Frameless Technique Research Articles

Frameless Stereotactic Biopsy of Brainstem Tumors Using the Stealth Autoguide: A Technical Note.

In the molecular era of neuro-oncology, it is increasingly necessary to obtain tissue for next-generation sequencing and methylome profile for prognosis and targeted oncological management. Brainstem tumors can be technically challenging to biopsy in the pediatric population. Frame-based and frameless techniques have previously been described and proven to be safe and efficacious in children. Recent cranial robotic guidance platforms have augmented the fluency of frameless stereotactic approaches, but the technical nuances of these procedures in children are not often discussed. We present a technical workflow for frameless stereotactic biopsy of brainstem tumors in children using the Medtronic Stealth Autoguide cranial robotic guidance platform and examine safety and efficacy of this surgical approach. A minimally invasive, frameless, transcerebellar approach is described, including operative steps and workflow. We assessed operative times, diagnostic accuracy and yield, and complication rates. Five patients underwent biopsy with the technique described. The youngest patient in our series was of 2 years. The intended target was achieved on postoperative imaging in all cases, and diagnostic tissue was obtained in all 5 patients. One patient had a clinically insignificant hemorrhage. Frameless stereotactic biopsy of the brainstem can be performed safely, efficiently, and accurately using the Medtronic Stealth Autoguide robotic platform in children as young as 2 years.

Intraoperative microelectrode recording during asleep deep brain stimulation of subthalamic nucleus for Parkinson Disease. A case series with systematic review of the literature

The use of microelectrode recording (MER) during deep brain stimulation (DBS) for Parkinson Disease is controversial. Furthermore, in asleep DBS anesthesia can impair the ability to record single-cell electric activity.The purpose of this study was to describe our surgical and anesthesiologic protocol for MER assessment during asleep subthalamic nucleus (STN) DBS and to put our findings in the context of a systematic review of the literature. Sixty-three STN electrodes were implanted in 32 patients under general anesthesia. A frameless technique using O-Arm scanning was adopted in all cases. Total intravenous anesthesia, monitored with bispectral index, was administered using a target controlled infusion of both propofol and remifentanil. A systematic review of the literature with metanalysis on MER in asleep vs awake STN DBS for Parkinson Disease was performed. In our series, MER could be reliably recorded in all cases, impacting profoundly on electrode positioning: the final position was located within 2 mm from the planned target only in 42.9% cases. Depth modification > 2 mm was necessary in 21 cases (33.3%), while in 15 cases (23.8%) a different track was used. At 1-year follow-up we observed a significant reduction in LEDD, UPDRS Part III score off-medications, and UPDRS Part III score on medications, as compared to baseline. The systematic review of the literature yielded 23 papers; adding the cases here reported, overall 1258 asleep DBS cases using MER are described. This technique was safe and effective: metanalysis showed similar, if not better, outcome of asleep vs awake patients operated using MER. MER are a useful and reliable tool during asleep STN DBS, leading to a fine tuning of electrode position in the majority of cases. Collaboration between neurosurgeon, neurophysiologist and neuroanesthesiologist is crucial, since slight modifications of sedation level can impact profoundly on MER reliability.

Long-term safety and efficacy of frameless subthalamic deep brain stimulation in Parkinson’s disease

BackgroundBilateral deep brain stimulation (DBS) of the subthalamic nucleus (STN) is standard of care for Parkinson’s disease (PD) patients and a correct lead placement is crucial to obtain good clinical outcomes. Evidence demonstrating the targeting accuracy of the frameless technique for DBS, along with the advantages for patients and clinicians, is solid, while data reporting long-term clinical outcomes for PD patients are still lacking.ObjectivesThe study aims to assess the clinical safety and efficacy of frameless bilateral STN-DBS in PD patients at 5 years from surgery.MethodsConsecutive PD patients undergoing bilateral STN-DBS with a frameless system were included in this single-center retrospective study. Clinical features, including the Unified Parkinson’s Disease Rating Scale (UPDRS) in its total motor score and axial sub-scores, and pharmacological regimen were assessed at baseline, 1 year, 3 years, and 5 years after surgery. The adverse events related to the procedure, stimulation, or the presence of the hardware were systematically collected.ResultsForty-one PD patients undergone bilateral STN-DBS implantation were included in the study and fifteen patients already completed the 5-year observation. No complications occurred during surgery and the perioperative phase, and no unexpected serious adverse event occurred during the entire follow-up period. At 5 years from surgery, there was a sustained motor efficacy of STN stimulation: STN-DBS significantly improved the off-stim UPDRS III score at 5 years by 37.6% (P < 0.001), while the dopaminergic medications remained significantly reduced compared to baseline (− 21.6% versus baseline LEDD; P = 0.036).ConclusionsOur data support the use of the frameless system for STN-DBS in PD patients, as a safe and well-tolerated technique, with long-term clinical benefits and persistent motor efficacy at 5 years from the surgery.

