Skull Base Research Articles

Safety and aesthetic evaluation of autologous dermal fat grafts for lateral Skull base defect reconstruction

ObjectiveThe selection of appropriate materials and techniques for reconstructing skull base defects is crucial for restoring function, minimizing complications, and enhancing aesthetics. Dermal fat grafts (DFGs) have been established in many surgeries for contour correction. However, there is little literature describing the application of free dermal fat grafts for reconstruction of lateral skull base surgery defects. Therefore, the aim of this study was to evaluate the clinical effect of using free dermal fat grafts in the reconstruction of lateral skull base defects.MethodsIn this study, 32 patients who underwent primary autologous free dermal fat graft reconstruction for lateral skull base defects were enrolled. Postoperative complications both in the donor and recipient area were evaluated. Three-dimensional (3D) reconstruction techniques were applied to visualize the fat graft shape and volume variations for the assessment of postoperative restoring function. A telephone questionnaire was used for the assessment of postoperative facial aesthetics and patient satisfaction.ResultsA total of 32 patients who met the inclusion criteria were included in the study, showing satisfying results in safety and aesthetics. Participants’ ages averaged at 42.03 years, with the youngest being 18 and the oldest at 75 years old. No patient had postoperative complications of abdominal wounds in the donor area, only two patients had postoperative infections and one patient had a postoperative effusion in the recipient area. The volume of the grafts ranged from a minimum of 24.4 cm³ to a maximum of 131 cm³, with the highest recorded resorption volume being 33.63 cm³. The average resorption rate of the dermal fat graft was 24.36%, ranging from a minimum of 11% to a maximum of 43%. 3D reconstruction based on MRI imaging data indicated that DFGs have a lower resorption rate than traditional free fat grafts. The telephone questionnaire revealed high patient satisfaction with facial aesthetics, with the majority rating their outcomes positively.ConclusionsDermal fat grafts have fewer complication and can provide better resistance to infection and radiation aspect. Based on 3D reconstruction techniques via MRI imaging data, we found that dermal fat grafts have lower resorption rate than traditional free fat grafts, which can be a suitable material for reconstruction of lateral skull base defects.

Causes and treatment of secondary sphenoid sinus infection post‐endoscopic transsphenoidal approach

AbstractObjectiveThis study analyzed the causes of sphenoid sinus (SS) infection (SSI) following endoscopic transsphenoidal skull base surgery and determined appropriate treatment methods.MethodsThis study included 31 cases of secondary SSI following the endoscopic transsphenoidal approach (ETSA; SSI group) and 246 cases without SSI (non‐SSI group). Data collected included post‐ETSA pathological results, types of artificial skull base reconstruction materials, and SS patency. For the SSI group, data included time from ETSA to symptom onset, endoscopic and imaging findings, intraoperative conditions during the second surgery, and changes in visual analog scale (VAS) scores.ResultsThe incidence of secondary SSI was 11.19%. In the SSI group, 26 patients (83.87%) reported headaches, and 24 (77.42%) had stenosis or closure of the SS ostium (SSO). The non‐SSI group reported no symptoms, and 236 patients (95.93%) had well‐opened SSOs. Centripetal hyperosteogeny (CHO) in the SS walls was observed in 20 patients (64.5%) in the SSI group. Absorbable materials were used in five cases (16.13%) and 215 cases (87.40%) in the SSI and non‐SSI groups, respectively, while non‐absorbable materials were used in 24 cases (77.42%) and 20 cases (8.13%), respectively. SSI risk was 9.42 times higher with non‐absorbable synthetic materials. VAS scores for SSI symptoms and Lund–Kennedy scores significantly decreased at 3 and 12 months post‐second surgery.ConclusionSecondary SSI after ETSA can cause persistent symptoms. Non‐absorbable synthetic repair materials should be avoided to prevent secondary SSI. Extended sphenoidectomy and removal of artificial materials can lead to rapid resolution of SSI symptoms.Level of Evidence4.

