Tethered cord syndrome: the low-lying and normally positioned conus.

We have previously proposed the existence of the tethered cord syndrome in the presence of a conus medullaris in the normal position. Our 12-year series of 73 patients with the tethered cord syndrome included 13 patients in whom the spinal cord terminated at or above the L1-L2 disc space. We compare the characteristics of these 13 with those of the 60 patients whose spinal cord terminated below the L1-L2 disc space. The parameters for comparison included neurological status at presentation and follow-up, the presence of cutaneous stigmata of occult spinal dysraphism, vertebral anomalies, and others. The frequency of occurrence of each parameter in the normally positioned group was essentially the same as its occurrence in the low-lying group.