Sciatica and the sciatic nerve
Nearly everyone is familiar with the term sciatica. The name comes from ‘ischiadicus’, the name of the long nerve (nervus ischiadicus) that runs in the leg. The sciatic nerve starts at the lower back, where it originates in the spinal cord and it runs down all the way to the toes via the vertebral foramen (foramen vertebrale). The sciatic nerve is therefore the longest nerve in our body. You should realise that that each nerve in this nerve bundle that runs from the spine to the toe, consists of a single neuron. The sciatic nerve therefore consists of many parallel running neurons.
The path of the nervus ischiadicus, the sciatic nerve
Why is this important for us to know? Because neurons are very sensitive to damage, primarily because they are so long and fragile. One of the most common types of damage to the sciatic nerve is hernia. In hernia, one of the vertebrate discs of the spine protrudes and presses on the sciatic nerve. The nerve cannot tolerate any pressure, whereupon the nerve tissue is affected. Exactly due to the fact that the neurons in the sciatic nerve are so vulnerable, problems develop quickly in the case of a hernia. What kind of problems are these?
Can we develop paralysis of the foot when the sciatic nerve is damaged?
Sciatica: hernia in your back creates problems!
A hernia bulges and presses on the sciatic nerve. The high pressure irritates the nerves, resulting in inflammation. The local inflammation causes the nerve to swell, but due to the hernia, there is no room for swelling. What happens then? This can only generate more pressure and subsequently more irritation. Moreover, irritated neurons produce far less palmitoylethanolamide, the protective tissue hormone. The drop in the amount of palmitoylethanolamide in the irritated nerve only increases the pain; just as the inflammation increases. Palmitoylethanolamide is the body’s own substance that restores balance in case of nerve problems. The concentration of this substance however drops. In cases of sciatica therefore, the production of palmitoylethanolamide in the nerves and connective tissues decreases as a result of chronic irritation, which goes hand in hand with increased problems.
Sciatic pain: an unpleasant neurological pain
Sciatic pain is a nerve pain, also called neuralgia. The nerve is irritated and transmits pain signals. Most of the pain is felt in the path of the nerve. Often you also feel nasty, shooting and stabbing pains from your leg, all the way through your calf down to your foot. Often even down to the toes. Sometimes the worse pain might be in the big toe, sometimes in the small toe. For a neurologist, this is an indication of where precisely the hernia is. If the pain is in the big toe, the hernia is usually higher up in the spine than if the pain is in the small toe.
In a hernia with damage to the sciatic nerve, a lot of pain will occur in the foot and the big toe.
Other characteristics of sciatica
A characteristic of sciatica or hernia pain is often having more pain in your foot than in your back where the hernia occurs. In fact, if most of the pain is indeed in the back, then most likely it is not a case of sciatica or hernia. More likely, it is pain caused by arthrosis in the vertebrae of the spine. Arthrosis of the spinal vertebrae is characterized more by an irritating pain in the lower back, while nerve pain is a far nastier, more piercing and radiating pain. Obviously, the sciatic nerve might be beleaguered at other levels and places other than only in the back or only by a hernia. However, hernia is the most common cause of sciatic pain. Sometimes people feel an irritated nerve that comes from another source, for example from a Baker’s cyst behind the knee joint. This is a swelling of a structure that can press on the nerve in the knee joint. Then you might also feel pains that radiate to the feet. Ultimately, there might be pressure exerted on the foot itself, for example from tarsal tunnel syndrome. The nerve is then pinched at the ankle and the pain radiates to the foot or the sole.
The path of the sciatic nerve in the lower leg
There are many pinch-points in the leg along the path of the sciatic nerve; the most common one is hernia.
Sensory disturbances following damage to the sciatic nerve