Integrative approaches in spinal cord stimulation: Neuropathic pain management and motor recovery in spinal cord injury. A narrative review.

Introduction: Spinal cord stimulation is a widespread treatment of chronic neuropathic pain from different conditions. Several novel and improving technologies have been recently developed to increase the effect of neuromodulation in patients refractory to pharmacological therapy. Research question: To explore spinal cord stimulation's mechanisms of action, indications, and management. Material and methods: The paper initially explores the mechanism of action of this procedure based on the generation of an electric field between electrodes placed on the posterior dural surface of the spinal cord probably interfering with the transmission of pain stimuli to the brain. Subsequently, the most consolidated criteria for selecting patients for surgery, which constitute a major issue of debate, were defined. Thereafter, the fundamental patterns of stimulation were summarized by exploring the advantages and side effects. Lastly, the most common side effects and the related management were discussed. Results: Proper selection of the patient is of paramount importance to achieve the best results from this specific neuromodulation treatment. Regarding the different types of stimulation patterns, no definite evidence-based guidelines exist on the most appropriate approach in relation to the specific type of neuropathic pain. Both burst stimulation and high-frequency stimulation are innovative techniques that reduce the risk of paresthesias compared with conventional stimulation. Discussion and conclusion: Novel protocols of stimulation (burst stimulation and high frequency stimulation) may improve the trade-off between therapeutic benefits and potential side effects. Likewise, decreasing the rates of hardware-related complications will be also useful to increase the application of neuromodulation in clinical settings.

The Immunomodulatory Effects of Fluorescein-Mediated Sonodynamic Treatment Lead to Systemic and Intratumoral Depletion of Myeloid-Derived Suppressor Cells in a Preclinical Malignant Glioma Model.

Fluorescein-mediated sonodynamic therapy (FL-SDT) is an extremely promising approach for glioma treatment, resulting from the combination of low-intensity focused ultrasound (FUS) with a sonosensitizer. In the present study, we evaluated the efficacy and immunomodulation of SDT with fluorescein as the sonosensitizer in immunocompetent GL261 glioma mice for the first time. In vitro studies demonstrated that the exposure of GL261 cells to FL-SDT induced immunogenic cell death and relevant upregulation of MHC class I, CD80 and CD86 expression. In vivo studies were then performed to treat GL261 glioma-bearing mice with FL-SDT, fluorescein alone, or FUS alone. Perturbation of the glioma-associated macrophage subset within the immune microenvironment was induced by all the treatments. Notably, a relevant depletion of myeloid-derived suppressor cells (MDSCs) and concomitant robust infiltration of CD8+ T cells were observed in the SDT-FL-treated mice, resulting in a significant radiological delay in glioma progression and a consequent improvement in survival. Tumor control and improved survival were also observed in mice treated with FL alone (median survival 41.5 days, p > 0.0001 compared to untreated mice), reflecting considerable modulation of the immune microenvironment. Interestingly, a high circulating lymphocyte-to-monocyte ratio and a very low proportion of MDSCs were predictive of better survival in FL- and FL-SDT-treated mice than in untreated and FUS-treated mice, in which elevated monocyte and MDSC frequencies correlated with worse survival. The immunostimulatory potential of FL-SDT treatment and the profound modulation of most immunosuppressive components within the microenvironment encouraged the exploration of the combination of FL-SDT with immunotherapeutic strategies.

Superior orbital fissure narrowing and tumor-associated pain in spheno-orbital meningiomas.

