Frame-based stereotactic neurosurgery in children under the age of seven: Freiburg University's experience from 99 consecutive cases

Safe First-Time use of Stereotactic Headband Fixation in a 5-Month-Old Child: An Economical and Easily Accessible Method

OBJECTIVE

We present a low-cost and easily accessible adaptation system to perform stereotactic procedures in infants.

METHODS

We used an adaptive device consisting of a headband with a plaster bandage, cotton bandage roll, and gauze bandages. Prior to its clinical application, the device was tested in our neuroscience laboratory using a simulation model of a size similar to that of a 5-month-old infant, during which no complications arose. The headband cast technique was subsequently reproduced in a 5-month-old patient, serving as a fixation point for the placement of a Micromar frame for biopsy of a thalamic lesion.

RESULTS

A stereotactic biopsy was successfully performed in a 5-month-old patient using a headband cast to secure the stereotactic frame. This method enabled precise targeting of the selected site, resulting in a histopathological diagnosis without any associated complications.

CONCLUSIONS

The adaptive device is safe, easily accessible, and reproducible, facilitating the performance of stereotactic diagnostic procedures in infants, accurately reaching the planned objective without causing injuries or additional complications.

Robot-assisted stereoelectroencephalography in young children: technical challenges and considerations

Robot-assisted stereoelectroencephalography (sEEG) is frequently employed to localize epileptogenic zones in patients with medically refractory epilepsy (MRE). Its methodology is well described in adults, but less so in children. Given the limited information available on pediatric applications, the objective is to describe the unique technical challenges and considerations of sEEG in the pediatric population. In this report, we describe our institutional experience with the technical aspects of robot-assisted sEEG in an exclusively pediatric epilepsy surgery unit, focusing on pre-, intra-, and post-operative nuances that are particular to the pediatric population. The pediatric population presents several unique challenges in sEEG, including reduced skull thickness relative to adults, incomplete neurologic development, and often special behavioral considerations. Pre-operative selection of putative epileptogenic zones requires careful multidisciplinary decision-making. Intraoperative attention to nuances in positioning, clamp selection, registration, and electrode placement are necessary. Activity considerations and electrode migration and removal are key post-operative considerations. Robot-assisted sEEG is a valuable tool in the armamentarium of techniques to characterize MRE. However, special considerations must be given to the pediatric population to optimize safety and efficacy.

Pediatric Anesthesia Outside the Operating Room: Case Management

Anesthesiology teams care for children in diverse locations, including diagnostic and interventional radiology, gastroenterology and pulmonary endoscopy suites, radiation oncology units, and cardiac catheterization laboratories. To provide safe, high-quality care, anesthesiologists working in these environments must understand the unique environmental and perioperative considerations and risks involved with each remote location and patient population. Once these variables are addressed, anesthesia and procedural teams can coordinate to ensure that patients and families receive the same high-quality care that they have come to expect in the operating room. This article also describes some of the considerations for anesthetic care in outfield locations.

Pediatric intrinsic brainstem lesions: clinical, imaging, histological characterization, and predictors of survival

PURPOSE

Brainstem lesions comprise 10-20% of all pediatric brain tumors. Over the past years, the benefits of stereotactic biopsy versus the use alone of MRI features to guide treatment have been controversial.

METHODS

Retrospective study with pediatric patients submitted to stereotactic brainstem biopsies between 2008 and 2018. Demographic, clinical, imaging, and surgical characteristics were recorded, as well as the histological diagnosis, complications, and survival. Predictors of survival were evaluated through Cox regression models after multivariate adjustment.

