Supplementary Material for: Long-Segment Type 1 Split Cord Malformation with Two-Level Split Cord Malformation and a Single Dural Sac at the Lower Split

<i>Objective and Importance:</i> Two-level bony spurs are rare and also a very long segment of bony spur is very rare. Bony spur with a single dural covering is not reported in the literature. Here, we report a case of prophylactic surgery performed on a patient with a bony spur with a single dural covering who showed a good postoperative outcome. This case highlights the importance of prophylactic surgery in such patients to avoid cord injuries. <i>Clinical Presentation:</i> Since birth a 1-year-old child had had a tuft of hair at the dorsal (D<sub>6</sub> and D<sub>7</sub>) region. The patient was examined and found to have scoliosis with convexity towards the right. There was no neurological deficit. MRI and CT spine scans showed 2-level type 1 split cord malformation (SCM) and there was a low-lying conus at the L<sub>3–4</sub> level. <i>Intervention:</i> The patient was operated on at the age of 1 year and 2 separate bony septae were observed. The upper one extended from D<sub>5</sub> to D<sub>9</sub> and the lower one was at the D<sub>11</sub> level. The bony spurs were excised. The filum was sectioned at the L<sub>4–5</sub> level by a separate incision. The patient had a good postoperative recovery. <i>Conclusion:</i> With meticulous planning and careful surgery, prophylactic surgery can have a very good outcome in long-segment and two-level type 1 SCM.