MR imaging in the tethered spinal cord syndrome.

MR examinations of the spine were reviewed in 25 patients with a clinical diagnosis of tethered spinal cord. In 21 patients (84%), the level of the tip of the conus was below the mid L2 vertebral body. The causes of the tethering were spinal lipomas (72%), tight filum terminale syndrome (12%), diastematomyelia (8%), and myelomeningocele (8%). These entities were readily identified in all instances. Bony dysraphisms were well demonstrated by MR. Interestingly, cavitary lesions/myelomalacia of the conus or the cord adjacent to the tethering lesion were seen with appropriate images in nine of 20 patients. This unexpected finding may have diagnostic and/or prognostic significance. Spinal MR was found to be extremely useful in the evaluation of the suspected tethered spinal cord. It was able to visualize the conus medullaris, assess the thickness of the filum terminale, identify traction lesions, and evaluate associated bony dysraphisms.