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Background Despite the widespread use of external ventricular drainage, revision rates, and associated complications are reported between 10 and 40%. Current available image-guided techniques using stereotaxy, endoscopy, or ultrasound for catheter placements remain time-consuming techniques. Recently, a smartphone-assisted guide with high precision has been described. The development of an easy-to-use, portable, image-guided system could reduce the need for multiple passes and improve the rate of accurate catheter placement. This study aims to prospectively compare in a randomized controlled manner the accuracy of the freehand pass technique versus an easy-to-use, portable, adjustable guiding device for ventriculostomy catheter placement. Methods/Design This is a single center, prospective, randomized trial with a blinded endpoint (ventricular catheter tip location) assessment. Adult patients with the indication for ventriculostomy, as proven by computed tomography (CT), will be randomly assigned to the treatment group or the control group. For patients in the treatment group, ventriculostomy will be performed using an adjustable guiding device and DICOM (Digital Imaging and Communications in Medicine) image-reading software assistance (for example, using a mini-tablet) based on preoperative CT imaging. Patients in the control group will receive standard freehand ventriculostomy using anatomical landmarks. The catheter may be placed for external drainage or internal (ventriculoperitoneal) shunting in both groups. The primary outcome measure is the rate of correct placements of the ventricular catheter, defined as a score of 1 to 3 on grading system for catheter tip location on a postoperative CT scan. Participants will be followed for the duration of hospital stay, an expected average of two weeks. The primary outcome will be determined by one of the authors blinded to the treatment allocation. We aim to include 236 patients in three years. Secondary outcome measures include: frequency of placements required, frequency of completed placements within the ventricle of the perforated part of the catheter tip, frequency of very early and early shunt failures (revision of the ventricular drainage within 24 hours and within the hospital stay), frequency and percentage of complications (procedure-related and nonsurgical) at discharge. Discussion This is the study design of a single center, prospective, randomized controlled trial to investigate whether guided ventriculostomy is superior to the standard freehand technique. One strength of this study is the prospective, randomized, interventional type of study testing a new easy-to-handle guided versus freehand ventricular catheter placement. A second strength of this study is that the power calculation is based on catheter accuracy using an available grading system for catheter tip location, and is calculated with the use of recent study results of our own population, supported by data from prominent studies. Trial registration Clinicaltrials.gov identifier: NCT02048553 (registered on 28 January 2014).

ObjectIn the past, the accuracy of surface matching has been shown to be disappointing. We aimed to determine whether this had improved over the years by assessing application accuracy of current navigation systems, using either surface matching or point-pair matching.MethodsEleven patients, scheduled for intracranial surgery, were included in this study after a power analysis had shown this small number to be sufficient. Prior to surgery, one additional fiducial marker was placed on the scalp, the “target marker,” where the entry point of surgery was to be expected. Using one of three different navigation systems, two patient-to-image registration procedures were performed: one based on surface matching and one based on point-pair matching. Each registration procedure was followed by the digitization of the target marker’s location, allowing calculation of the target registration error. If the system offered surface matching improvement, this was always used; and for the two systems that routinely offer an estimate of neuronavigation accuracy, this was also recorded.ResultsThe error in localizing the target marker using point-pair matching or surface matching was respectively 2.49 mm and 5.35 mm, on average (p < 0.001). In those four cases where an attempt was made to improve the surface matching, the error increased to 6.35 mm, on average. For the seven cases where the system estimated accuracy, this estimate did not correlate with target registration error (R2 = 0.04, p = 0.67).ConclusionThe accuracy of navigation systems has not improved over the last decade, with surface matching consistently yielding errors that are twice as large as when point-pair matching with adhesive markers is used. These errors are not reliably reflected by the systems own prediction, when offered. These results are important to make an informed choice between image-to-patient registration strategies, depending on the type of surgery at hand.

