A smaller group of pain problems are caused by tumours, infections, or as a result of an accident.
However, most pain is caused by the ageing (degeneration) of different parts of the spine.
Pain is classified into somatic - when different tissues of the back are painful: muscles, vertebrae, joints, intervertebral discs; and neurogenic - when the pain is caused by pressure or damage of the nerves. Often, it is the combination of both.
From a time-wise point of view, the first tissue affected during life are the intervertebral discs, whose ageing or protrusion triggers degenerative changes. A protrusion/swelling of a disc can compress the nerves and cause radicular pain. When a disc looses its thickness, a reduction in the nerve openings can occur and the compression of nerve roots can be even greater.
The degeneration of a disc is accompanied by changes in the bone marrow of the neighbouring discs, which is also considered as a possible source of pain. The segment of the neighbouring vertebrae and disc can often become unstable, the vertebrae perform unnatural movements in relation to each other, and a new type of pain appears.
If the frontal weight-bearing system of the spine, composed of the discs and the bodies of vertebrae is disrupted, in a matter of time, the weight load is transferred to the dorsal system - the facet joints, which are subjected to arthritis and could be another source of pain.
Painful muscle spasms accompany most of the back pain problems.
Back pain can be present even if there is not proven source of it.
This happens in central pain (with a defect in the processing of pain in the brain), during stress and psychological problems or in some cases of infections.