INTRODUCTION: Spheno-orbital meningiomas (SOMs) represent a distinct subtype of meningioma characterized by their unique multi-compartmental invasion pattern. Previous studies have investigated correlations between SOMs and visual manifestations. However, our comprehension of pain associated with SOMs remains limited. This study aims to provide insight into the pathophysiology underlying SOM-related pain through measurements of tumor volume and superior orbital fissure (SOF) narrowing. METHODS: This retrospective study included patients who underwent surgical resection of a SOM between 2000 and 2022. Preoperative CT and/or MRI scans were analyzed, and the tumor volume of each segment was measured. Bony 3D reconstructions were used to measure the area of the SOF, and SOF narrowing was calculated. RESULTS: The study cohort included 66 patients diagnosed with SOMs, among which 25.8% (n = 17) presented with pain. Postoperatively, 14/17 (82.4%) of patients reported pain improvement. There was no significant correlation between the total volume or the volume of tumor within each compartment and the presence of pain on presentation (p > 0.05). The median SOF narrowing was significantly different between patients presenting with and without tumor-associated pain with median of 11 mm2 (IQR 2.8-22.3) and 2 mm2 (IQR 0-6), respectively (p = 0.005). Using logistic regression, a significant correlation between the degree of SOF narrowing and the presence of SOM-associated pain on presentation was identified, with an aOR of 1.2 (95% CI 1.12-1.3, p = 0.02). CONCLUSION: While the exact cause of tumor-associated pain remains unclear, SOF narrowing seems to play a role in pain among SOM patients. Based on the radiological characteristics, SOF neurovascular decompression is recommended in SOM patients.

The vectorial technique: a novel neuronavigation-based tool to measure angles of exposure during skull base dissections.

The angle of exposure (AnE) represents a metric that is particularly useful for analyzing circular bony structures during skull base dissections. The authors aimed to develop and validate a neuronavigation-based method to measure the AnE. A formula based on vectorial geometry and the coordinates of three points collected with a neuronavigation system was developed to measure the AnE. The method was validated using a plexiglass phantom head. To demonstrate its applicability, the authors measured the AnE in 6 cadaveric specimens after exposure of the hypoglossal canal using a far-medial approach (FMA) and a far-lateral transtubercular approach (FLTA) and in 6 different specimens after exposure of the jugular foramen using an FLTA and a retrosigmoid approach (RSA). The mean angles measured at 45°, 90°, and 180° using a goniometer during the validation test were 44.8° ± 1.1°, 90.8° ± 1.2°, and 179.7° ± 0.8° using the novel formula (p > 0.05). In the first illustrative application, the mean AnEs for the FMA and FLTA were 129° ± 0.9° and 243° ± 1.9°, respectively. In the second scenario, the mean AnEs were 192° ± 1.3° for the FTLA and 143° ± 2.1° for the RSA. The neuronavigation-based technique described is a highly accurate method to measure the AnE.

Exoscope-assisted temporal bone resection: operative videos of the lateral and total techniques.

Skull base malignancies arising from the parotid gland, skin, or external auditory canal (EAC) can potentially involve the temporal bone. Management of these invasive tumors represents a true challenge considering the critical neurovascular relationships. Exoscope-assisted temporal bone resection (TBR) plays a crucial role in addressing such malignancies. The extent of disease is evaluated using the Pittsburgh staging system, which then guides the boundaries of resection. Lateral TBR (LTBR) relies on removal of the EAC and lateral ossicles and is generally appropriate for stage T1 and T2 tumors. Total TBR (TTBR) is reserved for high-grade tumors involving the petrous apex. The video can be found here: https://stream.cadmore.media/r10.3171/2023.10.FOCVID23135.

Volumetric Analysis of Spheno-Orbital Meningiomas: Prognostic Correlation and a Compartmentalized Approach.

