Deep Implantation Research Articles

Techniques for the Application of Stereotactic Head Frames Based on a 25-Year Experience.

The use of skull fixed stereotactic head frames remains an integral part of neurosurgical practice. Methods for the positioning, anesthesia, and fixation have been described in various publications. The authors describe the steps used currently that reflect a 25-year experience with stereotactic frame application. Photographs were obtained throughout the set-up and frame application process. The step-by-step methods were described with accompanying figures. Consent was obtained from that patient to allow for photographs throughout the frame application process. Consent was also obtained from a separate patient for videotaping the entire application process. Descriptive tags are embedded in the video to assist with the instruction of the senior author's (MWM) methods. The senior author has used the described method in over 1,000 cases. A recent analysis of the patient pain experience has been reported and is well tolerated. Supplemental devices beyond the manufacturers' standard equipment have been employed or developed: ethyl chloride spray, angled front posts, frame positioner, and torque wrenches. There have been no shunt perforations, no cranial vault penetrations, one titanium mesh cranioplasty deformation, three pin site infections (3 patients; 4,000 pin sites; 0.075%), and one thermal injury (0.025%). Stereotactic head frame application remains an important part of neurosurgical practice. The steps in application employed here after a 25-year experience appear to make the procedure well tolerated by patients. The authors hope this instructional article will be of value to new users who practice stereotactic radiosurgery, frame-based biopsy, depth electrode placement, or deep brain stimulator implantation.

Tractography patterns of subthalamic nucleus deep brain stimulation.

Deep brain stimulation therapy is an effective symptomatic treatment for Parkinson's disease, yet the precise mechanisms responsible for its therapeutic effects remain unclear. Although the targets of deep brain stimulation are grey matter structures, axonal modulation is known to play an important role in deep brain stimulation's therapeutic mechanism. Several white matter structures in proximity to the subthalamic nucleus have been implicated in the clinical benefits of deep brain stimulation for Parkinson's disease. We assessed the connectivity patterns that characterize clinically beneficial electrodes in Parkinson's disease patients, after deep brain stimulation of the subthalamic nucleus. We evaluated 22 patients with Parkinson's disease (11 females, age 57 ± 9.1 years, disease duration 13.3 ± 6.3 years) who received bilateral deep brain stimulation of the subthalamic nucleus at the National Institutes of Health. During an initial electrode screening session, one month after deep brain stimulation implantation, the clinical benefits of each contact were determined. The electrode was localized by coregistering preoperative magnetic resonance imaging and postoperative computer tomography images and the volume of tissue activated was estimated from stimulation voltage and impedance. Brain connectivity for the volume of tissue activated of deep brain stimulation contacts was assessed using probabilistic tractography with diffusion-tensor data. Areas most frequently connected to clinically effective contacts included the thalamus, substantia nigra, brainstem and superior frontal gyrus. A series of discriminant analyses demonstrated that the strength of connectivity to the superior frontal gyrus and the thalamus were positively associated with clinical effectiveness. The connectivity patterns observed in our study suggest that the modulation of white matter tracts directed to the superior frontal gyrus and the thalamus is associated with favourable clinical outcomes and may contribute to the therapeutic effects of deep brain stimulation. Our method can be further developed to reliably identify effective deep brain stimulation contacts and aid in the programming process.

Characterisation of the deuterium recycling at the W divertor target plates in JET during steady-state plasma conditions and ELMs

