[Neurophysiological monitoring in spine surgery. Spinal cord stimulation]. / Monitorización neurofisiológica en la cirugía de la columna. Estimulación medular.

INTRODUCTION: Neurophysiological monitoring in spine surgery can be performed by a number of methods, although there is no general agreement about which is the best. AIM: The aim of this study was to evaluate our experiences using the method of spinal cord stimulation with recording carried out on the peripheral nerve. PATIENTS AND METHODS: We studied 51 patients with scoliosis who were submitted to surgical correction. Stimuli were administered with the cathode located in the dorsal epidural space, two levels above the curve to be corrected, and recording was performed on the posterior tibial nerve in the popliteal fossa. RESULTS: Potential was obtained in 78% of cases, with a very low number of averages and the maximum reduction in the amplitude of the potential was found to be 33%. Spinal cord stimulation evokes muscular responses in several muscles and sensory responses in the sural nerve. None of the patients who were monitored using this method presented postoperative neurological deficits added to their previous pathology. CONCLUSIONS: The neurogenic potentials obtained by epidural spinal cord stimulation are very useful for monitoring spine surgery because they are very stable, they can be obtained quickly, they avoid the need to interfere with the anaesthetist's field and because, albeit to a small extent, they may contain information about motor pathways. The main drawback is that it is not always possible to place the electrode and that in 22% of cases we have not managed to obtain the motor component and we have therefore had to be cautious in evaluating it, since its disappearance would only give rise to a partial reduction in the potential.

Monitorización neurofisiológica en la cirugía de la columna. Estimulación medular / Neurophysiological monitoring in spine surgery. Spinal cord stimulation

Introducción. Existen varios métodos de monitorización neurofisiológica de la cirugía de la columna, si bien no hay consenso en cuál es el mejor método para realizarla. Objetivo. Evaluar nuestra experiencia con el método de la estimulación medular con registro en el nervio periférico. Pacientes y métodos. Hemos estudiado 51 pacientes con escoliosis sometidos a corrección quirúrgica. Se aplica el estímulo con el cátodo situado en el espacio epidural dorsal, dos niveles vertebrales por encima de la curva que se va a corregir y se registra en el nervio tibial posterior en el hueco poplíteo. Resultados. Se ha obtenido un potencial en el 78 por ciento de los casos, con un número muy bajo de promedios y una disminución máxima de la amplitud del potencial del 33 por ciento. La estimulación medular evoca respuestas motoras en varios músculos, y sensitivas en el nervio sural. Ninguno de los pacientes monitorizados con este método ha presentado déficit neurológicos posoperatorios sobreañadidos a su patología previa. Conclusiones. Los potenciales neurogénicos que se obtienen mediante estimulación medular epidural son muy útiles en la monitorización de la cirugía espinal por su alta estabilidad, rapidez en su obtención, ausencia de interferencia en el campo del anestesista y porque, aun en una pequeña porción, contienen posiblemente información de vías motoras. Las desventajas son que no siempre es posible la colocación del electrodo, que en el 22 por ciento de los casos no hemos logrado obtener un registro y que hay que ser cautelosos en la valoración del componente motor, ya que su desaparición únicamente daría lugar a una reducción parcial del potencial (AU)

Introduction. Neurophysiological monitoring in spine surgery can be performed by a number of methods, although there is no general agreement about which is the best. Aim. The aim of this study was to evaluate our experiences using the method of spinal cord stimulation with recording carried out on the peripheral nerve. Patients and methods. We studied 51 patients with scoliosis who were submitted to surgical correction. Stimuli were administered with the cathode located in the dorsal epidural space, two levels above the curve to be corrected, and recording was performed on the posterior tibial nerve in the popliteal fossa. Results. Potential was obtained in 78% of cases, with a very low number of averages and the maximum reduction in the amplitude of the potential was found to be 33%. Spinal cord stimulation evokes muscular responses in several muscles and sensory responses in the sural nerve. None of the patients who were monitored using this method presented postoperative neurological deficits added to their previous pathology. Conclusions. The neurogenic potentials obtained by epidural spinal cord stimulation are very useful for monitoring spine surgery because they are very stable, they can be obtained quickly, they avoid the need to interfere with the anaesthetist’s field and because, albeit to a small extent, they may contain information about motor pathways. The main drawback is that it is not always possible to place the electrode and that in 22% of cases we have not managed to obtain the motor component and we have therefore had to be cautious in evaluating it, since its disappearance would only give rise to a partial reduction in the potential (AU)