Surgical management of chondrosarcomas of the skull-base and temporal bone.

OBJECTIVES: To analyze the overall long-term outcome of surgically treated skull base and temporal bone chondrosarcomas. METHODS: The medical records of patients with surgically treated skull base and temporal bone chondrosarcomas between 1983 and 2024 were thoroughly evaluated. RESULTS: Out of a total of over 5000 skull base surgeries performed at our center, only 29 patients had histopathologically confirmed chondrosarcomas of the skull base and temporal bone. The mean of patients age was 45.6, and the male-to-female ratio was 1.9:1. The most common symptoms included hearing loss (58.6%), tinnitus (41.4%), diplopia (31%), dysphonia (24.1%), dysphagia (20.7%), vertigo (10.3%), and dizziness (10.3%). The most frequent locations of lesions among the 29 patients are as follows: petroclival region (34.5%), jugular foramen (27.6%), petrous apex (17.2%), middle ear (13.8%), others (3.4%). TO, IFTA, IFTB, IFTC, POTS, and combined surgical approaches were commonly used. The rate of gross total removal and recurrence was 82.6% and 13.8% respectively. The follow-up duration of 6 patients was more than five years and less than ten years whereas ten patients had more than ten years of follow-up. CONCLUSIONS: Chondrosarcoma of the skull base and temporal bone is a very rare pathology. Due to its multiple potential sites of origin and histological specificity, it presents us with significant challenges. Gross total removal is the primary treatment for chondrosarcoma of the skull base and temporal bone. Personalized decision-making should be considered based on the following aspects: tumor, patient, and surgeon's factors. Postoperative radiation therapy is complementary to surgical treatment in grades II and III lesions to achieve long-term survival.

Trigeminal Schwannoma Surgery: Challenges in Preserving Facial Sensation.

Treatments of schwannoma have dramatically improved in the previous few decades, but preservation of the functions of the originating nerve, such as facial sensation in trigeminal schwannomas, still remains challenging. As the preservation of facial sensation in trigeminal schwannomas has not been analyzed in detail, we here review our surgical experience of more than 50 trigeminal schwannoma patients, particularly focusing on their facial sensation. Since the facial sensation in each trigeminal division showed a different perioperative course even in a single patient, we investigated patient-based outcomes (average of the three divisions in each patient) and division-based outcomes separately. In the evaluation of patient-based outcomes, facial sensation remained postoperatively in 96% of all the patients, and improved in 26% and worsened in 42% of patients with preoperative hypesthesia. Posterior fossa tumors tended to most rarely disrupt facial sensation preoperatively, but were the most difficult to preserve facial sensation postoperatively. Facial pain was relieved in all six patients with preoperative neuralgia. In the division-based evaluation, facial sensation remained postoperatively in 83% of all the trigeminal divisions, and improved in 41% and worsened in 24% of the divisions with preoperative hypesthesia. The V3 region was most favorable before and after surgery, with the most frequent improvement and the least frequent functional loss. To clarify current treatment outcomes of the facial sensation and to achieve more effective preservation, standardized assessment methods of perioperative facial sensation may be required. We also introduce detailed MRI investigation methods for schwannoma, including contrast-enhanced heavily T2-weighted (CISS) imaging, arterial spin labeling (ASL), and susceptibility-weighted imaging (SWI), preoperative embolization for rare vascular-rich tumors, and modified techniques of the transpetrosal approach.

Neuroendoscopy: intraventricular and skull base tumor resection in children.