RESULTS

Twenty-six patients (mean age of 8.8 ± 4.3 years and 14 female). Diagnosis was reached on 84.6% (95% CI 65.1-95.6%) of the patients. Glioma was diagnosed on 20 cases (11 high-grade and 9 low-grade lesions). There was no association between age and gender and the dichotomized histological diagnosis. Contrast enhancement, diffuse distribution, invasion of adjacent structures, and remote injury were present on 62.5%, 75.0%, 62.5%, and 25.0% of the cases. Hydrocephalus at admission was present on almost half of the patients (46.2%). Only radiological invasion of adjacent structures had a possible association with high-grade lesions (p = 0.057). Surgical trajectory was trans-cerebellar in most of the cases (79.9%). There were no major complications and only two minor/transitory complications. Poorer survival was independently associated with high-grade lesions (HR 32.14, 95% CI 1.40-735.98, p = 0.030) and contrast enhancement at MRI (HR 36.54, 95% CI 1.40-952.26, p = 0.031).

CONCLUSIONS

Stereotactic biopsy was safe and allows successful tissue sampling for a definite diagnosis. Poorer survival was independently associated with high-grade and contrast-enhancing lesions.

Stereotactic Placement of Intratumoral Catheters for Continuous Infusion Delivery of Herpes Simplex Virus -1 G207 in Pediatric Malignant Supratentorial Brain Tumors

OBJECTIVE

The engineered herpes simplex virus-1 G207, is a promising therapeutic option for central nervous system tumors. The first-ever pediatric phase 1 trial of continuous-infusion delivery of G207 via intratumoral catheters for recurrent or progressive malignant brain tumors is ongoing. In this article, we describe surgical techniques for the accurate placement of catheters in multiple supratentorial locations and perioperative complications associated with such procedures.

METHODS

A prospective study of G207 in children with recurrent malignant supratentorial tumors is ongoing. Preoperative stereotactic protocol magnetic resonance imaging was performed, and catheter trajectories planned using StealthStation planning software. Children underwent placement of 3-4 silastic catheters using a small incision burr hole and the Vertek system. Patients had a preinfusion computed tomography scan to confirm correct placement of catheters.

RESULTS

Six children underwent implantation of 3-4 catheters. Locations of catheter placement included frontal, temporal, parietal, and occipital lobes, and the insula and thalamus. There were no clinically significant perioperative complications. Postoperative computed tomography scans coupled with preoperative MRI scans demonstrated accurate placement of 21 of 22 catheters, with 1 misplaced catheter pulled back to an optimal location at the bedside. One patient had hemorrhage along the catheter tract that was clinically asymptomatic. Another patient had cerebrospinal fluid leak from a biopsy incision 9 days after surgery that was oversewn without complication.

CONCLUSIONS

The placement of multiple intratumoral catheters in pediatric patients with supratentorial tumors via frameless stereotactic techniques is feasible and safe. Intratumoral catheters provide a potentially effective route for the delivery of G207 and may be employed in other trials utilizing oncolytic virotherapy for brain tumors.

Method to perform safety stereotactic procedures in children under 2 years of age

INTRODUCTION

Stereotactic procedures have been used in neurosurgery for many years. In children especially, care should be considered to avoid complication caused by fixation of the frame in a not fully developed skull bone. We present our method to adapt the frame in children under 2 years of age.

METHODS

Twelve procedures in patients under 24 months were performed between 2003 and 2015. Micromar frame was used. It was adapted with a small pillow made of gauss attached to the posterior part to hold the head, then four pins were fixed without adjustment. We analyze for each patient age, indication, histopathology, and complications.

RESULTS

Eleven patients with a mean age of 13.5 months (range 9 to 22 months) underwent 12 stereotactic procedures. In all cases, biopsy samples were obtained, histopathology was positive in 11/12 cases. No complications occurred.

CONCLUSION

Stereotactic frame procedures need special attention in small children where the skull bones are not fully developed. We present a simple method to perform this surgery in patients under 2 years of age.

Stereotactic biopsy of cerebellar lesions: straight versus oblique frame positioning

OBJECTIVE

Biospies of brain lesions with unknown entity are an everyday procedure among many neurosurgical departments. Biopsies can be performed frame-guided or frameless. However, cerebellar lesions are a special entity with a more complex approach. All biopsies in this study were performed stereotactically frame guided. Therefore, only biopsies of cerebellar lesions were included in this study. We compared whether the frame was attached straight versus oblique and we focused on diagnostic yield and complication rate.

