Toward the prediction of neurological injury from tethered spinal cord: investigation of cord motion with magnetic resonance.

Experience with spinal dysraphism has taught that spinal cord tethering will eventually produce neurological deficit. The primary diagnostic and monitoring tool, magnetic resonance (MR) scanning, almost always produces images consistent with cord tethering, even in asymptomatic or improved, previously operated patients. This presents a problem in selecting appropriate candidates for prophylactic intervention. Ideally, a method of monitoring should predict functional deterioration. Real-time ultrasonography, electrophysiological tests, and phase-motion MR studies could potentially be adapted for this purpose. The authors have evaluated the latter technique in both symptomatic and asymptomatic dysraphic patients with tethering. Studies of cervical cord motion show a clear separation between results in patients with cord expansion from hydromyelia and those with pure tethering. Symptomatic patients with progressive deficit or pain have limited cervical cord motion which improves after surgical untethering. MR studies of cord motion have definite promise in the prediction of deficit from spinal cord tethering and should be further evaluated in comparison with ultrasound and electrophysiologic methods.