Subcortical neuronal activity is highly relevant for mediating communication in large-scale brain networks. While electroencephalographic (EEG) recordings provide appropriate temporal resolution and ...coverage to study whole brain dynamics, the feasibility to detect subcortical signals is a matter of debate. Here, we investigate if scalp EEG can detect and correctly localize signals recorded with intracranial electrodes placed in the centromedial thalamus, and in the nucleus accumbens. Externalization of deep brain stimulation (DBS) electrodes, placed in these regions, provides the unique opportunity to record subcortical activity simultaneously with high-density (256 channel) scalp EEG. In three patients during rest with eyes closed, we found significant correlation between alpha envelopes derived from intracranial and EEG source reconstructed signals. Highest correlation was found for source signals in close proximity to the actual recording sites, given by the DBS electrode locations. Therefore, we present direct evidence that scalp EEG indeed can sense subcortical signals.
Objective
To investigate whether functional sweet spots of deep brain stimulation (DBS) in the subthalamic nucleus (STN) can predict motor improvement in Parkinson disease (PD) patients.
Methods
...Stimulation effects of 449 DBS settings in 21 PD patients were clinically and quantitatively assessed through standardized monopolar reviews and mapped into standard space. A sweet spot for best motor outcome was determined using voxelwise and nonparametric permutation statistics. Two independent cohorts were used to investigate whether stimulation overlap with the sweet spot could predict acute motor outcome (10 patients, 163 settings) and long‐term overall Unified Parkinson's Disease Rating Scale Part III (UPDRS‐III) improvement (63 patients).
Results
Significant clusters for suppression of rigidity and akinesia, as well as for overall motor improvement, resided around the dorsolateral border of the STN. Overlap of the volume of tissue activated with the sweet spot for overall motor improvement explained R2 = 37% of the variance in acute motor improvement, more than triple what was explained by overlap with the STN (R2 = 9%) and its sensorimotor subpart (R2 = 10%). In the second independent cohort, sweet spot overlap explained R2 = 20% of the variance in long‐term UPDRS‐III improvement, which was equivalent to the variance explained by overlap with the STN (R2 = 21%) and sensorimotor STN (R2 = 19%).
Interpretation
This study is the first to predict clinical improvement of parkinsonian motor symptoms across cohorts based on local DBS effects only. The new approach revealed a distinct sweet spot for STN DBS in PD. Stimulation overlap with the sweet spot can predict short‐ and long‐term motor outcome and may be used to guide DBS programming. ANN NEUROL 2019;86:527–538
Multiple surgical targets for treating obsessive-compulsive disorder with deep brain stimulation (DBS) have been proposed. However, different targets may modulate the same neural network responsible ...for clinical improvement. We analyzed data from four cohorts of patients (N = 50) that underwent DBS to the anterior limb of the internal capsule (ALIC), the nucleus accumbens or the subthalamic nucleus (STN). The same fiber bundle was associated with optimal clinical response in cohorts targeting either structure. This bundle connected frontal regions to the STN. When informing the tract target based on the first cohort, clinical improvements in the second could be significantly predicted, and vice versa. To further confirm results, clinical improvements in eight patients from a third center and six patients from a fourth center were significantly predicted based on their stimulation overlap with this tract. Our results show that connectivity-derived models may inform clinical improvements across DBS targets, surgeons and centers. The identified tract target is openly available in atlas form.
Deep brain stimulation (DBS) for Parkinson's disease often alleviates the motor symptoms, but causes cognitive and emotional side effects in a substantial number of cases. Identification of the motor ...part of the subthalamic nucleus (STN) as part of the presurgical workup could minimize these adverse effects. In this study, we assessed the STN's connectivity to motor, associative, and limbic brain areas, based on structural and functional connectivity analysis of volunteer data. For the structural connectivity, we used streamline counts derived from HARDI fiber tracking. The resulting tracks supported the existence of the so-called "hyperdirect" pathway in humans. Furthermore, we determined the connectivity of each STN voxel with the motor cortical areas. Functional connectivity was calculated based on functional MRI, as the correlation of the signal within a given brain voxel with the signal in the STN. Also, the signal per STN voxel was explained in terms of the correlation with motor or limbic brain seed ROI areas. Both right and left STN ROIs appeared to be structurally and functionally connected to brain areas that are part of the motor, associative, and limbic circuit. Furthermore, this study enabled us to assess the level of segregation of the STN motor part, which is relevant for the planning of STN DBS procedures.
Objectives
We aimed to investigate the efficacy of new subperception stimulation paradigms including 1.2 kHz‐high‐frequency stimulation (HFS) and advanced‐HFS field‐shaping algorithm (dorsal horn HFS ...DHHFS) in refractory cases which initially benefited from conventional spinal cord stimulation (SCS) and lost the effect throughout time.
Materials and Methods
In the context of a rescue‐therapy, patients underwent externalization of the implanted SCS‐leads and were tested with multiple combinations of new SCS paradigms. Pain intensity was analyzed using the numeric rating scale (NRS), and data were collected preoperatively and at multiple postoperative follow‐ups.
Results
Thirty‐seven patients underwent externalization of the leads. Mean preoperative NRS‐score was 8.1/10 points (SD ± 0.9) for the ON‐stimulation period. Patients received a combination of either tonic, burst and 1.2 kHz‐HFS, or burst and 1.2 kHz‐HFS, DHHFS, or 1.2 kHz‐HFS and DHHFS, or 1.2 kHz‐HFS alone. The mean postoperative NRS‐score after the testing‐phase was 3.8/10 points (SD ± 2.5), showing a 48.0% mean reduction (p < 0.001). In total, 29 patients reported a significant reduction above 50% in NRS‐scores and therefore were reimplanted with new generators that could deliver the new paradigms. Eight patients underwent full SCS‐system explantation. The patients who continued with the new paradigms (n = 29) reported mean NRS‐scores of 3.5/10 points (SD ± 1.7) 12 months postoperatively, still showing a significant reduction of 43.3% when compared to preoperative scores (p < 0.001).
Conclusion
Rescue‐therapy with combination of multiple waveforms, including tonic, burst, 1.2 kHz‐HFS, and DHHFS, was associated with a significant pain relief in patients with failed conventional SCS. This approach is a safe and efficient and should be considered before explantation of the SCS‐system.
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