When the nerve keeps firing: an institutional experience and systematic review on delayed response after microvascular decompression for trigeminal neuralgia.

BACKGROUND: This study aimed to investigate the occurrence of delayed response following microvascular decompression (MVD) in patients with trigeminal neuralgia (TN) and identify potential contributing factors. Additionally, we present two cases with delayed relief observed at our institution. METHOD: Two TN patients with delayed response and clear intra-operative arterial findings are presented in this study. Furthermore, we conducted a systematic review by searching electronic bibliographic databases, including MEDLINE (PubMed), Web of Science, Scopus, and Embase, from inception to 2022. RESULTS: We identified a total of 28 full-text articles involving 322 TN patients who experienced delayed pain relief. Out of these, only 11 studies provided sufficient evidence and were included in the final analysis. Among the patients, 73.46% were female. The mean incidence rate of delayed response after MVD treatment for TN was 10.5%, with a range of 0.95 to 57.14% across different studies. The mean age of these patients was 59.86 years. The reported time to pain relief in the existing reports was at least 4 days post-surgery. In 72.88% of the reported cases, right-side dominance was observed. The majority of delayed cases experienced pain relief within 3 months, with a median time of 1 month. CONCLUSIONS: A thorough examination of the probability of delayed pain relief after MVD for TN and understanding the characteristics of this phenomenon can offer surgeons valuable post-operative guidance and aid in decision-making regarding potential immediate reoperation.

Electrophysiological predictors of hearing deterioration based on AEP monitoring during petroclival meningioma resection.

The objective of this study was to calculate the risk of postsurgical hearing deterioration as a function of changes in the amplitude and latency of the most stable components (waves III and V) of the auditory evoked potential (AEP) during petroclival meningioma resection surgery. We retrospectively analyzed intraoperative AEP monitoring results and pre- and postsurgical hearing status in 40 consecutive patients who were surgically treated for petroclival meningiomas. Statistical analyses were conducted to identify the most sensitive and specific way to predict hearing dysfunction after surgery. Patients' mean age was 59 ± 10 years, and 31 (77.5%) were women. Twelve (30%) patients presented with clinically detectable hearing impairment preoperatively. At the first postoperative assessment, four of those 12 patients reported subjective improvement, and eight reported hearing deterioration. Of those eight, four remained stable and four recovered hearing by the last assessment. Wave III latency reached its highest specificity (100%) and sensitivity (71.43%) at x = 143%. Wave V latency, on the other hand, reached its highest sensitivity (71%) and specificity (93%) at x = 124%. Finally, wave V amplitude reached its highest sensitivity (100%) and specificity (79%) at x = 74%. Intraoperative alterations of wave III latency and wave V amplitude seem to be highly sensitive and specific at predicting the risk of auditory dysfunction in patients undergoing petroclival meningioma resection and should be used to determine maximum resection with preservation of function.

Minimal exposure maximal precision ventriculoperitoneal shunt: how I do it.

BACKGROUND: Ventriculoperitoneal shunt is among the most frequent neurosurgical procedures, complicated by infection and obstruction. The first is influenced by number of skin incisions, catheter exposure and manipulation, and the latter by catheter position. METHOD: Presenting our neuronavigated laparoscopic-assisted minimal exposure shunt technique performed on 40 consecutive adults. No patient presented infection or distal catheter migration (mean follow-up 12 months). Ventricular catheter malpositioning associated with electromagnetic neuronavigation inaccuracy occurred in two patients with slit ventricles. CONCLUSION: This technique demonstrates low infection/malfunction rate, postoperative pain, and cosmetic advantages. Limiting factors are availability of laparoscopic surgeons and neuronavigation if not familiar with the approach.

The endoscope-assisted contralateral paramedian approach to large falcine meningiomas.

BACKGROUND: Resection of large falcine meningiomas can be challenging as overlaying cortical brain is endangered during the surgical approach. METHOD: We describe the endoscope-assisted contralateral paramedian approach to large left-falcine meningiomas to avoid retraction of the ipsilateral thin layer of eloquent brain cortex. CONCLUSIONS: The contralateral paramedian approach enables complete tumor resection with endoscopic-assisted removal of tumor remnants in the superior aspect of the resection cavity, sparing any manipulation of ipsilateral brain tissue.