During the last 30 years, the neurosurgeons have witnessed a revolution in the practice of interventricular surgery. The advent of neuroendoscopy at the end of the 1980s has allowed a minimally invasive management of a very large series of pathologies in pediatric neurosurgery ranging from hydrocephalus to arachnoid cyst to intraventricular tumors. The progresses in the management of hydrocephalus, intracranial cyst, and the fluid filled collection nevertheless has been more rapid and radical due to the simpler equipment that is necessary to perform this kind of surgery. The intraventricular tumors instead have been addressed in a slower way, and for many years, the only endoscopic procedure that was allowed on interventricular tumors was a biopsy associated with the management of hydrocephalus. Only very small tumors have been considered operable for complete removal during many years due to the limitations of the neuroendoscopic equipment and to the small calibers of the working channel. More recently, the advent of new devices and new surgical techniques are offering new perspectives on the possibility of intraventricular tumor surgery in children. In this review, we describe the historical perspective of the learning curve of intraventricular tumor surgery under neuroendoscopic control and try to offer a view of the future perspective in the removal of larger intraventricular tumors, analyzing the main indications for intraventricular endoscopic tumor surgery. We offer as well an historical perspective of the evolution of skull base surgery and endonasal transsphenoidal approach for skull-based tumors in children. This kind of surgery that has acquired widespread acceptance for many pathologies in adult age has diffused more slowly in pediatric neurosurgery due to the anatomical limitation observed in these age range. Also in this field, the slow evolution of the technique and of the technology available to neurosurgeons has allowed a very significant expansion of indication for the minimally invasive removal of skull base tumors in children.

Management principles of cranial base tumor with aneurysm.

Skull base tumors are challenging to treat because of their deep location, complex anatomy, and close proximity to important blood vessels and nerves. Furthermore, some patients with cranial tumors are found to have aneurysms, but there is no consensus on how to evaluate the impact of aneurysms on surgery and how to handle the lesions safely and effectively. We retrospectively reviewed our database to identify all patients with a skull base tumor treated in the Department of Neurosurgery of Beijing Tiantan Hospital affiliated with Capital Medical University from 2019 to 2021. The records of patients with skull base tumors associated with aneurysms were analyzed. The operative methods and postoperative follow-up information were collected. We analyzed a total of 481 patients with skull base tumors, comprising 224 males and 257 females with a mean age of 48 ± 14 years. Twenty-four patients (24/481, 5.0%) were diagnosed with aneurysms. For eight patients, it was considered necessary to perform aneurysm treatment before or during the tumor resection surgery. For the other 16 patients, the recommendation was to monitor the aneurysm or perform elective aneurysm treatment after tumor resection. All patients with both skull base tumors and aneurysms benefited from treatment. No severe postoperative complications occurred. We summarized the final treatment plan for all patients with skull base tumors with aneurysms and proposed a protocol to decrease the surgical risk of patients with skull base tumors associated with aneurysms.

Dermoid cyst of the infratemporal fossa: a case report of surgical resection by infratemporal fossa type B approach.

OBJECTIVE: This is a case report of a dermoid cyst located in the infratemporal fossa and its surgical removal using infratemporal fossa type B approach. CASE REPORT: A 15-year-old male was referred from a local clinic after an incidental finding of a mass lesion in the skull base area on computed tomography (CT). Pre-operative magnetic resonance imaging showed a large cystic mass lesion, expanding to the foramen ovale with fat component in the right infratemporal fossa region. The lesion was completely excised using an infratemporal fossa type B approach. CONCLUSION: An extremely rare case of dermoid cysts of the infratemporal fossa was managed with infratemporal fossa type B approach without severe complication.

[Trigeminal neuromas: modern diagnosis and treatment]. / Trigeminal'nye nevrinomy: sovremennaya diagnostika i lechenie.