BACKGROUND AND OBJECTIVES: Spheno-orbital meningiomas arise from the arachnoid villi cap cells at the sphenoid ridge and have the ability to spread through soft tissue extension and cranial bone invasion. Owing to their orbital hyperostosis and intraorbital soft tissue extension, they commonly present with ophthalmologic manifestations. This study aims to investigate the correlation between tumor volume with the presenting symptoms and postoperative outcomes. METHODS: This retrospective study analyzed patients who underwent surgical resection of spheno-orbital meningiomas. Tumor volumes in different compartments were measured using preoperative and postoperative imaging. Linear and logistic regression analyses were used to identify correlations between tumor volumes and presenting symptoms preoperatively and postoperative outcomes. RESULTS: Sixty-six patients were included in this study, of whom 86.4% had proptosis, 80.3% had decreased visual acuity (VA), 30.3% had visual field defects, and 13.6% had periorbital edema. Preoperatively, proptosis linearly correlated with intraosseous tumor volume (coefficient = 0.6, P < .001), while the decrease in baseline VA correlated with the intraorbital tumor volume (coefficient = 0.3, P = .01). The odds of periorbital edema were found to increase with an increase in intraosseous tumor volume with an adjusted odds ratio of 1.4 (95% CI, 1.1-1.7, P = .003), while the odds of visual field defects were found to increase with an increase in intraorbital tumor volume with an adjusted odds ratio of 2.7 (95% CI, 1.3-5.6, P = .01). Postoperatively, the volume of intraosseous tumor resected linearly correlated with the improvement in proptosis (coefficient = 0.7, P < .001), while the volume of intraorbital tumor resected linearly correlated with improvement in VA (coefficient = 0.5, P < .001) and with a larger effect size in patients presenting with moderate-to-severe decrease in VA preoperatively (coefficient = 0.8). CONCLUSION: Underscoring the importance of each tumor compartment relative to the patient's symptomatology serves as a valuable guide in implementing a compartmentalized resection approach tailored to the surgical objectives.

Therapeutic response to pazopanib: case report and literature review on molecular abnormalities of aggressive prolactinomas.

Introduction: Aggressive prolactinomas (APRLs) pose a significant clinical challenge due to their high rate of regrowth and potentially life-threatening complications. In this study, we present a case of a patient with an APRL who had a trial of multiple therapeutic modalities with the aim to provide a review of molecular abnormalities and management of APRLs by corroborating our experience with previous literature. Methods: A total of 268 articles were reviewed and 46 were included. Case reports and series, and studies that investigated the molecular and/or genetic analysis of APRLs were included. Special care was taken to include studies describing prolactinomas that would fall under the APRL subtype according to the European Society of Endocrinology guidelines; however, the author did not label the tumor as "aggressive" or "atypical". Addiontionally, we present a case report of a 56-year-old man presented with an invasive APRL that was resistant to multiple treatment modalities. Results: Literature review revealed multiple molecular abnormalities of APRLs including mutations in and/or deregulation of ADAMTS6, MMP-9, PITX1, VEGF, POU6F2, CDKN2A, and Rb genes. Mismatch repair genes, downregulation of microRNAs, and hypermethylation of specific genes including RASSF1A, p27, and MGMT were found to be directly associated with the aggressiveness of prolactinomas. APRL receptor analysis showed that low levels of estrogen receptor (ER) and an increase in somatostatin receptors (SSTR5) and epidermal growth factor receptors (EGFR) were associated with increased invasiveness and higher proliferation activity. Our patient had positive immunohistochemistry staining for PD-L1, MSH2, and MSH6, while microarray analysis revealed mutations in the CDKN2A and POU6F2 genes. Despite undergoing two surgical resections, radiotherapy, and taking dopamine agonists, the tumor continued to progress. The patient was administered pazopanib, which resulted in a positive response and the patient remained progression-free for six months. However, subsequent observations revealed tumor progression. The patient was started on PD-L1 inhibitor pembrolizumab, yet the tumor continued to progress. Conclusion: APRLs are complex tumors that require a multidisciplinary management approach. Knowledge of the molecular underpinnings of these tumors is critical for understanding their pathogenesis and identifying potential targets for precision medical therapy.

Prevention of Post-Operative Pain after Elective Brain Surgery: A Meta-Analysis of Randomized Controlled Trials.