The midline suboccipital subtonsillar approach to the cerebellomedullary cistern: how I do it.

BACKGROUND: Lesions lateral to the lower brainstem in an area extending from the foraminae of Luschka to the foramen magnum are rare and include different pathologies. There is no consensus on an ideal surgical approach. METHOD: To gain access to this area, we use the midline suboccipital subtonsillar approach (STA). This midline approach with unilateral retraction of the cerebellar tonsil enables entry into the cerebellomedullary cistern. CONCLUSIONS: The STA offers excellent access with a panoramic view of the cerebellomedullary cistern and its structures and therefore can be useful for a number of different pathologies in the lower petroclival area.

Turn left where you felt unhappy: how affect influences landmark-based wayfinding.

The present work investigated the impact of affect in landmark-based wayfinding. We assumed that affect-laden landmarks improve wayfinding performance and have an impact on later landmark recognition. To investigate our hypotheses, we ran two experiments in a virtual maze. In Experiment 1, we investigated how affect-laden landmarks influence wayfinding and recognition in comparison with neutral landmarks. The aim of Experiment 2 was to focus on the affective valence of a landmark. The memory tasks of both experiments were repeated after 1 week in order to assess memory consolidation. Results showed that the best wayfinding and recognition performance occurs when negatively laden landmarks were used. In comparison with neutral and positively laden landmarks, recognition performance hardly decreased over time for the negatively laden landmarks. Our results not only support findings in the field of emotion research but also expand the concept of semantic landmark salience with respect to emotional responses.

Rigid, Variable-View Endoscope in Neurosurgery: First Intraoperative Experience.

INTRODUCTION: The endoscope became a highly valued visualization tool in neurosurgery. However, technical limitations caused by the rigidity of current standard endoscopes significantly decrease ergonomy in transcranial neurosurgery. Further technological developments will aid enlarging the surgical applicability. OBJECTIVE: To evaluate the intraoperative features of a rigid variable-view endoscope in neurosurgery. METHODS: We assessed a 4 mm rigid rod lens endoscope (EndoCAMeleon, Karl Storz, Tuttlingen, Germany) in the intraoperative setting. The device offers a variable angle of view from 15° to 90° in one plane. The endoscope was used in 3 cases (aneurysm clipping, vestibular schwannoma surgery, endoscopic third ventriculostomy) for inspection. RESULTS: Direct insertion of the device through the craniotomy/burr hole with the lowest angled view (15°) was always possible. Neurovascular structures crossing the access route could be visualized and avoided. This allowed a targeted positioning of the endoscope's tip in the operating field. Once the target point was reached, viewing direction was changed in one plane from 15° to 90° according to anatomic demands. As the endoscope's tip does not move while the lens is rotated, surrounding neurovascular structures are not at risk to be injured. However, turning of the lens-controlling wheel in proximity to delicate structures may be inconvenient. CONCLUSION: The rigid, variable-view endoscope has the potential to become an appreciated visualization tool in neuroendoscopy. The steerable lens enables a tremendous expansion of the visual field, resulting in higher efficiency for surgeons and increased safety for patients.

Vestibular schwannoma surgery via the retrosigmoid transmeatal approach.

BACKGROUND: Aims of modern vestibular schwannoma surgery are complete tumor resection with functional facial nerve and hearing preservation, if possible. Here we present our technique of bimanual dissection for vestibular schwannoma resection through the retrosigmoid approach. METHOD: A slightly curved surgical incision is planned two fingers behind the ear extending from the level of the tip of the ear to 1 cm below the mastoid tip. The retrosigmoid craniectomy exposes the sinus knee, the inferior border of the transverse sinus, the medial border of the sigmoid sinus and horizontal segment of the occipital squama. The dura is opened under the microscope in semilunar fashion parallel to the course of the sigmoid sinus. We open the IAC with a high-speed diamond drill from lateral to medial, opening the canal for 180° of its circumference. The intrameatal part of the vestibular schwannoma is partially removed and the facial nerve identified Thereafter, we open the capsule and debulk the tumor with an ultrasonic surgical aspirator in the CPA. Once the tumor's mass is significantly reduced, a bimanual dissection of the cleavage plane between capsule and the surrounding arachnoid is performed. Starting from below, the capsule is elevated with a tumor grasping forceps and the arachnoid membrane is peeled off. Following the cleavage plane, the facial nerve is separated in a medial to lateral direction from the VS's capsule. Throughout the whole procedure the field is irrigated with warm Ringer's solution. We seal the drilled posterior lip of the IAC as well as eventually opened mastoid air cells with a free muscle or fat patch. CONCLUSION: Vestibular schwannoma surgery through the retrosigmoid approach is a safe procedure that allows gaining good functional results.