Trigeminal neuroma (TN) is a benign neoplasm arising from trigeminal nerve sheath. The tumor can grow from any part of the nerve from the root in posterior cranial fossa to peripheral extracranial branches. Symptoms of trigeminal neuroma are variable and usually depend on location and dimensions of tumor. We present a review devoted to the problem of TN. Surgery was the only possible option in patients with TN for a long time. However, radiotherapy became one of the options and sometimes alternative to surgical treatment since the late 1980s. Besides active management of patients with TN, follow-up with regular radiographic control of small asymptomatic tumors also seems to be reasonable. When evaluating treatment outcomes, physicians consider quality of life and return to previous work and activity in addition to resection quality, neurological impairment, relapse-free period and tumor growth control. However, assessment of these indicators after certain treatment is rare. Thus, it is difficult to determine treatment strategy with maximum ratio of effectiveness and quality of life. Therefore, optimization of TN treatment is currently an urgent problem that requires further study.

[Surgical and combined treatment of patients with craniovertebral junction meningioma: a single-center retrospective study of 196 cases]. / Analiz rezul'tatov khirurgicheskogo i kombinirovannogo lecheniya patsientov s meningiomami oblasti kraniovertebral'nogo perekhoda: odnotsentrovoe retrospektivnoe issledovanie 196 sluchaev.

Treatment of craniovertebral junction meningioma is a difficult task. Surgical treatment is the gold standard for these patients. However, it is associated with high risk of neurological impairment, while combined treatment (surgery + radiotherapy) provides more favorable outcomes. OBJECTIVE: To present the results of surgical and combined treatment of patients with craniovertebral junction meningioma. MATERIAL AND METHODS: There were 196 patients with craniovertebral junction meningioma who underwent surgical or combined (surgery + radiotherapy) treatment at the Burdenko Neurosurgery Center between January 2005 and June 2022. The sample included 151 women and 45 men (3.4:1). Resection of tumor was performed in 97.4% of patients, craniovertebral junction decompression with dural defect closure - 2%, ventriculoperitoneostomy - 0.5%. As the second stage, 40 patients (20.4%) underwent radiotherapy. RESULTS: Total resection was achieved in 106 patients (55.2%), subtotal - 63 (32.8%), partial - 20 (10.4%), tumor biopsy was performed in 3 (1.6%) cases. Intraoperative complications occurred in 8 patients (4%), postoperative complications - in 19 (9.7%) cases. Radiosurgery was carried out in 6 (15%) patients, hypofractionated irradiation - 15 (37.5%), standard fractionation - 19 (47.5%) patients. Tumor growth control after combined treatment made up 84%. CONCLUSION: Clinical outcomes in patients with craniovertebral junction meningioma depend on tumor dimensions, topographic and anatomical localization of tumor, resection quality and relationship with surrounding structures. Combined treatment of anterior and anterolateral meningiomas of the craniovertebral junction is preferable compared to total resection.

Pediatric vestibular schwannoma without evidence of neurofibromatosis: consecutive 18 microsurgical experiences.

PURPOSE: Sporadic vestibular schwannoma (VS) is rare in children in contrast to adults, and detailed investigations of case series of these patients using a single fixed protocol are scarce. This study presents our surgical experience of pediatric VSs without clinical evidence of neurofibromatosis type 2 (NF2) at the initial diagnosis. METHODS: Among 1385 consecutive sporadic VS surgeries, 18 pediatric patients (1.3%; 11-18 years old) were retrospectively investigated. RESULTS: The most common initial symptom was hearing disturbance (72.2%), and 6 patients (33.3%) experienced a delayed diagnosis (over 2 years after initial symptom onset). Preoperative image characteristics of these tumors included a solid tumor, hypervascularity, and significant extension into the internal acoustic meatus, when compared with adults. Preoperative embolization was successfully accomplished for 2 recent hypervascular tumors. The tumor resection rate was 95-100% under sufficient intraoperative neuromonitoring, and no additional surgery was required during the follow-up period (average: 57.9 months). No patients experienced permanent facial nerve palsy, and serviceable hearing function was preserved in 6 of 11 patients. Signs of NF2, such as bilateral VSs, were not identified in any patients during the follow-up. CONCLUSION: Safe and sufficient tumor resection was achieved under detailed neuromonitoring in pediatric patients with sporadic VS, although this tends to be difficult owing to hypervascularity, a small cranium, and significant meatal extension. Preoperative embolization may help safe resection of hypervascular tumors. Subsequent development of NF2 has not been observed up to the most recent follow-up, but careful observation is essential for these younger patients.

