Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44016, United States of America. Advanced Platform Technology Center, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, 10701 East Blvd, 151 W/APT, Cleveland, OH 44106-1702, United States of America.
J Neural Eng. 2018 Jun;15(3):034001. doi: 10.1088/1741-2552/aa9f32. Epub 2017 Dec 5.
Our objective was to determine how readily disruption of the blood-brain barrier (BBB) occurred as a result of bone drilling during a craniotomy to implant microelectrodes in rat cortex. While the phenomenon of heat production during bone drilling is well known, practices to evade damage to the underlying brain tissue are inconsistently practiced and reported in the literature.
We conducted a review of the intracortical microelectrode literature to summarize typical approaches to mitigate drill heating during rodent craniotomies. Post mortem skull-surface and transient brain-surface temperatures were experimentally recorded using an infrared camera and thermocouple, respectively. A number of drilling conditions were tested, including varying drill speed and continuous versus intermittent contact. In vivo BBB permeability was assayed 1 h after the craniotomy procedure using Evans blue dye.
Of the reviewed papers that mentioned methods to mitigate thermal damage during craniotomy, saline irrigation was the most frequently cited (in six of seven papers). In post mortem tissues, we observed increases in skull-surface temperature ranging from +3 °C to +21 °C, dependent on drill speed. In vivo, pulsed-drilling (2 s-on/2 s-off) and slow-drilling speeds (1000 r.p.m.) were the most effective methods we studied to mitigate heating effects from drilling, while inconclusive results were obtained with saline irrigation.
Neuroinflammation, initiated by damage to the BBB and perpetuated by the foreign body response, is thought to play a key role in premature failure of intracortical recording microelectrodes. This study demonstrates the extreme sensitivity of the BBB to overheating caused by bone drilling. To avoid damage to the BBB, the authors recommend that craniotomies be drilled with slow speeds and/or with intermittent drilling with complete removal of the drill from the skull during 'off' periods. While saline alone was ineffective at preventing overheating, its use is still recommended to remove bone dust from the surgical site and to augment other cooling methods.
我们旨在确定在大鼠皮层中植入微电极的开颅手术中，骨钻会在多大程度上导致血脑屏障（BBB）破裂。虽然骨钻过程中产生热量的现象是众所周知的，但在文献中，规避对下面脑组织损伤的做法并不一致，也没有得到报告。
我们对皮质内微电极文献进行了综述，以总结减轻啮齿动物开颅术中钻热的典型方法。使用红外摄像机和热电偶分别对死后颅骨表面和短暂脑表面温度进行了实验记录。测试了多种钻孔条件，包括改变钻速和连续与间歇接触。在颅骨切开术 1 小时后，使用 Evans 蓝染料测定 BBB 通透性。
在所综述的提到在开颅术期间减轻热损伤方法的论文中，盐水冲洗是最常被引用的（在七篇论文中的六篇中）。在死后组织中，我们观察到颅骨表面温度升高范围从+3°C 到+21°C，取决于钻速。在体内，脉冲钻孔（2 秒 ON/2 秒 OFF）和低速钻孔（1000 r.p.m.）是我们研究中减轻钻孔加热效应最有效的方法，而盐水冲洗的结果则不确定。
BBB 损伤引发的神经炎症，以及异物反应的延续，被认为在皮质内记录微电极过早失效中起着关键作用。这项研究表明，BBB 对骨钻引起的过热非常敏感。为了避免 BBB 损伤，作者建议用低速钻孔，或用间歇性钻孔，在“关”期间将钻头完全从颅骨中取出。虽然单独使用盐水不能有效防止过热，但仍建议使用盐水清除手术部位的骨屑，并增强其他冷却方法。
