Selective dorsal rhizotomy (SDR) or selective posterior rhizotomy refers to selectively cutting a portion of the sensory nerves of a limb or limbs that have spasticity, a form of muscle tightness. Rhizotomy is another name for cutting a nerve root or that portion of a peripheral nerve that lies within the spinal canal. Dorsal or posterior refers to that portion of the nerve root that contains the sensory fibers as opposed to the ventral or anterior root that contains the motor fibers or those fibers that tell a muscle to move. Selective refers to the fact that the cutting is incomplete and the portion of sensory nerve fibers that are cut is directed by some form of “selection” process. There are many different selection criteria that have been used to determine which sensory nerve fibers are cut in this operation. In general, in North America the selection process involves electrically stimulating bundles of sensory fibers and monitoring the pattern of muscle contraction in the body that occurs in response. There is an expected pattern of muscle contraction that should be seen depending on which fiber bundle is stimulated. When this occurs, the response is labeled as “normal” and when muscles other than those expected to contract are seen to contract then the response is labeled as abnormal. Lesioning is typically isolated to those sensory nerve fibers whose stimulation causes “abnormal” patterns of muscle contraction.
The surgeon performing this procedure at Function was one of the first to do it in North America, introducing it to Northeastern United States in 1986. He first introduced the use of multichannel recording of electrical activity in muscles resulting from nerve stimulations for SDR surgeries and also participated in the development of nerve mapping procedures to protect the nerve supply to bladder, bowel and sexual organs during the procedure. He has now performed over 300 of these procedures.
Selective Dorsal Rhizotomy