Long-term outcomes of grade I/II skull base chondrosarcoma: an insight into the role of surgery and upfront radiotherapy.

PURPOSE: To clarify the need for post-operative radiation treatment in skull base chondrosarcomas (SBCs). METHODS: A retrospective analysis of patients with grade I or II SBC. Patients were divided according to post-surgical treatment strategies: (A) planned upfront radiotherapy and (B) watchful waiting. Tumor control and survival were compared between the treatment groups. The median follow-up after resection was 105 months (range, 9-376). RESULTS: Thirty-two patients (Grade 1, n = 16; Grade 2, n = 16) were included. The most frequent location was petroclival (21, 64%). A gross total resection (GTR) was achieved in 11 patients (34%). Fourteen (44%) underwent upfront radiotherapy (group A) whereas 18 (56%) were followed with serial MRI alone (group B). The tumor control rate for the entire group was 77% and 69% at 10- and 15-year, respectively. Upfront radiotherapy (P = 0.25), extent of resection (P = 0.11) or tumor grade (P = 0.83) did not affect tumor control. The majority of Group B patients with recurrent tumors (5/7) obtained tumor control with repeat resection (n = 2), salvage radiotherapy (n = 2), or a combination of both (n = 1). The 10-year disease-specific survival was 95% with no difference between the group A and B (P = 0.50). CONCLUSION: For patients with grade I/II SBC, a reasonable strategy is deferral of radiotherapy after maximum safe resection until tumor progression or recurrence. At that time, most patients can be successfully managed with salvage radiotherapy or surgery. Late recurrences may occur, and life-long follow-up is advisable.

Role of Preoperative Embolization in Management of Central Nervous System Tumours.

Preoperative embolization plays a significant role as an adjunct to surgical intervention in the cases of certain vascular tumours of the brain. While the procedure has resulted in facilitated resection of the tumour, and has reduced morbidity and mortality, its application remains debatable within the neurosurgical community, owing to rare, but major post-procedural complications. Herein, we have reviewed the literature to assess the safety and efficacy of preoperative angiographic embolization for brain tumours.

Ophthalmic and orbital considerations in the evaluation of skull base malignancies.

INTRODUCTION: The orbital contents, afferent and efferent visual pathways, and the cranial nerves involved in eye movement, corneal sensation and eyelid closure traverse the skull base, a region bounded by the intracranial cavity, the paranasal sinuses, and the deep spaces of the face and head. As such, tumors from above or below have potential to affect some aspect of the visual system. METHODS: We discuss here the clinical ophthalmologic and orbital considerations in the evaluation of patients with these tumors, as well as the ophthalmic sequelae of treatment with radiation or surgery (or both). And for the surgeon, we discuss the ophthalmic and orbital considerations in surgical planning, the role of the orbital surgeon in skull base surgery, and briefly discuss transorbital approaches to the skull base. RESULTS AND CONCLUSION: Ophthalmic and orbital dysfunction may be the main source of disability in patients with skull base malignancy; it is thus incumbent on those who manage patients with tumors of this region to be aware of the ophthalmic, neuro-ophthalmic and orbital manifestations, so as to best tailor therapy and monitor treatment outcomes.

125 I interstitial brachytherapy in management of pediatric skull base tumors.

BACKGROUND: The purpose of this study was to present our preliminary assessment of the safety and efficacy of 125 I interstitial brachytherapy (IBT) in the management of pediatric skull base tumors. METHODS: Thirty pediatric patients with skull base tumors treated with 125 I IBT from April 2007 to May 2017 were included in this study. The probabilities of local control (LC) and overall survival (OS) were calculated by the Kaplan-Meier method. RESULTS: The one- and two-year LC rates were 96.7% and 74.8%, respectively. The one- and two-year OS rates were 93.3% and 72.2%, respectively. No severe acute toxicity was observed. Severe late toxicities were observed in one (3.33%) of 30 patients. CONCLUSION: 125 I IBT is effective and safe in the management of pediatric skull base tumors, with satisfactory cosmetic and functional outcomes.