Late neurological sequelae due to brainstem irradiation for an assumed glioma.

PURPOSE: There is ongoing discussion whether radiotherapy might be beneficial in the treatment of intracranial cavernomas, however long-term sequelae due to brainstem irradiation may exist. CASE REPORT: The case of a 72-year-old female is reported who received radiotherapy in the pre-MRI era due to a suspected intra-axial pontine lesion. Later on she developed severe trigeminal neuropathy and an MRI was performed 27 years after irradiation of the brainstem. On these images a large cavernous malformation with signs of multiple haemorrhages instead of the pontine glioma was seen accompanied by a substantial atrophy of brainstem structures. CONCLUSION: This case impressively demonstrates the long-term outcome of brainstem irradiation and reflects that cavernomas do not respond to radiotherapy.

Belief revision and way-finding.

Belief revision is required when veridical information surfaces that contradicts what was previously thought to be the case. In way-finding, belief revision frequently occurs, for example, when the travelled route has led one astray, instead of to one's chosen destination. In past cognitive research, the topics of belief revision and way-finding have been treated in isolation. Here, we introduce an approach for linking the two fields and assess belief revision as it occurs in the process of way-finding. We report the results of two experiments that put participants in (virtual) situations where elements of a previously learned route description do not match the actual environment (thereby requiring the revision of a previously held belief). Experiment 1 puts participants in a highly artificial virtual environment where the landmarks to be used in navigation have a low degree of semantic salience (houses of various color). Experiment 2 puts subjects in a photorealistic environment where the objects to be used in navigation are well-known landmarks (such as the Eiffel Tower) and thus have a high degree of semantic salience. In both experiments, participants are confronted with T-junctions, where a landmark that was expected to indicate the correct route is discovered to be in an unexpected location. The results of the experiments show that a participant's choice of route, in such cases, is affected by differences in the structure of the relevant initial instruction. More precisely, the route chosen by participants is affected by whether the relevant landmark was described as being on the same side of the path as they were instructed to turn (congruent case) or as located on the opposite side of the path as they were instructed to turn (incongruent case).

Detection and quantification of farnesol-induced apoptosis in difficult primary cell cultures by TaqMan protein assay.

Apoptosis can be detected reliably by assaying for cleaved caspase-3, for which active caspase-3 antibodies are used in several methods, such as immunocytochemistry, enzyme-linked immunosorbent assay, and western blot. In this study, we used TaqMan protein assay (TPA), a novel method for protein detection and quantification that detects proteins by amplification of substitute DNA templates. TPA uses antibodies and proximity ligation for quantitative real-time PCR. Meningiomas are primarily benign intracranial tumors. Primary cell cultures of meningiomas are often unsuitable for sensitive protein detection methods. We optimized a TPA to detect active caspase-3 and evaluated its ability to detect farnesol-induced apoptosis in primary meningioma cells. The specificity and sensitivity of the inactive and active caspase-3 assay were determined using recombinant caspase-3. Apoptosis was induced in meningiomas in the presence of 0.2 µM farnesol as shown by immunocytochemistry of single-stranded DNA. Also, viability decreased by over 90 % after treatment with 1.2 µM farnesol for 24 h. The TPA detected a significant increase in active caspase-3 after treatment with 2 and 4 µM farnesol for 2 h, which could not be detected using standard methods such as western blot and immunofluorescence. In addition, TPA determined that meningiomas show disparate sensitivities to low concentrations of farnesol. Caspase-3 expression fell significantly in cells that were treated with 0.25 µM farnesol for 2 h. Further, by TPA, active caspase-3 peaked after 2 h and declined with longer incubation times. This study demonstrates that cleaved caspase-3 is detected and quantified reliably in meningiomas by TPA.