Background and Objective: To analyze the effects of several drug for pain prevention in adults undergoing craniotomy for elective brain surgery. Material and Methods: A systematic review and meta-analysis were conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. The inclusion criteria were limited to randomized controlled trials (RCTs) that evaluated the effectiveness of pharmacological treatments for preventing post-operative pain in adults (aged 18 years or older) undergoing craniotomies. The main outcome measures were represented by the mean differences in validated pain intensity scales administered at 6 h, 12 h, 24 h and 48 h post-operatively. The pooled estimates were calculated using random forest models. The risk of bias was evaluated using the RoB2 revised tool, and the certainty of evidence was assessed according to the GRADE guidelines. Results: In total, 3359 records were identified through databases and registers' searching. After study selection, 29 studies and 2376 patients were included in the meta-analysis. The overall risk of bias was low in 78.5% of the studies included. The pooled estimates of the following drug classes were provided: NSAIDs, acetaminophen, local anesthetics and steroids for scalp infiltration and scalp block, gabapentinoids and agonists of adrenal receptors. Conclusions: High-certainty evidence suggests that NSAIDs and acetaminophen may have a moderate effect on reducing post-craniotomy pain 24 h after surgery compared to control and that ropivacaine scalp block may have a bigger impact on reducing post-craniotomy pain 6 h after surgery compared to control. Moderate-certainty evidence indicates that NSAIDs may have a more remarkable effect on reducing post-craniotomy pain 12 h after surgery compared to control. No moderate-to-high-certainty evidence indicates effective treatments for post-craniotomy pain prevention 48 h after surgery.

Purely nasal floor mucosa-free graft for reconstruction after endoscopic endonasal transellar approach: an anatomical and clinical analysis.

BACKGROUND/OBJECTIVE: In this radioanatomical study with clinical correlate, we study a variation of the 'extended nasal floor mucosa' (ENFM) free-graft, the purely nasal floor mucosa (PuNFM) free-graft. The objectives of this study are to evaluate the coverage surface area provided by the PuNFM, study the adequacy of the PuNFM in the reconstruction of endoscopic endonasal approach (EEA) transsellar postoperative defects and compare and evaluate this reconstructive technique with current sellar region reconstruction practices. METHODS: Dissections were performed on five cadaveric specimens. PuNFM were harvested bilaterally and the area provided for reconstruction was calculated. Twenty-five consecutive cases of pituitary adenomas resected through an EEA were analyzed to estimate the sellar defect surface area (SDSA) after a transsellar EEA and calculate the area of PuNFM bilaterally. RESULTS: The median cadaveric SDSA was 4.77 cm2, with a median left and right side PuNFM area of 5.09 and 5.19 cm2, respectively. Clinically, the median SDSA was 5.36 cm2, and the total radiological PuNFM surface area was 5.46 cm2, with modified Knosp grade >2 tumors having larger SDSA than that of Knosp grade <2 tumors. The PuNFM graft proved to be most effective for covering modified Knosp <2 tumor defects. CONCLUSIONS: The PuNFM represents a variation of the ENFM free-graft sellar defect reconstruction technique that provides sufficient surface area to reconstruct the majority of the sellar defects related to transsellar EAA for pituitary adenomas. This technique may positively impact sinonasal function and quality of life. Future prospective clinical studies are needed to verify these findings.

Thermal Analysis of an Ultrasonic Aspirator Micro Claw Tool Compared With Standard High-Speed Drilling During Internal Auditory Canal Opening in a Cadaveric Model.

