The use of noninvasive electromagnetic neuronavigation for slit ventricle syndrome and complex hydrocephalus in a pediatric population

Image Quality and Related Outcomes of the ShuntScope-Guided Catheter Implantation in Adult Hydrocephalus: Experience of 63 Procedures

BACKGROUND

 Ventricular catheter (VC) placement in the selected subset of adult hydrocephalus can be highly challenging due to abnormal anatomical configuration or the need for trans-aqueductal stent placement. Transluminal endoscopy with the ShuntScope has been invented to increase the success rate of catheter placement. This study evaluates the image qualities of ShuntScope and related surgical outcomes in adults.

METHODS

 A retrospective analysis of all adult patients undergoing VC placement using the ShuntScope from November 2011 to July 2022 in the authors' department was performed. Demographic, clinical, and radiologic data were evaluated. The visualization quality of the intraoperative endoscopy was stratified into excellent, medium, and poor, and compared to the postoperative catheter tip placement. Follow-up evaluation included the surgical revision rate due to proximal catheter misplacement.

RESULTS

 A total of 63 ShuntScope-assisted surgeries have been performed on 60 adults. The mean age of the patients was 48.43 years. The most common underlying pathology was a tumor- or cyst-related cerebrospinal fluid (CSF) impairment in 38.33%, followed by a pseudotumor cerebri in 21.66%. The achieved image quality was excellent in 39.68%, medium in 47.62%, and poor in 12.7%. Ideal catheter placement was achieved in 79.37%. There were no intraoperative complications associated with the use of the ShuntScope. The revision rate due to suboptimal proximal VC placement was 4.76% during a mean follow-up period of 27.75 months. A statistical correlation between the image quality and accuracy of the catheter position was observed (p < 0.001).

CONCLUSION

 The ShuntScope can be considered an important addition to standard surgical tools in treating a selected subset of adult hydrocephalus. Direct visualization might even help achieve correct placement of the catheter in the cases with blurred vision and limited visual overview.

Intraoperative ultrasound-guided ventricular cannulation in patients with normal-sized ventricles

INTRODUCTION

Many pathologies require normal-sized ventricle cannulation, which may be technically challenging even with neuronavigation guidance. This study presents a series of ventricular cannulation of normal-sized ventricles using intraoperative ultrasound (iUS) guidance and the outcomes of patients treated by this technique, for the first time.

METHODS

The study included patients who underwent ultrasound-guided ventricular cannulation of normal-sized ventricles (either ventriculoperitoneal (VP) shunting or Ommaya reservoir) between January 2020 and June 2022. All patients underwent iUS-guided ventricular cannulation from the right Kocher's point. The inclusion criteria for normal-sized ventricles were as follows: (1) Evans index <30%, and (2) widest third ventricle diameter <6mm. Medical records and pre-, intra- and post-operative imaging were retrospectively analyzed.

RESULTS

Nine of the 18 included patients underwent VP shunt placement; 6 had idiopathic intracranial hypertension (IIH), 2 had resistant cerebrospinal fluid fistula following posterior fossa surgery, and 1 had iatrogenic intracranial pressure elevation following foramen magnum decompression. Nine patients underwent Ommaya reservoir implantation, 6 of whom had breast carcinoma and leptomeningeal metastases and 3 hematologic disease and leptomeningeal infiltration. All catheter tip positions were achieved in a single attempt, and none were placed suboptimally. Mean follow-up was 10 months. One IIH patient (5.5%) had early shunt infection which necessitated shunt removal.

CONCLUSION

iUS is a simple and safe method for accurate cannulation of normal-sized ventricles. It provides an effective real-time guidance option for challenging punctures.

The accuracy and safety of intraoperative ultrasound-guided external ventricular drainage in intraventricular hemorrhage

Severe IVH often results in a poor outcome. Currently, EVD is a standard treatment for IVH, but there is little research to show whether using ultrasound to guide the catheter placement improves outcome. Patients with severe IVH who had iUS-guided EVD (the iUS-guided group) were enrolled retrospectively and compared with a group who had EVD performed without ultrasound guidance (the control group) from January 2016 to July 2022. Data were collected on accuracy of the catheter placement, complications and outcome at 3 months assessed by mRS. The accuracy of the EVD placement was classified as optimal placement, sub-optimal placement and misplacement according to the position of the catheter tip. The complications reported are catheter-related hemorrhage, intracranial infection and hydrocephalus. There were 105 cases enrolled, with 72 patients in the iUS-guided group having 131 catheters inserted and 33 patients in the group where ultrasound was not used with a total of 59 catheters. 116 (88.55%) were optimally placed, 12 (9.16%) sub-optimal and 3 (2.29%) misplaced in the iUS-guided group, while 25 (42.37%) were in optimally placed, 30 (50.85%) sub-optimal and 4(6.78%) misplaced in the control group. Accuracy of placement was highly significantly improved using ultrasound (P < 0.001). The operation time and the average catheterized time were longer in the iUS-guided group (P < 0.05), but the complication rates were no different between the groups. The mRS at three months was not significantly different between the two groups. Using iUS to place EVD catheters in patients with severe IVH is a safe technique delivering more accurate catheter placement without increasing the complication rate compared with freehand placement.

The effect of image-guided ventricular catheter placement on shunt failure: a systematic review and meta-analysis

INTRODUCTION

Cerebrospinal fluid (CSF) diversion for the treatment of hydrocephalus is one of the most common neurosurgical procedures. Over the years, the development of the neuronavigation system has allowed the surgeon to be guided in real time during the procedures. Nevertheless, to date, the revision rate remains as high as 30-40%. The aim of this study was to investigate the role of intraoperative image guidance in the prevention of shunt failure. We herein report the first literature meta-analysis of image guidance and shunt revision rate in the pediatric population.

METHODS

Principal online databases were searched for English-language articles published between January, 1980, and December, 2021. Analysis was limited to articles that included patients younger than 18 years of age at the time of primary V-P shunt. Articles reporting combined results of free-hand and image-guided placement of ventricular catheter (VC) were included. The main outcome measure of the study was the revision rate in relation to the intraoperative tools. Secondary variables collected were the age of the patient and ventricle size. Statistical analyses and meta-analysis plots were done via R and RStudio. Heterogeneity was formally assessed using Q, I², and τ² statistics. To examine publication bias was performed a funnel plot analysis.