Live surgery in neurosurgical training courses: essential infrastructure and technical set-up.

BACKGROUND: Training courses in neurosurgery are essential educational elements of residency. Teaching methods vary due to cultural differences, monetary restrictions and infrastructure conditions. Anatomical dissection courses combined with annotated live surgeries performed by senior surgeons have proved to be best accepted by students. OBJECTIVE: In this technical note, we provide detailed information about the necessary requirements, resources and optimal performance of live surgeries in neurosurgical training courses. METHODS AND RESULTS: From 2007 to 2012, 12 neurosurgical training courses with live surgeries were organised at the Department of Neurosurgery. Here, we share our experience and report the essential set-up for these courses. Our department organised seven skull base, four cervical spine and one spinal cord stimulation hands-on dissection course with live surgeries. The course structure included lectures, cadaver dissections and live surgeries. The technical set-up included video transmission via an IP-based network with fibreglass backbone between the operating theatre (OR) and lecture room. During surgery, bidirectional discussions offered the participants the ability to interject and ask questions. Important issues included the careful selection of live operated patients with clearly presented pathology for the didactic cases used to demonstrate the technique. A live surgery should include the entire procedure: intraoperative set-up, positioning, anaesthesiological procedures and handling of intraoperative situations. CONCLUSION: A professionally prepared step-by-step educational program including surgical anatomy, cadaver dissection and live surgeries with online discussion offers a high level of training and enriches both the participants and instructors.

Two-Stage Resection of a Giant Trigeminal Schwannoma in a Non-Neurofibromatosis Type 2 Pediatric Patient: A Case Report, Systematic Review, and Intraoperative Video.

BACKGROUND: Trigeminal schwannoma is an uncommon tumor in pediatric patients. Several surgical approaches have been described in the literature. METHODS: The case of an 11-year-old boy with a giant dumbbell-shaped trigeminal schwannoma removed through a 2-stage approach was presented with an intraoperative video. Using PubMed and Scopus, the literature on trigeminal schwannoma in pediatric patients was searched according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. RESULTS: The search strategy yielded 312 titles, of which 13 were included in the review. Cases of trigeminal schwannoma were described, with a highly variable clinical presentation and anatomical arrangement in cranial fossae. Two-stage approaches were reported, although most studies described single-stage approaches. Common postoperative outcomes were a range of disturbances of cranial nerve V. CONCLUSIONS: The surgical approach varies based on the tumor conformation. However, a 2-stage pterional subtemporal and semisitting retrosigmoid approach is a safe, practical, and effective strategy for the removal of dumbbell-shaped trigeminal schwannoma in a pediatric patient.

Cognitive decline assessment in speakers of understudied languages.

Projected trends in population aging have forecasted a massive increase in the number of people with dementia, in particular in sub-Saharan Africa and the Middle East and North Africa (MENA) region. Cognitive decline is a significant marker for dementia, typically assessed with standardized neuropsychological tools that have been validated in some well-researched languages such as English. However, with the existing language diversity, current tools cannot cater to speakers of understudied languages, putting these populations at a disadvantage when it comes to access to early and accurate diagnosis of dementia. Here, we shed light on the detrimental impact of this language gap in the context of the MENA region, highlighting inadequate tools and an unacceptable lack of expertise for a MENA population of a half billion people. Our perspective calls for more research to unravel the exact impact of the language gap on the quality of cognitive decline assessment in speakers of understudied languages. Highlights: Cognitive decline is a marker for dementia, assessed with neuropsychological tests.There is a lack of culturally valid tests for speakers of understudied languages.For example, suboptimal cognitive tests are used in the Middle East and North Africa region.Linguistic diversity should be considered in the development of cognitive tests.

Before the Knife: A Detailed Step-by-Step Description of an Optimized Semi-Sitting Position in Posterior Fossa Surgery.