BACKGROUND: The ultrasonic aspirator micro claw tool (UAmCT) can be used to remove the bone of the internal auditory canal (IAC) during vestibular schwannoma resection via the retrosigmoid approach (RSA) without the risk of a spinning drill shaft. However, the thermal profile of the UAmCT during IAC removal has not been reported. OBJECTIVE: To compare the thermal profile of the UAmCT during access of the IAC to that of a conventional high-speed drill (HSD) and to present an illustrative case of this application. METHODS: IAC opening via RSA was performed in 5 embalmed cadaveric specimens using the UAmCT with 3, 8, and 15 mL/min irrigation on the left and the HSD at 75 000 revolutions per minute and 0%, 14%, and 22% irrigation on the right. Peak bone surface temperatures were measured 4 times in 20-second intervals, and statistical analyses were performed using SPSS software. An illustrative case of a vestibular schwannoma resected via an RSA using the UAmCT to access the IAC is presented. RESULTS: The IAC was opened in all 5 specimens using both the UAmCT and HSD without complication. The mean peak bone surface temperatures were significantly lower with the UAmCT compared with the HSD ( P < .001). The UAmCT did not meaningfully prolong the operating time in the illustrative case, and the IAC was accessed without complication. CONCLUSION: The UAmCT may be a safe and effective alternative to HSD for IAC opening during vestibular schwannoma resection via the RSA. Larger studies under clinical conditions are required to further validate these findings.

Early Minimally Invasive Removal of Intracerebral Hemorrhage (ENRICH): Study protocol for a multi-centered two-arm randomized adaptive trial.

Background: Intracerebral hemorrhage (ICH) is a potentially devastating condition with elevated early mortality rates, poor functional outcomes, and high costs of care. Standard of care involves intensive supportive therapy to prevent secondary injury. To date, there is no randomized control study demonstrating benefit of early evacuation of supratentorial ICH. Methods: The Early Minimally Invasive Removal of Intracerebral Hemorrhage (ENRICH) Trial was designed to evaluate the minimally invasive trans-sulcal parafascicular surgery (MIPS) approach, a technique for safe access to deep brain structures and ICH removal using the BrainPath® and Myriad® devices (NICO Corporation, Indianapolis, IN). ENRICH is a multi-centered, two-arm, randomized, adaptive comparative-effectiveness study, where patients are block randomized by ICH location and Glasgow Coma Score (GCS) to early ICH evacuation using MIPS plus standard guideline-based management vs. standard management alone to determine if MIPS results in improved outcomes defined by the utility-weighted modified Rankin score (UWmRS) at 180 days as the primary endpoint. Secondary endpoints include clinical and economic outcomes of MIPS using cost per quality-adjusted life years (QALYs). The inclusion and exclusion criteria aim to capture a broad group of patients with high risk of significant morbidity and mortality to determine optimal treatment strategy. Discussion: ENRICH will result in improved understanding of the benefit of MIPS for both lobar and deep ICH affecting the basal ganglia. The ongoing study will lead to Level-I evidence to guide clinicians treatment options in the management of acute treatment of ICH. Trial registration: This study is registered with clinicaltrials.gov (Identifier: NCT02880878).

Radial Forearm Free Flap with Parapharyngeal Pedicle Corridor for Reconstruction of Anterior Skull Base Defects.

BACKGROUND: The radial forearm free flap (RFFF) is an indispensable tool for the reconstruction of a range of defects, including those of the skull base. Several options for routing of the RFFF pedicle have been described, and the parapharyngeal corridor (PC) has been proposed as an option and employed for a nasopharyngeal defect. However, there are no reports of its use for the reconstruction of anterior skull base defects. The objective of this study is to describe the technique for free tissue reconstruction of anterior skull base defects using the RFFF and routing of the pedicle via the PC. METHODS: Relevant neurovascular landmarks and critical surgical steps for reconstruction of anterior skull base defects with an RFFF and routing of the pedicle via the PC are reported using an illustrative clinical case and cadaveric dissections. RESULTS: We present a case of a 70-year-old man who underwent endoscopic transcribriform resection of cT4N0 sinonasal squamous cell carcinoma and was left with a large anterior skull base defect that persisted despite several repair attempts. An RFFF was utilized to repair the defect. This report is the first description of the clinical use of the PC for free tissue repair of an anterior skull base defect. CONCLUSIONS: The PC is an option for routing the pedicle during the reconstruction of anterior skull base defects. When the corridor is prepared as described in this case, a direct route exists from the anterior skull base to cervical vessels, simultaneously maximizing the reach of the pedicle and minimizing the risk of kinking.