Experiments in the JET tokamak equipped with the ITER-like wall (ILW) revealed that the inner and outer target plate at the location of the strike points represent after one year of operation intact tungsten (W) surfaces without any beryllium (Be) surface coverage. The dynamics of near-surface retention, implantation, desorption and recycling of deuterium (D) in the divertor of plasma discharges are determined by W target plates. As the W plasma-facing components (PFCs) are not actively cooled, the surface temperature (Tsurface) is increasing with plasma exposure, varying the balance between these processes in addition to the impinging deuteron fluxes and energies. The dynamic behaviour on a slow time scale of seconds was quantified in a series of identical L-mode discharges (JET Pulse Number (JPN)) by intra-shot gas analysis providing the reduction of deuterium retention in W PFCs by 1/3 at a base temperature (Tbase) range at the outer target plate between 65 °C and 150 °C equivalent to a Tsurface span of 150 °C and 420 °C. The associated recycling and molecular D desorption during the discharge varies only at lowest temperatures moderately, whereas desorption between discharges rises significantly with increasing Tbase. The retention measurements represent the sum of inner and outer divertor interaction at comparable Tsurface. The dynamic behaviour on a fast time scale of ms was studied in a series of identical H-mode discharges (JPN ) and coherent edge-localized mode (ELM) averaging. High energetic ELMs of about 3 keV are impacting on the W PFCs with fluxes of which is about four times higher than inter-ELM ion fluxes with an impact energy of about Eim = 200 eV. This intra-ELM ion flux is associated with a high heat flux of about 60 MW m−2 to the outer target plate which causes Tsurface rise by Δ T = 100 K per ELM covering finally the range between 160 °C and 1400 °C during the flat-top phase. ELM-induced desorption from saturated near-surface implantation regions as well as deep ELM-induced deuterium implantation areas under varying baseline temperature takes place. Subsequent refuelling by intra-ELM deuteron fluxes occurs and a complex interplay between deuterium fuelling and desorption can be observed in the temporal ELM footprint of the surface temperature (IR thermography), the impinging deuteron flux (Langmuir probes), and the Balmer radiation (emission spectroscopy) as representative for the deuterium recycling flux. In contrast to JET-C, a pronounced second peak, ≃ 8 ms delayed with respect to the initial ELM crash, in the Dα radiation and the ion flux has been observed. The peak can be related to desorption of implanted energetic intra-ELM D+ diffusing to the W surface, and performing local recycling.

Predictors of Permanent Pacemaker Implantations and New-Onset Conduction Abnormalities With the SAPIEN 3 Balloon-Expandable Transcatheter Heart Valve.

This study investigates the influence of implantation depth and prosthesis oversizing on conduction abnormalities (CA) and permanent pacemaker implantation (PPI) after SAPIEN 3 (Edwards Lifesciences, Irvine, California) implantation. CA and PPIs are frequent complications after transcatheter aortic valve replacement with a next-generation balloon-expandable transcatheter heart valve (SAPIEN 3). The potential underlying mechanisms are incompletely understood. Of 244 patients treated with SAPIEN 3,208 without a previous pacemaker and 184 without baseline CA were analyzed. We assessed the association of angiographic implantation depth (% of frame height below the annulus) and degree of oversizing with PPI and CA. New PPI and new or worsened CA or PPI occurred in 16% (34 of 208) and 31% (57 of 184), respectively. Patients requiring PPI had a higher prevalence of atrial fibrillation (44% vs. 24%; p = 0.017), complete right bundle branch block (27% vs. 5%; p = 0.001), and bradycardia (<60 beats/min, 38% vs. 21%; p = 0.034). In patients with new CA or PPI, implantation depth was lower (at septal side: 29 ± 8% vs. 25 ± 7%; p = 0.003), and rate of oversizing was higher (19% [11 of 57] vs. 6% [8 of 126]; p = 0.007). Independent predictors of new or worsened CA or PPI were implantation depth at septal side (odds ratio [OR]: 1.063 [95% confidence interval (CI): 1.017 to 1.110]; p = 0.006 per % of frame below the aortic annulus), oversizing (OR: 3.489 [95% CI: 1.236 to 9.848]; p = 0.018), and QRS duration (OR: 1.033 [95% CI: 1.011 to 1.056]; p = 0.003 per ms). Implantation depth and prosthesis oversizing were associated with a higher rate of new CA or PPI using the SAPIEN 3. Thus, avoidance of deep implantation and extreme oversizing may reduce these complications.

Radiopaque Ruler-Guided Frozen Elephant Trunk Technique.

Frozen elephant trunk (FET) technique combines open surgery and endovascular repair for extensive thoracic aortic aneurysms. When a FET is inserted into the descending thoracic aorta, it is difficult to confirm its proper positioning. Here we report a radiopaque ruler-guided FET technique. On the basis of preoperative computed tomography, we create a roadmap which shows the relationship between the descending thoracic aorta and vertebrae. During surgery, a radiopaque ruler placed beneath the patient's back provides the accurate target position under fluoroscopy. Our technique is effective to prevent spinal cord injury because it avoids an overly deep implantation of a FET.

