Background: The advent of deep brain stimulation (DBS) of the subthalamic nucleus (STN) for Parkinson's disease 30 years ago has ushered a global breakthrough of DBS as a universal method for therapy and research in wide areas of neurology and psychiatry. The literature of the last three decades has described numerous concepts and practices of DBS, often branded as novelties or discoveries. However, reading the contemporary publications often elicits a sense of déjà vu in relation to several methods, attributes, and practices of DBS. Here, we review various applications and techniques of the modern-era DBS and compare them with practices of the past.
Summary: Compared with modern literature, publications of the old-era functional stereotactic neurosurgery, including old-era DBS, show that from the very beginning multidisciplinarity and teamwork were often prevalent and insisted upon, ethical concerns were recognized, brain circuitries and rational for brain targets were discussed, surgical indications were similar, closed-loop stimulation was attempted, evaluations of surgical results were debated, and controversies were common. Thus, it appears that virtually everything done today in the field of DBS bears resemblance to old-time practices, or has been done before, albeit with partly other tools and techniques. Movement disorders remain the main indications for modern DBS as was the case for lesional surgery and old-era DBS. The novelties today consist of the STN as the dominant target for DBS, the tremendous advances in computerized brain imaging, the sophistication and versatility of implantable DBS hardware, and the large potential for research.
Key messages: Many aspects of contemporary DBS bear strong resemblance to practices of the past. The dominant clinical indications remain movement disorders with virtually the same brain targets as in the past, with one exception: the STN. Other novel brain targets - that are so far subject to DBS trials - are the pedunculopontine nucleus for gait freezing, the anteromedial internal pallidum for Gilles de la Tourette and the fornix for Alzheimer's disease. The major innovations and novelties compared to the past concern mainly the unmatched level of research activity, its high degree of sponsorship, and the outstanding advances in technology that have enabled multimodal brain imaging and the miniaturization, versatility, and sophistication of implantable hardware. The greatest benefit for patients today, compared to the past, is the higher level of precision and safety of DBS, and of all functional stereotactic neurosurgery.
Introduction: Deep brain stimulation (DBS) is an established treatment for Parkinson's disease (PD) and other movement disorders. The ventral intermediate nucleus of the thalamus is considered as the target of choice for tremor disorders, including tremor-dominant PD not suitable for DBS in the subthalamic nucleus (STN). In the last decade, several studies have shown promising results on tremor from DBS in the posterior subthalamic area (PSA), including the caudal zona incerta (cZi) located posteromedial to the STN. The aim of this study was to evaluate the long-term effect of unilateral cZi/PSA-DBS in patients with tremor-dominant PD.
Methods: Thirteen patients with PD with medically refractory tremor were included. The patients were evaluated using the motor part of the Unified Parkinson Disease Rating Scale (UPDRS) off/on medication before surgery and off/on medication and stimulation 1-2 years (short-term) after surgery and at a minimum of 3 years after surgery (long-term).
Results: At short-term follow-up, DBS improved contralateral tremor by 88% in the off-medication state. This improvement persisted after a mean of 62 months. Contralateral bradykinesia was improved by 40% at short-term and 20% at long-term follow-up, and the total UPDRS-III by 33% at short-term and by 22% at long-term follow-up with stimulation alone.
Conclusions: Unilateral cZi/PSA-DBS seems to remain an effective treatment for patients with severe Parkinsonian tremor several years after surgery. There was also a modest improvement on bradykinesia.
Introduction: Intraoperative microelectrodes recording with the Ben Gun microdrive system are often used during DBS surgery. An accurate location of these microelectrodes will directly influence the interest of this recording. We have studied the imprecision of implantation of these microelectrodes.
Methods: We have analyzed the stereotactic position of 135 microelectrodes implanted with the Ben Gun microdrive during DBS surgery of 16 patients with advanced Parkinson's disease. An intracranial CT was obtained and integrated to a stereotactic planification system. We recorded the stereotactic coordinates of the 5 microelectrodes inserted simultaneously in a cross-shape. The coordinates of each microelectrode were compared with coordinates of the other 4 electrodes inserted simultaneously with the Ben Gun and visible on the same iCT image. Thus, this procedure avoids errors from image fusion and from brain shift. We calculate (1) the three-dimensional Euclidian deviation of microelectrodes, (2) the deviation in X- and Y-axes on reconstructed probe's eye view MR images, and (3) the deviation from the 2-mm theoretical distance between the central electrode and 4 satellite microelectrodes.
Results: The median deviation was 0.64 mm in 3-D and 0.58 mm in 2-D probe's eye view. Satellite electrodes were located from the central electrode theoretically at 2.0 mm and practically within the range 1.9-2.1 mm, 1.5-2.5 mm, 1.0-3.0 mm, and 0.5-3.5 mm for, respectively, 9.3%, 53.7%, 88.0%, and 98.1%, thus highlighting the significant deviation from the theoretical distance. Position imprecisions were similar for the 4 satellite microelectrodes. The imprecision was similar in X-axis and Y-axes and statistically less in Z-axis. For bilateral implantation, the second implantation of the same patient was not associated with a greater risk of deviation of the microelectrodes than for the first side implanted.