Mind the Gap: The Journey of Skull Base Specialties Toward Gender Parity

Abstract Background There are increased efforts to promote gender diversity in skull base specialties. Aims/Objectives This study seeks to evaluate changes within neurotology, rhinology, and skull base neurosurgery (SBNS) over the past decade. Methods Information regarding fellows training in the past 10 years, current faculty members and fellowship directors, and grants and awards were extracted from the American Neurotology Society, American Rhinologic Society, and North American Skull Base Society Web sites, tabulated, and summarized. Chi-square analysis compared the proportional makeup of female fellows within related fields. Results In the past decade in neurotology, men constituted 89 of 128 (69.53%) fellows, 132 of 170 (77.64%) faculty members, and 25 of 29 (86.2%) fellowship directors. Within rhinology, men constituted 211 of 279 (75.63%) fellows, 113 of 141 (80.14%) faculty members, and 32 of 35 (91.4%) fellowship directors. In SBNS programs, men constituted 94 of 105 (90%) fellows, 120 of 133 (90%) faculty members, and 43 of 44 (97.73%) fellowship directors. In neurotology fellowships, the proportion of women increased (12%, p = 0.06) from 2012–2017 to 2018–2022. Similarly, SBNS and rhinology had statistically insignificant increases of 4.28% (p = 0.86) and 8.70% (p = 0.87). Conclusion The representation of women is consistent across all three skull base specialties. Although the overall number of women in each field is increasing, it changes slowly. Significance The gender makeup across all three skull base specialties is similar.

The feasibility and clinical outcome of endoscopic transorbital transcavernous approaches with or without petrosectomy for petroclival lesions.

Petroclival tumors such as petroclival meningiomas or trigeminal schwannomas extending to the posterior cranial fossa are challenging to treat due to their deep-seated location and proximity to critical neurovascular structures. This study aimed to evaluate the feasibility, safety, and clinical outcomes of endoscopic transorbital surgery for the resection of central skull base tumors involving the petroclival area. The authors conducted a retrospective analysis of 32 patients with petroclival tumors including meningiomas and trigeminal schwannomas who underwent endoscopic transorbital surgery between September 2017 and December 2022. Preoperative clinical and radiological data were collected, and patients were followed up postoperatively for a median period of 34.7 months. Surgical technique, complications, and clinical outcomes were assessed. Endoscopic transorbital surgery provided a minimally invasive and direct corridor to the petroclival region. All 32 patients successfully underwent tumor resection, with gross-total or near-total tumor resection achieved in 28 patients. The mean tumor diameter was 3.5 cm. Based on tumor pathology, the endoscopic transorbital transcavernous trans-Meckel's cave approach (21 cases) or transorbital anterior transpetrosal approach (11 cases) was selected. The most common complication was facial paresthesia in 4 of 21 patients with trigeminal schwannomas and in 1 of 11 patients with petroclival meningiomas. Diplopia due to fourth cranial nerve injury occurred in 3 of 11 patients with petroclival meningiomas. Postoperative clinical improvement in neuralgic pain was observed in 3 of 4 patients. One patient developed a temporary facial palsy (House-Brackmann grade III) and another patient had transient paraparesis after removal of petroclival meningioma. Endoscopic transorbital surgery appears to be a safe and effective technique for the resection of petroclival lesions, offering excellent visualization and access to the tumor while minimizing morbidity. However, further studies with larger patient cohorts and longer follow-up are warranted to validate the long-term efficacy and safety of this approach. This study contributes to the growing body of evidence supporting the utility of endoscopic transorbital techniques in skull base surgery.

Transoral penetrating craniocerebral injury: a case report and literature review

A penetrating brain injury is a rare type of neurosurgical trauma associated with extremely high mortality and disability rates. Penetrating skull base injuries caused by arrows seldom occur because injuries caused by such weapons are more likely to be accidental. However, the number of self-inflicted injuries is increasing, and these injuries have varying patterns and high mortality rates. We report a case of a transoral penetrating craniocerebral injury caused by an arrow in a suicidal patient. Preoperative imaging is crucial for detecting and planning the surgical approach. Surgery is an effective treatment for this type of injury. Additionally, we reviewed previous case reports on this type of injury to provide recommendations for its clinical detection and treatment.

Development and validation of a predictive scoring model for complications following endoscopic endonasal skull base surgery.

