Kleinstueck Frank S, Diederich Chris J, Nau William H, Puttlitz Christian M, Smith Jason A, Bradford David S, Lotz Jeffrey C
Department of Orthopaedic Surgery, University of California at San Francisco, California, USA.
Spine (Phila Pa 1976). 2003 Aug 1;28(15):1700-8; discussion 1709. doi: 10.1097/01.BRS.0000083160.16853.6E.
Human cadaveric lumbar spines were used to assess the temperature and thermal dose distribution during intradiscal electrothermal therapy in vitro.
To determine whether intradiscal electrothermal therapy produces adequate tissue temperatures to denature annular collagen or ablate nerve cells.
Several hypothesized mechanisms for the effect of intradiscal electrothermal therapy have been suggested and include: 1) shrinkage of the nucleus and/or the annulus fibrosus by contraction of collagen fibers; and 2) thermal ablation of sensitive nerve fibers in the outer annulus.
Intradiscal electrothermal therapy was performed using the standard clinical protocol on 12 lumbar specimens in a 37.0 degrees C water bath using the SpineCath by Oratec. Temperatures were recorded simultaneously at 40 different locations in the disc. Thermal dose (Equivalent Minutes 43.0 degrees C) was calculated at each temperature point.
The highest temperature measured (out of 520 points) was 64.0 degrees C and was within 1 mm of the heating coil. Temperatures in excess of 60 degrees C were all within 1 to 2 mm of the intradiscal electrothermal therapy catheter surface, the 50 to 60 degrees C range extended approximately 6 mm, above 48 degrees C extended approximately 7 mm, and above 45 degrees C extended to approximately 10 mm. Less than 2% of points achieved temperatures sufficient for collagen denaturation (>60 degrees C). On average, 42.5% of points accumulated >250 Equivalent Minutes 43.0 degrees C, a conservative common dose threshold for thermal necrosis of cells. The time history of thermal measurements demonstrated that the disc temperature had not reached steady state by the end of the heating protocol (16.5 minutes).
Except for a very limited margin (1-2 mm) around the catheter, the temperature necessary to induce collagen shrinkage was not observed within the disc. Temperatures sufficient to ablate nerves were developed in some areas but were not reliably produced in clinically relevant regions, such as the posterior annulus. These results suggest that beneficial clinical outcomes may be critically dependent on probe placement or other factors unknown.
使用人类尸体腰椎在体外评估椎间盘内电热疗法期间的温度和热剂量分布。
确定椎间盘内电热疗法是否能产生足够的组织温度以使环状胶原蛋白变性或消融神经细胞。
已经提出了几种关于椎间盘内电热疗法作用的假设机制，包括：1）通过胶原纤维收缩使髓核和/或纤维环收缩；2）对外层纤维环中敏感神经纤维的热消融。
在37.0摄氏度的水浴中，使用奥雷克公司的SpineCath按照标准临床方案对12个腰椎标本进行椎间盘内电热疗法。在椎间盘的40个不同位置同时记录温度。在每个温度点计算热剂量（等效分钟数43.0摄氏度）。
测量的最高温度（在520个点中）为64.0摄氏度，且在加热线圈1毫米范围内。超过60摄氏度的温度都在椎间盘内电热疗法导管表面1至2毫米范围内，50至60摄氏度范围延伸约6毫米，48摄氏度以上延伸约7毫米，45摄氏度以上延伸至约10毫米。不到2%的点达到了足以使胶原蛋白变性的温度（>60摄氏度）。平均而言，42.5%的点累积了>250等效分钟数43.0摄氏度，这是细胞热坏死的保守常用剂量阈值。热测量的时间历程表明，在加热方案结束时（16.5分钟）椎间盘温度尚未达到稳态。
除了导管周围非常有限的边缘区域（1 - 2毫米）外，在椎间盘内未观察到诱导胶原收缩所需的温度。在某些区域产生了足以消融神经的温度，但在临床相关区域，如后纤维环，并未可靠产生。这些结果表明，有益的临床结果可能严重依赖于探头放置或其他未知因素。
