Stereotactic and Functional Neurosurgery最新文献

Introduction: High-intensity focused ultrasound (HIFU) has evolved significantly since its introduction to neurosurgery over 15 years ago. In the past decade, its clinical use has expanded to treat a broader range of surgical domains and indications. However, the pace and pattern of this evolution remain poorly characterized within the literature. This systematic review aimed to synthesize global research on HIFU in neurosurgery over the past 10 years, identifying trends across indications and regions.

Methods: Following PRISMA guidelines, we identified clinical studies involving HIFU in neurosurgical practice from January 1, 2014, to November 1, 2024. Studies were categorized by application and country of origin, and a quantitative analysis was performed to assess distribution and trends in these factors.

Results: A total of 498 studies were included. Research output increased over the period, from 13 studies in 2014 to 92 in 2024. While the scope of clinical applications expanded from 6 to 13 domains over this period, a disparity in research volume persisted, with movement disorders - particularly essential tremor (62.0%) and Parkinson's disease (29.9%) - accounting for the majority of publications. Nonetheless, growth was observed in previously underrepresented domains such as neurooncology, psychiatry, epilepsy, chronic pain, and neurovascular disorders. Geographically, the USA accounted for the largest share of publications (38.4%), followed by Switzerland (11.6%) and the UK (8.2%). Over this period, study quality improved with a shift from case reports and pilot studies toward an increasing number of cohort studies and randomized controlled trials.

Conclusion: This review outlines the accelerating, yet uneven, exploration of HIFU in neurosurgical practice over the past decade. While movement disorders remain the central focus of this technology, expanding interest in underexplored indications indicates a shifting landscape. At the same time, the maturation of study designs reflects a strengthening evidence base. As the field advances, increased global collaboration and greater attention to budding applications are necessary.

Introduction: Asleep deep brain stimulation (DBS) is limited by its reliance on interventional/intraoperative MRI in many cases. A frameless stereotaxy system can be used in combination with optical navigation for initial coarse alignment, followed by a navigational iCT scan to enable asleep DBS in standard operating rooms, aiming to improve accessibility and precision.

Methods: This retrospective study analyzed 32 patients (33 procedures) undergoing DBS electrode placement using the SmartFrame OR™ system (ClearPoint Neuro Inc., San Diego, CA). Radial targeting error and operative duration were assessed. Surgical workflows combined O-arm imaging (Medtronic Inc, Minneapolis, MN) and StealthStation™ S8 neuronavigation (Medtronic Inc, Minneapolis, MN, USA). Targets included the ventral intermediate nucleus (VIM), subthalamic nucleus (STN), globus pallidus internus, hippocampus, and thalamic nuclei.

Results: Median radial targeting error was 0.40 mm (range: 0-1.6 mm), with bilateral procedures showing marginally lower errors (0.35 mm vs. 0.50 mm unilateral). The VIM exhibited the highest precision (0.35 mm), while STN targeting had slightly higher error (0.53 mm). Median operative time was 189 min (140-275 min), with bilateral procedures requiring longer durations (190 vs. 155 min, p = 0.001). No major complications occurred, and no revisions were needed.

Conclusion: The ClearPoint SmartFrame OR™ system achieved submillimeter accuracy and operational efficiency comparable to MRI-guided platforms while eliminating MRI dependency. Its integration with O-arm and Stealth Navigation enhances accessibility, reduces costs, and maintains safety, positioning it as a scalable solution for asleep DBS in standard neurosurgical settings.

Introduction: Skull density ratio (SDR) is an important criterion for predicting efficacy of high-intensity focused ultrasound (HIFU) thalamotomy for essential tremor and tremor-dependent Parkinson's disease. Bisphosphonates are known to increase bone density and are postulated to raise SDR and improve HIFU energy transmission efficiency. However, the impact of bisphosphonate pre-treatment on HIFU outcomes has not been investigated.

Methods: A retrospective analysis was conducted on the sonication parameters of patients with SDR <0.45 who were pre-treated off-label with bisphosphonates prior to HIFU. For comparison, the sonication parameters were also collected for patients with SDR <0.45 not pre-treated with bisphosphonates, patients with mid-range SDR (0.45-0.49), and patients with high SDR (0.5-0.55). All patients underwent HIFU thalamotomy between March 2022 and December 2024.