RESULT

A total of 9 studies involving 2017 pediatric patients were included in the meta-analysis. 55.9% of procedures were carried out with the aid of intraoperative tools, while 44.1% procedures were conducted free hand. The intraoperative tools used were ultrasound (9.1%), electromagnetic neuronavigation (21.07%), endoscope (67.32%), and combined images (2.4%).The image-guided placement of VC was not statistically associated with a lower revision rate. The pooled OR was 0.97 [CI 95% 0.88-1.07] with an I² statistics of 34%, t² of 0.018 and a p-value of 0.15 at heterogeneity analysis.

CONCLUSION

Our analysis suggest images guidance during VC shunt placement does not statistically affect shunt survival. Nevertheless, intraoperative tools can support the surgeon especially in patients with difficult anatomy, slit ventricles or complex loculated hydrocephalus.

Intraoperative ultrasound-guided compared to stereotactic navigated ventriculoperitoneal shunt placement: study protocol for a randomised controlled study

BACKGROUND

Ventriculoperitoneal shunt (VPS) placement is one of the most frequent neurosurgical procedures and the operation is performed in a highly standardised manner under maintenance of highest infection precautions. Short operation times are important since longer duration of surgery can increase the risk for VPS complications, especially infections. The position of the proximal ventricular catheter influences shunt functioning and survival. With freehand placement, rates of malpositioned VPS are still high. Several navigation techniques for improvement of shunt placement have been developed. Studies comparing these techniques are sparse. The aim of this study is to prospectively compare ultrasound (US) guided to stereotactic navigated shunt placement using optical tracking with the focus on operation time and efficiency.

METHODS

In this prospective randomised, single-centre, partially-blinded study, we will include all patients undergoing VPS placement in our clinic. The patients will be randomised into two groups, one group undergoing US-guided (US-G) and the other group stereotactic navigated VPS placement using optical tracking. The primary outcome will be the surgical intervention time. This time span consists of the surgical preparation time together with the operation time and is given in minutes. Secondary outcomes will be accuracy of catheter positioning, VPS dysfunction and need for revision surgery, total operation and anaesthesia times, and amount of intraoperative ventricular puncture attempts as well as complications, any morbidity and mortality.

DISCUSSION

To date, there is no prospective data available comparing these two navigation techniques. A randomised controlled study is urgently needed in order to provide class I evidence for the best possible surgical technique of this frequent surgery.

TRIAL REGISTRATION

Business Administration System for Ethical Committees (BASEC) 2019-02157, registered on 21 November 2019, https://www.kofam.ch/de/studienportal/suche/88135/studie/49552 ; clinicalTrials.gov: NCT04450797 , registered on 30 June 2020.

How I do it: ultrasound-guided placement of ommaya reservoir in a patient with small ventricles and cavum septum pellucidum

BACKGROUND

Intraventricular chemotherapy via Ommaya reservoir is an important part of the treatment in patients with malignant central nervous system tumors. In these patients, catheter placement can be challenging due to the normal-sized ventricles.

METHOD

Intraoperative ultrasound guidance was used for Ommaya reservoir placement in a 56-year-old patient with multiple intracranial and leptomeningeal metastases who had cavum septum pellucidum et vergae malformation. The catheter was successfully placed into the frontal horn of the lateral ventricle outside the cavum.

CONCLUSION

Intraoperative ultrasound is a suitable image guidance system in patients with slit-like or normal-sized ventricles. It can also be used in patients with ventricular malformations.

Safety and accuracy of frameless electromagnetic-navigated (AXIEMTM)-guided brain lesion biopsies: a large single-unit study

BACKGROUND

Brain biopsies are required to establish a definitive histological diagnosis for brain lesions that have been identified on imaging in order to guide further treatment for patients.

OBJECTIVE

Various navigation systems are in use but little up to date evidence is available regarding the safety and accuracy of a frameless, electromagnetic technique to target brain lesions.

METHODS

Data was collected retrospectively on all patients that had brain biopsies at our institution from 01/01/2010 to 31/12/2017. Operation notes, neuropathology reports, and clinical notes on electronic patient record were used to determine whether biopsy of adequate identifiable abnormal tissue was achieved, whether a definitive diagnosis was established, any adverse events occurred, and if a repeat biopsy was carried out.

RESULTS

Three hundred seventy-one AxiEM (Medtronic, Minneapolis, USA)-guided brain tumor biopsies were performed in this 8-year period. Three hundred forty-nine (94.07%) procedures provided definitive tissue diagnosis, 22 (5.93%) were non diagnostic; in 6 cases (1.62%), repeat biopsy was performed and adverse events which caused clinical compromise were observed in 4 patients (1.08%).

CONCLUSIONS

The AxiEM is a fast, effective, and safe frameless and pinless neuronavigational system. It offers a high degree of accuracy required for the establishment of a definitive diagnosis, permitting optimal further treatment, and thus improving patient outcomes.

Image Guidance for Ventricular Shunt Surgery: An Analysis of Hospital Charges

BACKGROUND

Image guidance for shunt surgery results in more accurate proximal catheter placement. However, reduction in shunt failure remains unclear in the literature. There have been no prior studies evaluating the cost effectiveness of neuronavigation for shunt surgery.

OBJECTIVE

To perform a cost analysis using available hospital charges of hypothetical shunt surgery performed with/without electromagnetic neuronavigation (EMN).

METHODS

Hospital charges were collected for physician fees, radiology, operating room (OR) time and supplies, postanesthesia care unit, hospitalization days, laboratory, and medications. Index shunt surgery charges (de novo or revision) were totaled and the difference calculated. This difference was compared with hospital charges for shunt revision surgery performed under 2 clinical scenarios: (1) same hospital stay as the index surgery; and (2) readmission through the emergency department.

RESULTS

Costs for freehand de novo and revision shunt surgery were $23 946.22 and $23 359.22, respectively. For stealth-guided de novo and revision surgery, the costs were $33 646.94 and $33 059.94, a difference of $9700.72. The largest charge increase was due to additional OR time (34 min; $4794), followed by disposable EMN equipment ($2672). Total effective charges to revise the shunt for scenarios 1 and 2 were $34 622.94 and $35 934.94, respectively. The cost ratios between the total revision charges for both scenarios and the difference in freehand vs EMN-assisted shunt surgery ($9700.72) were 3.57 and 3.70, respectively.

CONCLUSION

From an economic standpoint and within the limitations of our models, the number needed to prevent must be 4 or less for the use of neuronavigation to be considered cost effective.

