Tethered cord syndrome versus low-placed conus medullaris in an over-distended spinal cord following initial repair for myelodysplasia.

We present findings obtained from a total of 100 patients who had previously undergone surgery for spina bifida and whose progress had been monitored by magnetic resonance imaging (MRI) in our meningomyelocele clinic. Fourteen of these patients (14.0%) developed delayed symptom(s) of progressive spinal neurologic dysfunction. In those with myeloschisis, increase of motor deficit was the most common clinical manifestation during infancy and early childhood (mean age: 6.8 years), whereas pain on back flexion was seen in patients who were over 15 years of age (mean age: 17.3 years). MRI carried out in myeloschisis patients invariably demonstrated that the conus medullaris was in an abnormally low position, suggesting over-distension of the spinal cord. This was irrespective of whether symptom(s) developed or not and did not correlate with the initial surgical procedure (reconstructive or otherwise) used. Patients with symptom(s) were revealed by MRI to have an extremely low conus set at the spinal level of S-1 or below; neurological examinations showed that the motor deficit occurred at high levels in the spine. Results from lipomeningocele patients were more erratic in terms of conus position and delayed development of neurological defects.(ABSTRACT TRUNCATED AT 250 WORDS)