Can Triggered Electromyograph Thresholds Predict Safe Thoracic Pedicle Screw Placement?

Raynor, Barry L.; Lenke, Lawrence G.; Kim, Yong-Jung; Hanson, Darrell S; Wilson-Holden, Tracy J.; Bridwell, Keith H.; Padberg, Anne M.

doi:10.1097/00007632-200209150-00012

Cited by 136 publications

(87 citation statements)

References 25 publications

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“…This includes the harmonious arc of the screws, tactile determination with a pedicle probe, intraoperative radiography, and EMG. Others have shown the utility of intraoperative EMG to detect thoracic pedicle screw breach [21,22]. On the contrary, at our institution, we have deemed EMG to be of limited use in the thoracic spine, and we are in the process of documenting this through a retrospective analysis.…”

Section: Discussionmentioning

confidence: 93%

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Accuracy of free-hand placement of thoracic pedicle screws in adolescent idiopathic scoliosis: how much of a difference does surgeon experience make?

et al. 2009

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The use of thoracic pedicle screws for the treatment of adolescent idiopathic scoliosis (AIS) has gained widespread popularity. However, the placement of pedicle screws in the deformed spine poses unique challenges, and surgeons experience a learning curve. The in vivo accuracy as determined by computed tomography (CT) of placement of thoracic pedicle screws in the deformed spine as a function of surgeon experience is unknown. We undertook a retrospective review to determine the effect of surgeon experience on the accuracy of thoracic pedicle screw placement in AIS. In 2005, we started to obtain routine postoperative CT scans on patients undergoing a spinal fusion. From a database of these patients, we selected AIS patients, who underwent a posterior spinal fusion. Fifteen consecutive patients for each of the following three groups stratified by attending surgeon experience were selected (N = 45): A) less than 20 cases of all pedicle screw constructs for AIS (surgeons \2 years of practice), B) 20-50 cases (surgeons 2-5 years of practice), and C) greater than 50 cases (surgeons greater than 5 years of practice). Intraoperative evaluation of all screws included probing of the pedicle screw tract, neurophysiologic monitoring, and fluoroscopic confirmation. A total of 856 thoracic pedicle screws were studied. Postoperative CT scans were evaluated by two spine surgeons and a consensus read established as follows: (1) In: intraosseous placement or B2-mm breach, (2) Out: [2-mm breach, either medial or lateral. Of the 856 screws, 104 demonstrated a [2-mm breach, for an overall rate of 12.1% (medial = 55, lateral = 49, P = 0.67). When the breach rates were stratified by surgeon experience, there was a trend toward decreased rate of breach for the most experienced surgeons, although this did not attain statistical significance (Group A: 12.7%, Group B: 12.9%, Group C: 10.8%, P = 0.58). However, the most experienced group (C) had a markedly decreased rate of medial breaches (3.5 vs. 7.4% and 8.4% for groups A and B, respectively, P \ 0.01). The breach rate for the concave periapical screws was not statistically different from the overall breach rate (13.0% vs. 12.1%, P = 0.93). In conclusion, the overall accuracy of placement of pedicle screws in the deformed spine was 87.9%, with no neurologic, vascular, or visceral complications. Meticulous technique allows spine surgeons with a range of surgical experience to accurately and safely place thoracic pedicle screws in the deformed spine. The most experienced surgeons demonstrated the lowest rate of medial breaches.

