Comparison of patient setup accuracy for optical surface-guided and X-ray-guided imaging with respect to the impact on intracranial stereotactic radiotherapy.

PURPOSE: The objective of this work is to estimate the patient positioning accuracy of a surface-guided radiation therapy (SGRT) system using an optical surface scanner compared to an X­ray-based imaging system (IGRT) with respect to their impact on intracranial stereotactic radiotherapy (SRT) and intracranial stereotactic radiosurgery (SRS). METHODS: Patient positioning data, both acquired with SGRT and IGRT systems at the same linacs, serve as a basis for determination of positioning accuracy. A total of 35 patients with two different open face masks (578 datasets) were positioned using X­ray stereoscopic imaging and the patient position inside the open face mask was recorded using SGRT. The measurement accuracy of the SGRT system (in a "standard" and an SRS mode with higher resolution) was evaluated using both IGRT and SGRT patient positioning datasets taking into account the measurement errors of the X­ray system. Based on these clinically measured datasets, the positioning accuracy was estimated using Monte Carlo (MC) simulations. The relevant evaluation criterion, as standard of practice in cranial SRT, was the 95th percentile. RESULTS: The interfractional measurement displacement vector of the SGRT system, σSGRT, in high resolution mode was estimated at 2.5 mm (68th percentile) and 5 mm (95th percentile). If the standard resolution was used, σSGRT increased by about 20%. The standard deviation of the axis-related σSGRT of the SGRT system ranged between 1.5 and 1.8 mm interfractionally and 0.5 and 1.0 mm intrafractionally. The magnitude of σSGRT is mainly due to the principle of patient surface scanning and not due to technical limitations or vendor-specific issues in software or hardware. Based on the resulting σSGRT, MC simulations served as a measure for the positioning accuracy for non-coplanar couch rotations. If an SGRT system is used as the only patient positioning device in non-coplanar fields, interfractional positioning errors of up to 6 mm and intrafractional errors of up to 5 mm cannot be ruled out. In contrast, MC simulations resulted in a positioning error of 1.6 mm (95th percentile) using the IGRT system. The cause of positioning errors in the SGRT system is mainly a change in the facial surface relative to a defined point in the brain. CONCLUSION: In order to achieve the necessary geometric accuracy in cranial stereotactic radiotherapy, use of an X­ray-based IGRT system, especially when treating with non-coplanar couch angles, is highly recommended.

Compromised Accuracy of Stereotactic Target Delineation Associated with Computed Tomography-Based Frame Registration: A Comparative Analysis of Magnetic Resonance Imaging-Computed Tomography Fusion.

INTRODUCTION: Recent advancements in stereotactic neurosurgical techniques have become increasingly reliant on image-based target planning. We devised a case-phantom comparative analysis to evaluate the target registration errors arising during the magnetic resonance imaging (MRI)-computed tomography (CT) image fusion process. METHODS: For subjects whose preoperative MRI and CT images both contained fiducial frame localizers, we investigated discrepancies in target coordinates derived from frame registration based on either MRI or CT. We generated a phantom target through an image fusion process, merging the framed CT images with their corresponding reference MRIs after masking their fiducial indicators. This phantom target was then compared with the original during each instance of target planning. RESULTS: In our investigative study with 26 frame registrations, a systematic error in the y-axis was observed as -0.89 ± 0.42 mm across cases using either conventional CT and/or cone-beam CT (O-arm). For the z-axis, errors varied on a case-by-case basis, recording at +0.64 ± 1.09 mm with a predominant occurrence in those merged with cone-beam CT. Collectively, these errors resulted in an average Euclidean error of 1.33 ± 0.93 mm. CONCLUSION: Our findings suggest that the accuracy of frame-based stereotactic planning is potentially compromised during MRI-CT fusion process. Practitioners should recognize this issue, underscoring a pressing need for strategies and advancements to optimize the process.

Evaluation of surgical treatment strategies and outcome for cerebral arachnoid cysts in children and adults.

