Department of Orthopedic Surgery, Centre Hospitalier Universitaire Vaudois, Avenue Pierre Decker 4, 1011 Lausanne, Switzerland.
Department of Neurosurgery, Centre Hospitalier Universitaire Vaudois, Avenue du Bugnon 46, 1011 Lausanne, Switzerland.
Spine J. 2014 Jan;14(1):73-9. doi: 10.1016/j.spinee.2013.06.008. Epub 2013 Aug 14.
Kyphotic deformities with sagittal imbalance of the spine can be treated with spinal osteotomies. Those procedures are known to have a high incidence of neurological complications, in particular at the thoracic level. Motor evoked potentials (MEPs) have been widely used in helping to avoid major neurological deficits postoperatively. Previous reports have shown that a significant proportion of such cases present with important transcranial MEP (Tc-MEP) changes during surgery with some of them being predictive of postoperative deficits.
Our aim was to study Tc-MEP changes in a consecutive series of patients and correlate them with clinical parameters and radiological changes.
STUDY DESIGN/SETTING: Retrospective case notes study from a prospective patient register.
Eighteen patients undergoing posterior shortening osteotomies (nine at thoracic and nine at lumbar levels) for kyphosis of congenital, degenerative, inflammatory, or post-traumatic origin were included.
Loss of at least 80% of Tc-MEP signal expressed as the area under the curve percentual change, of at least one muscle.
We studied the relation between outcome measure (80% Tc-MEP loss in at least one muscle group) and amount of posterior vertebral body shortening as well as angular correction measured on computed tomography scans, occurrence of postoperative deficits, intraoperative blood pressure at the time of the osteotomy, and hemoglobin (Hb) change.
All patients showed significant Tc-MEP changes. In particular, greater than 80% MEP loss in at least one muscle group was observed in five of nine patients in the thoracic group and four of nine patients in the lumbar group. No surgical maneuver was undertaken as a result of this loss in an effort to improve motor responses other than verifying the stability of the construct and the extent of the decompression. Four patients developed postoperative deficits of radicular origin, three of them recovering fully at 3 months. No relation was found between intraoperative blood pressure, Hb changes, and Tc-MEP changes. Severity of Tc-MEP loss did not correlate with postoperative deficits. Shortening of more than 10 mm was linked to more severe Tc-MEP changes in the thoracic group.
Transcranial MEP changes during spinal shortening procedures are common and do not appear to predict severe postoperative deficits. Total loss of Tc-MEP (not witnessed in our series) might require a more drastic approach with possible reversal of the correction and wake-up test.
脊柱后凸畸形伴矢状面失平衡可采用脊柱截骨术治疗。这些手术的神经并发症发生率较高，尤其是在胸椎水平。运动诱发电位（MEP）已广泛用于帮助避免术后出现严重的神经功能缺陷。先前的报告显示，在手术过程中，相当一部分病例存在重要的经颅 MEP（Tc-MEP）变化，其中一些变化可预测术后缺陷。
我们旨在研究连续系列患者的 Tc-MEP 变化，并将其与临床参数和影像学变化相关联。
研究设计/设置：前瞻性患者登记处的回顾性病例研究。
18 例因先天性、退行性、炎症或创伤后原因导致的后凸畸形而行后路短缩截骨术（9 例在胸椎，9 例在腰椎）的患者。
至少一个肌肉的 Tc-MEP 信号面积的至少 80%损失，表达为曲线下面积百分比变化。
我们研究了结果测量值（至少一个肌肉组 80% Tc-MEP 损失）与计算机断层扫描测量的后路椎体缩短量和角度矫正值、术后缺陷的发生、截骨时的术中血压以及血红蛋白（Hb）变化之间的关系。
所有患者均表现出明显的 Tc-MEP 变化。特别是，在胸椎组的 9 例患者中有 5 例和腰椎组的 9 例患者中有 4 例出现至少一个肌肉组 Tc-MEP 损失大于 80%。除了验证结构的稳定性和减压的程度外，没有进行任何手术操作来改善运动反应，因为这会导致 Tc-MEP 损失。4 例患者出现神经根源性术后缺陷，其中 3 例在 3 个月时完全恢复。术中血压、Hb 变化与 Tc-MEP 变化之间未发现相关性。Tc-MEP 损失的严重程度与术后缺陷无关。胸椎组缩短超过 10mm 与 Tc-MEP 变化更严重相关。
脊柱短缩过程中的经颅 MEP 变化很常见，似乎并不能预测严重的术后缺陷。我们的研究中未出现 Tc-MEP 完全丧失（未观察到），可能需要更激进的方法，可能需要逆转矫正并进行唤醒试验。
