Is Clinical Examination and MRI Study Enough for the Assessment of Tethered Cord Syndrome in Scoliosis? The Preliminary Results of a Longitudinal Prospective Study

Abstract

Background: It is demonstrated that tethered cord syndrome is not necessarily identical to low lying conus medullaris and a separate entity of this syndrome with normally placed conus medullaris is also well recognized. Besides, normal clinical history and neurological exam does not preclude the diagnosis of this syndrome either. Subclinical changes in bladder function have also been described as an insidious sign of this problem. Recognition of the aforementioned types of tethered cord syndrome seems to be vital in patients who are candidate for correction of congenital scoliosis.

Materials and Methods: Through this study, 1000 patients candidate for surgical correction of congenital scoliosis are assessed with whole CNS MRI, urodynamic study, and CT myelography in a single center. The cases without any obvious clinical signs and symptoms of tethered cord syndrome and normal MRI and CT myelography but with abnormal urodynamic parameters indicating neurogenic bladder are selected. These cases undergo surgery and the filum terminale is cut. The surgical findings are recorded and the postoperative status is then evaluated by a follow-up MRI and urodynamic study performed three months after the surgery. The possible improvements in urinary status then will be recorded and meticulously analyzed.

Results: Among the first 250 cases of scoliosis, 32 had abnormal urodynamic studies and normal clinical and radiological assessments. In seven, fatty changes were seen in the filum terminale and among the others tight filum terminale was discovered in 18 patients. Significant improvement in urinary status was also evident in 21 cases (65%). Rise of the conus medullaris in MRI was seen in only one case during the follow-up.

Conclusion: It seems that clinical examination and MRI are not enough to rule out tethered cord in congenital scoliosis. Further evaluation with urodynamic study is essential to identify some subclinical urinary problems or to recognize the normally placed conus medullaris variant before corrective surgery of this deformity.