Department of Neurology and Clinical Neurophysiology, Clinica Fornaca di Sessant, Corso Vittorio Emanuele II, 10128 Turin, Italy.
Department of Neurosurgery, Clinica Fornaca di Sessant, Corso Vittorio Emanuele II, 10128 Turin, Italy.
Clin Neurophysiol. 2019 Apr;130(4):573-581. doi: 10.1016/j.clinph.2018.11.029. Epub 2018 Dec 26.
We describe a stimulus-evoked EMG approach to minimize false negative results in detecting pedicle breaches during lumbosacral spinal instrumentation.
In 36 patients receiving 176 lumbosacral pedicle screws, EMG threshold to nerve root activation was determined using a focal probe inserted into the pilot hole at a depth, customized to the individual patients, suitable to position the stimulating tip at the point closest to the tested nerve root. Threshold to screw stimulation was also determined.
Mean EMG thresholds in 161 correctly fashioned pedicle instrumentations were 7.5 mA ± 2.46 after focal hole stimulation and 21.8 mA ± 6.8 after screw stimulation. Direct comparison between both thresholds in individual pedicles showed that screw stimulation was always biased by an unpredictable leakage of the stimulating current ranging from 10 to 90%. False negative results were never observed with hole stimulation but this was not true with screw stimulation.
Focal hole stimulation, unlike screw stimulation, approaches absolute EMG threshold as shown by the lower normal limit (2.6 mA; p < 0.05) that borders the upper limit of threshold to direct activation of the exposed root.
The technique provides an early warning of a possible pedicle breakthrough before insertion of the more harmful, larger and threaded screw.
我们描述了一种刺激诱发肌电图（EMG）方法，以最大限度地减少在腰骶部脊柱器械置入时检测椎弓根破裂的假阴性结果。
在 36 例接受 176 个腰骶部椎弓根螺钉置入的患者中，使用插入导孔的焦点探头来确定神经根激活的 EMG 阈值，导孔深度根据个体患者进行定制，以将刺激尖端置于最接近测试神经根的位置。还确定了螺钉刺激的阈值。
在 161 个正确成形的椎弓根器械中，焦点孔刺激后的平均 EMG 阈值为 7.5mA±2.46，螺钉刺激后的阈值为 21.8mA±6.8。在各个椎弓根之间对两种阈值进行直接比较表明，螺钉刺激总是受到刺激电流不可预测泄漏的影响，范围为 10 到 90%。用孔刺激从未观察到假阴性结果，但用螺钉刺激则不然。
与螺钉刺激不同，焦点孔刺激接近绝对 EMG 阈值，这表现在其较低的正常下限（2.6mA；p<0.05）接近暴露神经根直接激活的阈值上限。
该技术在插入更有害、更大和螺纹的螺钉之前，为可能的椎弓根突破提供了早期预警。