Conclusion: A significant percentage of microelectrodes for MER can deviate substantially from their theoretical target during DBS procedures. An iCT can be used to estimate the potential deviation of microelectrodes and improve the interpretation of MER during the procedure.
Introduction: Microvascular decompression (MVD) is an efficacious neurosurgical intervention for patients with medically intractable neurovascular compression syndromes. However, MVD may occasionally cause life-threatening or altering complications, particularly in patients unfit for surgical operations. Recent literature suggests a lack of association between chronological age and surgical outcomes for MVD. The Risk Analysis Index (RAI) is a validated frailty tool for surgical populations (both clinical and large database). The present study sought to evaluate the prognostic ability of frailty, as measured by RAI, to predict outcomes for patients undergoing MVD from a large multicenter surgical registry.
Methods: The American College of Surgeons-National Surgical Quality Improvement Program (ACS-NSQIP) database (2011-2020) was queried using diagnosis/procedure codes for patients undergoing MVD procedures for trigeminal neuralgia (n = 1,211), hemifacial spasm (n = 236), or glossopharyngeal neuralgia (n = 26). The relationship between preoperative frailty (measured by RAI and 5-factor modified frailty index [mFI-5]) for primary endpoint of adverse discharge outcome (AD) was analyzed. AD was defined as discharge to a facility which was not home, hospice, or death within 30 days. Discriminatory accuracy for prediction of AD was assessed by computation of C-statistics (with 95% confidence interval) from receiver operating characteristic (ROC) curve analysis.
Results: Patients undergoing MVD (N = 1,473) were stratified by RAI frailty bins: 71% with RAI 0-20, 28% with RAI 21-30, and 1.2% with RAI 31+. Compared to RAI score 19 and below, RAI 20 and above had significantly higher rates of postoperative major complications (2.8% vs. 1.1%, p = 0.01), Clavien-Dindo grade IV complications (2.8% vs. 0.7%, p = 0.001), and AD (6.1% vs. 1.0%, p < 0.001). The rate of primary endpoint was 2.4% (N = 36) and was positively associated with increasing frailty tier: 1.5% in 0-20, 5.8% in 21-30, and 11.8% in 31+. RAI score demonstrated excellent discriminatory accuracy for primary endpoint in ROC analysis (C-statistic: 0.77, 95% CI: 0.74-0.79) and demonstrated superior discrimination compared to mFI-5 (C-statistic: 0.64, 95% CI: 0.61-0.66) (DeLong pairwise test, p = 0.003).
Conclusions: This was the first study to link preoperative frailty to worse surgical outcomes after MVD surgery. RAI frailty score predicts AD after MVD with excellent discrimination and holds promise for preoperative counseling and risk stratification of surgical candidates. A risk assessment tool was developed and deployed with a user-friendly calculator:
Introduction: Directional deep brain stimulation (DBS) leads have become widely used in the past decade. Understanding the asymmetric stimulation provided by directional leads requires precise knowledge of the exact orientation of the lead in respect to its anatomical target. Recently, the DiODe algorithm was developed to automatically determine the orientation angle of leads from the artifact on postoperative computed tomography (CT) images. However, manual DiODe results are user-dependent. This study analyzed the extent of lead rotation as well as the user agreement of DiODe calculations across the two most common DBS systems, namely, Boston Scientific's Vercise and Abbott's Infinity, and two independent medical institutions.
Methods: Data from 104 patients who underwent an anterior-facing unilateral/bilateral directional DBS implantation at either Northwestern Memorial Hospital (NMH) or Albany Medical Center (AMC) were retrospectively analyzed. Actual orientations of the implanted leads were independently calculated by three individual users using the DiODe algorithm in Lead-DBS and patients' postoperative CT images. The deviation from the intended orientation and user agreement were assessed.
Results: All leads significantly deviated from the intended 0° orientation (p < 0.001), regardless of DBS lead design (p < 0.05) or institution (p < 0.05). However, the Boston Scientific leads showed an implantation bias toward the left at both institutions (p = 0.014 at NMH, p = 0.029 at AMC). A difference of 10° between at least two users occurred in 28% (NMH) and 39% (AMC) of all Boston Scientific and 76% (NMH) and 53% (AMC) of all Abbott leads.
Conclusion: Our results show that there is a significant lead rotation from the intended surgical orientation across both DBS systems and both medical institutions; however, a bias toward a single direction was only seen in the Boston Scientific leads. Additionally, these results raise questions into the user error that occurs when manually refining the orientation angles calculated with DiODe.
