Retethering risk in pediatric spinal lipoma of the conus medullaris

OBJECTIVE Lipoma of the conus medullaris (LCM) causes neurological symptoms known as tethered cord syndrome (TCS). The symptoms can be seen at diagnosis and during long-term follow-up. In this report, pediatric patients with LCMs who underwent untethering surgery, under the policy of performing surgery if diagnosed regardless of symptoms, were retrospectively reviewed to evaluate long-term surgical outcomes. Possible risk factors for retethered cord syndrome (ReTCS) were evaluated in the long-term follow-up period. METHODS A total of 51 consecutive pediatric patients with LCMs who underwent a first untethering surgery and were followed for > 100 months were retrospectively analyzed. The surgery was performed with the partial removal technique. Pre - and postoperative clinical and radiological data were reviewed to analyze the outcomes of surgery and identify potential risk factors for ReTCS. RESULTS During follow-up, 12 patients experienced neurological deterioration due to ReTCS. The overall 10-year and 15-year progression-free survival rates were 82.3% and 75.1%, respectively. On univariate analysis, a lipoma type of lipomyelomeningocele (OR 11, 95% CI 2.50-48.4; p = 0.0014), patient age at the time of surgery (OR 0.41, 95% CI 0.14-1.18; p = 0.0070), and the mean patient growth rate after surgery (OR 2.00, 95% CI 1.12-3.41; p = 0.0040) were significant factors associated with ReTCS. Cox proportional hazard models showed that a lipoma type of lipomyelomeningocele (HR 5.16, 95% CI 1.54-20.1; p = 0.010) and the mean growth rate after surgery (HR 1.88, 95% CI 1.00-3.50; p = 0.040) were significantly associated with the occurrence of ReTCS. CONCLUSIONS More complex lesions and a high patient growth rate after surgery seemed to indicate increased risk of ReTCS. Larger prospective studies and registries are needed to define the risks of ReTCS more adequately.