Accuracy Comparison between Frameless Biopsy and Frame-Based Biopsy: A Retrospective Study of a Case Series

Abstract Objective To compare the efficacy and safety of frameless and frame-based techniques for biopsies of intracranial lesions in an exclusive assistance service at a public health center in Brazil (SUS). Method A review of 65 medical records of patients with brain lesions who underwent a frame-based or frameless biopsy from September 2017 to July 2019 was performed. Results Among the 65 patients who underwent biopsy, 42 were male, and 23 were female. The mean age was 53.1 years. Most patients (49; 75.4%) presented hemispheric lesions, and, of these, 27 were in the frontal lobe (41,5%). The diagnostic rate was 78.5% (51 of 65 patients), and glial neoplasia was the most common diagnosis. In addition to glial neoplasia, a wide range of pathologies were diagnosed, such as toxoplasmosis, metastasis, lymphoma, inflammatory lesions, and abscesses. Among the 14 patients (21.5%) with inconclusive results, 8 had gliosis without neoplasia (12.3%), 4 had necrosis (6.1%), and 2 had insufficient samples (3%).The morbidity rate was 9.2%, with 4 cases of hemorrhage, 1 case of infection, and 1 case of worsening of neurological deficits. The mortality rate was 6.1% and occurred in all cases with hemorrhage.There were no significant differences in the diagnosis or complication (morbidity and mortality) rates between the frame-based and frameless groups. Conclusion The frame-based and frameless techniques for stereotactic biopsy present similar efficacy and safety.

Awake Deep Brain Stimulation Surgery Without Intraoperative Imaging Is Accurate and Effective: A Case Series.

The success of deep brain stimulation (DBS) surgery depends on the accuracy of electrode placement. Several factors can affect this such as brain shift, the quality of preoperative planning, and technical factors. It is crucial to determine whether techniques yield accurate lead placement and effective symptom relief. Many of the studies establishing the accuracy of frameless techniques used intraoperative imaging to further refine lead placement. To determine whether awake lead placement without intraoperative imaging can achieve similar minimal targeting error while preserving clinical results. Eighty-two trajectories in 47 patients who underwent awake, frameless DBS lead placement with the Fred Haer Corporation STarFix system for essential tremor or Parkinson's disease were analyzed. Neurological testing during lead placement was used to determine appropriate lead locations, and no intraoperative imaging was performed. Accuracy data were compared with previously performed studies. The Euclidean error for the patient cohort was 1.79 ± 1.02 mm, and the Pythagorean error was 1.40 ± 0.95 mm. The percentage symptom improvement evaluated by the Unified Parkinson's Disease Rating Scale for Parkinson's disease or the Fahn-Tolosa-Marin scale for essential tremor was similar to reported values at 58% ± 17.2% and 67.4% ± 24.7%, respectively. The operative time was 95.0 ± 30.3 minutes for all study patients. Awake, frameless DBS surgery with the Fred Haer Corporation STarFix system does not require intraoperative imaging for stereotactic accuracy or clinical effectiveness.

Non-robotized frameless stereotactic magnetic resonance guided laser interstitial thermal therapy for hypothalamic hamartoma.

