Neurophysiologic Intraoperative Monitoring During Surgery for Tethered Cord Syndrome

Abstract

Tethered cord syndrome (TCS) occurs when the distal spinal cord is adherent to inelastic tissue. This results in sensorimotor deficits in the lower extremities, bowel and bladder dysfunction, and musculoskeletal deformities. Tethered cord syndrome is often found in childhood, but may be first noticed in adults as well. The symptoms are usually progressive unless halted by surgical correction of the spinal cord tethering. Surgery for TCS can be complicated by inadvertent injury to nerves that are either embedded in the tether or in close proximity to it. In an attempt to reduce this iatrogenic injury, neurophysiologic intraoperative monitoring is used to identify neural structures in the surgical field and reduce the risk of injury. Many neurophysiologic intraoperative monitoring paradigms have been used in TCS surgery, including free running and stimulated electromyography of the muscles of the lower extremities, external anal and external urethral sphincter electromyography, tibial, clitoral, and dorsal penile somatosensory evoked potentials, and bulbocavernosus reflex testing. It is widely believed that neurophysiologic intraoperative monitoring helps reduce morbidity of TCS surgery, but data supporting this are limited. This article will review the various neurophysiologic intraoperative monitoring paradigms that can be used in TCS surgery and discuss the data supporting the use of these paradigms.

Lipomyelomeningocele: pathology, treatment, and outcomes

“…6 Stimulated electromyography, however, allows for identification of functional nerve roots and delineation of nervous tissue from filum and scar elements. 36,38 In particular, external anal sphincter monitoring allows assessment of the pudendal nerve comprised by the S2-4 nerve roots and provides a good approximation of external urethral sphincter injury as well, although it may not well approximate injury to the parasympathetic nerves that supply the detrusor muscle. 36 …”

“…6,28,38 Somatosensory evoked potentials monitor the integrity of the dorsal column pathway, and frequently the tibial nerve is monitored for evaluation of the L4-S3 nerve roots, although this method is limited by long averaging times and fluctuations in response. 36,38 Motor evoked potentials may be obtained for the quadriceps, anterior tibial, and gastrocnemius muscles, as well as bilateral external anal sphincters using needle electrodes to monitor the lumbosacral nerve roots. 28 Because younger children have more immature myelinated fibers, monitoring of motor evoked potentials may require double-train stimulation to obtain useful motor evoked potential amplitudes.…”

Nevrofysiologisk monitorering under kirurgi

“…Ved hjelp av slik kartleggingsteknikk (mapping) kan fungerende strukturer bli identifisert og bevart (24,25). Somatosensorisk fremkalte responser av n. tibialis er av mindre betydning, fordi signifikante signalforandringer ved den type operasjoner er uvanlig, men undersøkelsene kan gi tilleggsinformasjon (26).…”

Management of urological dysfunction in pediatric patients with spinal dysraphism: review of the literature

“…28 It is possible to monitor the external urethral sphincter by way of a special ring electrode on a Foley catheter. 34 However, in a pediatric population, urethral size may be prohibitive to this monitoring strategy. The combination of free-run and stimulated EMG allows for continuous EMG monitoring and assessment of structures during dissection, which may be beneficial when encountering dysmorphic neural elements.…”