METHODS

We evaluated 20 patients who underwent the procedure between 2009 and 2017. Median age was 56.5 years. 12 (60%) Patients showed a left sided lesion, 6 (30%) showed a lesion in the right cerebellum and 2 (10%) patients showed a midline lesion.

RESULTS

The stereotactic frame was mounted oblique in 12 (60%) patients and straight in 8 (40%) patients. Postoperative CT scan showed small, clinically silent blood collection in two (10%) of the patients, one (5%) patient showed haemorrhage, which caused a hydrocephalus. He received an external ventricular drain. In both patients with small haemorrhage the frame was positioned straight, while in the patient who showed a larger haemorrhage the frame was mounted oblique. In all patients a final histopathological diagnosis was established.

CONCLUSION

Cerebellar lesions of unknown entity can be accessed transcerebellar either with the stereotactic frame mounted straight or oblique. Also for cerebellar lesions the procedure shows a high diagnostic yield with a low rate of severe complications, which need further treatment.

Target location after deep cerebral biopsies using low-volume air injection in 75 patients. Results and technical note

BACKGROUND

Stereotactic biopsy is a minimally invasive technique that allows brain tissue samples to be obtained with low risk. Classically, different techniques have been used to identify the biopsy site after surgery.

OBJECTIVE

To describe a technique to identify the precise location of the target in the postoperative CT scan using the injection of a low volume of air into the biopsy cannula.

METHODS

Seventy-five biopsies were performed in 65 adults and 10 children (40 males and 35 females, median age 51 years). Frame-based biopsy was performed in 46 patients, while frameless biopsy was performed in the remaining 29 patients. In both systems, after brain specimens had been collected and with the biopsy needle tip in the center of the target, a small volume of air (median 0.7 cm³) was injected into the site.

RESULTS

A follow-up CT scan was performed in all patients. Intracranial air in the selected target was present in 69 patients (92%). No air was observed in two patients (air volume administered in these 2 cases was below 0.7 cm³), while in the remaining four patients blood content was observed in the target. The diagnostic yield in this series was 97.3%. No complications were found to be associated with intracranial air injection in any of the 75 patients who underwent this procedure.

CONCLUSIONS

The air-injection maneuver proposed for use in stereotactic biopsies of intracranial mass lesions is a safe and reliable technique that allows the exact biopsy site to be located without any related complications.

Biopsies of pediatric brainstem lesions display low morbidity but strong impact on further treatment decisions

OBJECTIVE

The course of malignant brain stem gliomas in childhood is rarely positive. Because of limited therapeutic options and potentially hazardous biopsies oncologist often relay on MRI diagnoses only for further therapy decisions. In this study we show that brain stem biopsies display a low morbidity rate and neuropathological assessment has a considerable impact on further treatment decision.

METHODS

Within 18-months five children with brainstem symptoms and the radiological diagnosis of a malignant brainstem glioma, were identified. From this time point it was possible to analyze all samples with the 450K methylome analysis. Other neuropathological techniques included classical histology with immunohistochemistry. Surgery was performed as biopsy, either microsurgical, frame-guided (Leksell), robot-assisted (ROSA) or navigated (BrainLab, two children).

RESULTS

Mean age of the children was 7.5years (range: newborn to 12years). There was no biopsy-related morbidity or mortality. The mean number of taken samples was 12 (range: 1-25). Histologic diagnosis could be established in all children, however, 450K methylome diagnosis was positive in only two out of five patients.

