Lesions of the discs between the vertebrae, caused by degeneration, unlucky movements, accidents. They may create problems when they press on nerve roots or (very rarely) on the spinal chord, but in most cases they are silent and don’t create pain. If there are neurological symptoms like loss of muscle strength (in the leg f.ex. impossibility to walk on heels and/or toes) or loss of skin sensitivity, treatment is urgent.