IN-VIVO EFFECTS OF SURGICAL SYMPATHECTOMY ON INTRAMEMBRANOUS BONE-RESORPTION

Bone modeling and remodeling are highly regulated processes in the mam malian skeleton. The exact mechanism by which bone can be modeled at a local site with little or no effect at adjacent anatomic sites is unk nown. Disruption of the control of modeling within the temporal bone m ay lead to various bone diseases such as otosclerosis, osteogenesis im perfecta, Paget's disease of bone, fibrous dysplasia, or the erosion o f bone associated with chronic otitis media. One possible mechanism fo r such delicate control may be related to the ubiquitous and rich symp athetic innervation of all periosteal surfaces. Previous studies have indicated that regional sympathectomy leads to qualitative alterations in localized bone modeling and remodeling. In this study, unilateral cervical sympathectomy resulted in significant increases in osteoclast surface and osteoclast number within the ipsilateral bulla of experim ental animals. The mechanisms by which sympathectomy leads to increase d local bone loss is unknown. Potential mechanisms include disinhibiti on of resorption, secondary to the elimination of periosteal sympathet ics, as well as indirect vascular effects.