Teratoma maduro del filum terminale. Extirpación guiada por estimulación directa de raíces nerviosas / Mature filum terminale teratoma. Excision guided by direct stimulation of nerve roots

Varón de 45 años, sin antecedentes de interés, que acudió a urgencias con cuadro progresivo de pérdida de fuerza en miembros inferiores a nivel distal con imposibilidad para la flexión dorsal del pie izquierdo, acompañado de disfunción neurógena de vejiga. En la RM se objetivó una lesión a nivel del filum terminale que interesaba completamente el diámetro transversal del saco dural, siendo la impresión diagnóstica radiológica de lipoma del filum terminale. Se llevó a cabo cirugía con monitorización neurofisiológica intraoperatoria empleando estimulación directa de raíces nerviosas, lo que permitió la extirpación de una tumoración compuesta por material sebáceo, grasa y pelo. El diagnóstico anatomopatológico fue de teratoma quístico maduro. El paciente presentó evolución postoperatoria favorable (AU)

A 45-year-old male patient, with no history of interest, consulted in emergency department due to a progressive loss of strength in the lower limbs at the distal level with impossibility for dorsal flexion of the left foot, as well as neurogenic bladder. The MRI revealed a mass at the filum terminale with completed occupation of transverse diameter of the dural sac. The radiological diagnosis was lipoma of filum terminale. The patient underwent surgery with intraoperative neurophysiological monitoring using direct stimulation of nerve roots, which allowed the removal of a tumour composed of sebaceous material, fat and hair. The anatomopathological study classified it as a mature cystic teratoma. Postoperative evolution was favorable (AU)

Importancia de la arteriografía cerebral y la monitorización neurofisiológica intraoperatoria en la endarterectomía carotídea / Importance of cerebral angiography and intraoperative neuromonitoring in carotid endarterectomy

Cada vez es más frecuente indicar una endarterectomía carotídea en función de la información proporcionada por pruebas no invasivas, como la eco-Doppler, la angio-RM o la angio-TAC, obviando la necesidad de la arteriografía. Presentamos un caso de estenosis carotídea sintomática izquierda del 80% en la que la arteriografía cerebral constató la ausencia del segmento A1 derecho y llenado del territorio cerebral anterior bilateral solo desde el lado izquierdo. A los 90 segundos del pinzamiento de las arterias en el cuello se produjo una disminución brusca de la oximetría cerebral y de la amplitud de los potenciales somatosensoriales, que cedieron tras el despinzamiento inmediato. Se desestimó realizar la endarterectomía y se colocó un stent carotídeo sin complicaciones. Este caso ejemplifica la importancia de conocer el estado de la circulación cerebral distalmente a la estenosis. De haberse intentado realizar la endarterectomía sin tener en cuenta la información proporcionada por la arteriografía, posiblemente habría ocurrido una isquemia bihemisférica grave (AU)

It is an increasingly common practice to indicate a carotid endarterectomy procedure based on the information provided by non-invasive tests like Duplex ultrasound, MR angiography or CT angiography, thereby obviating the performance of a conventional cerebral angiography. We present a case of symptomatic left carotid artery 80% stenosis in which cerebral angiography showed absence of the right A1 segment and bilateral anterior cerebral artery territories that filled only from a left injection. Just 90 seconds after carotid artery clamping at the neck, brain oximetry and somatosensory evoked potentials significantly dropped, that recovered after immediate clamp removal. Endarterectomy was dismissed and a carotid stent was successfully placed. This case highlights the importance of knowing the dynamics of cerebral blood circulation distal to the stenosis. If endarterectomy had been attempted, unawareness of the information provided by the cerebral angiography would have likely result in severe bi-hemispheric ischemia (AU)

Documento de consenso para la monitorización neurofisiológica intraoperatoria multimodal en procedimientos neuroquirúrgicos. Fundamentos básicos / Consensus document for multimodal intraoperatory neurophisiological monitoring in neurosurgical procedures. Basic fundamentals