Placement of Ommaya Reservoirs Using Electromagnetic Neuronavigation and Neuroendoscopy: A Retrospective Study with Cost-Benefit Analysis

BACKGROUND

Placement of intraventricular catheters in oncology patients is associated with high complication rates. Placing Ommaya reservoirs with the zero-error precision protocol (ZEPP), a combination of neuronavigation (AxiEM stereotactic navigation) and direct verification of catheter tip placement with a flexible neuroendoscope, is associated with decreased complication rates as a result of increased catheter placement accuracy. However, the ZEPP costs more than traditional methods of catheter placement, and the question of whether this increased accuracy with the ZEPP is cost-effective is unknown.

METHODS

We performed a single-center retrospective chart review of 50 consecutive ommaya reservoir patient placements between 2010 and 2017. Twenty-five ventricular catheters were placed using the ZEPP protocol, and 25 ventricular catheters were placed using only AxiEM stealth navigation. Postoperative catheter accuracy and complication rates were assessed. A cost-benefit analysis was then conducted to determine if the overall cost for placing Ommaya reservoirs with the ZEPP was effective compared with the alternative method of using neuronavigation alone.

RESULTS

In the non-ZEPP cohort, 10 of 25 catheters were placed within the optimal location compared with 25 of 25 catheters placed in the ZEPP cohort. Three complications occurred in the non-ZEPP cohort: 2 malpositioned catheters required surgical revision and 1 catheter-related hemorrhage resulted in a prolonged stay in the intensive care unit. No complications occurred in the ZEPP cohort. A cost-benefit analysis showed $4784 savings per patient with ZEPP utilization because of the high complication-associated costs.

CONCLUSIONS

Implementation of the ZEPP for verifying ventricular catheter placement in Ommaya reservoirs improved catheter tip accuracy, resulted in lower complication rates, and was more cost-effective when compared with the non-ZEPP cohort, which used only neuronavigation. The ZEPP can be used for ventricular shunt catheter placement to decrease complications and verify catheter tip accuracy in Ommaya or standard ventriculoperitoneal shunts.

Adjustable Ghajar Guide Technique for Accurate Placement of Ventricular Catheters: A Pilot Study

Objective

An adjustable Ghajar guide is presented to improve the accuracy of the original Ghajar guide technique. The accuracy of the adjustable Ghajar guide technique is also investigated.

Methods

The coronal adjustment angle from the orthogonal catheter trajectory at Kocher’s point is determined based on coronal head images using an electronic picture archiving and communication system. For the adjustable Ghajar guide, a protractor is mounted on a C-shaped basal plate that is placed in contact with the margin of a burrhole, keeping the central 0° line of the protractor orthogonal to the calvarial surface. A catheter guide, which is moved along the protractor and fixed at the pre-determined adjustment angle, is then used to guide the ventricular catheter into the frontal horn adjacent to the foramen of Monro. The adjustable Ghajar guide technique was applied to 20 patients, while a freehand technique based on the surface anatomy of the head was applied to another 47 patients. The accuracy of the ventricular catheter placement was then evaluated using postoperative computed tomography scans.

Results

For the adjustable Ghajar guide technique (AGT) patients, the bicaudate index ranged from 0.23 to 0.33 (mean±standard deviation [SD]: 0.27±0.03) and the adjustment angle ranged from 0° to 10° (mean±SD: 5.2°±3.2°). All the AGT patients experienced successful cerebrospinal fluid diversion with only one pass of the catheter. Optimal placement of the ventricular catheter in the ipsilateral frontal horn approximating the foramen of Monro (grade 1) was achieved in 19 patients (95.0%), while a suboptimal trajectory into a lateral corner of the frontal horn passing along a lateral wall of the frontal horn (grade 3) occurred in 1 patient (5.0%). Thus, the AGT patients experienced a significantly higher incidence of optimal catheter placement than the freehand catheterized patients (95.0% vs. 68.3%, p=0.024). Moreover, none of the AGT patients experienced any tract hemorrhages along the catheter or procedure-related complications.

Conclusion

The proposed adjustable Ghajar guide technique, using angular adjustment in the coronal plane from the orthogonal trajectory at Kocher’s point, facilitates accurate freehand placement of a ventricular catheter for hydrocephalic patients.

Shunt Surgery in Idiopathic Intracranial Hypertension Aided by Electromagnetic Navigation

BACKGROUND

Idiopathic intracranial hypertension (IIH) is characterized by increased cerebrospinal fluid (CSF) pressure and normal or slit ventricles. Lumboperitoneal shunting had been favored by many investigators for CSF diversion in IIH for decades; however, it has been associated with various side effects. Because of the small ventricular size adequate positioning of a ventricular catheter is challenging.

OBJECTIVES

Here, we investigated the usefulness of electromagnetic (EM)-guided ventricular catheter placement for ventriculoperitoneal shunting in IIH.

METHODS

Eighteen patients with IIH were included in this study. The age of patients ranged from 5 to 58 years at the time of surgery (mean age: 31.8 years; median: 29 years). There were 2 children (5 and 11 years old) and 16 adults. Inclusion criteria for the study were an established clinical diagnosis of IIH, lack of improvement with medication, and the presence of small ventricles. In all patients EM-navigated placement of the ventricular catheter was performed using real-time tracking of the catheter tip for exact positioning close to the foramen of Monro. Postoperative CT scans were correlated with intraoperative screen shots to validate the position of the catheter.

RESULTS

In all patients EM-navigated ventricular catheter placement was achieved with a single pass. There were no intraoperative or postoperative complications. Postoperative imaging confirmed satisfactory positioning of the ventricular catheter. No proximal shunt failure was observed during the follow-up at a mean of 41.5 months (range: 7-90 months, median: 40.5 months).

CONCLUSIONS

EM-navigated ventricular catheter placement in shunting for IIH is a safe and straightforward technique. It obviates the need for sharp head fixation, the head of the patient can be moved during surgery, and it may reduce the revision rate during follow-up.

Endoscopic intracranial surgery enhanced by electromagnetic-guided neuronavigation in children

PURPOSE

Navigated intracranial endoscopy with conventional technique usually requires sharp head fixation. In children, especially in those younger than 1 year of age and in older children with thin skulls due to chronic hydrocephalus, sharp head fixation is not possible. Here, we studied the feasibility, safety, and accuracy of electromagnetic (EM)-navigated endoscopy in a series of children, obviating the need of sharp head fixation.