Various strategies have been proposed for the treatment of gelastic seizures due to hypothalamic hamartomas (HH), advancing from surgical removal techniques toward functional disconnection strategies. One of the most recent procedure is the Magnetic Resonance guided Laser Interstitial Thermal Therapy (MRg-LITT), which has progressively proved to be a safe and effective technique for hamartomas ablation. In this paper, the authors' preliminary experience with the first two patients treated with this technique in Italy is presented, in order to underline the feasibility of a pure non robotized frameless technique (FS MRg-LITT) while confirming the procedure effectiveness on seizure control. Patients undergoing FS MRg-LITT for the treatment of HH related gelastic seizures since January 2020 were included. A two steps procedure was performed by using the neuronavigation system to define the entry point, the trajectories and to assess the accuracy. Visualase Laser Ablation System was then used for the MR guided ablation of the HH. A multidisciplinary (neurosurgeons, epileptologist, neuroradiologist) institutional board evaluated the patients both in the perioperative period and during follow-up. A total number of 2 pediatric patients were described. The mean operative time resulted to be 6 hours while the mean accuracy was 0.4 mm. No perioperative complications were reported. The mean length of stay was 4 days. Lastly, at 1-year follow-up both patients resulted to be seizure free and endocrinological functions were preserved. FS MRg-LITT for the treatment of HH-related epilepsy could represent an effective technique, being able to guarantee adequate level of accuracy and potentially extending the accessibility of MRg-LITT by lowering its costs and simplifying the overall procedure.

P07.02 Robot-assisted stereotactic brain biopsy combined with cortical mapping using navigated transcranial magnetic stimulation

Abstract BACKGROUND Frame-based stereotactic biopsy has been for decades the gold-standard method for taking samples of brain tumors for the histopathological diagnostic in cases when surgery was contraindicated. However, novel frameless techniques have been developed in order to facilitate the procedure for the neurosurgeon, and for the patient as well. Preoperative cortical mapping techniques enable the planning of the trajectory with the sparing of eloquent areas. MATERIAL AND METHODS A preoperative cortical mapping using navigated transcranial magnetic stimulation was performed in the case of a 37-year-old male that presented with headache. The MRI scan revealed multiple lesions located frontal lobe and temporal lobe on the right hemisphere and frontal and occipital lobes on the left hemisphere. The results of the preoperative cortical mapping were integrated into the neuronavigation system and used for the planning of the frameless based stereotactic brain biopsy. A biopsy procedure was performed using a robotic arm according to the planned trajectory. RESULTS The targeted lesion was the right frontal one. The planned trajectory took into account the results from the cortical mapping using nTMS, and the eloquent areas were avoided. The robotic arm guided the procedure and aligned to the entry point and trajectory. According to the histopathological result the lesion was a grade II diffuse astrocytoma. There were no perioperative complications. CONCLUSION To our knowledge, this is the first report that describes the use of a robot-guided frameless brain biopsy system combined with the preoperative mapping of the eloquent cortical areas using navigated transcranial magnetic stimulation. This approach is a safe one and carries less burden for the patient as well as for the surgeon.

Globus Pallidus Internus Deep Brain Stimulation Using Frame-Based vs. Frameless Stereotaxy in Dystonia: A Single-Center Experience.

Objective: Bilateral globus pallidus internus deep brain stimulation (GPi-DBS) is an established and effective therapy for primary refractory dystonia. However, the comparison of frameless vs. frame-based DBS surgery technique is still controversial. This retrospective study aims to compare the clinical outcome of two GPi-DBS surgical techniques for patients affected by primary generalized or multi-segmental dystonia.Methods: For lead's stereotaxic placement, 10 patients underwent frame-based surgery and the other 10 subjects DBS surgery with a frameless technique. Clinical features were evaluated at baseline and 6 and 12 months after surgery by means of the Burke–Fahn–Marsden Dystonia Rating Scale.Results: Frame-based GPi-DBS and frameless stereotaxic group revealed a comparable clinical outcome with no surgical complications.Conclusions: Frameless technique is safe and well-tolerated by patients and showed similar effectiveness of the frame-based stereotaxic surgery during GPi-DBS for primary dystonia. Notably, it could be a valid alternative solution because of the great advantage in improving the patient's discomfort during awake surgery.

Robot-Assisted Stereotaxy Reduces Target Error: A Meta-Analysis and Meta-Regression of 6056 Trajectories.

