Preuntethering and Postuntethering Courses of Syringomyelia Associated With Tethered Spinal Cord

BACKGROUND: There has been controversy regarding the management of syringomyelia associated with tethered spinal cord. Previous reports on the topic have included only a small number of patients, considered open/closed spinal dysraphism together, or had a short follow-up. OBJECTIVE: To review a uniform group of patients with syringomyelia associated with tethered cord and treated mainly by untethering alone. METHODS: Of the 135 patients operated on for closed spinal dysraphism between 2003 and 2008, 33 patients with preoperative syringomyelia were identified. The preoperative/postoperative clinical data and syrinx index (ratio of the syrinx area and the cord area) were retrospectively reviewed. The syrinx index of each patient was plotted as an individual graph to outline the temporal change of the syrinx before and after untethering surgery. RESULTS: Five patients showed symptom progression during the preoperative period, and 4 of the 5 had an additional magnetic resonance imaging before the operation that showed progression of the syringomyelia. Postoperatively, 31 of 32 patients (97%) who underwent postoperative follow-up imaging showed long-term stability or a decrease in the syrinx index. Four symptomatically stable patients showed a transient increase in the syrinx index during the initial postoperative 6 months, which later decreased spontaneously. In 1 patient with retethering, the syrinx index increased 6 months before the onset of new urinary symptoms. CONCLUSION: Untethering alone may be sufficient for the management of syringomyelia associated with tethered cord. A transient increase in the syrinx index during the initial postoperative period may be observed without additional surgery if patients are symptomatically stable.