Department of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa 52242, USA.
Neurosurg Focus. 2012 Mar;32(3):E11. doi: 10.3171/2012.1.FOCUS11333.
Vagus nerve stimulation (VNS) has demonstrated benefit in patients with medically intractable partial epilepsy. As in other therapies with mechanical devices, hardware failure occurs, most notably within the VNS lead, requiring replacement. However, the spiral-designed lead electrodes wrapped around the vagus nerve are often encased in dense scar tissue hampering dissection and removal. The objective in this study was to characterize VNS lead failure and lead revision surgery and to examine VNS efficacy after placement of a new electrode on the previously used segment of vagus nerve.
The authors reviewed all VNS lead revisions performed between October 2001 and August 2011 at the University of Iowa Hospitals and Clinics. Twenty-four patients underwent 25 lead revisions. In all cases, the helical electrodes were removed, and a new lead was placed on the previously used segment of vagus nerve. All inpatient and outpatient records of the 25 lead revisions were retrospectively reviewed.
Four cases were second lead revisions, and 21 cases were first lead revisions. The average time to any revision was 5 years (range 1.8-11.1 years), with essentially no difference between a first and second lead revision. The most common reason for a revision was intrinsic lead failure resulting in high impedance (64%), and the most common symptom was increased seizure frequency (72%). The average duration of surgery for the initial implantation in the 15 patients whose VNS system was initially implanted at the authors' institution was much shorter (94 minutes) than the average duration of lead revision surgery (173 minutes). However, there was a significant trend toward shorter surgical times as more revision surgeries were performed. Sixteen of the 25 cases of lead revision were followed up for more than 3 months. In 15 of these 16 cases, the revision was as effective as the previous VNS lead. In most of these cases, both the severity and frequency of seizures were decreased to levels similar to those following the previous implantation procedure. Only 1 complication occurred, and there were no postoperative infections.
Lead revision surgery involving the placement of a new electrode at the previously used segment of vagus nerve is effective at decreasing the seizure burden to an extent similar to that obtained following the initial VNS implantation. Even with multiple lead revisions, patients can obtain VNS efficacy similar to that following the initial lead implantation. There is a learning curve with revision surgery, and overall the duration of surgery is longer than for the initial implantation. Note, however, that complications and infection are rare.
迷走神经刺激（VNS）已被证明对药物难治性部分性癫痫患者有益。与其他具有机械装置的疗法一样，硬件会发生故障，尤其是在 VNS 导联中，需要更换。然而，螺旋设计的导联电极缠绕在迷走神经周围，常常被致密的瘢痕组织包裹，妨碍解剖和移除。本研究的目的是描述 VNS 导联故障和导联修正手术，并检查在先前使用的迷走神经段上放置新电极后 VNS 的疗效。
作者回顾了 2001 年 10 月至 2011 年 8 月期间在爱荷华大学医院进行的所有 VNS 导联修正手术。24 例患者接受了 25 次导联修正。在所有情况下，都移除了螺旋电极，并在先前使用的迷走神经段上放置了新的导联。对 25 次导联修正的所有住院和门诊记录进行了回顾性分析。
有 4 例为第二次导联修正，21 例为第一次导联修正。任何修正的平均时间为 5 年（范围 1.8-11.1 年），第一次和第二次导联修正之间基本没有差异。修正的最常见原因是内在导联故障导致高阻抗（64%），最常见的症状是癫痫发作频率增加（72%）。在作者所在机构最初植入 VNS 系统的 15 名患者中，初始植入手术的平均手术时间要短得多（94 分钟），而导联修正手术的平均手术时间要长（173 分钟）。然而，随着更多的修正手术的进行，手术时间呈显著缩短趋势。25 例导联修正中有 16 例的随访时间超过 3 个月。在这 16 例中，15 例修正与之前的 VNS 导联一样有效。在这些病例中，大多数情况下，癫痫发作的严重程度和频率都降低到与之前植入程序相似的水平。只有 1 例并发症发生，且无术后感染。
涉及在先前使用的迷走神经段放置新电极的导联修正手术，可有效降低癫痫发作的负担，达到与初始 VNS 植入相似的程度。即使进行多次导联修正，患者也能获得与初始导联植入相似的 VNS 疗效。修正手术存在学习曲线，且总体手术时间长于初始植入。然而，需要注意的是，并发症和感染较为罕见。
