Occult Tethered Cord

(N. R. Selden) Object Controversy exists regarding proper indications for surgical lysis of the terminal filum in children with voiding dysfunction and tethered spinal cord. Recently, surgery has been offered to children who have a normally positioned conus medullaris and no terminal filum abnormality visible on 1.5-tesla magnetic resonance images (referred to as minimal or occult tethered cord syndrome [TCS]). The author evaluates existing clinical and scientific evidence relevant to this controversy. Methods Five retrospective, observational, noncontrolled studies of surgical terminal filum lysis for occult TCS in children were identified. Two further studies in which the authors reported surgical results in children with a normal-level conus medullaris were also identified. Conclusions These studies document encouraging clinical outcomes following surgery. Clinicopathological evidence suggests that occult TCS may result from radiographically occult structural abnormalities of the terminal filum. Although a preponderance of Class III clinical evidence supports the use of surgical filum lysis to treat occult TCS, no Class I or II evidence exists. Clinical practice varies; therefore, performance of a prospective randomized clinical trial of surgical terminal filum lysis for the treatment of occult TCS is advocated.