BackgroundHyponatremia generally occurs after transsphenoidal surgery (TSS) in a delayed fashion. Most patients with delayed postoperative hyponatremia (DPH) are asymptomatic or only express non-specific symptoms; consequently, DPH is associated with prolonged hospitalization. No consensus has been reached on which patients are at greatest risk of developing DPH. We reviewed patients with DPH and evaluated predictive factors for DPH.MethodsWe retrospectively analyzed 107 consecutive patients who underwent endoscopic TSS for pituitary adenoma (January 2010–December 2016). Patients with DPH (hyponatremia group) and without DPH (normonatremia group) were compared according to their nadir sodium levels on postoperative days 3 to 10. We documented the patients’ demographics, clinical features, and postoperative physiological characteristics.ResultsTwenty-five (23.4%) patients developed DPH after endoscopic TSS. The patients’ mean age was 54 ± 17 years, and 63.6% of the patients were female. The overall prevalence of DPH was 23.4%. The non-parametric χ2 test and the Mann–Whitney U test revealed statistically significant differences in age, use of antihypertensive drugs, nonfunctioning pituitary adenoma, and higher yet normal preoperative thyroid-stimulating hormone level between the hyponatremia and normonatremia groups (P < 0.05). Logistic regression analysis revealed that only older age was a useful independent predictive factor for DPH (odds ratio, 1.05; 95% confidence interval, 1.01–1.08; P = 0.01). The serum sodium levels on postoperative day 2 were significantly lower in the hyponatremia than normonatremia group (P < 0.01) and were negatively correlated with age (r = − 0.25, P < 0.05). The cut-off age for predicting DPH was 55 years. The hospital stay was significantly longer in the hyponatremia than normonatremia group (P < 0.01).ConclusionsAge of more than 55 years was an independent predictive factor for DPH even after adjusting for potential confounders. Older age was negatively correlated with the serum sodium level on postoperative day 2. Preventing early decreases in the sodium level could reduce the risk of DPH.Trial registration1707-027

BackgroundStereotactic 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.MethodsWe 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.ResultsA 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 11.0 mm vs. 7.1 mm (p < 0.001) for the amygdala and 12.4 mm vs. 8.5 mm (p < 0.001) for the hippocampal head, respectively. There were no hemorrhages or clinical complications in either group.ConclusionsBased 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.

Background and objectiveSurgical approaches to the petrous apex region are extremely challenging; while subtemporal approaches and variations represent the milestone of the surgical modules to reach such deep anatomical target, in a constant effort to develop minimally invasive neurosurgical routes, the endoscopic endonasal approach (EEA) has been tested to get a viable corridor to the petroclival junction. Lately, another ventral endoscopic minimally invasive route, i.e., the superior eyelid endoscopic transorbital approach, has been proposed to access the most lateral aspect of the skull base, including the petrous apex region. Our anatomic study aims to compare and combine such two endoscopic minimally invasive pathways to get full access to the petrous apex. Three-dimensional reconstructions and quantitative and morphometric data have been provided.Material and methodsFive human cadaveric heads (10 sides) were dissected. The lab rehearsals were run as follows: (i) preliminary pre-operative CT scans of each specimen, (ii) pre-dissection planning of the petrous apex removal and its quantification, (iii) petrous apex removal via endoscopic endonasal route, (iv) post-operative CT scans, (v) petrous apex removal via endoscopic transorbital route, and (v) final post-operative CT scan with quantitative analysis. Neuronavigation was used to guide all dissections.ResultsThe two endoscopic minimally invasive pathways allowed a different visualization and perspective of the petrous apex, and its surrounding neurovascular structures. After both corridors were completed, a communication between the surgical pathways was highlighted, in a so-called connection area, surrounded by the following important neurovascular structures: anteriorly, the internal carotid artery and the Gasserian ganglion; laterally, the internal acoustic canal; superiorly, the abducens nerve, the trigeminal root, and the tentorium cerebelli; inferomedially, the remaining clivus and the inferior petrosal sinus; and posteriorly, the exposed area of the brainstem. Used in a combined fashion, such multiportal approach provided a total of 97% of petrous apex removal. In particular, the transorbital route achieved a mean of 48.3% removal in the most superolateral portion of the petrous apex, whereas the endonasal approach provided a mean of 48.7% bone removal in the most inferomedial part. The difference between the two approaches was found to be not statistically significant (p = 0.67).ConclusionThe multiportal combined endoscopic endonasal and transorbital approach to the petrous apex provides an overall bone removal volume of 97% off the petrous apex. In this paper, we highlighted that it was possible to uncover a common path between these two surgical pathways (endonasal and transorbital) in a so-called connection area. Potential indications of this multiportal approach may be lesions placed in or invading the petrous apex and petroclival regions that can be inadequately reached via transcranial paths or via an endonasal endoscopic route alone.

