Intraoperative neurophysiological monitoring in tethered cord surgery

Abstract Tethered cord syndrome (TCS) is a complex and progressive clinical and radiological condition, secondary to an embryologic failure of spinal cord development, which induces various types of spinal dysraphisms. Most of these congenital disorders are amenable to surgical treatment. The goals of surgery are to avoid or arrest the progression of symptoms and, to a lesser degree, to reverse the existing neurological deficits. Surgery for tethered cords ranges from simple cutting of the filum terminale to more complex resection of lipomas, which often strictly adhere to and include neural structures. The incidence of transient complications has been reported in up to 13%, while permanent neurological injuries occur in up to 4.5% of the cases. Over the past two decades the use of intraoperative neurophysiology (ION) has received increasing credit as a valuable strategy to minimize morbidity. The ION techniques utilized in tethered cord surgery include a combination of monitoring and mapping techniques. This chapter will address in detail the various ION techniques that can be used either to functionally identify ambiguous neural tissue or to continuously monitor the functional integrity of pathways involved in sensorimotor function and sphincter control.