Stereotactic and Functional Neurosurgery最新文献

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.

Introduction: MR-guided laser interstitial thermal therapy (MRgLITT) is a minimally invasive technique for treating deep-seated brain lesions. However, the dynamics of imaging changes that occur after the ablation are not well characterized. This study aimed to describe the clinical outcomes and volume changes that occur over time after MRgLITT.

Methods: We retrospectively collected clinical and imaging data of all adult patients who underwent MRgLITT of brain tumors (primary and metastatic) between 01/2020 and 06/2024. Volumes and diameters of the lesions were measured on gadolinium-enhanced T1-weighted images using Brainlab Elements. Local control was assessed at the last follow-up.

Results: Twenty-nine patients with 32 treated lesions were available for assessment. Most lesions (n = 21) were metastatic, while 11 lesions were gliomas. The mean follow-up period was 23.4 ± 13.1 months. The average preoperative tumor volume was 2.8 ± 1.8cc. Post-ablation, the lesions' volumes increased on average by 250% (up to 450%) in the first month after surgery compared to the preoperative volumes. The enhancing ring extended distally beyond the tip of the catheter for an average of 4.5 ± 1.8 mm. Glial lesions had a median progression-free survival of 8.5 months. The volume of metastatic lesions decreased below the preoperative volume on average 3 months after surgery. Local control was achieved in 16 of 21 metastatic lesions (76%) and was significantly better for lesions smaller than 4cc in volume and 16 mm in maximal diameter that could be completely covered by the thermal damage estimation. Nodular enhancement at 3 months post-surgery was correlated with local failure.

Conclusion: MRgLITT can achieve good local control in metastatic brain lesions and should be considered early during follow-up after radiosurgery when local failure is suspected. The enhancing lesion extends beyond the tip of the catheter and enlarges during the first month post-ablation before gradually decreasing in size. Failure to decrease in size after 3 months or appearance of a nodular enhancement should raise suspicion of local failure.

Introduction: Intraoperative microelectrode recording (MER) is a widely employed technique for the physiological identification of the subthalamic nucleus (STN) during deep brain stimulation (DBS) surgery targeting the STN. However, failure to detect typical STN activity may raise concerns about diagnostic accuracy and treatment efficacy. Objective of this study were to retrospectively evaluate the clinical characteristics and long-term outcomes of patients with advanced Parkinson's disease (PD) in whom STN neuronal activity was not detected during intraoperative MER and to explore the implications of this finding for differential diagnosis and DBS candidacy.

Methods: Among 624 STN-DBS procedures performed at Juntendo University Hospital between 2012 and 2024, we identified 3 patients (0.5%) in whom intraoperative MER failed to detect typical STN neuronal activity. Clinical records were reviewed retrospectively, including demographic data, levodopa responsiveness, preoperative images, intraoperative MER findings, surgical decision-making processes, and postoperative clinical courses.

Results: All 3 patients were male, in their 60s at the time of surgery, with disease durations ranging from 5 to 7 years. Cognitive function was preserved in all cases. Gait disturbance was a prominent early symptom, and all patients experienced relatively early wearing-off phenomena. None exhibited dyskinesia, yet all showed good responsiveness to levodopa, confirmed by preoperative levodopa challenge tests. Despite multiple MER trajectories, no characteristic STN neuronal firing patterns were observed. DBS electrodes were implanted according to the initial surgical plan in 2 cases; in the other case, implantation was aborted. Following surgery, all patients demonstrated progressive axial motor deterioration. Based on their clinical course and imaging findings, all were ultimately diagnosed with or strongly suspected to have progressive supranuclear palsy-parkinsonism (PSP-P).

Conclusions: The absence of detectable STN activity during intraoperative MER may reflect underlying neurodegenerative pathology distinct from idiopathic PD, such as PSP-P. These findings suggest that MER, beyond its role in anatomical targeting, may serve as a valuable intraoperative biological indicator for diagnostic refinement. Even within a multidisciplinary setting led by movement disorder specialists, distinguishing PD from PSP-P prior to surgery remains a significant challenge. Improved diagnostic accuracy is critical to optimize patient selection for DBS and to prevent ineffective or potentially deleterious interventions.