Results: The bisphosphonate pre-treatment group (28 patients) and the low-SDR untreated group (29 patients) both had mean SDRs of 0.41. Respectively, the bisphosphonate-treated and low-SDR untreated group had mean final sonication energy of 23 kJ versus 26 kJ, final sonication duration of 27.1 versus 28.6 s, mean maximum temperature of 52.8°C versus 53.2°C, and average of 5.6 versus 4.9 sonications per treatment (p > 0.05 for each comparison). No significant differences between the two low-SDR groups were found for the thermal efficiency of sonication. Compared to the bisphosphonate-treated low-SDR group, the mid- and high-SDR groups exhibited significantly decreased sonication energy (p < 0.0001), final sonication duration (p < 0.0001), and higher final sonication max temperature (p < 0.01). Across all patients, a negative correlation was observed between SDR and final sonication energy (p < 0.0001, r = -0.48) and a positive correlation was observed between SDR and last sonication temperature (p < 0.005, r = 0.27), although in the low-SDR cohort, a correlation was not observed. No clinically significant differences were found in demographics, self-reported tremor improvement, or incidence of side effects.

Conclusion: No significant differences were found in sonication response parameters between the bisphosphonate-treated and untreated low-SDR groups, whereas mid- and high-SDR groups had significantly reduced sonication energy and time to produce greater heat. These findings show that while bisphosphonates are an established way of raising bone density in osteoporosis, pre-treatment with bisphosphonates does not shift the sonication response from that of a low SDR to a mid-range SDR. Additionally, other factors besides just skull density likely determine the thermal response to sonication.

Introduction: Deep brain stimulation (DBS) is an established treatment for Parkinson's disease (PD). The traditional method for accurate implantation is awake microelectrode recordings (MERs) to map out the borders of the target nucleus. However, a significant portion of patients are unable to tolerate awake surgical procedures. Asleep MER techniques under different general anesthesia regimens have been described with variable effects on recording quality and required a lower inhaled sevoflurane level to obtain single unit recordings. Hence, a reliable method for asleep MER mapping is needed without compromising patient safety and comfort. We aimed to assess the feasibility and quality of basal ganglia MER under general anesthesia using inhalational agents including adding nitrous oxide as an adjunct to sevoflurane (N₂O-GA).

Methods: This study retrospectively examined PD patients undergoing DBS implantation targeting either the subthalamic nucleus (STN) or the globus pallidus internus (GPi) at a single center. Anesthetic data on end-tidal (ET) sevoflurane and nitrous oxide, with the derived minimum alveolar concentration (MAC) were captured during the time of MER mapping. We evaluated the feasibility of identifying target nuclei borders, the quality of neuronal unit isolation, and the physiological dimensions of the targeted nuclei. We calculated the concordance between the nuclei sizes based on MER mapping and imaging. We also reported the firing characteristics of isolated units.

Results: We identified 18 patients (34 nuclei) who underwent STN (n = 11) and GPi (n = 7) DBS implantation. Background activity changes were reliable in all patients for border identification. The length of the tract identified by MER was highly concordant with the anatomical tract length identified by postoperative imaging (concordance correlation coefficient: 0.84, p < 0.001). Firing in both nuclei showed higher bursting rates. Pallidal cells showed typical firing patterns with "pauser" cells in the GPe and continuous firing in the GPi. No complications were observed during follow-up. A total of 16 patients had MER data available for offline analysis. We identified 516 units (single/multi) across MER 28 tracts (STN = 284, GP = 232). In the 14 patients received the N₂O-GA, anesthetic depth was maintained at 0.97 ± 0.06 MAC, compared to 0.525 ± 0.04 MAC in the sevoflurane-only cases.

Conclusion: MER under N₂O-GA is feasible for DBS target nuclei identification for both STN and GPi and offers a safe and accurate surgical approach for PD patients unable to tolerate awake mapping.

Introduction: Gamma Knife radiosurgery (GKRS) is an established treatment for trigeminal neuralgia; however, predictors of pain relief following treatment remain unclear. We aimed to identify the factors associated with pain relief after the index GKRS session for trigeminal neuralgia.

Methods: We retrospectively analyzed a series of 204 patients with trigeminal neuralgia treated with GKRS between 1998 and 2023 (mean age 65.2 years, 68.5% female). Patient variables (pretreatment Roswell Park and Barrow Neurological Institute [BNI] pain scores, symptom duration, prior therapies, multiple sclerosis (MS) status), MRI metrics (neurovascular contact and trigeminal nerve dimensions), and radiosurgery parameters (isocenter location and radiation dose, including biologically effective dose [BED]) were assessed. Responders were defined as BNI

Results: At last follow-up (median 20 months, range 6 months to 26 years), 57.3% of patients achieved pain relief. At ≥3-year follow-up, 74.1% of patients maintained adequate pain relief. MS and prior interventions were associated with lower response rates: MS patients had 27.7% response vs. 57.7% without MS (p = 0.008), and prior microvascular decompression (MVD) had 34.4% vs. 62.7% without prior MVD (p = 0.005). GKRS as first-line therapy yielded better outcomes than when used after other treatments (63.9% vs. 38.9%, p = 0.045). Responders had a smaller trigeminal nerve (mean diameter 3.04 vs. 3.42 mm, p = 0.007) and a greater isocenter-to-brainstem orthogonal distance (4.2 vs. 3.5 mm, p = 0.02). A BED ≥2000 Gy was associated with higher response rate (75.8% vs. 48.8%, p = 0.006). In multivariate analysis, absence of MS, no prior MVD, smaller nerve diameter, and BED ≥2000 Gy independently predicted pain relief.