OBJECTIVE: The best treatment strategies for cerebral arachnoid cysts (CAC) are still up for debate. In this study, we present CAC management, outcome data, and risk factors for recurrence after surgical treatment, focusing on microscopic/endoscopic approaches as compared to minimally invasive stereotactic procedures in children and adults. METHODS: In our single-institution retrospective database, we identified all patients treated surgically for newly diagnosed CAC between 2000 and 2022. Microscopic/endoscopic surgery (ME) aimed for safe cyst wall fenestration. Stereotactic implantation of an internal shunt catheter (STX) to drain CAC into the ventricles and/or cisterns was used as an alternative procedure in patients aged ≥ 3 years. Treatment decisions in favor of ME vs. STX were made by interdisciplinary consensus. The primary study endpoint was time to CAC recurrence (TTR). Secondary endpoints were outcome metrics including clinical symptoms and MR-morphological analyses. Data analysis included subdivision of the total cohort into three distinct age groups (AG1, < 6 years; AG2, 6-18 years; AG3, ≥ 18 years). RESULTS: Sixty-two patients (median age 26.5 years, range 0-82 years) were analyzed. AG1 included 15, AG2 10, and AG3 37 patients, respectively. The main presenting symptoms were headache and vertigo. In AG1 hygromas, an increase in head circumference and thinning of cranial calvaria were most frequent. Thirty-five patients underwent ME and 27 STX, respectively; frequency did not differ between AGs. There were two (22.2%) periprocedural venous complications in infants (4- and 10-month-old) during an attempt at prepontine fenestration of a complex CAC, one with fatal outcome in a 10-month-old boy. Other complications included postoperative bleeding (2, 22.2%), CSF leaks (4, 44.4%), and meningitis (1, 11.1%). Overall, clinical improvement and significant volume reduction (p = 0.008) were seen in all other patients; this did not differ between AGs. Median follow-up for all patients was 25.4 months (range, 3.1-87.1 months). Recurrent cysts were seen in 16.1%, independent of surgical procedure used (p = 0.7). In cases of recurrence, TTR was 7.9 ± 12.7 months. Preoperative ventricular expansion (p = 0.03), paresis (p = 0.008), and age under 6 years (p = 0.03) were significant risk factors for CAC recurrence in multivariate analysis. CONCLUSIONS: In patients suffering from CAC, both ME and STX can improve clinical symptoms at low procedural risk, with equal extent of CAC volume reduction. However, in infants and young children, CAC are more often associated with severe clinical symptoms, stereotactic procedures have limited use, and microsurgery in the posterior fossa may bear the risk of severe venous bleeding.

Robot-assisted transcerebellar stereotactic approach to the posterior fossa in pediatric patients: a technical note.

PURPOSE: During the last decade, there has been renewed interest in stereotactic approaches to diffuse intrinsic pontine gliomas (DIPGs) in children, due to the development of new concepts in molecular biology and management, and subsequent need for tissue sampling. Stereotactic frame-based and robot-assisted techniques are associated with reduced target error and have been incorporated into standard practice at our institution. METHODS: Four children (age 2-7 years) underwent a robot-assisted frame-based transcerebellar approach using the Leksell G frame coupled with Renishaw's neuromate® stereotactic robot. The procedures included 3 biopsies (two brainstem tumors and one cerebellar hemispheric lesion) and 1 depth electrode implantation into a low-grade tumor remnant (ganglioglioma) of the middle cerebellar peduncle causing drug-resistant epilepsy in a young girl. Targeting was based on MRI, and in one case, 18F-FET-PET was coregistered to MRI to improve sampling accuracy. The frame was applied 180° rotated compared to standard orientation, and patients were positioned prone during surgery and stereotactic preoperative CT scan. Postoperative CT scan ruled out complications and was coregistered to preoperative MRI to check the target accuracy. RESULTS: No complications occurred, and targeting was accurate in all cases. All tissue samplings provided proper histology; depth electrode EEG exploration was diagnostic and led subsequent resective surgery. CONCLUSIONS: According to our experience, the transcerebellar frame-based robotic stereotactic approach to the cerebellum and the brainstem is feasible, safe, and effective even in young children.

Decision-making in stereotactic epilepsy surgery.

Surgery can cure or significantly improve both the frequency and the intensity of seizures in patients with medication-refractory epilepsy. The set of diagnostic and therapeutic interventions involved in the path from initial consultation to definitive surgery is complex and includes a multidisciplinary team of neurologists, neurosurgeons, neuroradiologists, and neuropsychologists, supported by a very large epilepsy-dedicated clinical architecture. In recent years, new practices and technologies have emerged that dramatically expand the scope of interventions performed. Stereoelectroencephalography has become widely adopted for seizure localization; stereotactic laser ablation has enabled more focal, less invasive, and less destructive interventions; and new brain stimulation devices have unlocked treatment of eloquent foci and multifocal onset etiologies. This article articulates and illustrates the full framework for how epilepsy patients are considered for surgical intervention, with particular attention given to stereotactic approaches.