Endoscopic Approaches to the Paramedian Skull Base: An Anatomic Comparison of Contralateral Endonasal and Transmaxillary Strategies.

BACKGROUND: The expanded endoscopic endonasal approach (EEA) is limited laterally by the internal carotid artery (ICA). The EEA to the paramedian skull base often requires complex maneuvers such as dissection of the Eustachian tube (ET) and foramen lacerum (FL), and ICA manipulation. An endoscopic contralateral transmaxillary approach (CTMA) has the potential to provide adequate exposure of the paramedian skull base while bypassing manipulation of the aforementioned anatomic structures. OBJECTIVE: To quantify and compare the surgical nuances of a CTMA and a contralateral EEA when approaching the paramedian skull base in cadaveric specimens. METHODS: Five adult cadaveric heads were dissected bilaterally (10 sides) using a contralateral EEA and a CTMA to expose targets of interest at the paramedian skull base. For each target in both approaches, the surgical freedom, angle of attack, the corridor's "perspective angle," and "turning angle" to circumvent the ICA, ET, and FL were obtained. RESULTS: The CTMA achieved superior surgical freedom at all targets ( P < .05) except at the root entry point of cranial nerve XII. The CTMA provided superior vertical and horizontal angles of " attack " to the majority of targets of interest. Except when approaching the root entry point of cranial nerve XII, the CTMA " turning angle " around the ICA, ET, and FL were wider with CTMA for all targets. CONCLUSION: A CTMA complements the EEA to access the paramedian skull base. A CTMA may limit the need for complex maneuvers such as ICA mobilization and dissection of the ET and FL when approaching the paramedian skull base.

Surgical management of spontaneous middle cranial fossa defects: a systematic review and meta-analysis of available reconstructive techniques and materials.

Different materials and techniques have been proposed for surgical repair of spontaneous middle cranial fossa (MCF) defects. However, conclusive evidence supporting their selection and impact on clinical outcomes is lacking. The study aims to conduct a systematic review and meta-analysis on materials and techniques employed to repair MCF defects and evaluate complications and rates of recurrent cerebrospinal fluid (CSF) leaks. A PRISMA-guided systematic review and meta-analysis were performed using MESH terms and specific keywords including studies published before May 2022. Primary outcomes included recurrence of CSF leak and complication rates by type of reconstructive material and technique utilized. Meta-analyses of proportions were performed using random effects and confidence intervals for individual proportions were calculated using the Clopper-Pearson method. Twenty-nine studies were included (n = 471 cases). Materials employed for repair were categorized according to defect size: 65% of defects were of unknown size, 24% were small (< 1 cm), and 11% were large (≥ 1 cm). Rigid reconstruction (RR) was significantly favored over soft reconstruction (SR) for larger defects (94% of cases, p < 0.05). Complications and recurrent CSF leak rates of SR and RR techniques were comparable for defects of all sizes (p > 0.05). Complication rates reported for these procedures are low regardless of technique and material. RR was universally preferred for larger defects and analysis of complication and recurrence rates did not reveal differences regardless of defect size. While RR was more frequently reported in smaller defects, SR was used by several centers, particularly for smaller MCF floor defects.

Quantitative Comparative Analysis of the Endoscope-Assisted Expanded Retrosigmoid Approach and the Far-Lateral Approach to the Inframeatal Area: An Anatomic Study With Surgical Implications.