El presente trabajo pretende establecer una guía de actuación consensuada entre anestesiólogos y neurofisiólogos para realizar una monitorización neurofisiológica intraoperatoria efectiva en procedimientos tanto neuroquirúrgicos, como en aquellos en los que existe un riesgo de lesión neurológica funcional. En la primera parte, se describen las principales técnicas utilizadas en la actualidad para la monitorización neurofisiológica intraoperatoria. En segundo lugar, se describen los factores anestésicos y no anestésicos que pueden afectar al registro eléctrico de las estructuras del sistema nervioso. Posteriormente, se analizan los efectos adversos de las técnicas más comunes derivados de su utilización. Y, por último, se describen las diferentes pautas a seguir tras la aparición de los diferentes eventos clínicos intraoperatorios.(AU)

The present work aims to establish a guide to action, agreed by anaesthesiologists and neurophysiologists alike, to perform effective intraoperative neurophysiological monitoring for procedures presenting a risk of functional neurological injury, and neurosurgical procedures. The first section discusses the main techniques currently used for intraoperative neurophysiological monitoring. The second exposes the anaesthetic and non-anaesthetic factors that are likely to affect the electrical records of the nervous system structures. This section is followed by an analysis detailing the adverse effects associated with the most common techniques and their use. Finally, the last section describes a series of guidelines to be followed upon the various intraoperative clinical events.(AU)

Drezotomía en el tratamiento del dolor por desaferentización: revisión de resultados y análisis de factores predictores de éxito / DREZotomy in the treatment of deafferentation pain: review of results and analysis of predictive factors for success

Antecedentes y objetivos El tratamiento del dolor por desaferentización mediante drezotomía espinal es una opción terapéutica contrastada en la literatura. En los últimos años, la drezotomía ha visto relegado su empleo a un segundo plano debido a la eclosión de las terapias neuromoduladoras. Los objetivos de este estudio son demostrar que la drezotomía continúa siendo un tratamiento efectivo y seguro, y analizar aquellos factores predictores de éxito. Pacientes y métodos Se realizó un estudio retrospectivo de todos los pacientes tratados en nuestro servicio mediante drezotomía espinal desde 1998 hasta 2018. Se excluyeron los casos de drezotomía bulbar. Se emplearon la escala visual analógica (EVA) y la reducción de la medicación habitual como variables resultado, y se analizaron variables demográficas, clínicas y quirúrgicas como factores predictores de éxito. Resultados Un total de 27 pacientes (51,9% mujeres) de 53,7 años de edad media fueron tratados mediante drezotomía. La etiología principal del dolor fue por avulsión de plexo braquial (55,6%) seguida de causa tumoral (18,5%). El tiempo medio de evolución del dolor fue de 8,4 años con una intensidad media de 8,7 según la EVA, pese a que el 63% de los pacientes habían recibido tratamiento neuroestimulador previo. Durante el postoperatorio inmediato un 77,8% de los pacientes presentaron una reducción del 50% o más en la EVA. Tras un seguimiento medio de 22 meses posdrezotomía, permaneció una reducción de al menos el 50% en la EVA en el 59,3% de los pacientes (reducción media de 4,9 puntos) permitiendo una reducción del tratamiento analgésico habitual en el 70,4% de ellos. La drezotomía en la avulsión de plexo braquial presentó una tasa de éxito (93%) superior al resto de patologías (41,7%) de manera significativa (p = 0,001) (AU)

Background and objectives The treatment of deafferentation pain by spinal DREZotomy is a proven therapeutic option in the literature. In recent years, use of DREZotomy has been relegated to second place due to the emergence of neuromodulation therapies. The objectives of this study are to demonstrate that DREZotomy continues to be an effective and safe treatment and to analyse predictive factors for success. Patients and methods A retrospective study was conducted of all patients treated in our department with spinal DREZotomy from 1998 to 2018. Bulbar DREZotomy procedures were excluded. A visual analogue scale (VAS) and the reduction of routine medication were used as outcome variables. Demographic, clinical and operative variables were analysed as predictive factors for success. Results A total of 27 patients (51.9% female) with a mean age of 53.7 years underwent DREZotomy. The main cause of pain was brachial plexus injury (BPI) (55.6%) followed by neoplasms (18.5%). The mean time of pain evolution was 8.4 years with a mean intensity of 8.7 according to the VAS, even though 63% of the patients had previously received neurostimulation therapy. Favourable outcome (≥ 50% pain reduction in the VAS) was observed in 77.8% of patients during the postoperative period and remained in 59.3% of patients after 22 months average follow-up (mean reduction of 4.9 points). This allowed for a reduction in routine analgesic treatment in 70.4% of them. DREZotomy in BPI-related pain presented a significantly higher success rate (93%) than the other pathologies (41.7%) (p = .001). No association was observed between outcome and age, gender, DREZ technique, duration of pain or previous neurostimulation therapies. There were six neurological complications, four post-operative transient neurological deficits and two permanent deficits (AU)

DREZotomy in the treatment of deafferentation pain: review of results and analysis of predictive factors for success. / Drezotomía en el tratamiento del dolor por desaferentización: revisión de resultados y análisis de factores predictores de éxito.