Technical efficacy and local recurrence after stereotactic radiofrequency ablation of 2653 liver tumors: a 15-year single-center experience with evaluation of prognostic factors.

PURPOSE: To assess the technical outcome and local tumor control of multi-probe stereotactic radiofrequency ablation (SRFA) in a large series of patients. Furthermore, to determine factors accounting for adverse outcomes. MATERIAL AND METHODS: Between 2003 and 2018, 865 patients were treated by SRFA for 2653 primary and metastatic liver tumors with a median tumor size of 2.0 cm (0.5 - 19 cm). Primary technical efficacy (PTE) and local recurrence (LR) were evaluated, and possible predictors for adverse events analyzed using uni- and multi-variable binary logistic regression. RESULTS: Overall, 2553 of 2653 tumors were successfully ablated at initial SRFA resulting in a PTE rate of 96.2%. Predictors of lower PTE rates were age > 70 years, tumor size > 5 cm, number of probes, location close to liver capsule/organs and segment II. LR occurred in 220 of 2653 tumors (8.3%) with the following predictors: age, tumor type/size, conglomerates, segments I/IVa/IVb, number of probes and location close to major vessels/bile duct. Multivariable analysis revealed tumor size > 5 cm (odds ratio [OR] 3.153), age > 70 years (OR 1.559), and location in segment II (OR 1.772) as independent prognostic factors for PTE, whereas tumor location close to major vessels (OR 1.653) and in segment IVb (OR 2.656) were identified as independent prognostic factors of LR. CONCLUSIONS: Stereotactic RFA is an attractive option in the management of primary or metastatic liver tumors with good local tumor control, even in large tumors. The presented prognostic factors for adverse local oncological outcome might help to stratify unfavorable tumors for ablation.

Frameless navigation-guided percutaneous rhizotomy of the trigeminal nerve: an appraisal of the literature.

Percutaneous rhizotomy is a cornerstone of trigeminal neuralgia treatment. The procedure is classically performed under intermittent fluoroscopic guidance. While frameless navigation has been advanced to overcome potential difficulties and risks of the technique, literature on the subject is limited, and a gap between actual use and published series is likely. We have assessed all available studies of percutaneous rhizotomy of the trigeminal nerve performed under frameless navigation. Technical and clinical data that has been reviewed included clinical outcome, type of navigation employed, type of rhizotomy performed, types and rate of complications, operative time, cannulation time, and cannulation rate. Reports are heterogeneous, and most of these aspects have been inconsistently described. Comparisons with non-guided procedures are mostly indirect. While no obvious disadvantages are apparent when employing navigation, the ability to draw conclusions is nonetheless limited. Navigation appears as an inviting adjunct to trigeminal rhizotomy, but publication of longer, rigorously evaluated series would be welcomed.

Gamma Knife radiosurgery for the treatment of cluster headache: a systematic review.

Cluster headache (CH) is a severe trigeminal autonomic cephalalgia that, when refractory to medical treatment, can be treated with Gamma Knife radiosurgery (GKRS). The outcomes of studies investigating GKRS for CH in the literature are inconsistent, and the ideal target and treatment parameters remain unclear. The aim of this systematic review is to evaluate the safety and the efficacy, both short and long term, of GKRS for the treatment of drug-resistant CH. A systematic review of the literature was performed to identify all clinical articles discussing GKRS for the treatment of CH. The literature review revealed 5 studies describing outcomes of GKRS for the treatment of CH for a total of 52 patients (48 included in the outcome analysis). The trigeminal nerve, the sphenopalatine ganglion, and a combination of both were treated in 34, 1, and 13 patients. The individual studies demonstrated initial meaningful pain reduction in 60-100% of patients, with an aggregate initial meaningful pain reduction in 37 patients (77%). This effect persisted in 20 patients (42%) at last follow-up. Trigeminal sensory disturbances were observed in 28 patients (58%) and deafferentation pain in 3 patients (6%). Information related to GKRS for CH are limited to few small open-label studies using heterogeneous operative techniques. In this setting, short-term pain reduction rates are high, whereas the long-term results are controversial. GKRS targeted on the trigeminal nerve or sphenopalatine ganglion is associated to a frequent risk of trigeminal disturbances and possibly deafferentation pain.