Simultaneous bilateral stereotactic procedure for deep brain stimulation implants: a significant step for reducing operation time.

OBJECT Currently, bilateral procedures involve 2 sequential implants in each of the hemispheres. The present report demonstrates the feasibility of simultaneous bilateral procedures during the implantation of deep brain stimulation (DBS) leads. METHODS Fifty-seven patients with movement disorders underwent bilateral DBS implantation in the same study period. The authors compared the time required for the surgical implantation of deep brain electrodes in 2 randomly assigned groups. One group of 28 patients underwent traditional sequential electrode implantation, and the other 29 patients underwent simultaneous bilateral implantation. Clinical outcomes of the patients with Parkinson's disease (PD) who had undergone DBS implantation of the subthalamic nucleus using either of the 2 techniques were compared. RESULTS Overall, a reduction of 38.51% in total operating time for the simultaneous bilateral group (136.4 ± 20.93 minutes) as compared with that for the traditional consecutive approach (220.3 ± 27.58 minutes) was observed. Regarding clinical outcomes in the PD patients who underwent subthalamic nucleus DBS implantation, comparing the preoperative off-medication condition with the off-medication/on-stimulation condition 1 year after the surgery in both procedure groups, there was a mean 47.8% ± 9.5% improvement in the Unified Parkinson's Disease Rating Scale Part III (UPDRS-III) score in the simultaneous group, while the sequential group experienced 47.5% ± 15.8% improvement (p = 0.96). Moreover, a marked reduction in the levodopa-equivalent dose from preoperatively to postoperatively was similar in these 2 groups. The simultaneous bilateral procedure presented major advantages over the traditional sequential approach, with a shorter total operating time. CONCLUSIONS A simultaneous stereotactic approach significantly reduces the operation time in bilateral DBS procedures, resulting in decreased microrecording time, contributing to the optimization of functional stereotactic procedures.

Multicenter experience of mixed deep brain stimulation implants for movement disorders

Multicenter experience of mixed deep brain stimulation implants for movement disorders

Mapping the "Depression Switch" During Intraoperative Testing of Subcallosal Cingulate Deep Brain Stimulation.

The clinical utility of monitoring behavioral changes during intraoperative testing of subcallosal cingulate deep brain stimulation is unknown. To characterize the structural connectivity correlates of deep brain stimulation-evoked behavioral effects using probabilistic tractography in depression. Categorization of acute behavioral effects was conducted in 9 adults undergoing deep brain stimulation implantation surgery for chronic treatment-resistant depression in a randomized and blinded testing session at Emory University. Patients were studied from September 1, 2011, through June 30, 2013. Post hoc analyses of the structural tractography patterns mediating distinct categories of evoked behavioral effects were defined, including the best response overall. Data analyses were performed from May 1 through July 1, 2015. Categorization of stimulation-induced transient behavioral effects and delineation of the shared white matter tracts mediating response subtypes. Among the 9 patients, 72 active and 36 sham trials were recorded. The following stereotypical behavior patterns were identified: changes in interoceptive (noted changes in body state in 30 of 72 active and 4 of 36 sham trials) and in exteroceptive (shift in attention from patient to others in 9 of 72 active and 0 sham trials) awareness. The best response was a combination of exteroceptive and interoceptive changes at a single left contact for all 9 patients. Structural connectivity showed that the best response contacts had a pattern of connections to the bilateral ventromedial frontal cortex (via forceps minor and left uncinate fasciculus) and to the cingulate cortex (via left cingulum bundle), whereas behaviorally salient but nonbest contacts had only cingulate involvement. The involvement of the 3 white matter bundles during stimulation of the best contacts suggests a mechanism for the observed transient "depression switch." This analysis of transient behavior changes during intraoperative deep brain stimulation of the subcallosal cingulate and the subsequent identification of unique connectivity patterns may provide a biomarker of a rapid-onset depression switch to guide surgical implantation and to refine and optimize algorithms for the selection of contacts in long-term stimulation for treatment-resistant depression.