The pursuit of improved accuracy for localization and electrode implantation in deep brain stimulation (DBS) and stereoelectroencephalography (sEEG) has fostered an abundance of disparate surgical/stereotactic practices. Specific practices/technologies directly modify implantation accuracy; however, no study has described their respective influence in multivariable context. To synthesize the known literature to statistically quantify factors affecting implantation accuracy. A systematic review and meta-analysis was conducted to determine the inverse-variance weighted pooled mean target error (MTE) of implanted electrodes among patients undergoing DBS or sEEG. MTE was defined as Euclidean distance between planned and final electrode tip. Meta-regression identified moderators of MTE in a multivariable-adjusted model. A total of 37 eligible studies were identified from a search return of 2,901 potential articles (2002-2018) - 27 DBS and 10 sEEG. Random-effects pooled MTE=1.91mm (95% CI: 1.7-2.1) for DBS and 2.34mm (95% CI: 2.1-2.6) for sEEG. Meta-regression identified study year, robot use, frame/frameless technique, and intraoperative electrophysiologic testing (iEPT) as significant multivariable-adjusted moderators of MTE (P <.0001, R2=0.63). Study year was associated with a 0.92-mm MTE reduction over the 16-yr study period (P=.0035), and robot use with a 0.79-mm decrease (P=.0019). Frameless technique was associated with a mean 0.50-mm (95% CI: 0.17-0.84) increase, and iEPT use with a 0.45-mm (95% CI: 0.10-0.80) increase in MTE. Registration method, imaging type, intraoperative imaging, target, and demographics were not significantly associated with MTE on multivariable analysis. Robot assistance for stereotactic electrode implantation is independently associated with improved accuracy and reduced target error. This remains true regardless of other procedural factors, including frame-based vs frameless technique.

A Simple Modified Technique for Frameless Brain Lesion Biopsy.

Published articles pertaining to possible ways to increase the accuracy of image-guided frameless surgery are abundant in the literature. Accurate target localization is dependent on many factors, of which noteworthy is the meticulous registration and constant fixation of instruments during the procedure. Frequent changing of instruments’ application or inadvertent destabilization of its fixation during surgery after registration might disrupt the preset navigation measurements, leading to inaccurate targeting. Technical wise, we managed to avoid the drawback of moving the aiming device repeatedly during the procedure, as we will discuss later.This retrospective study aims to evaluate the feasibility and reliability of a simple frameless technique we used in navigation-guided brain biopsy and to show how it refines the accuracy of frameless biopsy procedures. All procedures were performed at our institution in the period from 2018 to 2019 and included 10 patients with different brain lesions. The mean operative time using our technique was noticeably short (18 minutes) and the standard deviation was 2.1. The used technique was easy, undemanding, and reliable in obtaining samples from brain tumors, guaranteeing more precision by applying an all-time fixed and stable navigation reference hardware.

An Outcomes Comparison of Patients Treated for Arteriovenous Malformation with LINAC-based Stereotactic Radiosurgery by a Standard Frame-Based Technique or a Frameless Technique Utilizing 3-Dimensional Rotational Angiography

An Outcomes Comparison of Patients Treated for Arteriovenous Malformation with LINAC-based Stereotactic Radiosurgery by a Standard Frame-Based Technique or a Frameless Technique Utilizing 3-Dimensional Rotational Angiography

Novel Approach of Linear Accelerator-Based Stereotactic Radiosurgery in an Adult Patient With Brain Arteriovenous Malformation: A Case Report and Clinical Outcome

Stereotactic radiosurgery (SRS) is a proven strategy for treating the central nervous system arteriovenous malformation (AVM). We intend to present a case of cerebral AVM in an adult patient, successfully treated with a linear accelerator (LINAC) based SRS using simplified setup techniques and an advanced planning system. In the current scenario, frame-based SRS is the standard of care with LINAC. Recently, it has proven that even frameless SRS has similar results. In our case, we used a frameless SRS technique with similar results. While calculating the dose in radiotherapy planning, we used the Acuros™ algorithm, which has proven dosimetric advantages compared to the traditional AAA™ algorithm.

Predictors of Treatment Interruption During Frameless Gamma Knife Icon Stereotactic Radiosurgery

