Surgical and Hardware-Related Adverse Events of Deep Brain Stimulation: A Ten-Year Single-Center Experience

IntroductionAlthough deep brain stimulation (DBS) is effective for treating a number of neurological and psychiatric indications, surgical and hardware-related adverse events (AEs) can occur that affect quality of life. This study aimed to give an overview of the nature and frequency of those AEs in our center and to describe the way they were managed. Furthermore, an attempt was made at identifying possible risk factors for AEs to inform possible future preventive measures.Materials and MethodsPatients undergoing DBS-related procedures between January 2011 and July 2020 were retrospectively analyzed to inventory AEs. The mean follow-up time was 43 ± 31 months. Univariate logistic regression analysis was used to assess the predictive value of selected demographic and clinical variables.ResultsFrom January 2011 to July 2020, 508 DBS-related procedures were performed including 201 implantations of brain electrodes in 200 patients and 307 implantable pulse generator (IPG) replacements in 142 patients. Surgical or hardware-related AEs following initial implantation affected 40 of 200 patients (20%) and resolved without permanent sequelae in all instances. The most frequent AEs were surgical site infections (SSIs) (9.95%, 20/201) and wire tethering (2.49%, 5/201), followed by hardware failure (1.99%, 4/201), skin erosion (1.0%, 2/201), pain (0.5%, 1/201), lead migration (0.52%, 2/386 electrode sites), and hematoma (0.52%, 2/386 electrode sites). The overall rate of AEs for IPG replacement was 5.6% (17/305). No surgical, ie, staged or nonstaged, electrode fixation, or patient-related risk factors were identified for SSI or wire tethering.ConclusionsMajor AEs including intracranial surgery–related AEs or AEs requiring surgical removal or revision of hardware are rare. In particular, aggressive treatment is required in SSIs involving multiple sites or when Staphylococcus aureus is identified. For future benchmarking, the development of a uniform reporting system for surgical and hardware-related AEs in DBS surgery would be useful.     

Deep Brain Stimulation for Dystonia: A Meta‐Analysis

Objective. To use a meta‐analysis on all reported cases of deep brain stimulation (DBS) for dystonia to determine which factors significantly influence outcome. The Burke‐Fahn‐Marsden (BFM) movement scale, the most reported measure, was chosen as the primary outcome measure for this analysis. Methods. A MEDLINE search identified 137 patients who underwent DBS for dystonia in 24 studies that had individual BFM scores. Individual patient data, including age at onset of dystonia, age at surgery, gender, distribution of dystonia, etiology of dystonia, presence of associated features, abnormality of preoperative imaging, prior stereotactic surgeries, nucleus stimulated, type of anesthesia used, use of physiologic monitoring, type of imaging used for localization, stimulation parameters used, time of response to stimulation, and timing of outcome assessment were entered into an SPSS database for statistical analysis. Results. The mean BFM percentage change (improvement in postoperative score from baseline) was 51.8% (range ?34% to 100%). Significantly better outcomes were achieved with stimulation of the globus pallidus internus (GPi) than with stimulation of the posterior portion of the ventral lateral (VLp) nucleus of the thalamus (p = 0.0001). The etiology of the dystonia also had a significant effect on outcomes. Statistically significant improvements in outcomes were seen for all etiologic categories, except encephalitis. Dystonia due to birth injury and encephalitis had significantly worse outcomes when compared to other etiologies. However, there were no significant differences in the outcomes of patients who were DYT1 (DYT1 is the gene associated with the disorder Dystonia Musculorum Deformans) gene positive, DYT1 gene negative, or had pantothenate kinase‐associated neurodegeneration (PKAN), tardive dyskinesia, and idiopathic and posttraumatic dystonias. Longer duration of dystonia symptoms correlated negatively with surgical outcome. A regression model using the three variables—stimulation site, etiology of dystonia, and duration of dystonia symptoms—explained 51% of the variance in outcomes. Conclusion. Deep brain stimulation of the GPi provides significant improvement in BFM scores in a variety of dystonic conditions.     

Deep Brain Stimulation for Neuropathic Pain

Objectives. To determine whether deep brain stimulation is an effective treatment for neuropathic pain of varied etiology. Material and Methods. Thirty‐four patients with intractable neuropathic pain were prospectively studied using visual analog scores, McGill Pain Questionnaire, and Quality of Life Questionnaires (EUROQOL EQ‐5D VAS, and SF‐36 v‐2). Patients had either deep brain stimulation of either the periventricular gray or ventroposterolateral nucleus of the thalamus, or both. Results. Seventy‐six percent of patients underwent permanent implantation. Overall reduction of pain intensity was 54%. The burning component of pain improved by 77%. Health‐related quality of life improved by 38%. Conclusions. Deep brain stimulation is an effective treatment for neuropathic pain. The factors that influence outcome, including etiology and site of stimulation, are discussed.     