METHODS

Seventeen children (ten boys, seven girls) between 12 days and 16.8 years (mean age 4.3 years; median 14 months) underwent EM-navigated intracranial endoscopic surgery based on 3D MR imaging of the head. Inclusion criteria for the study were intraventricular cysts, arachnoid cysts, aqueduct stenosis for endoscopic third ventriculostomy (ETV) with distorted ventricular anatomy, the need of biopsy in intraventricular tumors, and multiloculated hydrocephalus. A total of 22 endoscopic procedures were performed. Patients were registered for navigation by surface rendering in the supine position. After confirming accuracy, they were repositioned for endoscopic surgery with the head fixed slightly on a horseshoe headholder. EM navigation was performed using a flexible stylet introduced into the working channel of a rigid endoscope. Neuronavigation accuracy was checked for deviations measured in millimeters on screenshots after the referencing procedure and during surgery in the coronal (z = vertical), axial (x = mediolateral), and sagittal (y = anteroposterior) planes.

RESULTS

EM-navigated endoscopy was feasible and safe. In all 17 patients, the aim of endoscopic surgery was achieved, except in one case in which a hemorrhage occurred, blurring visibility, and we proceeded with open surgery without complications for the patient. Navigation accuracy for extracranial markers such as the tragus, bregma, and nasion ranged between 1 and 2.5 mm. Accuracy for fixed anatomical structures like the optic nerve or the carotid artery varied between 2 and 4 mm, while there was a broader variance of accuracy at the target point of the cyst itself ranging between 2 and 9 mm.

CONCLUSIONS

EM-navigated endoscopy in children is a safe and useful technique enhancing endoscopic intracranial surgery and obviating the need of sharp head fixation. It is a good alternative to the common opto-electric navigation system in this age group.

Electromagnetic navigation-guided surgery in the semi-sitting position for posterior fossa tumours: a safety and feasibility study

BACKGROUND

Electromagnetic (EM)-guided neuronavigation is an innovative technique and a viable alternative to opto-electric navigation. We have performed a safety and feasibility study using EM-guided neuronavigation for posterior fossa surgery in the semi-sitting position in a selected subset of patients.

METHODS

Out of 284 patients with posterior fossa tumours operated upon over a period of 40 months, a subset of 15 patients was thought to possibly benefit from EM navigational guidance and was included in this study. There were six children and nine adults (aged between 8 and 84 years; mean age, 34.6 years) with different neoplasms in the brainstem or close to the midline. All patients had contrast-enhanced three-dimensional (3D) magnetic resonance imaging (MRI) of the head preoperatively. EM-guided navigation was used to identify and preserve the venous sinuses during craniotomy and to determine the trajectory to the lesion using various approaches. Neuronavigation accuracy was repeatedly checked for deviations measured in millimetres on screen shots during surgery before and after dural opening in the coronal (z = vertical), axial (x = mediolateral) and sagittal (y = anteroposterior) plane.

RESULTS

Referencing of the patient in the supine position was fast and easy. There was no loss of navigation accuracy after repositioning of the patient in the semi-sitting position (mean, 2.5 mm ± 0.92 mm). Identification of the pathological structure using EM navigation was achieved in all instances. Optimal angulation of the neck was selected individually to permit a comfortable position for the surgeon with full access to the lesion avoiding over-flexion. Deviation of accuracy at the surface of the target lesion ranged between 2.5 and 5.8 mm (mean, 3.9 mm ± 1.1 mm).

CONCLUSIONS

EM-guided neuronavigation in the semi-sitting position was safe and technically feasible. It enabled fast and accurate referencing without loss of navigation accuracy despite repositioning of the patient. In contrast to conventional opto-electric neuronavigation there were no line of sight problems.

Image Guidance in Ventricular Cerebrospinal Fluid Shunt Catheter Placement

BACKGROUND:

Ventricular shunt placement for treating hydrocephalus is one of the most common neurosurgical procedures. The rate of shunt failure, however, has not appreciably changed with time.

OBJECTIVE:

To investigate whether intraoperative image guidance using ultrasound or stereotaxy contributes to accurate shunt catheter placement and survival.

METHODS:

We performed a systematic literature review using PubMed and MEDLINE databases for studies that use ultrasound and frameless stereotaxy for ventricular catheter placement for hydrocephalus. All articles assessed the accuracy of catheter tip placement and/or overall shunt survival, and the rate of accurate shunt catheter placement, the overall failure rate, and the average time to shunt failure were extracted for analysis.

RESULTS:

Although each modality (ultrasound/stereotaxy) did not increase catheter placement accuracy, a combined random-effects meta-analysis of 738 catheters (136 guided by ultrasound, 168 guided by frameless stereotaxy, and 434 freehand) demonstrated a weak benefit of image guidance (risk ratio: 1.19, 95% confidence interval: 1.02-1.39, P = .02), but this result was limited by considerable heterogeneity among studies (I2 = 86%, P &lt; .001 by Cochrane's Q test). A meta-analysis could not be performed for shunt survival due to heterogeneity in data reporting.

CONCLUSION:

Although image guidance offers a promising solution to lower the risk of inaccurate catheter placement, which could lead to lower premature failure of ventricular shunts, our review demonstrated that there is not yet a clear benefit of these technologies. Current literature is limited to case series and cohort studies, and significant between-study heterogeneity in methodology and reporting currently limits a higher order analysis.

Real-time ultrasound guidance for ventricular catheter placement in pediatric cerebrospinal fluid shunts

PURPOSE

Cerebrospinal fluid shunt failure is related to additional morbidity. Misplacement of ventricular catheters occurs in 40 % with freehand technique and is a risk factor for shunt failure. The goal of this study was to analyze the impact of intraoperative real-time ultrasound on catheter positioning and outcome in children.

METHODS

We compared children receiving ultrasound-guided procedures to matched historical freehand controls. Burr hole and convex probes were used (ProSound Alpha 6, Hitachi Aloka Medical Ltd., Tokyo, Japan). Catheter position was graded as grade I (optimal), II (contralateral ventricle or contact with ventricular structures), or III (misplacement). Correlation analysis was performed to identify determinants of outcome.