PurposeThe Gamma Knife (GK) Icon allows for the delivery of stereotactic radiosurgery using a thermoplastic mask in combination with intrafraction motion monitoring using high definition motion management. The system pauses treatment if the magnitude of motion in all directions exceeds 1 to 1.5 mm, causing a break in treatment and prolongation of the session. We reviewed the records of patients treated in a frameless manner on our GK Icon system to determine predictors for treatment interruption. Methods and MaterialsWe reviewed the records of patients treated between May 2019 and May 2020 on the GK Icon using a frameless technique for brain metastases, gliomas, schwannomas, and meningiomas. We recorded treatment time as noted in the plan document, actual treatment delivery time, and any pauses in treatment. We tabulated baseline characteristics including age, gender, diagnosis, performance status, and shifts at time of treatment. We used a receiver operating curve analysis to determine a timepoint corresponding with treatment interruption. We then conducted a logistic regression analysis to generate odds ratios for likelihood of treatment. ResultsWe identified 150 patients meeting inclusion criteria. The majority (82%) were patients with brain metastases. The median age was 63 and the median dose was 27 Gy (16-30 Gy) in 3 fractions (1-5 fractions). The median treatment time was 23 minutes (4-108 minutes). Sixty-nine patients (46%) had at least 1 pause in treatment (range, 1-7). Receiver operating curve analysis revealed treatment time >19 minutes and rotation >0.47 degrees to be associated with interruption. Multivariable logistic regression revealed rotation >0.47 degrees and treatment time >19 minutes as predictive of interruption. ConclusionsFor patients with rotations exceeding 0.47 degrees or an extended treatment time, physicians should expect treatment interruptions, consider fractionation to lessen table time, or use a frame-based approach.

Superior accuracy and precision of SEEG electrode insertion with frame-based vs. frameless stereotaxy methods

Stereotactic electroencephalography (SEEG) has largely become the preferred method for intracranial seizure localization in epileptic patients due to its low morbidity and minimally invasive approach. While robotic placement is gaining popularity, many centers continue to use manual frame-based and frameless methods for electrode insertion. However, it is unclear how these methods compare in regard to accuracy, precision, and safety. Here, we aim to compare frame-based insertion using a CRW frame (Integra®) and frameless insertion using the StealthStation™ S7 (Medtronic®) navigation system for common temporal SEEG targets. We retrospectively examined electrode targets in SEEG patients that were implanted with either frame-based or frameless methods at a level 4 epilepsy center. We focused on two commonly used targets: amygdala and hippocampal head. Stealth station software was used to merge pre-operative MR with post-operative CT images for each patient, and coordinates for each electrode tip were calculated in relation to the midcommissural point. These were compared to predetermined ideal coordinates in regard to error and directional bias. A total of 81 SEEG electrodes were identified in 23 patients (40 amygdala and 41 hippocampal head). Eight of 45 electrodes (18%) placed with the frameless technique and 0 of 36 electrodes (0%) placed with the frame-based technique missed their target and were not clinically useful. The average Euclidean distance comparing actual to ideal electrode tip coordinates for frameless vs. frame-based techniques was 11.0mm vs. 7.1mm (p< 0.001) for the amygdala and 12.4mm vs. 8.5mm (p< 0.001) for the hippocampal head, respectively. There were no hemorrhages or clinical complications in either group. Based on this series, frame-based SEEG insertion is significantly more accurate and precise and results in more clinically useful electrode contacts, compared to frameless insertion using a navigation guidance system. This has important implications for centers not currently using robotic insertion.

A comparative outcomes analysis of patients treated for arteriovenous malformation with LINAC-based stereotactic radiosurgery by a standard frame-based technique or a frameless technique utilizing 3-dimensional rotational angiography

Previous work at our institution treating arteriovenous malformation (AVM) with radiosurgery (RS) demonstrated superior nidus visualization and geometric accuracy with use of 3-dimensional rotational angiography (3DRA) compared to biplanar digital subtraction angiography. We have since adopted a unique radiosurgical protocol that utilizes 3DRA in the planning of linear accelerator (LINAC)-based RS delivered in a frameless manner. This study seeks to compare clinical outcomes between patients treated by this novel approach and those treated by our historic frame-based protocol. Clinical data were queried for all patients treated for AVM by single-fraction RS from 2003 to 2017. RICs were identified and classified as radiologic, symptomatic, or permanent. Excellent outcome was defined as nidus obliteration without intracranial hemorrhage (ICH) or symptomatic RIC. Clinical predictors of study outcomes were identified through univariate and multivariate logistic regression using backwards elimination to optimize a predictive model. 131 AVMs in 124 patients were included with a median follow-up of 88 months. 59 AVMs received frame-based RS and 72 AVMs received frameless RS. Rate of obliteration was 64% for frame-based RS and 61% for frameless RS (p = 0.70). Radiologic, symptomatic, and permanent RICs rates were 68%, 17%, and 8%, respectively, for frame-based cases, versus 40% (p < 0.01), 8% (p = 0.13), and 3% (p = 0.15), respectively, for frameless cases. Excellent outcome was achieved in 49% of frame-based cases and 53% of frameless cases (p = 0.68). These results illustrate the safety and effectiveness of frameless LINAC-based AVM RS utilizing 3DRA.

