Tethered cord syndrome and the conus in a normal position.

The intent of this article is to propose the existence of the tethered cord syndrome in patients whose conus is in a normal position. The tethered cord syndrome has been a well-recognized entity, occurring in the pediatric and adult population. A central tenet to this syndrome is that the conus medullaris must be "abnormally" low, regardless of the tethering lesion. Our 12-year series of 73 patients with tethered cord syndrome included 13 patients in whom the cord terminated at or above the L1-L2 space. These patients otherwise displayed characteristics usually associated with the patient with an abnormally low conus. Most patients with progressive neurological deterioration responded to surgery. The preoperative radiographic evaluation and the operative findings usually demonstrated a thickened filum. Tethered cord syndrome may occur in the patient who has a conus in the "normal" position.