<b><i>Purpose:</i></b> The risk/benefit-ratio of deep brain stimulation (DBS) depends on focusing the electrical field onto the target volume, excluding side-effect eliciting structures. Directional leads limiting radial current diffusion can target stimulation but add a spatial degree of freedom that requires control to align multimodal imaging datasets and for anatomical interpretation of stimulation. Unpredictable postoperative lead rotations have been reported. The extent and timing of rotation from the surgically intended alignment remain uncertain, as does the time point at which directional stimulation can be safely initiated without risking unexpected shifts in stimulation volume. We present a retrospective analysis of clinically indicated, repeated neuroimaging controls postimplantation in patients with directional DBS systems, which allow estimation of the amount and timing of postoperative lead rotation. <b><i>Methods:</i></b> Data from 67 patients with directional leads and multiple cranial computer tomographies (CCT) and/or rotation fluoroscopies at different postoperative time points were included. Rotation angles were detected based on CCT artifacts (<i>n</i> = 56) or direct visualization of lead segments on rotation fluoroscopies (<i>n</i> = 52). Cross-validation of both methods was conducted in patients who received both imaging modalities (<i>n</i> = 51). <b><i>Results:</i></b> Rotation angles deviated significantly (∼30°) from their intended 0° anterior/posterior orientation. Rotation was firmly established within the first postoperative day, with no additional torque in subsequent scans. The two methods highly correlated (right hemisphere: <i>R</i><sup>2</sup> = 0.94, left hemisphere: <i>R</i><sup>2</sup> = 0.91). <b><i>Conclusion:</i></b> Both methods for measuring rotation angles led to comparable results and can be used interchangeably. Directional stimulation settings can safely be initiated after the first postoperative day, without risking subsequent lead rotation-related anatomical shifts.
Objectives: Deep brain stimulation (DBS) programming is based on clinical response testing. Our clinical pilot trial assessed the feasibility of image-guided programing using software depicting the lead location in a patient-specific anatomical model.Methods: Parkinson's disease patients with subthalamic nucleus-DBS were randomly assigned to standard clinical-based programming (CBP) or anatomical-based (imaging-guided) programming (ABP) in an 8-week crossover trial. Programming characteristics and clinical outcomes were evaluated.Results: In 10 patients, both programs led to similar motor symptom control (MDS-UPDRS III) after 4 weeks (medicationOFF/stimulationON; CPB: 18.27 ± 9.23; ABP: 18.37 ± 6.66). Stimulation settings were not significantly different, apart from higher frequency in the baseline program than CBP (p = 0.01) or ABP (p = 0.003). Time spent in a program was not significantly different (CBP: 86.1 ± 29.82%, ABP: 88.6 ± 29.0%). Programing time was significantly shorter (p = 0.039) with ABP (19.78 ± 5.86 min) than CBP (45.22 ± 18.32).Conclusion: Image-guided DBS programming in PD patients drastically reduces programming time without compromising symptom control and patient satisfaction in this small feasibility trial.
BACKGROUND Clinical trials have established subthalamic deep-brain-stimulation (STN-DBS) as a highly effective treatment for motor symptoms of Parkinson disease (PD), but in clinical practice outcomes are variable. Experienced centers are confronted with an increasing number of patients with partially “failed” STN-DBS, in whom motor benefit doesn’t meet expectations. These patients require a complex multidisciplinary and standardized workup to identify the likely cause. OBJECTIVE To describe outcomes in a series of PD patients undergoing lead revision for suboptimal motor benefit after STN-DBS surgery and characterize selection criteria for surgical revision. METHODS We investigated 9 PD patients with STN-DBS, who had unsatisfactory outcomes despite intensive neurological management. Surgical revision was considered if the ratio of DBS vs levodopa-induced improvement of UPDRS-III (DBS-rr) was below 75% and the electrodes were found outside the dorsolateral STN. RESULTS Fifteen electrodes were replaced via stereotactic revision surgery into the dorsolateral STN without any adverse effects. Median displacement distance was 4.1 mm (range 1.6-8.42 mm). Motor symptoms significantly improved (38.2 ± 6.6 to 15.5 ± 7.9 points, P < .001); DBS-rr increased from 64% to 190%. CONCLUSION Patients with persistent OFFmotor symptoms after STN-DBS should be screened for levodopa-responsiveness, which can serve as a benchmark for best achievable motor benefit. Even small horizontal deviations of the lead from the optimal position within the dorsolateral STN can cause stimulation responses, which are markedly inferior to the levodopa response. Patients with an image confirmed lead displacement and preserved levodopa response are candidates for lead revision and can expect significant motor improvement from appropriate lead replacement.