Accurate reduction is the key to successful treatment of bone fractures. Complicated zygomaticomaxillary complex fracture, known as one of the most challenging facial bone fractures, is often hard to achieve an accurate reduction, thus leading to facial deformity. In this study, twenty patients with unilateral complicated zygomaticomaxillary complex fractures were included and randomly divided into experimental and control groups, which is with and without the aid of surgical navigation, respectively. The pre- and postoperative imaging data were collected and then analysed using Geomagic Studio 11 software and Brainlab iPlan CMF 3.0. A more precise reduction was showed in the experimental group according to the measurement results of both software programmes than in the control group. In conclusion, surgical navigation showed great value in performing accurate reductions of complicated zygomaticomaxillary complex fractures and restoring facial contour.

BackgroundStereotactic biopsy is consistently employed to characterize cerebral lesions in patients who are not suitable for microsurgical resection. In the past years, technical improvement and neuroimaging advancements contributed to increase the diagnostic yield, the safety, and the application of this procedure. Currently, in addition to histological diagnosis, the molecular analysis is considered essential in the diagnostic process to properly select therapeutic and prognostic algorithms in a personalized approach. The present study reports our experience with frameless stereotactic brain biopsy in this molecular era.MethodsOne hundred forty consecutive patients treated from January 2013 to September 2018 were analyzed. Biopsies were performed using the Brainlab Varioguide® frameless stereotactic system. Patients’ clinical and demographic data, the time of occupation of the operating room, the surgical time, the morbidity, and the diagnostic yield in providing a histological and molecular diagnosis were recorded and evaluated.ResultsThe overall diagnostic yield was 93.6% with nine procedures resulting non-diagnostic. Among 110 patients with glioma, the IDH-1 mutational status was characterized in 108 cases (98.2%), resulting wild-type in all subjects but 3; MGMT methylation was characterized in 96 cases (87.3%), resulting present in 60 patients, and 1p/19q codeletion was founded in 6 of the 20 cases of grade II–III gliomas analyzed. All the specimens were apt for molecular analysis when performed. Bleeding requiring surgical drainage occurred in 2.1% of the cases; 8 (5.7%) asymptomatic hemorrhages requiring no treatment were observed. No biopsy-related mortality was recorded. Median length of hospital stay was 5 days (IQR 4–8) with mean surgical time of 60.77 min (± 23.12) and 137.44 ± 24.1 min of total occupation time of the operative room.ConclusionsStereotactic frameless biopsy is a safe, feasible, and fast procedure to obtain a histological and molecular diagnosis.

Background For the navigation of transcranial magnetic stimulation (TMS), various techniques are available. Yet, there are two basic principles underlying them all: electric-field-navigated transcranial magnetic stimulation (En-TMS) and line-navigated transcranial magnetic stimulation (Ln-TMS). The current study was designed to compare both methods. Methods To explore whether there is a difference in clinical applicability, workflow, and mapping results of both techniques, we systematically compared motor mapping via En-TMS and Ln-TMS in 12 patients suffering from brain tumors. Results The number of motor-positive stimulation spots and the ratio of positive spots per overall stimulation numbers were significantly higher for En-TMS (motor-positive spots: En-TMS vs. Ln-TMS: 128.3 ± 35.0 vs. 41.3 ± 26.8, p < 0.0001; ratio of motor-positive spots per number of stimulations: En-TMS vs. Ln-TMS: 38.0 ± 9.2 % vs. 20.0 ± 14.4 %, p = 0.0031). Distances between the En-TMS and Ln-TMS motor hotspots were 8.3 ± 4.4 mm on the ipsilesional and 8.6 ± 4.5 mm on the contralesional hemisphere (p = 0.9124). Conclusions The present study compares En-TMS and Ln-TMS motor mapping in the neurosurgical context for the first time. Although both TMS systems tested in the present study are explicitly designed for application during motor mapping in patients with brain lesions, there are differences in applicability, workflow, and results between En-TMS and Ln-TMS, which should be distinctly considered during clinical use of the technique. However, to draw final conclusions about accuracy, confirmation of motor-positive Ln-TMS spots by intraoperative stimulation is crucial within the scope of upcoming investigations.