CONCLUSION

Despite the technically difficult biopsies, all specimens were sufficient for immunohistochemical diagnosis, however, 450K methylome analysis could only be better established where multiple small samples were taken, instead of few larger ones. Based on the preoperative radiological diagnosis suggesting malignant brainstem glioma, all children would have been treated with combined radiation and temozolomid chemotherapy. Nevertheless, due to the availability of histology and molecular diagnostics, individualized therapy could be performed, preventing in two out of five children from unnecessary radiation and chemotherapy.

Benefit and Complications of Frame-Based Stereotactic Biopsy in Old and Very Old Patients

OBJECTIVE

Stereotactic biopsy is an everyday procedure implemented in numerous neurosurgical departments. The procedure is performed to obtain tumor tissue of unclear diagnosis. Going in hand with low complication rates and high diagnostic yield, stereotactic biopsies can be performed in adults and children likewise for histopathologic evaluation of lesions in eloquent localizations. However, little is known about whether aged patients do benefit from stereotactic biopsy or rather the therapy that is derived from histopathologic results. In this study, we therefore focused on old (80-84 years) and very old patients (85 years and older) to evaluate whether stereotactic biopsy should be performed leading to further therapy. We also assessed the complication rates of the procedure in this aged population.

METHODS

We performed a retrospective analysis of our database and included all patients older than 80 years who underwent stereotactic biopsy at our department from October 2005 until May 2016. Forty-seven patients were included in this study. These patients were divided into 2 subgroups: group 1 consisted of patients from 80 to 84 years old and group 2 of patients aged 85 years and older. All patients underwent stereotactic biopsy to establish histopathologic diagnosis. We excluded patients who underwent cyst puncture or puncture of a hemorrhage because the procedure was not performed for diagnostic purposes. We assessed gender, neuroradiologic diagnosis, Karnofsky Performance Score (KPS), number of tissue samples taken, histopathologic diagnosis, localization, postoperative hemorrhage, modality of anesthesia anticoagulation, and further therapy.

RESULTS

Group 1 consisted of 34 patients and group 2 of 13 patients. KPS was 80 and 70, respectively. A histopathologic diagnosis was possible in all but 1 patient. In group 1, 61.8% of the patients agreed to further postoperative therapy (radiation, 35.3%; chemotherapy, 11.8%; combined radiochemotherapy, 11.8%; complication that prevented therapy, 2.9%), as did 53.8% of the patients in group 2 (resection, 7.7%; radiation, 15.4%; combined radiochemotherapy, 30.7%). In group 1, 38.2% declined further therapy, as did 64.1% in group 2.

CONCLUSIONS

Also in old and very old patients, a final histopathologic diagnosis should be established to provide adequate therapy. Our data show that most of these aged patients want to be treated.

Benefit of Stereotactic Procedures in a Series of 43 Children

OBJECTIVES

Stereotactic biopsies are procedures that enable neurosurgeons to obtain tissue samples of brain tumors located in eloquent areas with a low risk of perioperative complications. In this study, we examined stereotactic procedures (STX) in children. We focused on effectiveness, safety, and histopathological results to evaluate the benefits of the procedure.

METHODS

We performed a retrospective analysis of our prospective database and included 43 children aged less than 18 years who underwent STX between 1998 and May 2015. All MRIs were evaluated by a single, experienced neuroradiologist. For all biopsies, Leksell stereotactic frame was used and fixed to the children's head with four pins. Entry and targetpoints were calculated by BrainLab navigation system. We assessed age, tumor localization, number of samples, histological diagnosis, and postoperative treatment.

RESULTS

Median age of the patients was 11 years (range 1-18 years), and median number of tissue samples taken was 12 (range 1 with mere puncture of a cyst to 36). Histopathological examination revealed a final diagnosis in all patients. 3 patients underwent puncture of a cyst. 27 patients had a postoperative imaging. Only in 3 patients, CT scan revealed blood in the area where the biopsy had been taken. All bleedings were small and without clinical sequelae.

CONCLUSION

Stereotactic procedures are accurate and save surgeries to obtain tumor tissue from eloquent areas to base further therapy on. This not only applies to adults but also to children of all ages.