Intraoperative MRI for Brain Tumors.

INTRODUCTION: The use of intraoperative imaging has been a critical tool in the neurosurgeon's armamentarium and is of particular benefit during tumor surgery. This article summarizes the history of its development, implementation, clinical experience and future directions. METHODS: We reviewed the literature focusing on the development and clinical experience with intraoperative MRI. Utilizing the authors' personal experience as well as evidence from the literature, we present an overview of the utility of MRI during neurosurgery. RESULTS: In the 1990s, the first description of using a low field MRI in the operating room was published describing the additional benefit provided by improved resolution of MRI as compared to ultrasound. Since then, implementation has varied in magnetic field strength and in configuration from floor mounted to ceiling mounted units as well as those that are accessible to the operating room for use during surgery and via an outpatient entrance to use for diagnostic imaging. The experience shows utility of this technique for increasing extent of resection for low and high grade tumors as well as preventing injury to important structures while incorporating techniques such as intraoperative monitoring. CONCLUSION: This article reviews the history of intraoperative MRI and presents a review of the literature revealing the successful implementation of this technology and benefits noted for the patient and the surgeon.

Combined frameless stereotactical biopsy and intraoperative cerebral angiography by 3D-rotational fluoroscopy with intravenous contrast administration: a feasibility study.

BACKGROUND: Mobile 3-dimensional fluoroscopes are an integral part of modern neurosurgical operating theatres and can also be used in combination with free available image post processing to depict cerebral vessels. In preparation of stereotactic surgery, preoperative Computed Tomography (CT) may be required for image fusion. Contrast CT may be of further advantage for image fusion as it regards the vessel anatomy in trajectory planning. Time-consuming in-hospital transports are necessary for this purpose. Mobile 3D-fluoroscopes may be used to generate a CT equal preoperative data set without an in-hospital transport. This study was performed to determine the feasibility and image quality of intraoperative 3-dimensional fluoroscopy with intravenous contrast administration in combination with stereotactical procedures. METHODS: 6 patients were included in this feasibility study. After fixation in a radiolucent Mayfield clamp a rotational fluoroscopy scan was performed with 50 mL iodine contrast agent. The image data sets were merged with the existing MRI images at a planning station and visually evaluated by two observer. The operation times were compared between the frame-based and frameless systems ("skin-to-skin" and "OR entry to exit"). RESULTS: The procedure proves to be safe. The entire procedure from fluoroscope positioning to the transfer to the planning station took 5-6 min with an image acquisition time of 24 s. In 5 of 6 cases, the fused imaging was able to reproduce the vascular anatomy accurately and in good quality. Both time end-points were significantly shorter compared to frame-based interventions. CONCLUSION: The images could easily be transferred to the planning and navigation system and were successfully merged with the MRI data set. The procedure can be completely integrated into the surgical workflow. Preoperative CT imaging or transport under anaesthesia may even be replaced by this technique in the future. Furthermore, hemorrhages can be successfully visualized intraoperatively and might prevent time delays in emergencies.

Accuracy and Safety of Customized Stereotactic Fixtures for Stereoelectroencephalography in Pediatric Patients.

Stereoelectroencephalography (SEEG) in children with intractable epilepsy presents particular challenges. Their thin and partially ossified cranium, specifically in the temporal area, is prone to fracture while attaching stereotactic systems to the head or stabilizing the head in robot's field of action. Postponing SEEG in this special population of patients can have serious consequences, reducing their chances of becoming seizure-free and impacting their social and cognitive development. This study demonstrates the safety and accuracy offered by a frameless personalized 3D printed stereotactic implantation system for SEEG investigations in children under 4 years of age. SEEG was carried out in a 3-year-old patient with drug-resistant focal epilepsy, based on a right temporal-perisylvian epileptogenic zone hypothesis. Fifteen intracerebral electrodes were placed using a StarFix patient-customized stereotactic fixture. The median lateral entry point localization error of the electrodes was 0.90 mm, median lateral target point localization error was 1.86 mm, median target depth error was 0.83 mm, and median target point localization error was 1.96 mm. There were no perioperative complications. SEEG data led to a tailored right temporal-insular-opercular resection, with resulting seizure freedom (Engel IA). In conclusion, patient-customized stereotactic fixtures are a safe and accurate option for SEEG exploration in young children.