Conclusion: Non-modifiable factors that affected response included absence of MS and smaller trigeminal nerve size. Modifiable factors that were associated with higher response rates included no prior MVD, placing the isocenter farther from the brainstem surface, and BED ≥2000 Gy. These findings support individualized treatment sequencing and GKRS planning to optimize outcomes of GKRS for trigeminal neuralgia.

Introduction: Stereoelectroencephalography (sEEG) is a commonly used invasive method of mapping the epileptogenic zone (EZ) in patients with drug-resistant epilepsy. Generating radiofrequency thermocoagulation (RF-TC) lesions during sEEG coverage, by connecting a radiofrequency generator to a single electrode, has recently emerged as an adjunct to resective surgery. However, single-electrode RF-TC has not been effective in maintaining long-term seizure control, largely due to the small heat lesion size it can produce, and, therefore, has limited use. The "cross-bonding" technique has recently been reported, where bipolar lesioning is performed between two different and separated electrodes, in an attempt to ablate larger areas of the EZ. The purpose of this study was to analyse cross-bonding lesion characteristics using the DIXI medical electrodes and DIXI interface system and determine optimal RF-TC parameters for safe and effective clinical practice.

Methodology: A chicken albumin in vitro model was created with DIXI sEEG electrodes, DIXI interface system, and a Cosman radiofrequency generator. RF power and interelectrode distance was altered and lesion size, time and confluence were recorded and analysed.

Results: Confluent lesions were reliably produced at interelectrode distances of up to 7 mm. The largest lesions were produced at a RF power of 4-5 W, where increases in power greater than this paradoxically produced smaller lesions. Maximal lesion dimensions for height, width, and depth of lesions were identified. Lesion expansion routinely continued beyond 180 s of current delivery, with averages close to 400 s for the largest lesions generated.

Conclusion: Our in vitro modelling of the cross-bonding technique supports the use of the DIXI sEEG electrodes for generating thermal lesions in a safe, effective, and reproducible manner.

Introduction: Parkinson's disease (PD) is a neurodegenerative disorder for which deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an established treatment. Despite standardized programming, some patients seem to respond very well to DBS (optimal responders), while others seem to react poorly (poor responders). The objective was to compare the area of tissue activated between optimal and poor responders and determine whether there is a potential optimal stimulation area.

Methods: For 338 PD patients with STN-DBS, four outcome categories on the Movement Disorders Society Unified Parkinson Disease Rating Scale (MDS-UPDRS) motor part were assessed: hemibody, rigidity, bradykinesia, and tremor score for left and right separately. For each outcome category, patients were divided into one of three responder groups, based on their percentage hemibody improvement (optimal responders, >70% improvement; responders, 30-70% improvement; poor responders, <30% improvement). For each of the resulting 12 groups, volumes of tissue activated (VTA) were modeled for every individual electrode based on the stimulation parameters during follow-up assessment. To enable the responder groups comparison, all VTAs were aggregated into a so-called heatmap in normalized space. As we were mainly interested in the difference in VTA location for the optimal and poor responders, only these group heatmaps were visually assessed in reference to the STN. For quantitative sub-analyses, the amount of current applied and spread of electrode location was compared.

Results: Considerable overlap between heatmaps of optimal and poor responders within the dorsolateral region of the STN was seen. The amount of current applied and spread of electrode location did not differ.

Conclusions: This study comparing anatomical group-level studies of VTAs of optimal responders with poor responders for STN-DBS in PD did not find an area of optimal stimulation to reduce variability in DBS outcome. However, the heatmap of optimal responders can facilitate easier DBS targeting. To reduce variability in DBS outcome, focus could shift more toward patient-specific anatomy and connectivity levels in order to determine the individual optimal subthalamic area for programming.

Introduction: Real-time monitoring during MR-guided focused ultrasound (MRgFUS) procedures has been considered essential to monitor tremor improvement and side effects in the alignment and/or verify phase before the actual MRgFUS treatment and following the ablative sonications. However, a subgroup of patients does not tolerate being awake during the entire procedure for a variety of reasons.

Case presentations: We performed MRgFUS treatments in three Parkinson's disease/Parkinsonism patients under general anesthesia. These patients had previously failed an attempt to undergo the procedure awake. All 3 patients who had the procedure under general anesthesia experienced significant improvement of their symptoms and experienced only transient adverse effects (e.g., balance problems, left facial droop) that were no longer evident at their first postoperative visit.

Conclusion: Our findings suggest that MRgFUS treatment under general anesthesia could possibly be done safely and may represent a valid therapeutic option for patients unable to tolerate the procedure awake.