4 Natural History of the Degenerative Cascade
KEY POINTS
Natural History of the Degenerative Cascade
The natural history of degenerative disc disease has been studied for many years. Lees and Turner, in 1963, followed 51 patients with cervical radiculopathy for 19 years and found that 25% had worsening of the symptoms, 45% had no recurrence, and 30% had what they classified as mild symptoms.1 Nurick studied the nonsurgical treatment of 36 patients with cervical myelopathy over 20 years.2 Sixty-six percent of the patients who presented with early symptoms did not progress, and approximately 66% of patients with moderate to severe symptoms did not progress either. The patients who progressed tended to be the younger patients.
Anatomy and General Mechanisms of Pain
Cortical bone, bone marrow, and periosteum have been found to be innervated by nerves containing nociceptive neuropeptides such as calcitonin, gene-related peptides, and substance P. Periosteal elevation, such as in cases of infection, tumor, or hematoma, can be painful. Periosteal tears in cases such as fractures, inflammation, or subsidence (e.g., in osteoarthritic conditions) can cause pain. Vascular congestion from bone infarcts or sickle cell can cause the intramedullary nerve fibers to initiate a painful response. Nociceptive nerve fibers have been identified in varying concentrations within the fibrous tissue of spondylolytic pars defects as well.