Stimulus-Evoked Electromyographic Monitoring During Minimally Invasive Transpedicular Implantation of Screws in Lumbosacral Spine: Threshold Value, Methodology and Clinical Effectiveness.
BACKGROUND
Stimulus-evoked electromyography (EMG) has been developed to increase the safety of transpedicular placement of screws. There is more consensus about this monitoring method in open surgery. Alarm thresholds for minimally invasive surgery are based on referential value for open surgery. Nevertheless, there are no uniform alarm criteria on this modality for minimally invasive surgery. Using an analysis of alarm threshold, methodology and clinical effectiveness on stimulus-evoked EMG monitoring for minimally invasive transpedicular implantation of screws in the lumbosacral spine, this study aims to reflect and recommend for optimizing accuracy.


METHODS
Using a selection of studies, an analysis of the pedicle breach rates and breach-related clinical complication rates was made between studies on minimally invasive surgery by applying different thresholds. A second analysis of the pedicle breach rates and breach-related clinical complication rates was made between studies on open and minimally invasive surgery by applying the same threshold.


RESULTS
In minimally invasive surgery, stimulus-evoked EMG has an acceptable accuracy in the detection of clinical relevant pedicle breaches. Suction limitation may alter the stimulation threshold. No significant differences in clinical effectiveness were observed between studies by applying thresholds of 5 mA, 7 mA, and 12 mA. However, a low threshold of 5 mA seems inappropriate for the tap stimulation.


CONCLUSIONS
In minimally invasive surgery, continuous stimulation of instrumentation devices is recommended. A minimum 5-mA threshold should be used for stimulation of the pedicle access needle. Use of higher-stimulation thresholds during tapping and incorporation of an adapted continuous suction system may optimize the accuracy of stimulus-evoked EMG.
Department of Intraoperative Neurophysiology, Mount Sinai West Hospital, New York, New York, USA; University of Cantabria, Santander, Cantabria, Spain. Electronic address: yfenwufriendship@gmail.com.
Yunfen
Y
Wu
Department of Neurosurgery, University Hospital "Marqués de Valdecilla", Santander, Cantabria, Spain; University of Cantabria, Santander, Cantabria, Spain.
Alfonso
A
Vázquez-Barquero
D001863:Bone Screws; D016206:Databases, Bibliographic / Q000706:statistics & numerical data; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D006801:Humans; D008159:Lumbar Vertebrae / Q000601:surgery; D008161:Lumbosacral Region / Q000601:surgery; D019060:Minimally Invasive Surgical Procedures / Q000295:instrumentation* / Q000379:methods*; D016343:Monitoring, Intraoperative; D013122:Spinal Diseases / Q000601:surgery; D013123:Spinal Fusion / Q000379:methods*; D016896:Treatment Outcome
Lumbosacral spine fixation; Minimally invasive; Monitoring; Pedicle screw; Threshold