Management of type II unruptured cesarean scar pregnancy: Comparison of gestational mass excision and uterine artery embolization combined with methotrexate

ObjectiveThis research was carried out to investigate the effectiveness, rationality, and safety of laparotomy management compared with uterine artery embolization (UAE) combined with methotrexate (MTX) for the treatment of deep implantation cesarean scar pregnancy (CSP II). Materials and methodsData from 29 patients seen between June 2008 and February 2012 were retrospectively analyzed. The patients were divided into the surgery group and the UAE combined with MTX group according to the treatment they received. We compared the clinical characteristics and treatment outcomes between the two groups. ResultsThe patients' clinical characteristics did not differ between the surgery group and the UAE combined with MTX group. However, the mean blood loss was decreased in the surgery group compared with the UAE combined with MTX group (90 ± 4.5 mL vs. 286 ± 5.2 mL, p < 0.05). No patients required blood transfusion in the surgery group, whereas two patients in the UAE combined with MTX group received blood transfusions. The length of time for the serum beta human chorionic gonadotropin (β-HCG) level to normalize, the time required for the disappearance of the gestational mass, and the duration of hospital stay were significantly less in the surgery group than in the UAE combined with MTX group (13.7 ± 1.0 days vs. 40.7 ± 1.7 days, 7.1 ± 1.3 days vs. 135.4 ± 6.7 days, and 11.0 ± 1.2 days vs. 41.4 ± 3.2 days, respectively; p < 0.01). Although the treatment success rate did not differ significantly between the two groups, the success rate was 100% for the surgery group and 73% for the UAE combined with MTX group. ConclusionSurgical treatment can remove gestational masses and allow wound repair. Moreover, laparotomy is available in almost all hospitals. Thus, surgery can be an effective and reasonable treatment for CSP II.

Clinical study on deep brain electrode implantation assisted by ROSA system

Objective To evaluate the accuracy and safety of deep brain electrode implantation assisted by robotized stereotactic assistant (ROSA) system. Methods A total of 6 epileptic patients who had difficulty in positioning of epileptogenic focus underwent deep brain electrode implantation assisted by ROSA system. Record the maximum and minimum distance of electrode deviation according to postoperative CT and MRI and calculate the average distance, so as to evaluate the accuracy of operation. Record intraoperative electrode related bleeding events, postoperative electrode related bleeding or ischemic events and complications during the follow-up period, so as to evaluate the safety of operation. Results A total of 37 electrodes were successfully implanted in all 6 cases, with a success rate of 100%. Implanted electrodes were mainly located in medial temporal lobe, hippocampus and insular lobe (5 cases) and parieto-lobe (one case). The maximum deviation distance was 8.79 mm, and minimum was 1.14 mm, with an average of (3.65 ± 1.82) mm. Neither intraoperative electrode related bleeding event nor postoperative electrode related bleeding or ischemic event was found. No patient suffered from severe complications, such as intracranial infection, electrode disjunction, undesirable healing of scalp and wound infection, during the follow-up period from 3 to 5 months (mean 3.67 months). Conclusions Deep brain electrode implantation assisted by ROSA system is safe and accurate. DOI: 10.3969/j.issn.1672-6731.2015.09.006

An essay of reflection: Why does preeclampsia exist in humans, and why are there such huge geographical differences in epidemiology?

This workshop had four main objectives: (A) Trying to look at the preeclampsia (PE) problem “from the Space Shuttle”: why preeclampsia has emerged in humans (a specific human reproductive feature among 4300 mammal species)? (B) Epidemiology: there are major geographical differences concerning early onset PE and late onset PE throughout the world. (C) Vascular: The very promising use of pravastatin in the treatment of the vascular maternal syndrome (based on the metabolism of carbon monoxide (CO), the role of inositol phosphate glycans P-type (IPG-P), a major role in comprehending the insulin resistance phenotype in preeclampsia. (D) Immunology: the specialty of these workshops since their start in 1998; our understanding of the role of the immune system and the regulation of the deep implantation of the human trophoblast (and the obligatory compromises between the fetal/placental unit and the mother) have reached a kind of “maturity,” following the pivotal studies exploring the biology of repetitive sperm exposure in the female genital tract. The meeting of people who never meet each other in the course of their normal professional lives (obstetricians, evolutionists, geneticists, immunologists, fundamentalist vascular biologists, epidemiologists, anthropologists, neonatologists, etc.) permitted some fruitful reflections to be made again this year.