RESULTS

The study group (n = 17) was balanced with the control group (n = 14) for variables such as mean age (4.7 vs 4.3 years) and preoperative frontal occipital horn ratio (FOHR; 0.45 vs 0.43). In the study group, grade I catheter position was achieved in 6 (35%) and grade II in 11 patients (65%), compared to 2 (18%) and 3 patients (27%) in the control group. While no grade III position occurred in the study group, it was found in nine control patients (43%) (P = 0.0029). Failure rate was highest in grade III (83%) compared to grade I catheters (50%).

CONCLUSIONS

This analysis demonstrated an improvement of catheter positioning with ultrasound guidance. In the absence of additional burden or risks, this method should be favored over freehand technique. It remains to be demonstrated in a randomized controlled fashion to what extent improved catheter position translates into improved outcome.

Pediatric hydrocephalus: systematic literature review and evidence-based guidelines. Part 3: Endoscopic computer-assisted electromagnetic navigation and ultrasonography as technical adjuvants for shunt placement

OBJECT

This systematic review was undertaken to answer the following question: Do technical adjuvants such as ventricular endoscopic placement, computer-assisted electromagnetic guidance, or ultrasound guidance improve ventricular shunt function and survival?

METHODS

The US National Library of Medicine PubMed/MEDLINE database and the Cochrane Database of Systematic Reviews were queried using MeSH headings and key words specifically chosen to identify published articles detailing the use of cerebrospinal fluid shunts for the treatment of pediatric hydrocephalus. Articles meeting specific criteria that had been delineated a priori were then examined, and data were abstracted and compiled in evidentiary tables. These data were then analyzed by the Pediatric Hydrocephalus Systematic Review and Evidence-Based Guidelines Task Force to consider evidence-based treatment recommendations.

RESULTS

The search yielded 163 abstracts, which were screened for potential relevance to the application of technical adjuvants in shunt placement. Fourteen articles were selected for full-text review. One additional article was selected during a review of literature citations. Eight of these articles were included in the final recommendations concerning the use of endoscopy, ultrasonography, and electromagnetic image guidance during shunt placement, whereas the remaining articles were excluded due to poor evidence or lack of relevance. The evidence included 1 Class I, 1 Class II, and 6 Class III papers. An evidentiary table of relevant articles was created. CONCLUSIONS/RECOMMENDATION: There is insufficient evidence to recommend the use of endoscopic guidance for routine ventricular catheter placement.

STRENGTH OF RECOMMENDATION

Level I, high degree of clinical certainty.

RECOMMENDATION

The routine use of ultrasound-assisted catheter placement is an option.

STRENGTH OF RECOMMENDATION

Level III, unclear clinical certainty.

RECOMMENDATION

The routine use of computer-assisted electromagnetic (EM) navigation is an option.

STRENGTH OF RECOMMENDATION

Level III, unclear clinical certainty.

Non-assisted versus neuro-navigated and XperCT-guided external ventricular catheter placement: a comparative cadaver study

BACKGROUND AND PURPOSE

Accurate placement of an external ventricular drain (EVD) for the treatment of hydrocephalus is of paramount importance for its functionality and in order to minimize morbidity and complications. The aim of this study was to compare two different drain insertion assistance tools with the traditional free-hand anatomical landmark method, and to measure efficacy, safety and precision.

METHODS

Ten cadaver heads were prepared by opening large bone windows centered on Kocher's points on both sides. Nineteen physicians, divided in two groups (trainees and board certified neurosurgeons) performed EVD insertions. The target for the ventricular drain tip was the ipsilateral foramen of Monro. Each participant inserted the external ventricular catheter in three different ways: 1) free-hand by anatomical landmarks, 2) neuronavigation-assisted (NN), and 3) XperCT-guided (XCT). The number of ventricular hits and dangerous trajectories; time to proceed; radiation exposure of patients and physicians; distance of the catheter tip to target and size of deviations projected in the orthogonal plans were measured and compared.

RESULTS

Insertion using XCT increased the probability of ventricular puncture from 69.2 to 90.2 % (p = 0.02). Non-assisted placements were significantly less precise (catheter tip to target distance 14.3 ± 7.4 mm versus 9.6 ± 7.2 mm, p = 0.0003). The insertion time to proceed increased from 3.04 ± 2.06 min. to 7.3 ± 3.6 min. (p < 0.001). The X-ray exposure for XCT was 32.23 mSv, but could be reduced to 13.9 mSv if patients were initially imaged in the hybrid-operating suite. No supplementary radiation exposure is needed for NN if patients are imaged according to a navigation protocol initially.

CONCLUSION

This ex vivo study demonstrates a significantly improved accuracy and safety using either NN or XCT-assisted methods. Therefore, efforts should be undertaken to implement these new technologies into daily clinical practice. However, the accuracy versus urgency of an EVD placement has to be balanced, as the image-guided insertion technique will implicate a longer preparation time due to a specific image acquisition and trajectory planning.

Newly developed electromagnetic tracked flexible neuroendoscope

Flexible endoscopes can be used in areas that are difficult to approach using rigid endoscopes. No current real-time navigation systems identify the tip of the flexible neuroendoscope. We have developed a flexible neuroendoscope mounted with a magnetic field sensor tip position-tracking system and evaluated the accuracy of this magnetic field neuronavigation system. Based on an existing flexible neuroendoscope, we created a prototype with a built-in magnetic field sensor in the tip. A magnetic field measurement device provides a magnetic field with a working volume of 500 × 500 × 500 mm in front of the device. The device consists of a flat field generator that creates a pulsed magnetic field, connected to a system control unit that interfaces with a computer. The magnetic field sensor (1.8 × 9 mm) was sealed in a site 0.9 mm from the endoscope tip. Accuracy of neuroendoscope tracking was measured using a three-dimensional coordinate-measuring machine that measures the position of objects along 3 axes, with an error of about 3 µm. The accuracy for this neuroendoscope with built-in magnetic field sensor was root mean square error of 1.2 mm and standard deviation of 0.5 mm. This magnetic field neuronavigation system enables real-time tracking of the tip of the flexible neuroendoscope. Application of this flexible neuroendoscope to intraoperative navigation appears promising, and may provide new advantages for minimally invasive endoscopic surgery.

The usefulness of electromagnetic neuronavigation in the pediatric neuroendoscopic surgery

OBJECTIVE

Neuroendoscopy is applied to various intracranial pathologic conditions. But this technique needs informations for the anatomy, critically. Neuronavigation makes the operation more safe, exact and lesser invasive procedures. But classical neuronavigation systems with rigid pinning fixations were difficult to apply to pediatric populations because of their thin and immature skull. Electromagnetic neuronavigation has used in the very young patients because it does not need rigid pinning fixations. The usefulness of electromagnetic neuronavigation is described through our experiences of neuroendoscopy for pediatric groups and reviews for several literatures.

