Hu Y, Luk K D K, Lu W W, Leong J C Y
Department of Orthopaedic Surgery, Duchess of Kent Children's Hospital, The University of Hong Kong, Hong Kong, ROC.
J Neurol Neurosurg Psychiatry. 2003 Jan;74(1):82-7. doi: 10.1136/jnnp.74.1.82.
To investigate the improvement in the reliability of intraoperative spinal cord monitoring by applying time-frequency analysis to somatosensory evoked potentials (SEP).
34 patients undergoing scoliosis surgery were studied. SEP were recorded during different stages of scoliosis surgery. Averaged SEP signals were analysed intraoperatively by short time Fourier transform (STFT). The time-frequency characteristics of SEP were observed during surgery. The main peak in the time-frequency interpretation of SEP was measured in peak time, peak frequency, and peak power. The changes in these variables were compared with the changes in latency and amplitude during different surgical stages.
During different surgical stages, changes in peak times and peak powers were found to correlate with the changes in latency and amplitude, respectively. Peak time showed more variability than latency (p < 0.01), while peak power showed less variability than amplitude (p < 0.01). The peak frequency of SEP appeared to be unchanged during surgery. SEP signals were found to have specific time-frequency characteristics, with the time-frequency distribution of the signals being located in a particular time-frequency space.
Time-frequency analysis of SEP waveforms reveals stable and easily identifiable characteristics. Peak power is recommended as a more reliable monitoring parameter than amplitude, while peak time monitoring was not superior to latency measurement. Applying time-frequency analysis to SEP can improve the reliability of intraoperative spinal cord monitoring.
通过对体感诱发电位（SEP）应用时频分析，研究术中脊髓监测可靠性的提高情况。
对34例接受脊柱侧弯手术的患者进行研究。在脊柱侧弯手术的不同阶段记录SEP。术中通过短时傅里叶变换（STFT）分析平均SEP信号。观察手术过程中SEP的时频特征。在峰值时间、峰值频率和峰值功率方面测量SEP时频解读中的主峰。将这些变量的变化与不同手术阶段潜伏期和波幅的变化进行比较。
在不同手术阶段，发现峰值时间和峰值功率的变化分别与潜伏期和波幅的变化相关。峰值时间的变异性比潜伏期更大（p < 0.01），而峰值功率的变异性比波幅更小（p < 0.01）。SEP的峰值频率在手术过程中似乎没有变化。发现SEP信号具有特定的时频特征，信号的时频分布位于特定的时频空间中。
SEP波形的时频分析揭示了稳定且易于识别的特征。推荐将峰值功率作为比波幅更可靠的监测参数，而峰值时间监测并不优于潜伏期测量。对SEP应用时频分析可提高术中脊髓监测的可靠性。