<b><i>Objective:</i></b> Deep brain stimulation (DBS) is an approved treatment for movement disorders. Despite high precision in electrode placement, side effects do occur by current spread to adjacent fibers or nuclei. Directional leads (D-leads) are designed to adapt the volume of stimulation relative to the position within the target by horizontal and vertical current steering directions. The feasibility of implanting these new leads, possible difficulties, and complications were the focus of this study. <b><i>Material and Methods:</i></b> This analysis is based on 31 patients who underwent a DBS procedure with D-leads and an implantable pulse generator (IPG) capable of multiple independent current control and 31 patients who received non-D-leads with a similar IPG. While trajectory planning and most steps of the surgical procedure were identical to conventional DBS lead implantation, differences in indication, electrode handling, lead control, and complications were documented and analyzed in comparison to a control group with ring electrodes. <b><i>Results:</i></b> During a consecutive series of 51 patients implanted with a DBS system, 31 patients (60.1%) were selected for implantation of D-leads and received 59 D-leads, 28 bilateral, and 3 unilateral implantations. The control group consisted of a consecutive series of a comparable time period, with 31 patients who received conventional ring electrodes. Indication of D-lead implantation was based on the anatomic conditions of the trajectory and target regions and the results of intraoperative test stimulations. In 1 patient, primary D-lead implantation on both sides was performed without any microelectrode implantation to minimize risk for hemorrhage. In the absence of an externally visible marker, the control of implant depth and of the orientation of the D-lead needs to be controlled by X-ray resulting in a longer fluoroscopy time and, therefore, higher X-ray dose compared to conventional lead implantations (415.53 vs. 328.96 Gy cm<sup>2</sup>; <i>p</i> = 0.09). Mean procedure duration for complete system implantation did not differ between either type of leads (ring electrodes vs. D-leads, 08:55 vs. 09:02 h:min). Surgical complications were unrelated to the type of electrode: surgical revision was necessary and successfully performed in 1 subcutaneous hematoma and 1 unilateral electrode dislocation. A rather rare complication, symptomatic idiopathic delayed-onset edema, was observed in 4 patients with D-leads. They recovered completely within 1–3 weeks, spontaneously or after short-term cortisone medication. In the control group, in a series of 31 patients (20 implanted with Medtronic 3389 lead and 11 with Boston Scientific Vercise lead), not a single problem of this kind was encountered at any time. <b><i>Conclusion:</i></b> Precise positioning of D-leads is more challenging than that of conventional DBS leads. By adding an external lead marker, control of optimal lead position and orientation is enhanced. In case of supposed increased risk for hemorrhage because of vessels crossing all possible trajectories in the pre-surgical navigated simulation program, primary D-lead implantation instead of the sharper microelectrodes may be a feasible alternative and it may offer more options than ring electrodes especially in these cases. Prospective studies comparing ring-mode stimulation to directional stimulation to examine the differences of the clinical effects have been started.
In experimental models of neuronal damage, therapeutic hypothermia proved to be a powerful neuroprotective method. In clinical studies of traumatic brain injury (TBI), this very distinct effect was not reproducible. Several meta-analyses draw different conclusions about whether therapeutic hypothermia can improve outcome after TBI. Adverse side effects of systemic hypothermia, such as severe pneumonia, have been held responsible by some authors to counteract the neuroprotective effect. Selective brain cooling (SBC) attempts to take advantage of the protective effects of therapeutic hypothermia without the adverse side effects of systemic hypothermia. Three different methods of SBC were applied in a patient who had severe TBI with recurrent increases of intracranial pressure (ICP) refractory to conventional forms of treatment: (1) external cooling of the scalp and neck using ice packs prior to hemicraniectomy, (2) external cooling of the craniectomy defect using ice packs after hemicraniectomy, and (3) cooling by epidural irrigation with cold Ringer solution after hemicraniectomy. External scalp cooling before hemicraniectomy, external cooling of the craniectomy defect, and epidural irrigation with cold fluid resulted in temperature differences (brain temperature to body temperature) of - 0.2°, - 0.7°, and - 3.6°C, respectively. ICP declined with decreasing brain temperature. Previous external cooling attempts for SBC faced the problem that brain temperature could not be lowered without a simultaneous decrease of systemic temperature. After hemicraniectomy, epidural irrigation with cold fluid may be a simple and effective way to lower ICP and apply one of the most powerful methods of cerebroprotection after severe TBI.
Objective. Gait disturbances causing impaired mobility are common in Parkinson’s disease after bilateral deep brain stimulation of the subthalamic nucleus. We describe subthalamic subregions where neurostimulation had a positive effect on gait or provoked gait disturbances. Methods. Sixty-eight patients were classified according to postoperative gait changes: (1) gait improvement, (2) no change, (3) de novo gait disturbances. We performed a segregation analysis for (1) and (3) by simulating volumes of tissue activated and comparing aggregated spatial data for the two groups and calculated probability maps to forecast gait performance and the parkinsonism control. Results. Twenty patients experienced complete remission of presurgical gait problems after stimulation. Nine patients showed de novo gait disturbances one year post-implantation. Active contacts were more ventrally located for de novo gait disturbances versus gait improvement. Strong correlations were found between clinical alterations in gait and the individual stimulation volume within the probabilistic outcome gait map (R2 = 0.78; p = 0.01), whereby clinical improvement in parkinsonism correlated with individual stimulation volume within the corresponding probabilistic outcome map (R2 = 0.39; p = 0.01). The probabilistic maps predict patients who experience long-term gait benefits based on their volume of tissue activated overlap, which was gait specific and showed no correlation with the global parkinsonism control heatmap. Interpretation. Probabilistic mapping showed high correlation for therapy outcomes, especially gait improvement. The concept of sweet- or badspots could not explain individual differences. The thin delineations between close substructures in the subthalamic nucleus correlated with individual gait changes after neurostimulation. Probabilistic mapping may direct future re-programming approaches for greater mobility in parkinsonian patients.
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