Introduction: Prompt dissemination of clinical trial results is essential for ensuring the safety and efficacy of intracranial neurostimulation treatments, including deep brain stimulation (DBS) and responsive neurostimulation (RNS). However, the frequency and completeness of results publication, and reasons for reporting delays, are unknown. Moreover, the patient populations, targeted anatomical locations, and stimulation parameters should be clearly reported for both reproducibility and to identify lacunae in trial design. Here, we examine DBS and RNS trials from 1997 to 2022, chart their characteristics, and examine rates and predictors of results reporting.
Methods: Trials were identified using
Results: Across 449 trials, representing a cumulative cohort of 42,769 patient interventions, there were 37 therapeutic indications and 44 stimulation targets. The most common indication and target were Parkinson's disease (40.55%) and the subthalamic nucleus (35.88%), respectively. Only 0.89% of trials were in pediatric patients (11.58% were mixed pediatric and adult). Explored targets represented 75% of potential basal ganglia targets but only 29% of potential thalamic targets. Allowing a 1-year grace period after trial completion, 34/169 (20.12%) had results reported on
Conclusion: We highlight key knowledge and performance gaps in DBS and RNS trial research. Over one-third of trials remain unpublished >1 year after completion; pediatric trials are scarce; most of the thalamus remains unexplored; about one-in-five trials fail to report stimulation parameters; and movement disorders comprise the most studied indications.
Introduction: As one of the most common medical conditions for which patients seek medical care, chronic pain can be debilitating. The relationship between chronic pain and sleep is thought to be bidirectional, suggesting that treatment of one can be beneficial to the other. There is mounting evidence that spinal cord stimulation (SCS) improves aspects of sleep. How meaningful that is to patients' lives has not been ascertained.
Objective: The aim of the current study was to further elucidate the effect of SCS on sleep by examining the relationship between pain outcome measures with the insomnia severity index (ISI) and to establish the minimally clinical important difference (MCID), which is defined as the smallest noticeable change that an individual perceives as clinically significant.
Materials and methods: We prospectively collected ISI, Epworth sleepiness scale (ESS), Numerical Rating Scale, McGill Pain Questionnaire-Short Form, Oswestry Disability Index, Beck Depression Inventory, and Pain Catastrophizing Scale data both pre- and postoperatively for chronic pain patients who underwent SCS placement and had long-term outcomes. The ISI is a well-studied questionnaire used to assess an individual's level of insomnia.
Results: We correlated the ESS and ISI with pain outcome measures in sixty-four patients at a mean follow-up of 9.8 ± 2.9 months. The ISI showed correlations with disability as measured through the Oswestry Disability Index (p = 0.014) and depression as measured through the Beck Depression Inventory (p = 0.024). MCID values for the ISI were calculated using both anchor- and distribution-based methods. The minimal detectable change method resulted in an MCID of 2.4 points, standard error of measurement resulted in an MCID of 2.6 points, and the change difference resulted in an MCID of 2.45. The receiver operating characteristic method yielded an MCID of 0.5-point change with an area under the curve of 0.61.
Conclusion: This study successfully established MCID ranges for the ISI outcome measure to help gauge improvement in insomnia after SCS. The ISI has ample evidence of its validity in assessment of insomnia, and MCID values of 2.4-2.6 correlate with improvement in disability and depression in our patients.
Introduction: Magnetic resonance-guided focused ultrasound (MRgFUS) represents an incisionless treatment option for essential or parkinsonian tremor. The incisionless nature of this procedure has garnered interest from both patients and providers. As such, an increasing number of centers are initiating new MRgFUS programs, necessitating development of unique workflows to optimize patient care and safety. Herein, we describe establishment of a multi-disciplinary team, workflow processes, and outcomes for a new MRgFUS program.
Methods: This is a single-academic center retrospective review of 116 consecutive patients treated for hand tremor between 2020 and 2022. MRgFUS team members, treatment workflow, and treatment logistics were reviewed and categorized. Tremor severity and adverse events were evaluated at baseline, 3, 6, and 12 months post-MRgFUS with the Clinical Rating Scale for Tremor Part B (CRST-B). Trends in outcome and treatment parameters over time were assessed. Workflow and technical modifications were noted.
Results: The procedure, workflow, and team members remained consistent throughout all treatments. Technique modifications were attempted to reduce adverse events. A significant reduction in CRST-B score was achieved at 3 months (84.5%), 6 months (79.8%), and 12 months (72.2%) post-procedure (p < 0.0001). The most common post-procedure adverse events in the acute period (<1 day) were gait imbalance (61.1%), fatigue and/or lethargy (25.0%), dysarthria (23.2%), headache (20.4%), and lip/hand paresthesia (13.9%). By 12 months, the majority of adverse events had resolved with a residual 17.8% reporting gait imbalance, 2.2% dysarthria, and 8.9% lip/hand paresthesia. No significant trends in treatment parameters were found.
Conclusions: We demonstrate the feasibility of establishing an MRgFUS program with a relatively rapid increase in evaluation and treatment of patients while maintaining high standards of safety and quality. While efficacious and durable, adverse events occur and can be permanent in MRgFUS.