Facet pain syndrome. Underlaying mechanisms of acute stage with thoracic spinal unit example
Резюме. The fixed small thoracic vertebra dislocation has been modeled on animals (rabbits) to simulate the biomechanics changes revealed on X-ray images (illustrated) in patients with thoracic zygapophyseal joints arthralgia. Involved spinal motional unit’s tissues were investigated by light microscopy after 7 and 14 days. The most reactive tissue was the fold of a capsule’s synovial membrane inside zigoapophyseal joint. Densely innervated by myelinated and unmyelinated nerve fibers synovial fold has been enlarged in average more than double as a result of edema and it was pinched closely between zygapophyseal facets. The intact synovial fold is presented for comparison. Specific changes of neural cell’s pools in substantia gelatinosa of Rolando and cells in lateral horn (sympathetic neural centers) of spinal cord gray matter were arose simultaneously on the level corresponded to displaced zygapophysal joints. Described mechanism triggers nociceptive afferentation from a swollen and squeezed synovial fold receptors with the facet pain syndrome of biomechanics nature.