Deep Brain Stimulation in Movement Disorders: From Experimental Surgery to Evidence‐Based Therapy

Deep brain stimulation (DBS) of 3 different targets is the most important therapeutic innovation of the past 30 years for patients with fluctuating Parkinson's disease (PD), disabling dystonia, tremors, and refractory Gilles de la Tourette syndrome. When compared with medical treatment alone, controlled studies have shown better motor, nonmotor, and particularly quality‐of‐life outcomes with large effect sizes for advanced complicated PD that cannot be improved with medication, and also for PD patients with only early fluctuations. Class 1 studies have also shown superiority over medical treatment for generalized, segmental, and botulinum‐toxin refractory focal cervical dystonia. Long‐term efficacy is established for all indications with open studies. For tremors, open studies have shown that DBS is remarkably effective on PD and essential tremor, but efficacy on severe essential tremor and cerebellar tremors is limited by a tendency for tolerance/habituation, including concerns about long‐term efficacy. Open studies of disabling Gilles de la Tourette syndrome show an improvement in tics. New developments hold a promise for further improvement. New hardware with directional stimulation and new stimulation paradigms are further areas of research. The targets of DBS are refined with new imaging processing that will help to diversify the surgical targets. New indications are being explored. Closed‐loop DBS using brain or peripheral sensor signals have shown favorable clinical short‐term results. Long‐term data are lacking, and it is hoped that similar approaches for other movement or behavioral disorders may be developed. Exciting new developments carry the hope for a more pathophysiology‐based approach for DBS for various brain circuit disorders. © 2019 International Parkinson and Movement Disorder Society     

丘脑底核脑深部刺激术治疗帕金森病137例报道

目的：总结丘脑底核脑深部刺激术（DBS）治疗帕金森病（PD）的经验。方法：自2000年3月至2007年12月应用DBS治疗PD137例，其中单侧丘脑底核刺激68例，双侧丘脑底核刺激69例。术后1年（108例）、3年（43例）和5年（20例）分别进行PD评定量表（UPDRS）运动评分。结果：脉冲发生器开启时，在“关”期和“开”期状态下，术后1，3和5年UPDRS运动评分症状改善率分别为55．8％、53．4％和45．2％及22．5％、23．2％和20．4％。手术并发症主要有：肺部感染1例，脉冲发生器植入处胸部皮下感染1例，积液3例，头部刺激电极和皮下导线连接处皮肤破溃1例。二次手术调整刺激电极深度2例。无永久性并发症。结论：掌握适应证，规范手术操作和术中影像学验证是提高DBS疗效，降低并发症的关键。     

Long‐Term Measurement of Therapeutic Electrode Impedance in Deep Brain Stimulation

Objective: Deep brain stimulation technology now allows a choice between constant current and constant voltage stimulation, yet clinical trials comparing the two are lacking. Impedance instability would theoretically favor constant current stimulation; however, few publications address this with long‐term follow‐up. In this report, we review our series for impedance change and discuss our findings and their implications for future study design. Materials and Methods: A retrospective chart review was performed of all consecutive patients seen in the outpatient clinic for deep brain stimulation adjustments at the University of Wisconsin–Madison from February 2006 to May 2007. The following data were extracted: Quadrapolar contact selection, frequency, voltage, pulse width, and measured impedance at the therapeutic parameters. Patients were selected if consecutive measurements of therapeutic impedances for the same patient were performed with the same frequency, pulse width, voltage, and configuration of active contacts. Results: A total of 63 patients with 110 electrodes had 301 documented programming visits. From these, 16 patients had 20 consecutive measurements with unchanged parameters in 19 electrodes at a median interval of 68 days and median follow‐up of 549 days after implantation. No significant intra‐patient intra‐electrode therapeutic impedance variability was observed in this study (SD = 105.3 Ω, paired t‐test, p= 0.312). In contrast, marked inter‐patient variability in impedance was noted. This variability could not be explained by stimulation target, measurement interval, time since implantation, monopolar vs. bipolar stimulation, stimulation voltage, or stimulation frequency. Conclusions: No significant change in the same electrode therapeutic impedance was identified. Given the assumption that stimulation current is the critical parameter influencing clinical outcomes, these findings would not disadvantage constant voltage stimulation. However, inter‐patient variability suggests a possible advantage for constant current stimulation when generalizing experience and comparisons over multiple patients. Further study of the relationship of stimulation efficacy to stimulation mode and impedance change is warranted.     

Neuromodulation in Dystonia: Current Aspects of Deep Brain Stimulation

Among the surgical treatment options for patients with medically refractory dystonia chronic deep brain stimulation (DBS) of different targets in the basal ganglia circuitry has become one of the most important tools. The globus pallidus internus nowadays is the target of choice, while there is only limited experience with other targets. At this time, patients with primary (genetic or sporadic) generalized and segmental dystonia, and patients with (complex) cervical dystonia are thought to be the best candidates for pallidal DBS. Advantages of DBS are its reversibility, its adjustability, and the continuous access to modify the target in the basal ganglia. The present review gives an account on the development of surgical neuromodulation therapy for dystonia, surgical approaches, hardware‐related problems, DBS programming and patient management, and clinical outcome. Studies conducted according to the practices of evidence‐based medicine confirm the results of early pilot studies. The wide majority of patients achieve beneficial lasting outcome at a relatively low rate of manageable side‐effects. Along with improvement of the movement disorder, studies report on amelioration of quality‐of‐life surrogates. We also provide an overview on DBS surgery in less common dystonic syndromes, such as craniofacial dystonia, status dystonicus, task‐specific dystonia, paroxysmal dystonia, camptocormia, and secondary dystonias, including choreoathetosis, hemidystonia, tardive dystonia, and pantothenate kinase‐associated neurodegeneration. Furthermore, we discuss the implications of intra‐operative microelectrode recordings and pallidal field potentials for the pathophysiology of dystonia and the particular possible mechanisms of DBS in dystonia. Finally, future perspectives are outlined.