This is a layman's term used to describe a common back problem and as such, it is not a clinical definition of any specific condition.
Sciatica pain is related to the sciatic nerve which is the thickest and strongest nerve in the body. This spinal nerve can sustain a hanging weight of 700kg (the weight of 7 adult men) before breaking. The roots of the Sciatic nerve control motory, sensory and mixed functions via the bones, muscles and skin and it divides into two sections which pass down from the spine, through the hips, into each leg.
Since none of the nerve roots corresponds physiologically, different types of pain can be produced; e.g. a dull ache is felt in the bone, numbness (acroparisthesia) in the skin, and sharp pain in muscles - and of course, these symptoms can overlap.
The Sciatic nerve is in close proximity to adjacent discs (1.2-1.5 mm) which is why so-called discongenic pain can arise. This pain, however, is caused by the tethering or rubbing of the nerve sleeve, and not by the discs themselves, while compression of the nerve doesn't necessarily cause any pain.
As a result of mechanical friction affecting any of the nerve roots, the condition can become inflammatory, which is extremely painful. If not treated properly this will lead to scarification in the area around the inflamed sleeve which in time would result in devascularisation (reduced blood supply to the veins).
The body reduces the supply of blood to certain veins if parts of the body are scarred and no longer require it as much as when the tissue was healthy. This process, which occurs as a result of the condition and also as a consequence of surgery, often produces referred pain along those nerves which are affected.
Manipulative treatment for sciatica is not a good idea because it causes trauma in the area around the nerve sleeve, which then has to heal a second time, further exacerbating the condition.
If elasticity of the soft tissues is diminished, localised or referred pain will be more readily produced. Chronic sufferers should therefore not be manipulated, but rather mobilisation should be used to remove friction on the affected nerve roots.
As a general guide regarding the symptoms of sciatic pain, the hip and groin are supplied by nerves from the L1 level, the thigh by L1 and L2, the knee by L3, the hamstring by L4; and the calf, ankle, leg or foot by L5 and S1 (affected in 85% of cases).
The treatment of sciatica is easily carried out by decompressing the sciatic nerve at the affected joint level in order to remove the source of friction against the nerve. Relief from pain is felt after only a few sessions when neuro-muscular and skeletal functions are restored.
The straight-leg raising test (Lasague Test) can give a good indication of the level of compression required and which section of the spine is causing the problem.
As with any chronic nerve root impingement, it can take several months for the nerve to rejuvenate properly and for the numbness to completely subside, as nerves rejuvenate at the rate of 24 hours per millimetre of nerve.
Spinal surgery (discectomy) is often performed with a view to remove some or all of a disc to relieve pressure on the sciatic nerve. However, the consequences of weakening the stability of the spinal column by removing or fusing discs together cause much more harm than the original condition and is entirely unnecessary when the same result can be achieved in a few weeks of physical therapy. The key to success (as with all physical therapy) is in finding a practitioner who is qualified and experienced in treating this condition.
It can safely be said that for the vast majority of spinal conditions surgery is neither necessary nor effective, as it almost always leads to long term complications and suffering for the patient, out of all proportion to the original condition.
The use of metal rods, screws and plates and the cutting away of parts of the spine, even the heating of discs to cause them to shrink (IDET procedure) represent a rather crude approach to the treatment of spinal problems and is not a method of 'treatment' that we can ever recommend.
The procedures of Orthopaedic Medicine outlined above do not involve operating on a patient, and all treatment is safe and manageable as well as being highly effective.