it is important that we know the real medical sciatica causes in order to be able to effectively treat it.
Most Common Causes of Sciatica
The most common causes of sciatica are 6 in number:
Lumbar herniated disc
In the case where the inner soft core of the (nucleus pulposus) disc is projected through a ruptured wall into or through the annulus (outer fibrous core) there by causing the irritation of the contiguous nerve root, a herniated disc is said to have occurred.
Around the area where the outer core of the intervertebral disc is a weak spot that is right under the spinal nerve root. Hence any herniation here will put pressure directly on the nerve. This nerve passes through the leg, any kind of pinched nerve in the lower spine will cause pain to flow along the path which the nerve runs through, all the way from the buttock to the legs.
Herniated discs are can also be called bulging disc, slipped disc, pinched nerve, or a protruding disc. The most common symptom of a lumbar herniated disc is the Sciatica.
Degenerative disc disease
Disc degeneration is a natural phenomenon that happens with aging, however, in some people degenerated discs in their lower back can cause an irritation in the nerve root and lead to sciatica.
A person is said to have Degenerative disc disease (DDD) when a weak disc causes too much micro-motion at the spinal level and inflamed proteins within the disc are exposed and cause and irritation in that area.
Degenerative disc disease is quite common as it’s among the sciatica causes, and it’s estimated that about 30% of people between the ages of 30-50 years old have some form or degree of disc degeneration, even though not all will experience the pain or ever have a formal diagnosis.
Low back pain which is associated with degenerative disc diseases is usually gotten from inflammation or abnormal micro-motion instability or a combination of the two.
Isthmic spondylolisthesis
The spinal condition called isthmic spondylolisthesis is a state or condition where a slight stress causes a vertebral body to slip forward on another vertebral body below. It is caused by a fracture in the bone which connects the two affected joints on the back of the spine. This condition also falls under sciatica causes.
With multiple collapses in disc space, fracture and the slipping forward of the vertebral body, the nerve can easily get pinched thereby leading to sciatica.
A fracture in the pars interarticularis (bridge between two joints) happens when stress is applied on the bone. This sort of fracture usually happens at a young age (about 5 to 7 years). However, most people do not notice the symptoms until they are much older.
Estimation shows that about 5 to 7% of the population has experienced either a pars interarticularis or a spondylolisthesis ( a slipped vertebrae), but most cases show no symptoms.
The small bone fracture usually does not cause pain or come with any symptoms. The fracture is most times causes by cumulative stress. The bone eventually breaks when it has experienced too much stress.
Lumbar spinal stenosis
Among the sciatica causes is the Lumber spinal stenosis. This condition happens when the spinal canal narrows. Lumbar spinal stenosis is associated with the natural aging process in the spine. It is quite common among adults, especially those over 60.
The condition is usually as a result of one or more reasons such as: overgrown soft tissues, a bulging disc which pressurizes the nerve root and an enlarged facet joint which can all lead to sciatica pains.
As we grow older, the spine changes. This often leads to degeneration in the vertebrae bones, muscles, ligaments and discs, all of which make the spinal column. These changes can be responsible for spinal stenosis
“Stenosis” is derived from the Greek word “choking”. It is usually caused by degenerative conditions like degenerative spondylolisthesis and/or osteoarthritis. Lumbar spinal stenosis occurs when the spinal nerves located in the lower back get choked.
Piriformis syndrome
Piriformis syndrome occurs when the piriformis muscle, which is located at the buttock region, shudders and causes aches in the buttock. The actions of the piriformis muscle could also irritate or cause discomfort to the nearby sciatic nerve which can cause pain, tingling sensation in the back of the leg as well as in the foot and numbness.
Although this is not a real radiculopathy (Sciatica), however the pain caused to the leg can feel like sciatica which is caused by nerve irritation.
Sacroiliac joint dysfunction
When the sacroiliac joint which is situated at the bottom of the spine is irritated, it can also cause an irritation to the L5 nerve which is on located above the sacroiliac joint. The pain caused is sciatica like. The leg pain which is felt resembles the sciatica which is caused by nerve irritation.
It’s generally thought that sacroiliac joint dysfunction or SI joint causes leg pain and/or low back pain. When it comes to leg pain, it can be quite difficult to handle and most times may feel like sciatica or the pain resulting from lumbar disc herniation.
More Causes of Sciatica
There are sciatica causes, which are less common than those listed above. These include:
- Scar Scar tissues compressing the nerve root can also cause sciatica.
- Muscle An inflammation resulting from muscle strain can pressurize the nerve root leading to sciatica.
- The body experiences a number of changes during pregnancy, such as gaining weight,, hormonal changes and a shift in one’s gravitational center. These changes can lead to sciatica during pregnancy.
- Spinal In special cases, a spinal tumor could encroach on a nerve root. This will cause pains in the lower back similar to sciatica.
- Although this is rare, however, and infection may happen around the lower back and affect the nerve root thereby causing sciatica.