Effective accuracy of stereoelectroencephalography: robotic 3D versus Talairach orthogonal approaches.

Stereoelectroencephalography (SEEG) was first developed in the 1950s by Jean Talairach using 2D angiography and a frame-based, orthogonal approach through a metallic grid. Since then, various other frame-based and frameless techniques have been described. In this study the authors sought to compare the traditional orthogonal Talairach 2D angiographic approach with a frame-based 3D robotic procedure that included 3D angiographic interoperative imaging guidance. MRI was used for both procedures during surgery, but MRI preplanning was done only in the robotic 3D technique. All study patients suffered from drug-resistant focal epilepsy and were treated at the same center by the same neurosurgical team. Fifty patients who underwent the 3D robotic procedure were compared to the same number of historical controls who had previously been successfully treated with the Talairach orthogonal procedure. The effectiveness and absolute accuracy, as well as safety, of the two procedures were compared. Moreover, in the 3D robotic group, the reliability of the preoperative MRI to avoid vascular structures was evaluated by studying the rate of trajectory modification following the coregistration of the intraoperative 3D angiographic data onto the preoperative MRI-based trajectory plans. Effective accuracy (96.5% vs 13.7%) and absolute accuracy (1.15 mm vs 4.00 mm) were significantly higher in the 3D robotic group than in the Talairach orthogonal group. Both procedures showed excellent safety results (no major complications). The rate of electrode modification after 3D angiography was 43.8%, and it was highest for frontal and insular locations. The frame-based, 3D angiographic, robotic procedure described here provided better accuracy for SEEG implantations than the traditional Talairach approach. This study also highlights the potential safety advantage of trajectory planning using intraoperative frame-based 3D angiography over preoperative MRI alone.

Venture in 101 Cranial Punctures: A Comparative Study between Frame-based versus Frameless Biopsy of 101 Intracranial Space Occupying Lesion.

Background:Presumptive diagnosis based solely on the clinical picture and imaging is not sufficient to provide appropriate treatment with certainty and hence histopathological confirmation of intracranial space occupying lesion (ICSOL) is essential. Needle biopsy via stereotactic frame-based or frameless neuronavigation technique is efficient procedure. The objective of this study is to compare their accuracy and efficacy and safety.Methods:This is a retrospective comparative study conducted among 101 biopsies of ICSOL. Patients data were retrieved from medical record. Data were analyzed in SPSS ver. 20. P value of <0.05 was considered significant.Results:Out of 101 patients, Frame-based stereotactic biopsy was done among 55 patients (54.4%) while 46 patients (45.6%) underwent frameless stealth neuronavigation guided biopsy. Male to female ration was 2.1:1. Age ranged from 5 to 82 years. 54.5% (55 patients) have deeper location of tumor while 45.5% (46 patients) have lobar location of tumor. Frontal (16.8%) and Thalamic (13.8%) were the common site. Mean size of tumor was 3.09±0.85cms. There was statistically significant difference in operative duration among study groups. Overall Diagnostic yield was 89.1%. Glioma was the most common (50.5%) diagnosis. Glioblastoma WHO Grade IV was 37.6% followed by lymphoma (12.8%).Conclusion:Needle biopsy via stereotactic frame-based or neuronavigation frameless technique is a safe and efficient procedure having high diagnostic yield. Reasons for negative biopsy could be missed target or retrieval of gliotic tissue.

A novel robot-guided minimally invasive technique for brain tumor biopsies.