BACKGROUND: The inframeatal area (IFMA) is a complex anatomic region of the posterior cranial fossa. Given its deep-seated location, tumors involving the IFMA represent a surgical challenge. OBJECTIVE: To objectively compare the endoscope-assisted expanded retrosigmoid approach (ERSA) and the far-lateral supracondylar transtubercular approach (FLTA) to address the IFMA. METHODS: Anatomic dissections were performed on 5 cadaveric heads (10 sides). The ERSAs were performed before and after the FLTAs. The surgical exposure, surgical freedom, and angles of attack to the IFMA were measured and compared for each approach. In addition, 2 illustrative clinical cases are reported. RESULTS: Compared with FLTA, ERSA yielded a nonsignificantly smaller mean area of exposure, whereas FLTA provided a significantly larger mean area of surgical freedom, compared with ERSA ( P = .002). The mean horizontal and vertical angles of attack were significantly different between the approaches. In the vertical plane, FLTA yielded the broadest angle of attack at the root entry zone of the lower cranial nerves (CN; P < .004), whereas ERSA did so at the dural entry zone of CN VII/VIII ( P = .006). In the horizontal plane, FLTA achieved its broadest angle of attack at the root entry zone of the lower CNs ( P = 1.83) while ERSA at the dural entry zone of CN VII/VIII ( P = .37). CONCLUSION: ERSA and FLTA granted a comparable exposure with the IFMA. Although FLTA may afford a larger area of surgical freedom, ERSA may be a suitable alternative to approach the IFMA, particularly to reach the most medial and superior aspects of this region. Conversely, FLTA may facilitate access to more caudally targets.

Contralateral Transmaxillary Approach to Petrous Apex Granuloma with Lateral Maxillotomy: 2-Dimensional Operative Video.

The endoscopic endonasal approach (EEA) has proven to be a valuable tool to access the petrous apex (PA).1 Although lesions located medial to the PA can be easily accessed through an EEA with minimal risk to the internal carotid artery (ICA), more laterally seated lesions represent a surgical challenge. The contralateral transmaxillary approach is an effective extension of the normal EEA to the PA, allowing a more lateral trajectory and thereby reducing the risks connected to paraclival ICA manipulation.2-4 This is a 47-year-old female presenting with tinnitus, hearing loss, and right facial twitching. The preoperative audiogram showed a 60 dB sensorineural hearing loss, and magnetic resonance imaging demonstrated an expansive lesion of the PA with high signal intensity in T1- and T2-weighted sequences. A high-riding jugular bulb ruled out the use of an infracochlear infralabyrinthine approach, and a middle cranial fossa approach was felt to render a high risk of recurrence due to the potential for incomplete resection. Ultimately, a contralateral transmaxillary approach was selected. Due to the extreme lateral position of the lesion, the maxillotomy was created in the lateral wall of the maxillary sinus to allow a coaxial approach to the PA. Postoperatively, the patient did not report new neurologic deficits. Anatomic pathology was consistent with cholesterol granuloma (Video 1). In the surgical management of PA granulomas, recognizing relevant anatomic structures such as the paraclival ICA, cochlea, jugular bulb, and vestibule preoperatively is of paramount importance to tailor the surgical approach and reduce its risks.

A Cost-Effective and Reproducible Cadaveric Training Model for Internal Carotid Artery Injury Management During Endoscopic Endonasal Surgery: The Submersible Peristaltic Pump.

