Can the conus medullaris in normal position be tethered?

Many have equated the term tethered spinal cord to a conus that is pathologically elongated. Most authorities have declared radiologic coni located inferior to the L-2 as pathologic. However, we have described previously a small series of patients in whom symptoms of a tethered spinal cord were evident clinically yet radiologically the conus medullaris was found to lie at a widely acceptable normal anatomic site. Following a review of the extant literature prior to our publication in 1993, several authors had operated on patients for symptoms of a distally tethered spinal cord in whom a conus was found to terminate at a 'normal' vertebral level. We believe that there is indeed a subset of the tethered cord patient population in whom the tip of the conus lies at even liberally accepted normal levels. We would encourage clinicians treating patients with symptoms of tethered cord syndrome not to treat the patient based simply on imaging but imaging coupled with clinical symptoms and physical exam. It is important to point out that in lieu of the many publications of conus termination that one accepts that there is no one single 'normal' position of the terminal cord but rather a normal range. Perhaps a superior way of interpreting 'tethered' cord is to view this as tautness of the cord and not necessarily elongation of the distal cord in every case.