BACKGROUND AND OBJECTIVES: The treatment of deafferentation pain by spinal DREZotomy is a proven therapeutic option in the literature. In recent years, use of DREZotomy has been relegated to second place due to the emergence of neuromodulation therapies. The objectives of this study are to demonstrate that DREZotomy continues to be an effective and safe treatment and to analyse predictive factors for success. PATIENTS AND METHODS: A retrospective study was conducted of all patients treated in our department with spinal DREZotomy from 1998 to 2018. Bulbar DREZotomy procedures were excluded. A visual analogue scale (VAS) and the reduction of routine medication were used as outcome variables. Demographic, clinical and operative variables were analysed as predictive factors for success. RESULTS: A total of 27 patients (51.9% female) with a mean age of 53.7 years underwent DREZotomy. The main cause of pain was brachial plexus injury (BPI) (55.6%) followed by neoplasms (18.5%). The mean time of pain evolution was 8.4 years with a mean intensity of 8.7 according to the VAS, even though 63% of the patients had previously received neurostimulation therapy. Favourable outcome (≥50% pain reduction in the VAS) was observed in 77.8% of patients during the postoperative period and remained in 59.3% of patients after 22 months average follow-up (mean reduction of 4.9 points). This allowed for a reduction in routine analgesic treatment in 70.4% of them. DREZotomy in BPI-related pain presented a significantly higher success rate (93%) than the other pathologies (41.7%) (p=.001). No association was observed between outcome and age, gender, DREZ technique, duration of pain or previous neurostimulation therapies. There were six neurological complications, four post-operative transient neurological deficits and two permanent deficits. CONCLUSION: Dorsal root entry zone surgery is effective and safe for treating patients with deafferentation pain, especially after brachial plexus injury. It can be considered an alternative treatment after failed neurostimulation techniques for pain control. However, its indication should be considered as the first therapeutic option after medical therapy failure due to its good long-term results.

Consensus document for multimodal intraoperatory neurophisiological monitoring in neurosurgical procedures. Basic fundamentals. / Documento de consenso para la monitorización neurofisiológica intraoperatoria multimodal en procedimientos neuroquirúrgicos. Fundamentos básicos.

The present work aims to establish a guide to action, agreed by anaesthesiologists and neurophysiologists alike, to perform effective intraoperative neurophysiological monitoring for procedures presenting a risk of functional neurological injury, and neurosurgical procedures. The first section discusses the main techniques currently used for intraoperative neurophysiological monitoring. The second exposes the anaesthetic and non-anaesthetic factors that are likely to affect the electrical records of the nervous system structures. This section is followed by an analysis detailing the adverse effects associated with the most common techniques and their use. Finally, the last section describes a series of guidelines to be followed upon the various intraoperative clinical events.

Importance of cerebral angiography and intraoperative neuromonitoring in carotid endarterectomy. / Importancia de la arteriografía cerebral y la monitorización neurofisiológica intraoperatoria en la endarterectomía carotídea.

It is an increasingly common practice to indicate a carotid endarterectomy procedure based on the information provided by non-invasive tests like Duplex ultrasound, MR angiography or CT angiography, thereby obviating the performance of a conventional cerebral angiography. We present a case of symptomatic left carotid artery 80% stenosis in which cerebral angiography showed absence of the right A1 segment and bilateral anterior cerebral artery territories that filled only from a left injection. Just 90seconds after carotid artery clamping at the neck, brain oximetry and somatosensory evoked potentials significantly dropped, that recovered after immediate clamp removal. Endarterectomy was dismissed and a carotid stent was successfully placed. This case highlights the importance of knowing the dynamics of cerebral blood circulation distal to the stenosis. If endarterectomy had been attempted, unawareness of the information provided by the cerebral angiography would have likely result in severe bi-hemispheric ischemia.