BACKGROUND: In an ample armamentarium in neurosurgery, the semi-sitting position has produced debate regarding its benefits and risks. Although the position is apparently intuitive, many have abandoned its use since its initial inception, because of reported complexity and potential complications, leading to impracticality. However, through standardization, it has been shown not only to be safe but to carry with it many advantages, including less risk of secondary neurovascular injuries and better visualization of the surgical field. As with any surgical technical nuance, the semi-sitting position has advantages and disadvantages that must be weighed before the decision is made to adopt it or not, not only in a case-by-case scenario but also from a departmental standpoint. As we attempt to show, the advantages from a standardized approach for the semi-sitting position in experienced institutions may be more than sufficient to significantly outweigh the disadvantages, making it the preferable option for most, although not all, posterior fossa surgical interventions. METHODS: In the present study, we aim to elaborate a straightforward narrative of the steps before incision, in an attempt to simplify the complexity of the position, alleviating its disadvantages and exponentially concentrating on its benefits. In nearly 100 steps, we carefully describe the points that culminate with the skin incision, initiating the intraoperative part of the procedure. Each step, therefore, is detailed in full, not in an effort to create a strict manual of the semi-sitting position but rather to facilitate understanding and put the technique into effect in a real-life scenario, thus simplifying what some depict as complex and time consuming. CONCLUSIONS: Although several of the steps described are also relevant and integral parts of other surgical positioning, we intend to create a protocol, in a stepwise fashion, to allow facilitated following, to be easily implemented in departments with different levels of experience. The steps comprise nursing care through to electrophysiologic and anesthesiologic approaches, along with neurosurgical cooperation, making it a team approach, not only to avoid position-related complications but also to optimize preoperative standardization, constructing a safe, efficient, and patient-centered scenario, to set the best possible stage for the next step: the intraoperative part of the intervention.

After the Knife: A Detailed Roadmap for Vestibular Schwannoma Resection in the Semi-Sitting Position - How I do it.

BACKGROUND: Vestibular schwannoma surgery remains a neurosurgical challenge, with known risks, dependent on a number of factors, from patient selection to surgical experience of the team. The semi-sitting position has gained popularity as an alternative to the traditional supine position for vestibular schwannoma resection due to potential advantages such as improved surgical exposure due to clearer surgical field and anatomical orientation. However, there is a lack of standardized protocols for performing the procedure in the semi-sitting position, leading to variations in surgical techniques and outcomes. METHODS: In this study, we aimed to establish a standardized approach for vestibular schwannoma resection using the semi-sitting position. Initiating after final position for semi-sitting, the authors have divided the surgical steps into five major parts for improved understanding and replication. Surgical techniques were analyzed through one hundred steps to identify commonalities, determining the optimal procedural steps for the semi-sitting position using surgical video for visual conceptualization. RESULTS: The analysis described one hundred steps for vestibular schwannoma resection in the semi-sitting position, with visual demonstration of the various parts of the procedure through surgical videos. Specific recommendations for each step were outlined, including appropriate approach, monitoring strategies, and tumor and posterior fossa structures manipulation. Five major parts of the procedure were identified, leading to a reproducible standardization of the surgical procedure of vestibular schwannoma resection in the semi-sitting position. CONCLUSIONS: This study provides a comprehensive standardized protocol for the semi-sitting procedure in vestibular schwannoma resection. By establishing a consistent approach, surgeons can minimize variations in surgical techniques and improve patient outcomes. The identified steps and recommendations can serve as a valuable resource for surgical teams involved in vestibular schwannoma resection and facilitate the dissemination and reproducibility of best practices.

New shift models for doctors in a large German University Neurosurgery Department: how they comply with the European Working Time Directive 3 years after implementation.