METHODS

Between January 2007 and July 2011, nine pediatric patients were managed with endoscopic surgery using electromagnetic neuronavigation (AxiEM, Medtronics, USA). The patients were 4.0 years of mean age (4 months-12 years) and consisted of 8 boys and 1 girl. Totally, 11 endoscopic procedures were performed. The cases involving surgical outcomes were reviewed.

RESULTS

The goal of surgery was achieved successfully at the time of surgery, as confirmed by postoperative imaging. In 2 patients, each patient underwent re-operations due to the aggravation of the previous lesion. And one had transient mild third nerve palsy due to intraoperative manipulation and the others had no surgery related complication.

CONCLUSION

By using electromagnetic neuronavigation, neuroendoscopy was found to be a safe and effective technique. In conclusion, electromagnetic neuronavigation is a useful adjunct to neuroendoscopy in very young pediatric patients and an alternative to classical optical neuronavigation.

Surgical pathway and management of pineal region tumours in children

BACKGROUND

Pineal region tumours are rare. Surgery is associated with high morbidity, and consensus on ideal management pathways remains variable.

METHOD

Patients with pineal region tumours were identified from the neuro-oncology database, and their data were retrospectively reviewed. Data collection included presentation, germ cell markers, tumour size and location, imaging, histology, treatment and control/relapse rates.

RESULTS

Twenty-four patients were treated at Alder Hey Children's Hospital between 1998 and 2010. Median age at diagnosis was 12.7 years. Sixteen patients presented with hydrocephalus. Twelve were successfully treated with endoscopic third ventriculostomy (EVT), and four required shunt insertion during follow-up. Fifteen patients had endoscopic biopsies. Eleven biopsies were performed at the same time as third ventriculostomy, and four patients without significant hydrocephalus had endoscopic image-guided biopsies. Eight patients had stereotactic biopsies (either because of slit ventricles at diagnosis or because of a ventriculoperitoneal shunt already in place), and only one patient had an open biopsy. No morbidity or mortality was associated with the biopsies. Histology showed four pineal parenchymal tumours, nine gliomas and eleven germ cell tumours. Thirteen patients underwent surgical resection. Significant tumour debulking was achieved in all of these patients, with gross total resection in 70 % of cases. There was one intraventricular haemorrhage (full recovery) and one mild hemiparesis. There was no surgical mortality.

CONCLUSION

The mainstay of hydrocephalus management is EVT which provides a safe and reliable route for biopsy. In our experience, craniotomy and tumour resection are effective and safe.

A prospective study of the safety and efficacy of frameless, pinless electromagnetic image-guided biopsy of cerebral lesions

BACKGROUND

In recent years, frameless navigation techniques have been reported to be safe and effective for biopsy of cerebral lesions.

OBJECTIVE

To evaluate the safety and efficacy of a technique of frameless, pinless electromagnetic-guided biopsy for brain lesions with the Medtronic Stealth AxiEM.

METHODS

Prospective data were collected on consecutive brain biopsies performed by a single surgeon (P.L.G.) with this technology between October 2007 and May 2010. One trajectory was made per lesion with multiple specimens taken for analysis. Outcome measures included measures of accuracy, histological yield, and complication rate.

RESULTS

A total of 150 biopsies were performed in 149 patients (84 male and 65 female patients; age range, 19.8-83.8 years). The consultant performed 49 procedures, supervising a trainee in the others. In only 1 case (0.7%) was there nondiagnosis consequent of a registration error and inaccurate trajectory. In 4 other cases (2.7%), no specific diagnosis was established, but abnormal tissue was identified histologically, and postoperative imaging confirmed accurate targeting of these lesions. There were no instances of intracranial hemorrhage or significant morbidity and no deaths directly attributable to the procedure. Four patients (2.7%) died within 30 days of the procedure but not of complications of surgery. One patient suffered a transitory neurological deficit.

CONCLUSION

Electromagnetic navigation is proven to be a simple, safe, and effective innovation for frameless and pinless biopsy of cerebral lesions. This technique is time efficient, and elimination of frame placement enhances patient comfort and facilitates the use of local anesthetic technique.

Use of magnetic resonance imaging to identify the edge of a dural tear in an infant with growing skull fracture: a case study

PURPOSE

Growing skull fractures can be a challenging surgical problem facing pediatric neurosurgeons. The goal of this manuscript was to describe an effective surgical method used to treat a growing skull fracture.

METHODS

We present a case study of a 2-month-old boy who fell from his mother's arms and hit his head on the floor; he underwent X-ray, magnetic resonance (MR), and computed tomography (CT) imaging before cranioplasty with dural plasty.

RESULTS

X-ray performed on admission revealed a diastatic fracture with a gap of 8 mm in the right frontal bone and a linear fracture in the right occipital bone. X-ray performed 37 days after injury demonstrated that the gap had increased to 25 mm, and the patient was diagnosed with a growing skull fracture of the right parietal bone. Cranioplasty with dural plasty was performed on day 39. A combination of MR and CT images enabled the edge of the dural tear to be plotted on a three-dimensional image of the skull, and this was used to estimate the location of the edge of the dural tear on the scalp.

CONCLUSIONS

We achieved excellent outcomes in terms of bony coverage and dural plasty. The combination of MR and CT images may be recommended for surgical repair of growing skull fracture in children.

Electromagnetic-guided neuronavigation for safe placement of intraventricular catheters in pediatric neurosurgery

OBJECT

Ventricular catheter shunt malfunction is the most common reason for shunt revision. Optimal ventricular catheter placement can be exceedingly difficult in patients with small ventricles or abnormal ventricular anatomy. Particularly in children and in premature infants with small head size, satisfactory positioning of the ventricular catheter can be a challenge. Navigation with electromagnetic tracking technology is an attractive and innovative therapeutic option. In this study, the authors demonstrate the advantages of using this technology for shunt placement in children.

METHODS

Twenty-six children ranging in age from 4 days to 14 years (mean 3.8 years) with hydrocephalus and difficult ventricular anatomy or slit ventricles underwent electromagnetic-guided neuronavigated intraventricular catheter placement in a total of 29 procedures.