Mature filum terminale teratoma. Excision guided by direct stimulation of nerve roots. / Teratoma maduro del filum terminale. Extirpación guiada por estimulación directa de raíces nerviosas.

A 45-year-old male patient, with no history of interest, consulted in emergency department due to a progressive loss of strength in the lower limbs at the distal level with impossibility for dorsal flexion of the left foot, as well as neurogenic bladder. The MRI revealed a mass at the filum terminale with completed occupation of transverse diameter of the dural sac. The radiological diagnosis was lipoma of filum terminale. The patient underwent surgery with intraoperative neurophysiological monitoring using direct stimulation of nerve roots, which allowed the removal of a tumour composed of sebaceous material, fat and hair. The anatomopathological study classified it as a mature cystic teratoma. Postoperative evolution was favorable.

Intraoperative neurophysiological monitoring of the phrenic nerve: utility and descriptions of the technique. / Monitorización neurofisiológica intraoperatoria del nervio frénico: utilidad y descripción de la técnica.

In surgical procedures of the supraclavicular and lateral cervical regions, as well as in cardiac and mediastinal surgeries, diaphragm function can be compromised by the risk of injury to the phrenic nerve and/or the C4 root. There are few publications that treat the intraoperative stimulation of these nerve structures to evaluate their functionality and, to our knowledge, until now it has not been hypothesized about whether it is possible to reduce the injury rates, which reach 26% in some cardiac surgery studies. We describe the technique used for the neurophysiological monitoring of the phrenic nerve. Also, its usefulness and advantages over other techniques are discussed. We conclude that, with the increasing incorporation in recent years of intraoperative neurophysiological monitoring, its application to the phrenic nerve is possible in procedures with a risk of injury and, thus, the reduction of iatrogenic injury rates may be feasible.

[Neurophysiological monitoring options in brain tumour resections. Consensus statement from the Spanish Society of Neurosurgery's (SENEC) Neuro-oncology Working Group and the Spanish Society of Clinical Neurophysiology (SENFC)]. / Opciones de monitorización neurofisiológica en la resección de tumoraciones cerebrales. Documento de consenso entre el Grupo de Trabajo de Neurooncología de la Sociedad Española de Neurocirugía (SENEC) y la Sociedad Española de Neurofisiología Clínica (SENFC).

Brain tumours located in or in proximity to eloquent areas are a significant neurosurgical challenge. Performing this kind of surgery with neurophysiological monitoring to improve resections with reduced permanent focal neurological deficit has become widely accepted in the literature. However, how to conduct this monitoring, the exact definition of an eloquent area and whether to perform this surgery with the patient awake or asleep are still subject to rigorous scientific debate. Members of the Neuro-oncology Working Group (GTNO) of the Spanish Society of Neurosurgery (SENEC) and members of the Spanish Society of Clinical Neurophysiology (SENFC) have published a consensus statement to explain the different neurophysiological monitoring options currently available in awake and asleep patients to obtain better surgical resection without neurological deficits. An exhaustive review of the literature has also been conducted.

Uso de la Dexmedetomidina en la Neurocirugía con el paciente despierto. A propósito de un caso clínico / Use of Dexmedetomidine in Neurosurgery with the patient awake. About a clinical case

Presentamos el caso de un paciente de 58 años, coordinado para resección de tumor temporo insular izquierdo mediante una craneotomía despierto. Se analiza en este trabajo, a partir de la descripción del caso clínico, las ventajas de la resección de este tipo de lesiones con el paciente despierto. La posibilidades de abordaje, despierto durante todo el procedimiento (awake), dormido-despierto-dormido (asleep-awake-asleep), dormido-despierto (asleep-awake). A su vez se analiza la técnica anestésica, la combinación de fármacos y especialmente las características de la Dexmedetomidina. Conclusiones: la neurocirugía con el paciente despierto, determina una serie de características y desafíos para el equipo anestésico tratante y la interacción con un equipo mulitidisciplinario (neurocirujanos, neurofisiologos, anestesiologos). Existen diferentes combinaciones de fármacos; siendo la Dexmedetomidina una opción que mejorar la satisfacción de los pacientes durante la etapa de despertar, así como las condiciones quirúrgicas con mínimas interferencia en la monitorización neurofisiológica.