Unravelling the (arte)fact of increased pacemaker rate with the Edwards SAPIEN 3 valve.

Early data on the Edwards SAPIEN 3 valve (S3-THV) have shown low rates of paravalvular leaks and vascular complications but relatively high 30-day permanent pacemaker implantation (PPMI) rates. No direct comparisons on clinical outcomes including PPMI rates are available for the S3-THV and the Edwards SAPIEN XT (XT-THV). We aimed to compare the 30-day PPMI rates in patients treated with the two prostheses and to assess the interplay among valve type, depth of implantation and PPMI rate. Two hundred and nine patients treated by TAVI were considered. The S3-THV was associated with higher PPMI rates compared to the XT-THV, both overall and in subgroups matched for several predictors of PPMI. However, in the S3-THV group, 30-day PPMI was strictly associated with deep valve implantation, and PPMI risk of high-implanted S3-THVs was similar to that of the overall XT-THV matched group. No cases of significant paravalvular leak were observed in the S3-THV group. The S3-THV was associated with a higher incidence of PPMI compared to the XT-THV. In the S3-THV group, pacemaker implantation was strictly associated with deep valve implantation. An implantation technique involving higher initial placement of the central marker (from 0 to 3 mm above the base of the aortic cusps) and, as a consequence, higher final valve depth might help in preventing post-TAVI PPMI with the S3-THV, without affecting the risk of paravalvular leak.

Optimal Implantation Depth and Adherence to Guidelines on Permanent Pacing to Improve the Results of Transcatheter Aortic Valve Replacement With the Medtronic CoreValve System: The CoreValve Prospective, International, Post-Market ADVANCE-II Study.

The aim of the CoreValve prospective, international, post-market ADVANCE-II study was to define the rates of conduction disturbances and permanent pacemaker implantation (PPI) after transcatheter aortic valve replacement with the Medtronic CoreValve System (Minneapolis, Minnesota) using optimized implantation techniques and application of international guidelines on cardiac pacing. Conduction disturbances are a frequent complication of transcatheter aortic valve replacement. Therates of PPI in the published reports vary according to bioprosthesis type and the indications for PPI. The primary endpoint was the 30-day incidence of PPI with Class I/II indications when the Medtronic CoreValve System was implanted at an optimal depth (≤6 mm below the aortic annulus). The timing and resolution of allnew-onset conduction disturbances were analyzed. A total of 194 patients were treated. The overall rate of PPI for Class I/II indications was 18.2%. An optimal depth was reached in 43.2% of patients, with a nonsignificantly lower incidence of PPI in patients with depths≤6 mm, compared with those with deeper implants (13.3% vs. 21.1%; p= 0.14). In a paired analysis, new-onset left bundle branch block and first-degree atrioventricular block occurred in 45.4% and 39.0% of patients, respectively, and resolved spontaneously within 30 days in 43.2% and 73.9%, respectively. In patients with new PPI, the rate of intrinsic sinus rhythm increased from 25.9% at 7 days to 59.3% at 30 days (p= 0.004). Optimal Medtronic CoreValve System deployment and adherence to international guidelines on cardiac pacing are associated with a lower rate of new PPI after transcatheter aortic valve replacement, compared with results reported in previous studies. (CoreValve Advance-II Study: Prospective International Post-Market Study [ADVANCE II]; NCT01624870).

Corrosion Behaviour of Nitrogen-Implantation Ti-Ta-Nb Alloy in Physiological Solutions Simulating Real Conditions from Human Body

We applied a new nitrogen-implantation technique (trademark Hardion+) using a source of nitrogen ions, electron cyclotron resonance that assures higher energy and deeper implantation than the conventional techniques. The N-implantation surface of the new Ti-25Ta-25Nb alloy was analyzed as follows: for the phase identification by x-ray diffraction (XRD) in a glancing geometry (1°); for the hardness by the nano-indentation method; for the corrosion behaviour in Ringer solutions of different pH values (simulating the real conditions from the human body) by cyclic and linear polarization, electrochemical impedance spectroscopy and the monitoring of the open circuit potentials and corresponding potential gradients. XRD pattern was indexed with face-centred cubic TiN compound partially substituted with TaN and NbN. The hardness increased about 2 times for the N-implantation alloy. The implantation layer had a protection effect, increasing the corrosion and passivation potentials and decreasing the tendency to passivation and passive current density, due to its compactness, reinforcement action. The corrosion current density and rate decreased by about 10 times and the polarization resistance increased by about 2 times, indicative of a more resistant nitride layer. The porosity was much reduced and the protection efficiency had values closed to 90%, namely the implantation treatment led to the formation of a dense, resistant layer. Impedance spectra showed that the capacitive behaviour of the N-implantation alloy was more insulating and protective. An electric equivalent circuit with two times constants was modelled.

