杵状棘突来自L_5棘突与游离S_1棘突骨性融合的影像学证据

Evidence from medical images manifests drumstick spinal process originates from the bony fusion of normal L_5 spinal process and isolated S_1 spinal process

目的国内学者认为,杵状棘突(DSP)是游离S1棘突与L5棘突融合而成,通过X线正位平片可确立诊断。本研究通过影像学及肉眼观察验证该观点。方法收集2004年12月至2016年7月X片检查符合DSP诊断的病例,观察其正侧位片,行CT及MR检查者观察正中矢状位图像,查找反映DSP组成的依据。行手术者肉眼观察。结果 16例符合X片诊断标准,正位DSP下部占据S1椎板中央缺损区,12例在侧位片DSP轮廓呈鱼鳍状,其中7例边缘光滑,4例远端后缘可见一凹痕,1例远端陈旧骨折移位。3例CT扫描者中,2例行矢状面重建,可见X片对应的DSP凹痕区变窄,狭窄区上下有硬化带。3例行MR检查,2例凹痕区T1WI及T2WI呈低信号,硬化带T1WI及T2WI呈高信号,1例凹痕区呈正常棘突间韧带信号。2例手术者中1例在DSP远端背侧辨出凹痕。结论本研究支持DSP由L5棘突及游离S1棘突融合而成的观点。普通平片可确诊DSP。

Objective Chinese medical specialists asserted that the drumstick spinal process（DSP）originated from the bony union of the normal L5 spinal process and isolated S1 spinal process from sacral spina bifida occulta. The imaging diagnosis is generally established based on the anteroposterior conventional radiograph image. This study was designed to verify the assertion by analysis of DSP images and direct visual inspection. Methods Cases met DSP imaging diagnosis criteria of plain radiographs from December, 2004 to July, 2016 were enrolled in the study, anteroposterior and lateral conventional radiographs of relative cases were observed to find DSP’s morphologic characteristics. If CT scanning or MR scanning was performed,sagittal reconstructed images at midline were observed to find the image evidence of DSP’s components. If open operation was performed, direct observation of DSP with naked eye was carried out. Results 16 cases satisfied the DSP’s imaging diagnosis on plain radiographs which showed the distal end of the spinal process connected with L5 laminae reached the central defective area of sacral spina bifida occulta were enrolled. The contour of DSP at the lateral radiograph was clearly visible in 12 cases, which exhibited fin morphology, among whom, 7 had smooth rim while 4 had a dent at the inferoposterior edge. CT scanning was done at three cases, two had sagittal CT images reconstructed which detected a narrowed region near the lower portion of DSP corresponding to the dent location found on plain radiographs and sclerotic bands could be detected adjacent to the narrow region distally and proximately. MR scanning was done on three cases. In two cases, sagittal MR images at the midline exhibited low T1 WI and T2 WI signals at the narrow area of DSP corresponding to the relative area at CT images and high T1 WI and T2 WI signals at bilateral margins adjacent to the narrow area distally and proximately, while in one case, the signals of the narrow area of DSP were similar to that of the normal L5S1 interspinal ligament, thus making it difficult to discern the existence of DSP.Open operation was performed on 2 cases, a dent could be found at inferoposterior edge of DSP in one case by naked eye. Conclusion This study can support the assertion that DSP comes from the bony union of the normal L5 spinal process and the isolated S1 spinal process of sacral spina bifida occulta. The narrow area at lower portion of DSP detected by reconstructed sagittal CT images is the union location.