RESULTS

The single-coil technology allows one to use flexible instruments, in this case the ventricular catheter stylet, to be tracked at the tip. Head movement during the operative procedure is possible without loss of navigation precision. The intraoperative catheter placement documented by screenshots correlated exactly with the position on the postoperative CT scan. There was no need for repeated ventricular punctures. There were no operative complications. Postoperatively, all children had accurate shunt placement. The overall shunt failure rate in our group was 15%, including 3 shunt infections (after 1 month, 5 months, and 10 months) requiring operative revision and 1 distal shunt failure. There were no proximal shunt malfunctions during follow-up (mean 23.5 months).

CONCLUSIONS

The electromagnetic-guided neuronavigation system enables safe and optimal catheter placement, especially in children and premature infants, alleviating the need for repeated cannulation attempts for ventricular puncture. In contrast to stereotactic techniques and conventional neuronavigation, there is no need for sharp head fixation using a Mayfield clamp. This technique may present the possibility of reducing proximal shunt failure rates and costs for hydrocephalus treatment in this age cohort.

Image-guided cerebrospinal fluid shunting in children: catheter accuracy and shunt survival

OBJECT

Cerebrospinal fluid shunt placement has a high failure rate, especially in patients with small ventricles. Frameless stereotactic electromagnetic image guidance can assist ventricular catheter placement. The authors studied the effects of image guidance on catheter accuracy and shunt survival in children.

METHODS

Pediatric patients who underwent placement or revision of a frontal ventricular CSF shunt were retrospectively evaluated. Catheters were placed using either anatomical landmarks or image guidance. Preoperative ventricular size and postoperative catheter accuracy were quantified. Outcomes of standard and image-guided groups were compared.

RESULTS

Eighty-nine patients underwent 102 shunt surgeries (58 initial, 44 revision). Image guidance was used in the placement of 56 shunts and the standard technique in 46. Shunt failure rates were not significantly different between the standard (22%) and image-guided (25%) techniques (p = 0.21, log-rank test). Ventricular size was significantly smaller in patients in the image-guided group (p < 0.02, Student t-test) and in the surgery revision group (p < 0.01). Small ventricular size did not affect shunt failure rate, even when controlling for shunt insertion technique. Despite smaller average ventricular size, the accuracy of catheter placement was significantly improved with image guidance (p < 0.01). Shunt accuracy did not affect shunt survival.

CONCLUSIONS

The use of image guidance improved catheter tip accuracy compared with a standard technique, despite smaller ventricular size. Failure rates were not dependent on shunt insertion technique, but an observed selection bias toward using image guidance for more at-risk catheter placements showed failure rates similar to initial surgeries.

Rhombencephalosynapsis - isolated anomaly or complex malformation?

BACKGROUND

Rhombencephalosynapsis (RES) is a rare malformation of the posterior cranial fossa, characterized by fusion of the cerebellar hemispheres, medial cerebellar peduncles and dentate nuclei. Over the period of 7 years 8 cases of this anomaly have been diagnosed in two pediatric centers in Warsaw including one on the prenatal magnetic resonance imaging (MRI).

MATERIAL/METHODS

Material consists of involves one fetus examined at the gestational age of 27 and 33 weeks and 7 children (5 girls and 2 boys) aged 8 months - 16 years. All of them underwent brain MRI with the use of 1.5T scanners.

RESULTS

In 1 case RES was an isolated anomaly, in 1 case it was accompanied by hydrocephalus only, in the remaining 6 cases RES was an element of a complex malformation. The additional anomalies were as follows: callosal hypoplasia in 3 children, abnormalities of gyration in 2, brainstem hypoplasia in 2, isolated fourth ventricle in 1, abnormal white matter signal intensity in 4 (in 2 cases in supratentorial compartment, in 1 in the cerebellum and in 1 in the pons), abnormally dilated extraaxial fluid collections in 2, syringohydromyelia in 2. In 5 cases RES was total, in 3 - partial.

CONCLUSIONS

Rhombencephalosynapsis has a very characteristic appearance on magnetic resonance imaging which allows diagnosis of this malformation at any age, including prenatal period.

Neuronavigation-assisted single transseptal catheter implantation and shunt in patients with posthemorrhagic hydrocephalus and accentuated lateral ventricles dilatation

Background:

To assess the treatment of posthemorrhagic hydrocephalus with accentuated lateral ventricles dilatation by employing a single biventricular neuronavigation-assisted transseptal-implanted catheter with programmable valve and distal peritoneal derivation.

Methods:

A neuronavigation-assisted single transseptal biventricular catheter implantation with distal peritoneal shunt system was performed in 11 patients with posthemorrhagic hydrocephalus and accentuated lateral ventricles dilatations between 2001 and 2010. Patients with concomitant third ventricle dilatation were excluded. Several sequential frustrated attempts of temporary drainage occlusion on both sides confirmed the isolation of the lateral ventricles. Neuronavigation was employed to accurately establish the catheter surgical corridor (trajectory) across the lateral ventricles and throughout the septum pellucidum. The neurological and radiological outcomes were assessed at least 6 months after the procedure.

Results:

Catheter implantation was successfully performed in all patients. Only one catheter was found to be monoventricular on delayed computer tomography controls. Procedure-related complications (bleeding of infections) were not observed. No additional neurological deficits were found after shunt surgery. Six months after procedure, none required additional ventricular catheter implantations or shunt revisions. Radiological and clinical controls confirmed the shunt function and the improved neurological status of all patients.

Conclusion:

Single neuronavigation-assisted transseptal-implanted biventricular catheter is a valid option for the treatment of posthemorrhagic hydrocephalus with accentuated lateral ventricles dilatation. This technique reduces the number of catheters and minimizes the complexity and timing of the surgical procedure as well as potential infection's risks associated with the use of multiple shunting systems.

A computed tomography-based localizer to determine the entry site of the ventricular end of a parietal ventriculoperitoneal shunt

BACKGROUND

One of the major principles of shunt insertion into the brain involves choosing an entry site that avoids eloquent cortex.

OBJECTIVE

We describe a novel tool to accurately locate the burr hole for insertion of the ventricular end of a catheter during parietal ventriculoperitoneal shunt surgery.

