脊柱侧弯手术中正常体感诱发电位时频特征分析

Time-frequency analysis of normal somatosensory evoked potentials during scoliosis surgery

目的提取脊柱术中体感诱发电位(SEP)的时频特征参数,确定时频域特征参数的正常值范围。方法选取1998年9月至2006年1月脊柱侧弯手术病人183例,其中皮层诱发电位168例有效(92%),女性129例,男性39例,年龄7～40岁(平均年龄16.8岁);下皮层诱发电位183例有效(100%),女性144例,男性39例,年龄7～40岁(平均年龄16.69岁)。运用短时傅立叶变换对手术中采集的体感诱发电位进行分析处理,提取信号在时频域的三个特征参数,并与时域分析方法进行比较。结果谱峰功率比波幅的变异系数更小,SEP(Cz′)的谱峰时间以(41.2±4.1)ms为中心,范围是29～55ms,谱峰频率以(53.6±6.2)Hz为中心,范围是37～79Hz;SEP(Cv)的谱峰时间以(30.1±2.9)ms为中心,范围是21～39ms,谱峰频率以(81.8±4.9)Hz为中心,范围是67～111Hz。结论运用短时傅立叶变换获得的脊柱手术时频谱具有稳定的时频特征参数分布,为建立自动判别标准及临床应用打下了基础。

Objective To extract time-frequency characteristics from somatosensory evoked potential （SEP） during surgical treatment of scoliosis, and confirm the distributing range of normal SEP in time-frequency domain（TFD）. Methods A total of 183 patients with scoliosis by surgery were enrolled during September 1998 to January 2006. Cortical evoked potentials of 168 （92%） cases were effective,female 129,male 39,aged 7 - 40 years,mean age 16.8 ;subcortical evoked potential of 183 （100%） cases were effective,femle 144,male 39, aged 7 - 40 years（mean age 16.69）. Short time fourier transform （STFT） were applied to analyze the intraoperative somatosensory evoked potential, three monitoring parameters in time-frequency domain were extracted and compared with time domain parameters. Results The peak power showed less variability than amplitude.Peak time of SEP （Cz＇） centered at （41.2 ＋ 4.1 ） ms ,from 29 to 55 ms, peak frequency centered at （53.6 ± 6.2 ） Hz, from 37 to 79 Hz; Peak time of SEP （Cv） centered at （30.1 ± 2.9） ms,from 21 to 39 ms and peak frequency centered at （81.8 ± 4.9） Hz,from 67 to 111 Hz. Conclusion It is demonstrated that normal SEP has a stable distribution range in TFD,which provides the basis in setting automatic judgment criteria for clinical monitoring.