We present the case of a 58-year-old patient, scheduled to resection of left insular tumor by an awake craniotomy. In this paper, from the description of the clinical case, we analyzed the advantages of a resection of this type of lesion with an awake patient. We discuss the surgical approach, and options of an awake patient all throughout the procedure, asleep-awake-asleep and asleep-awake. Also, the anesthetic technique, the combination of drugs and especially the characteristics of Dexmedetomidine are analyzed. Conclusions: neurosurgery with an awake patient, determines a series of characteristics and challenges for the anesthetic and multidisciplinary team (neurosurgeons, neurophysiologists, anesthesiologists). There are different combinations of drugs, with Dexmedetomidine being an option that would improve patient satisfaction during the awakening stage, as well as surgical conditions with minimal interference in neurophysiological monitoring.

Repeated sugammadex reversal of muscle relaxation during lumbar spine surgery with intraoperative neurophysiological multimodal monitoring.

Intraoperative neurophysiological monitoring during spine surgery is usually acomplished avoiding muscle relaxants. A case of intraoperative sugammadex partial reversal of the neuromuscular blockade allowing adequate monitoring during spine surgery is presented. A 38 year-old man was scheduled for discectomy and vertebral arthrodesis throughout anterior and posterior approaches. Anesthesia consisted of total intravenous anesthesia plus rocuronium. Intraoperatively monitoring was needed, and the muscle relaxant reverted twice with low dose sugammadex in order to obtain adequate responses. The doses of sugammadex used were conservatively selected (0.1mg/kg boluses increases, total dose needed 0.4mg/kg). Both motor evoqued potentials, and electromyographic responses were deemed adequate by the neurophysiologist. If muscle relaxation was needed in the context described, this approach could be useful to prevent neurological sequelae. This is the first study using very low dose sugammadex to reverse rocuronium intraoperatively and to re-establish the neuromuscular blockade.

[Anaesthetic management of excision of a cervical intraspinal tumor with intraoperative neurophysiologic monitoring in a pregnant woman at 29 weeks]. / Manejo anestésico en la extirpación de una tumoración intrarraquídea cervical con monitorización neurofisiológica intraoperatoria en una paciente gestante de 29 semanas.

The intraoperative neurophysiological monitoring is a technique used to test and monitor nervous function. This technique has become essential in some neurosurgery interventions, since it avoids neurological injuries during surgery and reduces morbidity. The experience of intraoperative neurophysiological monitoring is limited in some clinical cases due to the low incidence of pregnant women undergoing a surgical procedure. A case is presented of a 29-weeks pregnant woman suffering from a cervical intraspinal tumour with intense pain, which required surgery. The collaboration of a multidisciplinary team composed of anaesthesiologists, neurosurgeons, neurophysiologists and obstetricians, the continuous monitoring of the foetus, the intraoperative neurophysiological monitoring, and maintaining the neurophysiological and utero-placental variables were crucial for the proper development of the surgery. According to our experience and the limited publications in the literature, no damaging effects of this technique were detected at maternal-foetal level. On the contrary, it brings important benefits during the surgery and for the final result.

Positioning of pedicle screws in adolescent idiopathic scoliosis using electromyography / Posição de parafusos pediculares na escoliose idiopática do adolescente com uso da eletromiografia / Posición de tornillos pediculares en escoliosis idiopática del adolescente con electromiografía

To analyze the occurrence of poor positioning of pedicle screws inserted with the aid of intraoperative electromyographic stimulation in the treatment of Adolescent Idiopathic Scoliosis (AIS).

Analisar a ocorrência do mau posicionamento de parafusos pediculares inseridos com auxílio de estimulação eletromiográfica intraoperatória, no tratamento de escoliose idiopática do adolescente (EIA).

Analizar la incidencia de la mala colocación de tornillos pediculares insertados con la ayuda de la estimulación electromiográfica intraoperatoria para el tratamiento de la Escoliosis Idiopática del Adolescente (EIA).

Intraoperative neurophysiological monitoring in peripheral nerve surgery: Technical description and experience in a centre.

