Investigation Of Spinal Cord Monitoring Technique During Spinal Surgery

Spine surgery is one of the most utility means to many spinal cord diseases. But a little false in surgery operation may give rise to the risk of spinal cord, which will cause to neurological functional disorder or permanent crippledom and paraplegia. With the development of modern advanced reshaping technique, surgical procedures are so complicated that there are high risks and more difficulties during the course of operation. Therefore, it is necessary to monitor intraoperational spinal cord function in order to observe spinal cord status in any time, to find the position and cause of spinal cord injure immediately and early, to adopt methods to prevent unreversible neurological function damage. Intraoperative evoked potential test (EP) can detect injury of nerve and its position promptly, thus to decrease operation risks, to relieve patient's distress, to increase operation efficiency, and to optimize operative procedure. However, there are many problems in the use of EP in monitoring spinal cord, such as large volume in existing equipment, worse movement behavior, not suitable to place in operation room, detecting parameters not sensitive to the injure and sensitive to noise, and so on.In this study, a portable intraoperative neural function monitoring system is designed aiming to existence problems in current spinal cord monitoring technique and equipment. The advanced universal serial bus is used for the interface of acquisition, transmission and control in the new monitoring system with virtue of agility procedure and hot plug. The printed circuit board has high integrated, low power consumption and minor space by application of surface mounted technique.CSEP data sampled during lateral curvature orthomorphia are processed by time-frequency analysis (TFA) of short time Fourier transform (STFT) and continuous wavelet transform (CWT). The more stable parameters in time-frequency domain (TFD) are suggested reflecting intraoperative spinal cord functional status with control of parameters in time domain. Compared with the spinal cord compression model (compression rate 30%) in rats, some significant results are obtained. ①Peak time in STFT of CSEP recording in rats after compression spinal cord 30% is changed from 28.06±7.27 ms to 35.05±9.94 ms. Peak frequency in STFT is changed from 36.67±10.08Hz to 50.01±17.32Hz. Peak power inSTFT is changed from 106.63±22.50 to 62.59±25.05. Peak time in CWT of CSEP recording in rats after compression spinal cord 30% is changed from 29.29±7.83ms to 39.84±8.20ms. Peak frequency in CWT is changed from 40.45±6.67Hz to 62.27±17.33Hz. Peak power in CWT is changed from 5746.64±1577.39 to 3879.82±1290.14. ②CSEP sampled in lateral curvature orthomorphia is used to monitor spinal cord function. Variability of peak time, peak frequency and peak power analysis in STFT is 9.40%, 14.34% and 1.71%(Cz-Fz)or 11.49%, 7.89% and 7.41%(Cv-Fz). Variability in CWT is 7.99%, 10.67% and 18.61%(Cz-Fz)or 6.03%, 8.11%, 22.12%(Cv-Fz).From this study, characteristic parameters of peak time, peak frequency and peak power in TFA are more stable and more sensitive than parameters of latency and amplitude in time domain. The monitor information obtained in CWT is more stable and precise than that of STFT because of the excellent time-frequency resolution. Time-frequency spectrum used in intraoperative monitor makes surgeon obtained operation information easily because different color in spectrum reflects the change of amplitude.