The endoscopic endonasal approach (EEA) has evolved into an established technique in skull base surgery. The authors previously examined 1002 EEA procedures and reported factors associated with postoperative complications. Here they report the development and validation of a scoring model based on risk factors to better predict complications following EEA. The authors developed an optimized EEA scoring model for predicting postoperative complications as evidenced by the area under the receiver operating characteristic (AUROC) curve using their previously published data in addition to data collected from the subsequent 292 EEA procedures from years 2010-2020. The model was built systematically by evaluating the contributions that different variables had on the overall predictive ability of the model. The aim was to design a model containing as few variables as possible for practicality and to facilitate calculation and use at the bedside. The Clavien-Dindo grading system was used to classify complications into grades I-V based on the level of intervention that was required to manage the complication, with grades III-V considered to be higher-grade (i.e., those requiring reoperation or ICU-level care or death). The authors identified 1294 EEA operations performed between July 2010 and July 2020 that met their inclusion criteria. Higher-grade complications were identified following 135 EEA operations. The variables that were ultimately included in the model were age, BMI, operative time, meningioma, chordoma, expanded intradural approach, and nasoseptal flap use. The final model yielded an acceptable AUROC curve of 0.72 and predicted a stepwise increase in the rate of higher-grade complications as the score increased. A score of 0-2 (low) on the grading system was associated with an average complication rate of 5.1%. A score of 3-5 (medium) was associated with an average complication rate of 12.6%. A score of 6 or above (high) was associated with an average complication rate of 26%. This EEA complications scoring model accurately categorizes patients into low-, medium-, and high-risk groups with readily obtained variables. A high score in this complications model does not suggest that a patient is ineligible for surgery, but rather highlights the importance of thorough case selection, operating with caution, and appropriate preoperative counseling.

Biphenotypic Sinonasal Sarcoma: Literature Review of a Peculiar Pathological Entity—The Neurosurgical Point of View

Background: Biphenotypic sinonasal sarcoma (BSNS) is a low-grade tumor of the sinonasal tract with frequent extension to the orbit and skull base. Due to its rare incidence and recent histopathological and molecular characterization, little data are available in regard to its natural history, treatment and surveillance protocol. Methods: A comprehensive literature review in Embase online electronic databases on BSNS was made. The analyzed factors included the patients’ sex and age, presenting symptoms and signs, anatomical origin and pattern of growth of the tumor, immunohistochemical and molecular features, time to treatment, type of treatment, surgical approach, extent of resection, peri- and post-operative complications, adjuvant therapies, clinical outcome, recurrence and overall survival rates. Results: This literature review involved 34 studies for an overall series of 149 cases of BSNS. The female (66.9%) and middle-aged populations (median 54.88 years old) were mainly affected. The most frequent clinical onset was nasal obstruction (81%), followed by facial discomfort (44%), epistaxis (15.5%) and ocular impairment (14.3%). Ethmoid sinus (67.8%) and nasal cavity (45.4%) were the most common anatomical site of tumor origin, while an extension to the orbit and skull base was registered in 28.7% and 24.5% of cases. Surgery was the main treatment, especially in the form of endoscopic endonasal approach (56.9%), and allowed for gross total resection in 79% of cases. The recurrence rate was 26.2%; three cases of tumor-related death were reported. Median follow-up was 4.6 years. Conclusions: Biphenotypic sinonasal sarcoma is a rare and unique tumoral entity in terms of biological and clinical behavior. Based on the current knowledge, surgery plays the leading role in treatment, accounting for gross total tumor resection in most cases, allowing for clinical symptom and sign resolution and presenting a low rate of perioperative complications. The type of approach and the aim of surgery should be assessed case by case according to patient and pathology features and the surgeon’s experience, as well as the aim of the treatment. Further studies including large surgical series and with long follow-up are required to define prognostic factors and guidelines of treatment for this peculiar pathological entity.

Prolonged use of chlormadinone acetate and risk of intracranial meningioma: A population-based cohort study.

