What is Sciatica
Sciatica is the old-fashioned word for what is now universally recognised as “nerve root pressure” of the giant sciatic nerve. Once it was believed that the sciatic nerve was involved in an inflammatory process or neuritis, and this was responsible for the severe pain that ensued.
However, a better understanding of the nervous anatomy in recent years now indicates that the problem is associated with pressure on the roots of the sciatic nerve as they emerge from between the lower vertebrae of the back. The condition is common, and pain in the lower back radiating down the lower limb is the usual symptom. Often there is a history of a sudden strain, or of lilting a heavy weight, sudden bending or stooping. or sudden back movements often in a rotatory manner.
This may produce a herniation of thenucleus pulposus, the inner part of the intervertebral disc, into the vertebral column that conveys the large spinal nerve roots. This, in turn, may mechanically irritate the nerves by direct pressure or some other form of transmitted pressure.
The sciatic nerve is made up of several large roots emanating from the spinal canal at various levels, and from between subsequent vertebrae. The most common lesion is between the fifth vertebra and the sacrum, the next adjoining part of the spinal column. Sometimes the fourth space is involved, and more rarely the third. Perhaps two or more of the spaces are affected.
Injuries to the intervertebral discs are commonly referred to as slipped discs or disc lesions. X-rays may not show any lesion in mild cases. In more severe forms, the bones may appear closer together, indicating that the disc has been injured. A more precise examination, called a myelogram, may be made. CT and MRI scans can also help diagnosis.
Pain is the chief symptom. It may occur a few hours after the injury, but may be delayed for days or even weeks. It may remain localised in the lower (lumbar) region of the back. More commonly it will follow the distribution of the sciatic nerve. This may extend down the back of the thigh (never the front), down the leg and possibly into the foot. Usually only one limb is affected. The pain may be severe and burning. It is aggravated by movement, such as bending, coughing, sneezing, turning over in bed. Merely lying still (often on the back in a semi flexed position) affords the greatest relief.
In more severe cases, the muscles on the affected side may gradually show signs of wasting. There may be a sensation of numbness, burning or tingling in the feet and along the affected track. The symptoms vary in accordance with the root affected by the lesion.
In the majority of cases, simple measures will bring relief, and the condition will eventually cure itself. Resting in bed in the position that gives maximum relief is recommended. Pain-killers, analgesics and sedatives may be necessary, particularly in the acute stages. Physiotherapy can often afford some relief.
Spinal manipulation can also yield positive benefits, and doctors and physiotherapists are becoming skilled in this treatment. In fact, the relief given can often be dramatic, as with simple but swift movements the mechanical pressure may be relieved.
Often an X-ray is carried out first to make certain there is no serious underlying cause (such as tumours of the vertebrae) that may be worsened by manipulation. Almost invariably there is no sign of sinister causes, and manipulation may be effectively carried out on several occasions. In fact, more doctors now believe this is the most effective form of therapy for mild cases, and the results they produce often confirm this.
Surgical operation for the removal of the protruding disc is sometimes carried out, but this is not lightly undertaken. If the patient shows no sign of improvement after six weeks or more of conservative treatment, or if the sciatic pain is recurrent, or if work involves much heavy lifting (with the risk of frequent recurrences), then the patient may be a candidate for surgery.
Another method that has gained some degree of popularity in the past few years is the injection of the enzyme chymopapain into the affected disc. This is claimed to shrink the prolapsed portion of the disc and so may produce major benefits in about one-third of those treated. Another third show some improvement and about a third arc not favourably influenced. This is carried out by specialist orthopaedic surgeons, as is any surgery in this area. All surgery requires hospitalisation. This has waxed and waned in popularity.