Beta oscillations, timing, and stuttering.

Beta oscillations, timing, and stuttering.

Compliant semiconductor scaffolds: building blocks for advanced neural interfaces.

Compliant semiconductor scaffolds: building blocks for advanced neural interfaces.

Practical considerations and nuances in anesthesia for patients undergoing deep brain stimulation implantation surgery.

The field of functional neurosurgery has expanded in last decade to include newer indications, new devices, and new methods. This advancement has challenged anesthesia providers to adapt to these new requirements. This review aims to discuss the nuances and practical issues that are faced while administering anesthesia for deep brain stimulation surgery.

Painful cutaneous laser stimuli induce event-related gamma-band activity in the lateral thalamus of humans.

Although the thalamus is an important module in "pain networks," there are few studies of the effect of experimental pain upon thalamic oscillations. We have now examined the hypothesis that, during a series of painful cutaneous laser stimuli, thalamic signals will show stimulus-related gamma-band spectral activity, which is modulated by attention to vs. distraction from the painful stimulus. When the series of laser stimuli was presented, attention was focused by counting the laser stimuli (count laser task), while distraction was produced by counting backward (count back plus laser task). We have studied the effect of a cutaneous laser on thalamic local field potentials and EEG activity during awake procedures (deep brain stimulation implants) for the treatment of essential tremor. At different delays after the stimulus, three low gamma- (30-50 Hz) and two high gamma-band (70-90 Hz) activations were observed during the two tasks. Greater high-gamma activation was found during the count laser task for the earlier window, while greater high-gamma activation was found during the count back plus laser task for the later window. Thalamic signals were coherent with EEG signals in the beta band, which indicated significant synchrony. Thalamic cross-frequency coupling analysis indicated that the phase of the lower frequency activity (theta to beta) modulated the amplitude of the higher frequency activity (low and high gamma) more strongly during the count laser task than during the count back plus laser task. This modulation might result in multiplexed signals each encoding a different aspect of pain.

In situ lithium diffusion measurement in solid ionic conductors using short-lived radiotracer beam of 8Li

We developed an in situ radiotracer method for diffusion studies in solids using short-lived α-emitting 8Li tracer. In the method, while implanting a pulsed 8Li beam into a solid material of interest, the α particles emitted into the implantation side of the sample surface were detected as a function of time. By changing the implantation depth and the detection angle against the sample surface according to lithium diffusivity (deep implantation and large angle with a large solid angle, or shallow implantation and small angle with a narrow solid angle), the method can be sensitive to a wide range of diffusion length ranging from micrometer scale to nanometer scale per second. The feasibility of the method was demonstrated by measuring the lithium diffusion coefficients to the order of 10−12cm2/s in lithium ionic conductors.

Adaptive evolution at immune system genes and deep pregnancy implantation in primates

A major evolutionary change in the lineage ancestral to humans, chimpanzee and gorilla (HCG) has been the embedding of the embryo into maternal tissue. Thus, the first layer of cells (trophoblast) to differentiate after fertilization must adapt to invade the uterus. Such event would likely leave signatures of positive selection at genes with roles in embryo implantation. Here, 163 pregnancy implantation genes are tested for evidence of adaptive diversification in the ancestral lineage to HCG. Two immune system genes, HLA-E and KIR2DL4 showed evidence of positive selection. Some of the positive selected sites involve amino acid substitution with predicted damaging effects on protein function, thus highlighting the possibility of antagonistic pleiotropic effects. Selection at a gene coding for a receptor expressed in uterine cells (KIR) that interacts with trophoblast human leukocyte antigen (HLA) genes suggests a main role for immunological adaptations in embryo deep invasion of the maternal endometrium.