Chlormadinone acetate (CMA) is a synthetic progestin for which cases of intracranial meningioma have been reported following prolonged exposure. An observational cohort study was conducted based on the French national health data system. Women aged 10-70 years and who started CMA between 2007 and 2017 were included. Participants were considered to be exposed if they had received a cumulative dose >360 mg of CMA during the first 6 months and very slightly exposed (control group) when they had received a cumulative dose ≤360 mg. The outcome was surgery or radiotherapy for one or more intracranial meningioma(s). Poisson models assessed the relative risk (RR) of meningioma. In total, 828,499 women were included: 469,976 in the exposed group (mean age 39.1 years, SD 10.1) and 358,523 in the control group (38.3 years, SD 11.0). Surgery or radiotherapy for intracranial meningioma between 2007 and 2017 was recorded for 164 and 104 women in the exposed and control groups, respectively. The incidence of meningioma was 18.5 and 6.8 per 100,000 person-years for the exposed and control groups respectively (crude RR = 2.7, 95% confidence interval [CI] 2.1-3.5; age-adjusted RR = 3.1, 95% CI 2.4-4.0). Meningioma incidence reached almost 47 cases/100,000 person-years in the most exposed group (>8.64 g), giving an age-adjusted RR of 6.9, 95% CI 5.1-9.2, relative to the control group. A strong dose-effect relationship was observed between prolonged use of CMA and risk of meningiomas. As with other progestogens, meningiomas associated with CMA are more likely to be found at the base of the skull.

The Impact of Venous Stenting for Patients with Idiopathic Intracranial Hypertension and Spontaneous Cerebrospinal Fluid Leak on Symptoms and Quality of Life

BACKGROUND: Elevated intracranial pressure can cause skull base defects and a spontaneous cerebrospinal fluid leak (CSF). Venous sinus stenting (VSS) has emerged as a promising treatment option for patients with a CSF leak in the setting of idiopathic intracranial hypertension (IIH). There is a lack of literature on symptomatology and quality of life (QOL) after VSS for IIH patients with a CSF leak. This study explores the effects of VSS on symptoms and QOL in IIH patients with a CSF leak. METHODS: This is a retrospective study on patients who have IIH complicated by a CSF leak and underwent VSS. A QOL questionnaire was developed from the migraine disability assessment test and the PROMIS-PI was given to patients included in this study. RESULTS: Ten patients were included in this study. Nine patients underwent endoscopic closure of CSF prior to stent placement and one patient was treated with VSS only. There was no evidence of CSF leak recurrence in this population following VSS. Headaches improved in 5/8, tinnitus in 5/6, and visual disturbance in 4/5 patients. Diamox was discontinued in 7 out of 8 patients after VSS. There was an improvement in headache (p=0.0140) specific questions and overall QOL (p=0.0061) on the QOL questionnaire. DISCUSSION: This preliminary study demonstrates that VSS is effective in alleviating many symptoms in IIH patients with a CSF leak, especially headaches. Diamox may be able to be discontinued in many patients following VSS. No CSF leak recurrence was noted in this patient population.

Paraganglioma With Intracranial Invasion Demonstrated on 68Ga-DOTATATE PET/CT.

68Ga-DOTATATE PET/CT demonstrates superior sensitivity compared with other cross-sectional and functional imaging techniques in detecting head and neck paragangliomas. It is the primary recommended imaging modality for the evaluation of head and neck paragangliomas, especially in patients suspected of having locally aggressive, multifocal, or metastatic disease, as well as those being considered for targeted peptide-receptor therapy. Herein, we demonstrate the 68Ga-DOTATATE PET/CT findings of a skull base paraganglioma with extensive local invasion and intracranial extension.

Imaging characteristics and treatment strategies for carotid artery occlusion caused by skull base fracture.

The internal carotid artery occlusion caused by head and neck trauma, also known as traumatic intracranial artery occlusion, is relatively rare clinically. Traumatic skull base fracture is a common complication of traumatic brain injury. Traumatic skull base fracture is one of the causes of traumatic internal carotid artery occlusion. If not detected early and treated in time, the prognosis of patients is poor. This editorial makes a relevant analysis of this disease.

British Skull Base Society Consensus on Vestibular Schwannoma Surveillance

Abstract Objective Surveillance plays a crucial role in managing patients with vestibular schwannomas (VSs). Consensus is lacking on the optimal duration, frequency, and modality of imaging. Standardizing this approach would ensure safe and effective care, reduce patient distress, and promote consistency in management decisions among clinicians. Methods In July 2022, a multi-disciplinary Delphi consensus was conducted at the British Skull Base Society Meeting. Expert United Kingdom-based skull-base surgeons and neuroradiologists were presented semi-systematic literature reviews summarizing current evidence on VS management. Anonymized opinions were collated and discussed to reach a majority vote, which was deemed the final consensus opinion. Results Recommendations for VS managed by surveillance are: (1) surveillance frequency should decrease over time; (2) surveillance may be discontinued when the remaining lifetime risk of VS growth is <0.5% (∼8.5 years); (3) factors such as age, VS size, VS location, and cystic components should be considered. Surveillance after surgery or radiotherapy has limited evidence but recommendations are: (4) surveillance should be adjusted based on residual tumor size or nodular enhancement. Imaging modality and sequences are recommended to be (5) high-resolution magnetic resonance imaging with T1, T2, FIESTA/CISS multiplanar sequences, contrast is not required in untreated cases, and linear reporting of measurements is pragmatically sufficient. Conclusion This consensus and literature review provides an evidence and expert opinion–based guide to help clinicians with the surveillance of patients with VS. Further research should focus on better understanding the dynamic nature of growth risks and the growth characteristics of postintervention VS to enable personalized growth risk stratification.

