Electromyographic thresholds after thoracic screw stimulation depend on the distance of the screw from the spinal cord and not on pedicle cortex integrity

Montes, Elena; Blas, Gema de; Regidor, Ignacio; Barrios, Carlos; Burgos, Jesús; Hevia, Eduardo; Palanca, J. M.; Correa, Carlos

doi:10.1016/j.spinee.2011.09.006

Cited by 21 publications

(12 citation statements)

References 24 publications

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“…Although traditionally thought to indicate medial pedicle wall breaches, the data by de Blas et al (10) suggested that decreased amplitudes were also affected by the distance of the thecal sac relative to the pedicle. Montes et al (12) confirmed this assumption in a porcine model finding that the electrical impedance was more dependent upon the distance between the screw and the neural structures than the integrity of the medial pedicular wall. Another aspect that has yet to be investigated to the knowledge of the authors is the impact of pedicular dimensions on t-EMG amplitudes.…”

Section: Discussionmentioning

confidence: 82%

“…Pedicle screw malposition is another means by which neurologic compromise can be precipitated, with an incidence reported to be as high as 40% with an estimated 1% rate of neurologic complication (11). Triggered screw electromyography (t-EMG) has been used to help identify malpositioned screws, with threshold stimulation varying based upon the spinal segment tested (lumbar versus thoracic), location within the curve (apical versus nonapical) and laterality with regard to the curve (concavity versus convexity) (3,10,12). Screw navigation is another means by which to minimize malpositioned screws.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Accuracy of robot-assisted pedicle screw insertion in adolescent idiopathic scoliosis: is triggered electromyographic pedicle screw stimulation necessary?

Shaw

Murphy²,

Devito³

2018

J Spine Surg

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Section: Discussionmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Accuracy of robot-assisted pedicle screw insertion in adolescent idiopathic scoliosis: is triggered electromyographic pedicle screw stimulation necessary?

Shaw

Murphy²,

Devito³

2018

J Spine Surg

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“…Note that strong bilateral responses to foraminal stimulation argues against absolute distance from the spinal cord as being the primary mediator of the probability of a response to pedicle screw testing. 41 Could our protocol be revised to improve upon our ability to differentiate between a medial malpositioning of a screw into the canal versus into a foramen? One way would be to place a probe along the pedicle track and take a lateral fluoroscopic image of that spine region.…”

Section: Can Our Methods Predict Foraminal Defects?mentioning

confidence: 99%

Neuromonitoring with pulse-train stimulation for implantation of thoracic pedicle screws: a blinded and randomized clinical study. Part 1. Methods and alarm criteria

Calancie¹,

Donohue

Harris

et al. 2014

SPI

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Object Reports of the accuracy of existing neuromonitoring methods for detecting or preventing medial malpositioning of thoracic pedicle screws have varied widely in their claimed effectiveness. The object of this study was to develop, test, and validate a novel neuromonitoring method for preventing medial malpositioning of pedicle screws in the thoracic spine during surgery. Methods This is a prospective, blinded and randomized study using a novel combination of input (4-pulse stimulus trains delivered within the pedicle track) and output (evoked electromyography from leg muscles) to detect pedicle track trajectories that—once implanted with a screw—would cause that screw to breach the pedicle's medial wall and encroach upon the spinal canal. For comparison, the authors also used screw stimulation as an input and evoked electromyogram from intercostal and abdominal muscles as output measures. Intraoperative electrophysiological findings were compared with postoperative CT scans by multiple reviewers blinded to patient identity or intraoperative findings. Results Data were collected from 71 patients, in whom 802 screws were implanted between the T-1 and L-1 vertebral levels. A total of 32 screws ended up with screw threads encroaching on the spinal canal by at least 2 mm. Pulse-train stimulation within the pedicle track using a ball-tipped probe and electromyography from lower limb muscles correctly predicted all 32 (100%) of these medially malpositioned screws. The combination of pedicle track stimulation and electromyogram response from leg muscles proved to be far more effective in predicting these medially malpositioned screws than was direct screw stimulation and any of the target muscles (intercostal, abdominal, or lower limb muscles) we monitored. Based on receiver operating characteristic analysis, the combination of 10-mA (lower alarm) and 15-mA stimulation intensities proved most effective for detection of pedicle tracks that ultimately gave rise to medially malpositioned screws. Additional results pertaining to the impact of feedback of these test results on surgical decision making are provided in the companion report. Conclusions This novel neuromonitoring approach accurately predicts medially malpositioned thoracic screws. The approach could be readily implemented within any surgical program that is already using contemporary neuromonitoring methods that include transcranial stimulation for monitoring motor evoked potentials.