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Section: Discussionmentioning

confidence: 93%

“…Neuromonitoring was utilized in all cases and included SSEPs, tcMEPS, and EMG evaluation of the thoracic pedicle screws. We utilize the EMG criteria established by Raynor et al [21] when assessing thoracic screws. There were three patients in this cohort who experienced neuromonitoring changes.…”

Section: Placement Of Thoracic Pedicle Screwsmentioning

confidence: 99%

Accuracy of free-hand placement of thoracic pedicle screws in adolescent idiopathic scoliosis: how much of a difference does surgeon experience make?

et al. 2009

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“…En las radiografías hechas en el postoperatorio, se consideraron 22 tornillos como medializados (5,2%) siguiendo los criterios descritos por Raynor y cols. 8 . En el escáner de control (TAC), no encontramos ningún tornillo en la categoría I (tornillos con una o más roscas mediales, intracanal), y 10 (8.5%) en categoría II 4 , recordemos que la categoría II se refiere a tornillos que tienen una o más roscas muy próximas a la pared medial del pedículo y que podrían haberla roto, aunque son considerados aceptables desde el punto de vista clínico.…”

Section: Discussionunclassified

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

García¹,

Herrera-Pérez²,

Lorensu³

et al. 2012

Coluna/Columna

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RESUMENObjetivo: 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. La instrumentación vertebral mediante el uso de tornillos pediculares ha ganado popularidad respecto al tradicional uso de ganchos o sistemas híbridos, debido fundamentalmente a tres característi-cas: poseer mayor capacidad de corrección tridimensional de la deformidad raquídea, mayores índices de fusión de las artrodesis, así como menores índices de revisión 1 . Pero, a pesar de su uso generalizado, la instrumentación transpedicular no está exenta de riesgos, y especialmente en la región torácica, supone un verdadero reto para el cirujano de raquis 1,3 . Por otra parte, la peculiaridad del pedículo de la vértebra torácica es única 2 , siendo más estrechos que a nivel lumbar, con mayores cambios de orientación en caso de deformidades, y con malformaciones congénitas en muchos casos, como la ausencia de canalización de los mismos. Si a esto añadimos la cercanía de estructuras vitales en esta región como son la médula espinal y los grandes vasos, nos encontramos con un recurso quirúrgico de alta complejidad técnica y cuyas complicaciones son potencialmente peligrosas. Como en la columna lumbosacra, la malposición inferior, superior o lateral de los tornillos torácicos puede lesionar raíces nerviosas, sin embargo, es la malposición medial de los mismos la más preocupante, pues la localización intracanal de dicho tornillo puede poner en peligro a la propia médula espinal, amenazando la integridad neurológica de nuestros pacientes.Coluna/Columna. 2012; 11(2): 169-70

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“…Monitoring EMG responses in these muscles requires electrodes at all levels to ensure adequate coverage of the appropriate myotome [17]. A similar concern exists for t-EMG responses in the rectus abdominis and the external oblique muscle, since they share common intercostal and subcostal nerves (T7-T12) [4,18].…”

Section: Discussionmentioning

confidence: 99%

“…Misplaced low thoracic pedicle screws (T6-T12) can be identified by recording muscle activity from either the rectus abdominis or intercostal muscles [1][2][3][4]. However, in a recent experimental work, our research group showed that ipsilateral stimulus-triggered EMG could not discriminate screws that interfered with the medial pedicle wall, but without contact with neural tissues, from those with accurate intraosseous placement in the low thoracic spine [5].…”

Section: Introductionmentioning

confidence: 99%

Recording triggered EMG thresholds from axillary chest wall electrodes: a new refined technique for accurate upper thoracic (T2–T6) pedicle screw placement

et al. 2011

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Can Triggered Electromyograph Thresholds Predict Safe Thoracic Pedicle Screw Placement?

Abstract: To assess thoracic pedicle screw placement, triggered electromyographic thresholds <6.0 mA, coupled with values 60-65% decreased from the mean of all other thresholds in a given patient, should alert the surgeon to suspect a medial pedicle wall breach.

Cited by 136 publications

References 25 publications

Accuracy of free-hand placement of thoracic pedicle screws in adolescent idiopathic scoliosis: how much of a difference does surgeon experience make?

Accuracy of free-hand placement of thoracic pedicle screws in adolescent idiopathic scoliosis: how much of a difference does surgeon experience make?

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

Recording triggered EMG thresholds from axillary chest wall electrodes: a new refined technique for accurate upper thoracic (T2–T6) pedicle screw placement

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