Automated neurosurgical stereotactic planning for intraoperative use: a comprehensive review of the literature and perspectives.

The creation of intracranial stereotactic trajectories, from entry point to target point, is still mostly done manually by the neurosurgeon. The development of automated stereotactic planning tools has been described in the literature. This systematic review aims to assess the effectiveness of stereotactic planning procedure automation and develop tools for patients undergoing neurosurgical stereotactic procedures. PubMed/MEDLINE, EMBASE, Google Scholar, CINAHL, PsycINFO, and Cochrane Register of Controlled Trials databases were searched from inception to September 1, 2019, at the exception of Google Scholar (from 1 January 2010 to September 1, 2019) in French and English. Eligible studies included all studies proposing automated stereotactic planning. A total of 1543 studies were screened. Forty-two studies were included in the systematic review, including 18 (42.9%) conference papers. The surgical procedures planned automatically were mainly deep brain stimulation (n = 14, 33.3%), stereoelectroencephalography (n = 12, 28.6%), and not specified (n = 10, 23.8%). The most frequently used surgical constraints to plan the trajectory were blood vessels (n = 32, 76.2%), cerebral sulci (n = 27, 64.3%), and cerebral ventricles (n = 23, 54.8%). The distance from blood vessels ranged from 1.96 to 4.78 mm for manual trajectories and from 2.47 to 7.0 mm for automated trajectories. At least one neurosurgeon was involved in 36 studies (85.7%). The automated stereotactic trajectory was preferred in 75.4% of the studied cases (range 30-92.9). Only 3 (7.1%) studies were multicentric. No study reported prospective use of the planning software. Stereotactic planning automation is a promising tool to provide valuable stereotactic trajectories for clinical applications.

Complications after frame-based stereotactic brain biopsy: a systematic review.

Stereotactic frame-based brain biopsy is one of the most used procedures to obtain brain tissue. This procedure is usually considered as mini-invasive, quick, efficient, and safe even if results of the different studies are widely heterogenous. The objective of this review of the literature is to describe and analyze the complications of stereotactic frame-based brain biopsy. About 132 articles were found after a research in the Medline database. We only considered English references published between 1994 and June 2019. Additional studies were found by using the references from articles identified in the original search. This systematic review was conducted according to PRISMA guidelines. After applying exclusion criteria, we eventually considered 25 relevant studies. The mortality rate varies from 0.7 to 4%. Overall morbidity ranges from 3 to 13%. Most of the complications are revealed by the following symptoms: neurological impairment (transient or permanent), seizure, and unconsciousness. Symptomatic hemorrhage range varies from 0.9 to 8.6%, whereas considering asymptomatic bleeding, the range may be up to 59.8%. Complications were clinically evident within minutes to a few hours after the biopsy. Corrective surgeries are very rare (< 1%). Complications occurring after a frame-based stereotactic brain biopsy are rare but with serious side effects. It rarely leads to death or to permanent neurological impairment. Description and classification of complications are often heterogeneous in the literature. The use of a grading scale could help comparisons between series from around the world. Future studies should establish a score that allows neurosurgeon to predict post-biopsy complications.

A detailed analysis of anatomical plausibility of crossed and uncrossed streamline rendition of the dentato-rubro-thalamic tract (DRT(T)) in a commercial stereotactic planning system.

BACKGROUND: An increasing number of neurosurgeons use display of the dentato-rubro-thalamic tract (DRT) based on diffusion weighted imaging (dMRI) as basis for their routine planning of stimulation or lesioning approaches in stereotactic tremor surgery. An evaluation of the anatomical validity of the display of the DRT with respect to modern stereotactic planning systems and across different tracking environments has not been performed. METHODS: Distinct dMRI and anatomical magnetic resonance imaging (MRI) data of high and low quality from 9 subjects were used. Six subjects had repeated MRI scans and therefore entered the analysis twice. Standardized DICOM structure templates for volume of interest definition were applied in native space for all investigations. For tracking BrainLab Elements (BrainLab, Munich, Germany), two tensor deterministic tracking (FT2), MRtrix IFOD2 ( https://www.mrtrix.org ), and a global tracking (GT) approach were used to compare the display of the uncrossed (DRTu) and crossed (DRTx) fiber structure after transformation into MNI space. The resulting streamlines were investigated for congruence, reproducibility, anatomical validity, and penetration of anatomical way point structures. RESULTS: In general, the DRTu can be depicted with good quality (as judged by waypoints). FT2 (surgical) and GT (neuroscientific) show high congruence. While GT shows partly reproducible results for DRTx, the crossed pathway cannot be reliably reconstructed with the other (iFOD2 and FT2) algorithms. CONCLUSION: Since a direct anatomical comparison is difficult in the individual subjects, we chose a comparison with two research tracking environments as the best possible "ground truth." FT2 is useful especially because of its manual editing possibilities of cutting erroneous fibers on the single subject level. An uncertainty of 2 mm as mean displacement of DRTu is expectable and should be respected when using this approach for surgical planning. Tractographic renditions of the DRTx on the single subject level seem to be still illusive.

