Update on peripheral nerve surgery.

OBJECTIVE: Minimally invasive surgical techniques have been described for the treatment of spinal pathology. Tethered cord syndrome is an under-diagnosed condition of abnormally rigid fixation of the spinal cord that results in spinal cord tension leading to ischemia. It can be the cause of incontinence, scoliosis, and chronic back and leg pain. In situations of spinal cord tether owing to fatty filum or tight filum terminale, the symptoms can be relieved by sectioning of the filum. We present a novel, minimally invasive technique for surgical untethering of the spinal cord by filum sectioning. The pathophysiology of tethered spinal cord and the advantages of minimally invasive surgical management of this entity are discussed. METHODS: Three patients (ages 14, 35, and 46 yr) presented with long-standing leg and back pain and neuroradiological features of tethered cord syndrome and thickened, fatty filum terminale. Two patients presented with scoliosis and, upon further history, had subclinical incontinence; one of these patients had abnormal urodynamic studies. RESULTS: All three patients underwent a minimally invasive approach to the L4/L5 level using the X-tube (Medtronic, Inc., Memphis, TN). A laminotomy was performed and the dura exposed. The dura was then opened and intradural microdissection delivered the fatty filum into the durotomy. Electrical stimulation was performed while the lower extremities and the anal sphincter were monitored for electromyographic activity. After acquisition of positive controls, the filum was identified by the lack of sphincter and lower extremity electromyographic responses and was then cauterized and cut. Dura was repaired with the use of endoscopic instrumentation. All patients had significant improvement of their leg and back pain, and one patient had resolution of the abnormal urodynamics. CONCLUSION: Tethered spinal cords can be safely and effectively untethered using minimally invasive surgery. This technique provides the advantage of reduced soft tissue injury, less postoperative pain, minimal blood loss, a smaller incision, and a shorter hospitalization. The minimal amount of tissue injury generated by this technique may also provide the added advantage of reduced scar formation and risk of retethering.