METHODS

Computed tomography (CT)-based measurements in 2 dimensions were used to mark the entry point with the help of an indigenously designed Vellore burr hole localizer (VL). Patients underwent surgery with either the conventional method to localize the burr hole (Keen point; group A; n = 28) or the VL (group B; n = 28). An independent observer determined the accuracy of shunt placement on postoperative CT scans. The VL is designed with a fixed horizontal arm that can be aligned with the CT or magnetic resonance reference plane and a vertical arm with a flexible sliding horizontal arm that is attached to it with an adjustable screw. By manipulating the flexible arm along the contour of the skull and using the scale provided on both the vertical and horizontal arms, we can mark the burr hole site for placement of a parietal ventriculoperitoneal shunt.

RESULTS

Overall accuracy in group A was 32.1%, whereas in group B, an accuracy of 82.1% could be achieved (P < .01).

CONCLUSION

Placement of a burr hole guided by the VL increases the accuracy of the desired entry point of the ventricular catheter.

Individualized ventricular access using multi-plane brain images

PURPOSE

Recently, many surgical techniques are applied to accurate ventricular catheterization. However, there are still some limitations in utilizing those methods. We introduce a simple method for the ventricular access and report two illustrative cases using our method.

METHODS

We marked the trajectory using the preoperative multi-planar brain images and verifying it with surface markers.

RESULTS

Two illustrative cases are shown, in which the surgeries were performed without difficulty and the outcomes were satisfactory.

CONCLUSION

Utilizing multi-planar brain images in ventricular access is cost-effective and competent method.

Modified bilateral subtemporal decompression for resistant slit ventricle syndrome

PURPOSE

Slit ventricle syndrome (SVS) remains a major problem for early shunted children. Several conservative and surgical treatment paradigms have been suggested; however, there is no consensus on the optimal surgical treatment. We present our experience using bilateral subtemporal decompressions with dura and arachnoid opening for the treatment of a subgroup of children with severe and resistant SVS.

METHODS

Fifteen children with severe and resistant SVS underwent a modified bilateral subtemporal craniectomy, with dura and arachnoid opening. Their clinical and radiological data were retrospectively reviewed.

RESULTS

Seven (46.6%) patients had a complete recovery from their symptoms with a follow-up of 5.9 ± 2.6 years.The remaining eight (53.3%), underwent additional surgeries. Four (26.6%), had a single proximal shunt revision after dilatation of their ventricles. Following these procedures these four children are well and stable with a follow-up of 1.8 ± 2 years. The other four had further cranial vault expansion, one of which was followed by a proximal shunt revision. Thus, 11 of these 15 patients (73.4%) had a very good outcome, attributable to this technique, with a mean follow-up of 4.5 ± 3 years.

CONCLUSIONS

Modified bilateral subtemporal decompression with dura and arachnoid opening yields a high cure rate for severe and resistant slit ventricle syndrome. Proximal shunt revision may be safely performed in a subset of patients that dilate their ventricles following the procedure. Further cranial expansion may be reserved for children with recurrent SVS symptoms who do not respond to STD and remain with very small ventricles.

Effect of electromagnetic-navigated shunt placement on failure rates: a prospective multicenter study

Object

As many as 40% of shunts fail in the first year, mainly due to proximal obstruction. The role of catheter position on failure rates has not been clearly demonstrated. The authors conducted a prospective cohort study of navigated shunt placement compared with standard blind shunt placement at 3 European centers to assess the effect on shunt failure rates.

Methods

All adult and pediatric patients undergoing de novo ventriculoperitoneal shunt placement were included (patients with slit ventricles were excluded). The first cohort underwent standard shunt placement using anatomical landmarks. All centers subsequently adopted electromagnetic (EM) navigation for routine shunt placements, forming the second cohort. Catheter position was graded on postoperative CT in both groups using a 3-point scale developed for this study: (1) optimal position free-floating in CSF; (2) touching choroid or ventricular wall; or (3) intraparenchymal. Episodes and type of shunt revision were recorded. Early shunt failure was defined as that occurring within 30 days of surgery. Patients with shunts were followed-up for 12 months in the standard group, for a median of 6 months in the EM-navigated group, or until shunt failure.

Results

A total of 75 patients were included in the study, 41 with standard shunts and 34 with EM-navigated shunts. Seventy-four percent of navigated shunts were Grade 1 compared with 37% of the standard shunts (p = 0.001, chi-square test). There were no Grade 3 placements in the navigated group, but 8 in the standard group, and 75% of these failed. Early shunt failure occurred in 9 patients in the standard group and in 2 in the navigated group, reducing the early revision rate from 22 to 5.9% (p = 0.048, Fisher exact test). Early shunt failures were due to proximal obstruction in 78% of standard shunts (7 of 9) and in 50% of EM-navigated shunts (1 of 2).

Conclusions

Noninvasive EM image guidance in shunt surgery reduces poor shunt placement, resulting in a significant decrease in the early shunt revision rate.

Perforation holes in ventricular catheters--is less more?

OBJECTIVE

Obstruction is a common cause of cerebrospinal fluid (CSF) shunt failure. Risk factors for proximal obstructive malfunction are suboptimal ventricular catheter positioning and slit-like ventricles. A new ventricular catheter design to decrease risk of obstruction was evaluated.

METHODS

A review of histopathological tissue investigation from occluded ventricular catheters (n = 70) was performed. A new ventricular catheter design was realized with six perforation holes. These catheters were compared to regular catheters (16 holes, Miethke, Aesculap) for flow characteristics using ink studies and flow velocity at hydrostatic pressure levels from 14 to 2 cmH(2)O in an experimental setup. The six-hole catheters were implanted in hydrocephalic patients with slit-like ventricles (n = 55). A follow-up was performed to evaluate the need of catheter revisions.

RESULTS

Histological evaluation showed that obstructive tissue involved 43-60% extraventricular tissue, including gliosis, connective and inflammatory cells. In flow characteristic studies, the 16-hole catheters showed that only proximal perforations are of functional relevance. For six-hole catheters, all perforations were shown to be relevant with remaining reserve capacity. Flow velocity however showed no significant differences between six and 16 perforations. The six-hole catheter was implanted in 55 patients with a mean follow-up period of 15 +/- 9 months. A total of 12 catheters were explanted, revealing an overall survival proportion of 77.4%.

CONCLUSION

In narrow ventricles, we assume that catheter perforations that are located also in the tissue might be a risk for CSF shunt obstruction. Fewer amounts of perforations in the catheters with equal flow features might decrease this risk when catheters can be implanted with adequate precision.