BACKGROUND: Internal carotid artery injury (ICAI) represents one of the most challenging complications in endoscopic endonasal neurosurgery and its rarity results in limited opportunities for trainees and surgeons to achieve proficiency in its management. Currently, available models for ICAI have employed costly systems that prevent their widespread use. The objective of this study is to validate an affordable submersible peristaltic pump (SPP)-based model as a reproducible and realistic paradigm for ICAI management training. METHODS: A laceration of the left parasellar internal carotid artery was purposely carried out in 2 human cadaveric heads. A blood substitute was perfused to ensure a perfusion flow of 1 L/min using an affordable SPP. A cohort of 20 neurosurgery and otolaryngology residents, fellows, and attendings were enrolled to evaluate the realism and content validity of the model using a validated 5-grade questionnaire. RESULTS: The model proved to mimic a real intraoperative scenario of ICAI with an expected output flow of 1 L/min. Questionnaire responses reported a realistic experience and the impact of this model on improving trainee surgical coordination and capability to rehearse the most accepted repair technique. The use of a fixed noninjected head allowed the reproducibility of the training session without the additional cost of new fresh-frozen heads. The affordable SPP allowed an impactful reduction of ICAI model training expenses maintaining high realism. CONCLUSIONS: The SPP-based ICAI model with noninjected cadaveric specimens is an affordable and cost-effective system that allows reproducibility and realism. These qualities favor greater adoption in neurosurgery and otolaryngology training curricula.

Neurophysiology-Guided Laser Interstitial Thermal Therapy: A Synergistic Approach For Motor Function Preservation. Technical Note.

BACKGROUND: Laser interstitial thermal therapy (LITT) is a minimally invasive ablative technique with specific indications for neuro-oncology, especially in the case of lesions in eloquent areas. Even being performed through a small catheter under stereotactic conditions, the risk of damaging vital structures such as white matter tracts or cortical eloquent areas is not negligible. The mechanism of damage can be related to catheter insertion or to excessive laser ablation. An accurate preoperative workup, aimed at locating the eloquent structures, can be combined with a real-time intraoperative neurophysiologic monitoring to reduce surgical morbidity while maximizing the efficacy of LITT. METHODS: We developed a synergistic approach for neurophysiology-guided LITT based on state-of-the-art technologies, namely, magnetoencephalography, diffusion tensor imaging, and intraoperative neurophysiologic monitoring. RESULTS: As a result, we improved the planning phase thanks to a more precise representation of functional structures that allows the simulation of different trajectories and the identification of the most suitable trajectory to treat the lesion while respecting the functional boundaries. Catheter insertion is conducted under continuous neurophysiologic feedback and the ablation phase is modeled on the functional boundaries identified by stimulation, allowing it to be extremely accurate. CONCLUSIONS: An integrated approached guided by neurophysiology is able to reduce the surgical morbidity even in a relatively accurate technique such as LITT. To the best of our knowledge, this represents the first report on this synergistic approach which could really impact the treatment of tumors in eloquent areas. Future studies are needed in the effort to implement this approach in functional or epilepsy neurosurgery as well.

Exoscope-Assisted Middle Cranial Fossa Approach for Repair of Tegmental Defects: A Cadaveric and Clinical Study.

BACKGROUND: Recent studies highlighted how exoscopes may be employed to approach the lateral skull base. The use of exoscope-assisted procedures to repair middle cranial fossa (MCF) defects has not been fully explored. The surgical microscope in the same circumstances has been associated with relevant limitations, such as its physical obstruction, among others. The aim of this study was to present a proof of concept of exoscope-assisted surgery for MCF defects. METHODS: A detailed step-by-step MCF approach was performed on 2 alcohol-preserved, latex-injected cadaveric specimens under exoscopic magnification. An illustrative clinical case of encephalocele secondary to a spontaneous tegmen tympani defect repaired via an exoscope-assisted MCF approach was presented. RESULTS: The most common sites of MCF defects, the tegmen tympani and the arcuate eminence, were successfully exposed under exoscopic magnification. Dissection was easily performed; no damage to the dura mater or to vascular or neural structures occurred. In the clinical case, the exoscope-assisted technique demonstrated adequate maneuverability and magnification quality. After localization, the encephalocele was resected, and the MCF defect was repaired. The surgeon's position was comfortable, and operative time was not prolonged. CONCLUSIONS: The exoscope allows adequate exposure of the MCF floor with identification and preservation of key anatomical structures. The exoscope represents a valuable alternative to the microscope in reconstruction of MCF defects, offering high-quality magnification and proven maneuverability.