BackgroundHigh-field intraoperative MRI (IoMRI) is part of the neurosurgical armamentarium to improve the extent of glioma resection (EOR).ObjectiveTo report our oncological and functional outcomes using IoMRI for neuronavigated glioma surgery.MethodsIn this prospective monocentric study, we reported 100 consecutive adult patients operated on for glioma using IoMRI with neuronavigation, under general anesthesia without intraoperative stimulation, from July 2014 to April 2017. The volumetric evaluation was based on the FLAIR hypersignal for non-enhancing tumors after Gadolinium infusion and on the T1 hypersignal after Gadolinium infusion for enhancing tumors. We evaluated the surgical workflow, the EOR and the clinical outcomes (using Karnofsky performance score (KPS)).ResultsSixty-nine patients underwent one IoMRI, and 31 from two IoMRI controls. At first IoMRI, the median tumor residue was higher in the FLAIR group than in the T1G+ group whereas no more difference was reported after the second IoMRI between the 2 groups (p = 0.56). Additional resection was performed 6 times more frequently in the FLAIR group (OR = 5.7, CI (1.9–17)). The median EOR was 100% (IQR, 93.6–100) whatever the tumor type (first surgery or recurrence) and location. Higher residues were reported only in the insula area (p = 0.004). The median KPS was 90 (IQR, 80–100) at discharge, 3, 6 and 12 months after surgery, with no statistical difference between low- and high-grade gliomas (p = 0.34).ConclusionIoMRI neuronavigated surgery provided maximal EOR whatever the type of glioma and location. IoMRI was all the more useful for non- or minimally enhancing tumors. The step by step surgical resection, introducing the concept of “staged volume” surgery, ensured a high security for the surgeon and low permanent morbidity for the patients.

Summary Background. Frameless stereotaxy or neuronavigation has evolved into a feasible technology to acquire intracaranial biopsies with good accuracy and little mortality. However, few studies have evaluated the diagnostic yield, morbidity, and mortality of this technique as compared to the established standard of frame-based stereotactic brain biopsy. We report our experience of a large number of procedures performed with one or other technique. Patients and methods. We retrospectively assessed 465 consecutive biopsies done over a ten-year time span; Data from 391 biopsies (227 frame-based and 164 frameless) were available for analysis. Patient demographics, peri-operative characteristics, and histological diagnosis were reviewed and then information was analysed to identify factors associated with the biopsy not yielding a diagnosis and of it being followed by death. Results. On average, nine tissue samples were taken with either stereotaxy technique. Overall, the biopsy led to a diagnosis on 89.4% of occasions. No differences were found between the two biopsy procedures. In a multiple regression analysis, it was found that left-sided lesions were less likely to result in a non-diagnostic tissue sample ( p = 0.023), and cerebellar lesions showed a high risk of negative histology ( p = 0.006). Postoperative complications were seen after 12.1% of biopsies, including 15 symptomatic haemorrhages (3.8%). There was not a difference between the rates of complication after either a frame-based or a frameless biopsy. Overall, peri-operative complications ( p = 0.030) and deep-seated lesions ( p = 0.060) increased the risk of biopsy-related death. Symptomatic haemorrhages resulting in death (1.5% of all biopsies) were more frequently seen after biopsy of a fronto-temporally located lesion ( p = 0.007) and in patients with a histologically confirmed lymphoma ( p = 0.039). Conclusions. The diagnostic yield, complication rates, and biopsy-related mortality did not differ between a frameless biopsy technique and the established frame-based technique. The site of the lesion and the occurrence of a peri-operative complication were associated with the likelihood of failure to achieve a diagnosis and with death after biopsy. We believe that using intraoperative frozen section or cytologic smear histology is essential during a stereotactic biopsy in order to increase the diagnostic yield and to limit the number of biopsy specimens that need to be taken.