Department of Cancer Therapy and Research, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
J Neurosurg. 2012 Nov;117(5):955-61. doi: 10.3171/2012.8.JNS112073. Epub 2012 Sep 7.
The authors undertook this study to investigate the incidence, cause, and clinical influence of short circuits in patients treated with deep brain stimulation (DBS).
After the incidental identification of a short circuit during routine follow-up, the authors initiated a policy at their institution of routinely evaluating both therapeutic impedance and system impendence at every outpatient DBS follow-up visit, irrespective of the presence of symptoms suggesting possible system malfunction. This study represents a report of their findings after 1 year of this policy.
Implanted DBS leads exhibiting short circuits were identified in 7 patients (8.9% of the patients seen for outpatient follow-up examinations during the 12-month study period). The mean duration from DBS lead implantation to the discovery of the short circuit was 64.7 months. The symptoms revealing short circuits included the wearing off of therapeutic effect, apraxia of eyelid opening, or dysarthria in 6 patients with Parkinson disease (PD), and dystonia deterioration in 1 patient with generalized dystonia. All DBS leads with short circuits had been anchored to the cranium using titanium miniplates. Altering electrode settings resulted in clinical improvement in the 2 PD cases in which patients had specific symptoms of short circuits (2.5%) but not in the other 4 cases. The patient with dystonia underwent repositioning and replacement of a lead because the previous lead was located too anteriorly, but did not experience symptom improvement.
In contrast to the sudden loss of clinical efficacy of DBS caused by an open circuit, short circuits may arise due to a gradual decrease in impedance, causing the insidious development of neurological symptoms via limited or extended potential fields as well as shortened battery longevity. The incidence of short circuits in DBS may be higher than previously thought, especially in cases in which DBS leads are anchored with miniplates. The circuit impedance of DBS should be routinely checked, even after a long history of DBS therapy, especially in cases of miniplate anchoring.
作者开展本研究旨在调查接受脑深部电刺激（DBS）治疗的患者中发生短路的发生率、原因和临床影响。
在常规随访中偶然发现短路后，作者在机构中制定了一项政策，即在每次门诊 DBS 随访时，无论是否存在可能表明系统故障的症状，都要常规评估治疗阻抗和系统阻抗。本研究报告了该政策实施 1 年后的结果。
在 7 名患者（在 12 个月研究期间接受门诊随访检查的患者的 8.9%）中发现了植入的 DBS 导联出现短路。从 DBS 导联植入到发现短路的平均时间为 64.7 个月。揭示短路的症状包括 6 例帕金森病（PD）患者的治疗效果减弱、眼睑张开的运动障碍或构音障碍，以及 1 例全身性肌张力障碍患者的肌张力恶化。所有出现短路的 DBS 导联均使用钛微型板固定在颅骨上。改变电极设置使 2 例 PD 患者的临床症状得到改善（2.5%），但其他 4 例患者没有改善。患有肌张力障碍的患者因先前的导联位置太靠前而重新定位和更换了导联，但没有改善症状。
与 DBS 因开路而突然丧失临床疗效不同，短路可能是由于阻抗逐渐降低所致，通过有限或扩展的潜在场以及缩短电池寿命，导致神经症状逐渐发展。DBS 中短路的发生率可能高于之前认为的，尤其是在 DBS 导联用微型板固定的情况下。即使在 DBS 治疗的长期历史之后，也应常规检查 DBS 的电路阻抗，尤其是在微型板固定的情况下。