INTRODUCTION: Intraoperative neurophysiological monitoring has experienced a spectacular development in the past 20 years, particularly in the fields of neurosurgery and spine surgery. it has become a useful, almost indispensable, tool in preventing nerve damage during surgery. The aim of this article is to describe the intraoperative technique and analyze its results in the field of peripheral nerve surgery. OBJECTIVE: To describe the usefulness of a technique in peripheral nerve surgery, the technique used and the experience in a centre. PATIENTS AND METHODS: A retrospective study was conducted on 30 cases of peripheral nerve surgery performed in this centre from 2009 to 2013, using the intraoperative monitoring technique. RESULTS: Of the total of 13 peripheral nerve tumors recorded, there were 11 excellent results and 2 good results, one temporary hypoesthesia and one with almost complete sensory, except for motor, recovery. Traumatic injury was recorded in 17 cases, of which 6 required performing a graft, and the remaining 11 cases only neurolysis was performed, with complete motor and sensory recovery. CONCLUSIONS: Intraoperative neurophysiological monitoring is a useful tool in the secondary surgery of peripheral nerve injury and the intraneural tumor pathology.

[Awake craniotomy. Considerations in special situations]. / Craneotomía en el paciente consciente. Consideraciones en situaciones especiales.

Awake craniotomy was the earliest surgical procedure known, and it has become fashionable again. In the past it was used for the surgical management of intractable epilepsy, but nowadays, its indications are increasing, and it is a widely recognized technique for the resection of mass lesions involving the eloquent cortex, and for deep brain stimulation. The procedure is safe, provides excellent results, and saves money and resources. The anesthesiologist should know the principles underlying neuroanesthesia, the technique of scalp blockade, and the sedation protocols, as well as feeling comfortable with advanced airway management. The main anesthetic aim is to keep patients cooperating when required (analgesia-based anesthesia). This review attempts to summarize the most recent evidence from the clinical literature, a long as the number of patients undergoing craniotomies in the awake state are increasing, specifically in the pediatric population.

Valor predictivo de la estimulación eléctrica de los tornillos pediculares torácicos en la mal posición medial de los mismos en la instrumentación de cirugía de columna / Valor preditivo da estimulação elétrica em casos de mal posicionamento de parafusos pediculares torácicos na cirurgia de coluna / Predictive value of electrical stimulation in cases of malposition of thoracic pedicle screws in spine surgery

OBJETIVO: Demostrar si la técnica de estimulación eléctrica permite la detección de la mal posición medial de los tornillos pediculares torácicos. RESULTADOS: Se analizaron 421 tornillos torácicos. Tuvimos alertas a la estimulación en 25 (5,93%) de los casos. A todos los pacientes se les realizó radiografía posoperatoria demostrando 22 tornillos (5,2%) medializados. Realizamos TAC en 17 pacientes (37%), con ningún tornillo en posición 1 y 10 tornillos en posición 2 (8,5%). Se consideraron tornillos medializados los que tenían respuesta positiva a estimulación inferior a 6 mA. CONCLUSIONES: la estimulación eléctrica nos ha permitido reducir el riesgo de posición medial de los tornillos torácicos, minimizando además el uso de radiografía intraoperatoria.

OBJETIVO: Demonstrar se a técnica de estimulação elétrica permite a detecção de mal posicionamento medial dos parafusos pediculares torácicos. RESULTADOS: Foram analisados 421 parafusos torácicos. Os alertas da estimulação ocorreram em 25 (5,93%) dos casos. Todos os pacientes foram submetidos à radiografia pós-operatória que demonstrou 22 parafusos (5,2%) medializados. Realizamos TC axial em 17 pacientes (37%), e não se encontrou nenhum parafuso na posição 1, sendo que 10 parafusos estavam na posição 2 (8,5%). Foram considerados parafusos medializados os que apresentaram resposta positiva à estimulação inferior a 6 mA. CONCLUSÕES: a estimulação elétrica permitiu a redução de risco de posição medial dos parafusos torácicos, minimizando o uso de radiografias intraoperatórias.

OBJECTIVE: To demonstrate that the electrical stimulation technique allows the detection of medial malpositioning of thoracic pedicle screws. RESULTS: We analyzed 421 thoracic screws. Stimulation alerts occurred in 25 (5.93%) cases. All patients underwent postoperative radiographs showing 22 medialized screws (5.2%). Axial CT scans were performed on 17 patients (37%), and no screw was found in position 1 and 10 of them were in position 2 (8.5%). Medialized screws were considered those who had a positive response to stimulation of less than 6 mA. CONCLUSIONS: Electrical stimulation allowed a reduction of risk of medial positioning of thoracic screws, minimizing the use of intraoperative radiographs.