Neurological deterioration in an adult patient with split cord malformation following untethering via filum sectioning: Case report.

Tethered cord syndrome is commonly caused by thick filum terminale and split cord malformation (SCM), which can coexist. If surgery is necessary, it should address both conditions for complete untethering. Some authors also suggest that resection of the septum should precede filum sectioning. Otherwise, cranial migration of the spinal cord after filum cut may cause further damage at the septum level. However, we found no example in the literature demonstrating any adverse effect if that order was not followed. A 34-year-old woman presented with worsening symptoms, including urinary retention, low back and leg pain after surgery at another center, where the thick filum terminale was cut without addressing a midline fibrous septum splitting the cord. We achieved complete untethering with a second surgery by septum resection. The patient's pain improved, but sphincteric disfunction persisted. Our case supports the opinion that in cases of coexisting SCM and thick filum terminale, complete untethering should be achieved by first septum resection, then filum sectioning, in that particular order.