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“…Presumably, the threshold currents for excitation of motor axons and Ia/Ib fibers are similar for stimulation of the caudal segments of the spinal cord ( Capogrosso et al, 2013 ). In the case of SCS through pedicle screws, the threshold currents rise as the distance between the screw and the neural structures increases ( Montes et al, 2012 ). The differences in threshold currents observed in our work ( Figure 3C ) may be associated with anatomical differences in the structure of the rat vertebrae.…”

Section: Discussionmentioning

confidence: 99%

Mapping of the Spinal Sensorimotor Network by Transvertebral and Transcutaneous Spinal Cord Stimulation

Shkorbatova

Lyakhovetskii

Павлова

et al. 2020

Front. Syst. Neurosci.

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Transcutaneous stimulation is a neuromodulation method that is efficiently used for recovery after spinal cord injury and other disorders that are accompanied by motor and sensory deficits. Multiple aspects of transcutaneous stimulation optimization still require testing in animal experiments including the use of pharmacological agents, spinal lesions, cell recording, etc. This need initially motivated us to develop a new approach of transvertebral spinal cord stimulation (SCS) and to test its feasibility in acute and chronic experiments on rats. The aims of the current work were to study the selectivity of muscle activation over the lower thoracic and lumbosacral spinal cord when the stimulating electrode was located intravertebrally and to compare its effectiveness to that of the clinically used transcutaneous stimulation. In decerebrated rats, electromyographic activity was recorded in the muscles of the back (m. longissimus dorsi), tail (m. abductor caudae dorsalis), and hindlimb (mm. iliacus, adductor magnus, vastus lateralis, semitendinosus, tibialis anterior, gastrocnemius medialis, soleus, and flexor hallucis longus) during SCS with an electrode placed alternately in one of the spinous processes of the VT12–VS1 vertebrae. The recruitment curves for motor and sensory components of the evoked potentials (separated from each other by means of double-pulse stimulation) were plotted for each muscle; their slopes characterized the effectiveness of the muscle activation. The electrophysiological mapping demonstrated that transvertebral SCS has specific effects to the rostrocaudally distributed sensorimotor network of the lower thoracic and lumbosacral cord, mainly by stimulation of the roots that carry the sensory and motor spinal pathways. These effects were compared in the same animals when mapping was performed by transcutaneous stimulation, and similar distribution of muscle activity and underlying neuroanatomical mechanisms were found. The experiments on chronic rats validated the feasibility of the proposed stimulation approach of transvertebral SCS for further studies.

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Electromyographic thresholds after thoracic screw stimulation depend on the distance of the screw from the spinal cord and not on pedicle cortex integrity

Cited by 21 publications

References 24 publications

Accuracy of robot-assisted pedicle screw insertion in adolescent idiopathic scoliosis: is triggered electromyographic pedicle screw stimulation necessary?

Accuracy of robot-assisted pedicle screw insertion in adolescent idiopathic scoliosis: is triggered electromyographic pedicle screw stimulation necessary?

Neuromonitoring with pulse-train stimulation for implantation of thoracic pedicle screws: a blinded and randomized clinical study. Part 1. Methods and alarm criteria

Mapping of the Spinal Sensorimotor Network by Transvertebral and Transcutaneous Spinal Cord Stimulation

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