BACKGROUND: Due to the European Working Time Directive (EWTD) and a new collective agreement for doctors working at University hospitals in 2006 new shift models had to be designed in the Department of Neurosurgery of the University Hospital Tübingen, Germany. The aim of the study was to show the fit of the models regarding the average weekly working time limits (aWTL), the daily maximum of 10-h working time (10-h dWT), and the staff expenditures 3 years after implementation. METHODS: The new shift model was implemented in 2008, and hence planning and documentation were done electronically. Adherence to the work schedules was measured, and aWTL adherence rates were compared. The relative number of 10-h dWT violations in 2009 and 2010 was analysed. Staff costs relative to performance before and after implementation were calculated and tested using analysis of variance (ANOVA). Four other departments without alteration of shift models served as a control group in cost trend analysis. RESULTS: In 2010 all doctors in the Department of Neurosurgery were able to stay within the limit of 54 h/week; one doctor without opt-out exceeded the 48 h/week limit (50.1 h/week). The median per capita rate of 10-h dWT violations in 2009 was 20.3 % of all eligible working days and further declined to 10.7 % in 2010 (p < 0.001). Staff costs per case-weight point did not change significantly (2007: 339.88€, 2009: 307.99€, 2010: 322.54€; p = 0.22) in neurosurgery or in the control group (2007: 633.72€, 2009: 637.06€, 2010: 690.30€; p = 0.67). CONCLUSIONS: After implementation of the new shift model, current monitoring and properly matching modifications led to long-term stability in complying with the EWTD regulations without increasing costs for staff expenditures.

Management of holocord pilocytic astrocytomas in children and adolescents: an update.

Holocord intramedullary low-grade astrocytomas in children and adolescents - involving most or all of the cervical and thoracic spinal cord - are a rare finding. Most of the tumors seem to be pilocytic astrocytomas. Surgical management strategies might not be as clear as in small and circumscribed intramedullary tumors. On the basis of 20 previously published cases and 3 own patients, we summarize and discuss possible treatment options and their risks and benefits. Surgery should be performed soon after establishment of the diagnosis, which per se is often delayed despite a long-standing presence of attributable symptoms or signs in most cases. Following multilevel laminotomy, excellent results can be achieved by electrophysiologically guided microsurgical tumor removal in a single-staged or multistaged approach. The surgical goal is resection as gross total as possible provided intraoperative monitoring indicates preservation of function. Small tumor remnants often remain stable in the due course. In case of unresectable regrowth or recurrence, chemotherapy or radiotherapy are the adjuvant treatment options.

Endoscopic-Assisted Resection of Anterior Foramen Magnum Meningiomas through a Midline Suboccipital Subtonsillar Approach.

Objective This study was aimed to demonstrate the resection of anterior foramen magnum meningiomas through an endoscopic-assisted posterior midline suboccipital subtonsillar approach. Design This study was designed with illustration of the surgical steps and safety of this approach. Setting Evidence of cerebrospinal fluid (CSF) cleft between the tumor and brainstem on MRI was studied ( Fig. 1A and B ). Preoperative tracheotomy was considered in cases of preoperative dysphagia to prevent any further neurological deterioration due to the bilateral access through the lower cranial nerves corridors. Semisitting position with extensive electrophysiological neuromonitoring and transesophageal echocardiogram was adopted. A standard midline incision with bilateral suboccipital craniotomy and C1-laminotomy was performed ( Fig. 2A ). After partial resection and elevation of the tonsils, tumor was debulked unilaterally around the lower cranial nerves and the vertebral artery, devascularized from the clival dura and then dissected from the brainstem ( Fig. 2B, C ). Endoscopic-assisted removal of its anterior portion followed. The same procedure was repeated from the opposite site for the contralateral portion, before approaching the purely anterior part with endoscope assistance ( Fig. 2D ). Participants Four consecutive patients were included in the study. Main Outcome Measures Grade of tumor resection and outcome (mRS) were primary measurement of this study. Results Clinical outcome and grade of resection are comparable to other series of patient treated with other foramen magnum approaches ( Fig. 1C and D ). Conclusion Anterior foramen magnum meningiomas can be safely removed through this relatively faster midline suboccipital approach with bilateral exposure of lower cranial nerves (CNs) and vertebral arteries and lower approach-related morbidity (no condyle drilling). The surgical corridor is created by the tumor during debulking reducing need for brain retraction and the removal of the anterior dural attachment coagulated under the microscope is verified and completed endoscopically with pituitary curettes (Simpson's grade II) ( Fig. 1C and D ). The link to the video can be found at: https://youtu.be/9eACAJVwQBs .