MECHANORECEPTORS IN INTERVERTEBRAL DISCS - MORPHOLOGY, DISTRIBUTION, AND NEUROPEPTIDES

Study Design, The present study investigated the occurrence and morpho logy of mechanoreceptors in human and bovine intervertebral discs and longitudinal ligaments. Objective. To determine the type and frequency of mechanoreceptors present in intervertebral discs and anterior long itudinal ligaments in two patient groups, those with tow back pain and those with scoliosis. Bovine coccygeal discs were examined. Summary o f Background Data. Nerves have been described in intervertebral tissue s, but there is little information on the endings;of these nerves and their receptors, stimulation of which can cause a nerve impulse. Metho ds. The presence of mechanoreceptors were investigated by immunolocali zation of nerves and neuropeptides. By examining sequential sections, the frequency of receptors was assessed. Results. Immunoreactivity to neural antigens showed mechanoreceptors in the anulus fibrosus and lon gitudinal ligaments of bovine and human specimens. Their morphology re sembled Pacinian corpuscles, Ruffini endings, and, most frequently, Go lgi tendon organs. They were found in 50% of discs investigated from p atients with low back pain and in 15% of those with scoliosis. Conclus ions. Mechanoreceptors were found in the outer 2-3 lamellae of the hum an intervertebral disc and anterior longitudinal ligament. Physiologic studies in other tissues indicate that these provide the individual w ith sensation of posture and movement, and in the case of Golgi tendon organs, of nociception. In addition to providing proprioception, mech anoreceptors are thought to have roles in maintaining muscle tone and reflexes. Their presence in the intervertebral disc and longitudinal l igament dan have physiologic and clinical implications.