As decisions regarding tumor diagnosis and subsequent treatment are increasingly based on molecular pathology, the frequency of brain biopsies is increasing. Robotic devices overcome limitations of frame-based and frameless techniques in terms of accuracy and usability. The aim of the present study was to present a novel, minimally invasive, robot-guided biopsy technique and compare the results with those of standard burr hole biopsy. A tubular minimally invasive instrument set was custom-designed for the iSYS-1 robot-guided biopsies. Feasibility, accuracy, duration, and outcome were compared in a consecutive series of 66 cases of robot-guided stereotactic biopsies between the minimally invasive (32 patients) and standard (34 patients) procedures. Application of the minimally invasive instrument set was feasible in all patients. Compared with the standard burr hole technique, accuracy was significantly higher both at entry (median 1.5 mm [range 0.2-3.2 mm] vs 1.7 mm [range 0.8-5.1 mm], p = 0.008) and at target (median 1.5 mm [range 0.4-3.4 mm] vs 2.0 mm [range 0.8-3.9 mm], p = 0.019). The incision-to-suture time was significantly shorter (median 30 minutes [range 15-50 minutes] vs 37.5 minutes [range 25-105 minutes], p < 0.001). The skin incision was significantly shorter (median 16.3 mm [range 12.7-23.4 mm] vs 28.4 mm [range 20-42.2 mm], p = 0.002). A diagnostic tissue sample was obtained in all cases. Application of the novel instrument set was feasible in all patients. According to the authors' data, the minimally invasive robot-guidance procedure can significantly improve accuracy, reduce operating time, and improve the cosmetic result of stereotactic biopsies.

Benefits of image-guided stereotactic hypofractionated radiation therapy as adjuvant treatment of craniopharyngiomas. A review.

Craniopharyngiomas account for 5.6-13% of intracranial tumors in children. Despite being histologically benign, these tumors remain a major neurosurgical challenge because of the typical tight adherence to adjacent critical structures. The optimal therapeutic approach for this disease is controversial. Large cystic size and adherence to neurovascular, neuroendocrine, and optic structures without a clear line of cleavage make complete resection problematic and often hazardous. For these reasons, partial resection and adjuvant treatment play an important role. Post-operative radiation therapy (RT) following either complete or incomplete tumor removal is associated with significantly decreased recurrence rates. The aim of this review is to analyze the potential advantage of the most modern technical advancements for RT of craniopharyngiomas. This narrative review on the topic of craniopharyngiomas was based on published data available on PUBMED/Medline. All data concerning adjuvant or upfront radiation therapy treatment of craniopharyngioma were reviewed and summarized. A more detailed analysis of fractionated frameless steretactic radiosurgery of these tumors is provided as well. We reviewed the possible improvement provided by intensity modulated beams, arc therapy, image guidance, proton radiation, and fractionated stereotactic radiosurgery. Many published findings on outcome and toxicity after RT involve the use of relatively outdated RT techniques. Technologic improvements in imaging, radiation planning, and delivery have improved the distribution of radiation doses to desired target volumes and reduced the dose to nearby critical normal tissues. Currently available techniques, providing image guidance and improved radiation doses distribution profile, have shown to maintain the efficacy of conventional techniques while significantly reducing the toxicity. Image-guided radiosurgery holds the dose distributions and precision of frame-based techniques with the remarkable advantage of multiple-session treatments that are better tolerated by sensitive peritumoral structures, such as the optic pathway and hypothalamus. This, together with the comfort of a frameless technique, candidates frameless image-guided radiosurgery to be the first option for the adjuvant post-operative treatment of craniopharyngiomas in children and young adults when total resection cannot be achieved, in particular those with hypothalamic involvement, and when the residual tumor is mostly solid.

Frameless Stereotaxis for Subthalamic Nucleus Deep Brain Stimulation: An Innovative Method for the Direct Visualization of Electrode Implantation by Intraoperative X-ray Control.

The recent introduction of frameless devices has enabled stereotactic neurosurgery to reach a level of accuracy that is comparable to traditional frame-based methodologies. Among frameless devices, the Nexframe appears to be very useful in implanting electrodes into the subthalamic nucleus or other structures for deep brain stimulation in Parkinson’s disease. However, frameless devices, including the Nexframe, limit the possibility of intraoperative visual control of the placement of electrodes in the brain. Utilizing intraoperative O-arm Computed tomography (CT) scan or high-field Magnetic Resonance Imaging (MRI) could overcome this limitation, but their high cost restricts their use. Thus, in this paper we propose an innovation in Nexframe surgical planning that allows the intraoperative use of a C-arm X-ray apparatus to establish: (1) the progression of the electrode guide tube and the electrode in the brain; (2) the accuracy of the electrode trajectory; and (3) the correct attainment of the target. The proposed frameless technique using the Nexframe has been developed and successfully applied in our practice. It was shown to be helpful in overcoming the major issues that are usually encountered when electrodes are placed in the brain with frameless neurosurgery and reduced the risk of having to re-operate on patients to reposition the electrodes.