Using Indocyanine Green Fluorescence Angiography to Evaluate the Impact of Surgical and Patient Factors on Posterior Septal Artery Perfusion in Endoscopic Skull Base Surgery

Abstract Background Nasoseptal flaps (NSF), perfused by the posterior septal artery (PSA), are heavily utilized in endonasal skull base surgery (ESBS). We use indocyanine green (ICG) fluorescence angiography to assess PSA perfusion. Methods A prospective study of adult ESBS patients assessed PSA perfusion using intraoperative ICG. PSA ICG fluorescence intensities (FIs) were quantified. Factors analyzed included demographics, comorbidities, prior sinonasal surgery, surgical approach, concurrent septoplasty, NSF harvest timing, and flap-related complications. t-Tests compared significant ICG baseline differences and changes from baseline. ICG enhancement was compared with postoperative magnetic resonance imaging (MRI). Results A total of 54 patients were studied. Of these, 35 NSFs were harvested, while the remaining 19 underwent cuts for rescue flaps. Mean PSA FI changed from baseline 118.1 ± 28.6 to 114.4 ± 32.3 following reconstruction. Tobacco users had lower baseline FI compared with non-tobacco users (78.3 ± 62.8 vs. 118.4 ± 29.1, p = 0.003). Transpterygoid approaches showed greater decrease from baseline (−25.8 ± 58.9 vs. −3.8 ± 32.1, p = 0.035) than transsphenoidal. No other studied factors, including revision case, timing of flap harvest, flap side, division of palatosphenoidal artery, or concurrent septoplasty, had a significant influence on ICG intensity. In total, 34 of 35 NSFs were viable. ICG fluorescence had a 100% sensitivity, 0% specificity, and 96.6% positive predictive value (PPV) for NSF viability, while MRI enhancement had a 100% sensitivity, 100% specificity, and 100% PPV for NSF viability. Conclusion ICG angiography may provide an intraoperative assessment of flap viability with comparable PPV as postoperative MRI. Tobacco use and transpterygoid approaches may be associated with decreased PSA perfusion.

A novel therapeutic pathway to the human cochlear nerve.

Traditional approaches to the human cochlear nerve have been impeded by its bony encasement deep inside the skull base. We present an innovative, minimally invasive, therapeutic pathway for direct access to the nerve to deliver novel regenerative therapies. Neuroanatomical studies on 10 cadaveric human temporal bones were undertaken to identify a potentially safe therapeutic pathway to the cochlear nerve. Simulations based on three-dimensional delineation of anatomical structures obtained from synchrotron phase-contrast imaging were analyzed. This enabled the identification of an approach to the nerve in the fundus of the internal auditory meatus by trephining the medial modiolar wall of the cochlea via the round window for a median depth of 1.48mm (range 1.21-1.91mm). The anatomical access was validated on 9 additional human temporal bones using radio-opaque markers and contrast injection with micro-computed tomography surveillance. We thus created an effective conduit for the delivery of therapeutic agents to the cochlear nerve.