A comparison of the efficacy, safety, and duration of frame-based and Remebot robot-assisted frameless stereotactic biopsy.

OBJECTIVE: The aim of this study was to compare the efficacy, safety, and duration of Remebot robot-assisted frameless brain biopsy with those of standard frame-based stereotactic biopsy. PATIENTS AND METHODS: A retrospective analysis of 66 patients undergoing stereotactic brain biopsy in our department from January 2015 to January 2019 was performed. We divided the patients into two groups: the frame-based group (n = 35) and the Remebot robot group (n = 31). Data on clinical characteristics, total procedure length, overall discomfort, diagnostic yield, complications, and postoperative length of hospital stay were retrospectively reviewed and compared between these two groups. RESULTS: No significant difference in diagnostic yield was detected in the two groups, with frame-based biopsy having a diagnostic yield of 91.4% and Remebot robot-assisted frameless brain biopsy having a diagnostic yield of 93.5%. The duration of the total procedure was 116.5 min for the frame-based biopsy and 80.1 min for the Remebot robot-assisted frameless brain biopsy (p < 0.001). There were no statistically significant differences in complication rate or postoperative duration of hospitalization between the two groups. The overall patient discomfort in the frame-based group was significantly greater than that in the Remebot robot group (visual analog scale score 2.7 ± 1.2 versus 1.5 ± 0.7, p = 0.001). CONCLUSIONS: Remebot robot-assisted frameless brain biopsy was as efficacious and safe as standard stereotactic frame-based biopsy. However, frameless biopsy can alleviate the suffering of the patient and reduce the total duration of the procedure. Remebot robot-assisted frameless brain biopsy is easy to use and better accepted by patients than frame-based biopsy.

Robotic-assisted stereotactic drainage of cerebral abscess and placement of ventriculostomy.

BACKGROUND: Robotic surgery has found increasing use in multiple subfields of neurosurgery. While the initial applications of stereotactic robotic surgery were for the placement of electrodes for extra-operative seizure monitoring, this technique has become increasingly relevant in other areas of neurosurgery. To the best of our knowledge, we report the first case of successful robotic surgery utilization to drain a cerebral abscess and place an external ventricular drain. CASE REPORT: The authors demonstrate a novel use for stereotactic robotic assistance to drain a cerebral abscess and place ventriculostomy in a 74-year-old female patient who presented with a left basal ganglia Streptococcus intermedius abscess and concomitant ventriculitis. Drainage of a deep-seated abscess and placement of ventriculostomy was successfully performed in this patient without intraoperative difficulties or complications. The total operative time, including registration was 64 minutes and the estimated blood loss was 25 mL. The patient recovered well and was discharged to inpatient rehabilitation on postoperative day 19. CONCLUSIONS: The use of robotic surgery to drain cerebral abscesses and place ventriculostomies is technically feasible and may potentially decrease operative time and increase accuracy and safety.

[Rolf Hassler: from leucotomy to stereotaxy]. / Rolf Hassler: von der Leukotomie zur Stereotaxie.

Rolf Hassler is one of the most renowned German specialists in psychiatry, neurology and neuroanatomy. Hassler's career exemplifies medicine as scientific endeavor. Relaying on an expertise in neuroanatomy gained at Oscar and Cecile Vogt's Kaiser Wilhelm Institute, especially regarding the structure of the thalamus, Hassler enabled Freiburg University's neurosurgery clinic the invention of stereotactic "stepped leucotomy" and established thalamotomy internationally in a leading way. While directing the Neuroanatomical/Neurobiological department of the Max Planck Institute for Brain Research from 1959 until 1982, Hassler continued to study the effects of stimulation and targeted subcortical electrocoagulation in the cat brain. The Freiburg trained neurosurgeon Gert Dieckmann helped Hassler to apply the newly gained knowledge for the stereotactic therapy of torticollis, tics and obsessions and compulsions. The use however of thalamotomy also as a surgical therapy for aggressiveness in children, mainly during the late 1960s and early 1970s, is starting to provoke public criticism. Contrary however to the accusation of a medicine shaped by Nazi ideology into a "science without humanity", Hasslers career reveals a problematic intrinsic to medicine: the together of "art of healing and science".