Phosphaturic Mesenchymal Tumor and Tumor-Induced Osteomalacia: A Report of 5 Cases, Including 2 Skull Base Cases With Arterial Spin Label Perfusion

Phosphaturic Mesenchymal Tumor and Tumor-Induced Osteomalacia: A Report of 5 Cases, Including 2 Skull Base Cases With Arterial Spin Label Perfusion

A challenging discrimination of an intensely [18F]PSMA-1007-avid solitary lesion at the skull base in a patient with biochemical recurrence of prostate cancer

A challenging discrimination of an intensely [18F]PSMA-1007-avid solitary lesion at the skull base in a patient with biochemical recurrence of prostate cancer

Integration of Augmented Reality in Temporal Bone and Skull Base Surgeries

Augmented reality technologies provide transformative solutions in various surgical fields. Our research focuses on the use of an advanced augmented reality system that projects 3D holographic images directly into surgical footage, potentially improving the surgeon’s orientation to the surgical field and lowering the cognitive load. We created a novel system that combines exoscopic surgical footage from the “ORBEYE” and displays both the surgical field and 3D holograms on a single screen. This setup enables surgeons to use the system without using head-mounted displays, instead viewing the integrated images on a 3D monitor. Thirteen surgeons and surgical assistants completed tasks with 2D and 3D graphical surgical guides. The NASA Task Load Index was used to assess mental, physical, and temporal demands. The use of 3D graphical surgical guides significantly improved performance metrics in cochlear implant surgeries by lowering mental, physical, temporal, and frustration levels. However, for Bonebridge implantation, the 2D graphical surgical guide performed better overall (p = 0.045). Participants found the augmented reality system’s video latency to be imperceptible, measuring 0.13 ± 0.01 s. This advanced augmented reality system significantly improves the efficiency and precision of cochlear implant surgeries by lowering cognitive load and improving spatial orientation.

Retrolabyrinthine approach to the lateral skull base: The value of preoperative temporal bone CT analysis

PurposeThe most used neurosurgical approach to reach cerebellar-pontine angle is the retrosigmoid route. This article describes the presigmoid approach which requires excellent knowledge of the labyrinthine block together with quantitative analysis of temporal bone CT. MethodsCT-based quantitative measurements were obtained in patients undergoing vestibular neurectomy with a presigmoid approach. Eighteen patients were enrolled, and five measures were taken: Trautmann’s area, the petro-clival angle, presigmoid dura length and its angle. The relationship between these measurements and hospitalization days, operating times, and complications was explored. ResultsThe posterior semicircilar canal (PSC)-sigmoid sinus (SS) distance, presigmoid dura- internal auditory canal (IAC)-PSC angle, and duration of surgery are predictors of complications. Specifically, a PSC-sigmoid sinus distance <11 mm, a dura presig-IAC-PSC angle <14 are associated with the highest risk of complications. ConclusionPreoperative temporal bone CT scan can guide the surgeon through the narrowest areas of the surgical approach. Trautmann’s triangle area and petro-clival angle reduction are challenging and can be faced with combined microscopic-endoscopic technique, and with optics angulation-rotation. The retrolabyrinthine approach can enable hearing preservation and minimal cerebellar retraction.

Use of Ultra-Short Echo Time MRI to Improve Temporal Bone Imaging.

The short T2 nature of cortical bone causes it to appear similar to air on MR, forcing clinicians to rely on computed tomography imaging, with its attendant ionizing radiation exposure, to define temporal bone structures. Through the use of novel MR sequences with ultra-short echo times (UTE), short T2 structures are now able to be visualized, allowing for improved understanding of anatomical relationships. Eight patients (50% female) undergoing MR imaging of the skull base for diagnostic purposes (62.5% for vestibular schwannoma surveillance) at a tertiary care center were enrolled to evaluate the safety and efficacy of UTE imaging. CT scans were completed in 37.5% of the patients as part of their workup and used for comparison purposes. The repetition time, short echo time, and long echo time for the UTE sequence were 11, 0.032, and 2.2 msec, respectively. The protocol added 6 min to the total scanning time, and all patients tolerated the sequence without issue. The ossicles, mastoid air cells, antrum, and epitympanum were able to be seen and had a high Dice similarity coefficient when compared to CT (>0.5). UTE allowed for clear delineation of all segments of the facial nerve with a signal-to-noise ratio of 35 (although the BRAVO sequences had a superior ratio of 140). Vestibular schwannomas were able to be distinguished from normal brain parenchyma. UTE is safe and effective for visualizing anatomic structures not normally seen on traditional MRI, potentially allowing for improved surgical planning in patients. 3 Laryngoscope, 134:4691-4696, 2024.

Surgical Management of Skull base and Spinal Chordomas: A Case Series with Comprehensive Review of the Literature

Surgical Management of Skull base and Spinal Chordomas: A Case Series with Comprehensive Review of the Literature