How technical progress reshaped behavioral neuroendocrinology during the last 50 years and some methodological remarks.

The first issue of Hormones and Behavior was published 50 years ago in 1969, a time when most of the techniques we currently use in Behavioral Endocrinology were not available. Researchers have during the last 5 decades developed techniques that allow measuring hormones in small volumes of biological samples, identify the sites where steroids act in the brain to activate sexual behavior, characterize and quantify gene expression correlated with behavior expression, modify this expression in a specific manner, and manipulate the activity of selected neuronal populations by chemogenetic and optogenetic techniques. This technical progress has considerably transformed the field and has been very beneficial for our understanding of the endocrine controls of behavior in general, but it did also come with some caveats. The facilitation of scientific investigations came with some relaxation of methodological exigency. Some critical controls are no longer performed on a regular basis and complex techniques supplied as ready to use kits are implemented without precise knowledge of their limitations. We present here a selective review of the most important of these new techniques, their potential problems and how they changed our view of the hormonal control of behavior. Fortunately, the scientific endeavor is a self-correcting process. The problems have been identified and corrections have been proposed. The next decades will obviously be filled with exciting discoveries in behavioral neuroendocrinology.

Thermal ablation of CT 'invisible' liver tumors using MRI fusion: a case control study.

Purpose: To evaluate whether 'invisible' liver tumors on CT can be treated by stereotactic radiofrequency ablation (SRFA) using fusion of pre-ablation MRI.Methods: In this retrospective case-control study, 60 patients (14 with Hepatocellular carcinoma (HCC) and 46 with metastatic liver tumors) with CT 'invisible' lesions underwent SRFA using MRI-fusion between June 2005 and June 2018 ('fusion group'). For comparison, 60 patients who underwent SRFA without image fusion were selected using nearest neighbor propensity score matching ('control group'). Endpoints consisted of local tumor control, safety, overall and disease-free survival.Results: Major complications occurred in 6/69 ablations (8.7%) in the fusion group and in 6/89 ablations (6.7%) in the control group (p = 0.434). Primary technical efficacy rate (i.e., successful initial ablation) was 96.6% (28/29) for HCC and 97.9% (166/170) for metastatic disease in the fusion group and 100% (33/33) and 93.3% (184/194) in the control group, respectively (p = 0.468 and 0.064). Local recurrence (LR) was observed in 1/29 (3.5%) HCCs and in 6/170 metastases (4.0%) in the fusion group and 1/33 (3.0%) and 21/196 (10.7%) in the control group, respectively. The LR rate of metastasis in the control group was significantly higher (p = 0.007), although differences in OS and DFS did not reach statistical significance.Conclusions: Image fusion using pre-procedural MRI allows for ablation of CT-'invisible' liver tumors that are otherwise untreatable. Moreover, local oncological control was higher in metastatic liver tumors versus matched controls which suggests it could be useful tool for all stereotactic radiofrequency ablation procedures.

Psychosurgery in the History of Stereotactic Functional Neurosurgery.

The paper invites to reappraise the role of psychosurgery for and within the development of functional stereotactic neurosurgery. It highlights the significant and long-lived role of stereotactic neurosurgery in the treatment of severe and chronic mental disorders. Stereotactic neurosurgery developed out of psychosurgery. It was leucotomy for psychiatric disorders and chronic pain that paved the way for stereotactic dorsomedial thalamotomy in these indications and subsequently for stereotactic surgery in epilepsy and movement disorders. Through the 1960s stereotactic psychosurgery continued to progress in silence. Due to the increased applications of stereotactic surgery in psychiatric indications, psychosurgery's renaissance was proclaimed in the early 1970s. At the same time, however, a public fearing mind control started to discredit all functional neurosurgery for mental disorders, including stereotactic procedures. In writing its own history, stereotactic neurosurgery's identity as a neuropsychiatric discipline became subsequently increasingly redefined as principally a sort of "surgical neurology," cut off from its psychiatric origin.