[An anatomical study on the applicability of direct endoscopic exclusion of the ethmoid arteries for devascularization of the anterior skull base structures]. / Anatomicheskoe issledovanie vozmozhnosti priamogo éndoskopicheskogo vykliucheniia reshetchatykh arterii dlia devaskuliarizatsii struktur perednikh otdelov osnovaniia cherepa.

The anterior skull base structures are the site of initial growth of histologically different tumors. The difficulties in their removal are often associated with significant vascularization, which may limit the amount of resection due to abundant intraoperative blood loss. Midline tumors are primarily fed by the ethmoid arteries that are not accessible to embolization. The aim of this work was a comparative experimental study of various direct approaches to the ethmoid arteries. MATERIAL AND METHODS: The study was conducted on anatomical specimens of 12 cadaveric heads of deceased people without pathology of the anterior skull base structures, orbits, nasal cavity, and paranasal sinuses (24 sides). In all specimens, the internal and external carotid arteries were stained with silicone. During anatomical dissection, four surgical approaches for exclusion of the ethmoid arteries were studied: 1) transorbital approach to the arteries using a bicoronal incision; 2) endoscopic retro-caruncular approach; 3) endoscopic endonasal transethmoidal approach to the ethmoid artery canals; 4) endoscopic endonasal transethmoidal transorbital approach to the ethmoid arteries in the orbit. RESULTS: We described a surgical technique for exclusion of the ethmoid arteries using the approaches and analyzed their advantages and disadvantages. We formulated an algorithm for choosing the method for direct endoscopic exclusion of the ethmoid arteries, depending on the surgical approach chosen for removal of the tumor and features of the tumor extracranial spread. CONCLUSION: The decision on tumor devascularization is based on assessment of tumor blood supply (CT angiography or MR angiography data). Our study demonstrated the advantages and disadvantages of various approaches to the ethmoid arteries for their exclusion in order to early devascularize anterior skull base tumors. All these approaches are less traumatic and characterized by a good cosmetic and functional outcome.

[Biopsy and resection of skull base tumors using transorbital endoscopic approaches: primary results]. / Biopsiia i udalenie novoobrazovanii osnovaniia cherepa s primeneniem transorbital'nykh éndoskopicheskikh dostupov: pervye rezul'taty.

AIM: Transorbital neuroendoscopic surgery is a new skull base surgery technique that uses the orbit as an artificial corridor to the anterior and middle skull base. The space is created between the periorbita and orbital walls by their additional resection and gentle traction of the orbital contents. Skull base structures are reached using cosmetic incisions. The major advantages of transorbital endoscopic approaches include their variety, possibility of their combination, and access to the central and lateral skull base lesions. The aim of this study was to analyze the primary results of transorbital endoscopic biopsy and resection of skull base lesions, which were performed at the N.N. Burdenko National Medical Research Center for Neurosurgery (Moscow, Russia). MATERIAL AND METHODS: In 2017-2018, the authors operated on 12 patients with skull base lesions using transorbital endoscopic approaches. The series included ten female and two male patients. The patient's age varied between 24 and 78 years. All patients were admitted for the first time. Half of them underwent biopsy, while the other half underwent tumor resection. The upper-lateral transorbital approach with an eyebrow incision was used in most (8/12) patients; the retrocaruncular approach was used in two cases; the lateral retrocanthal approach was applied in one case; the upper-medial approach with an eyebrow incision was used in one patient. RESULTS: The histological diagnosis was established in all six biopsies: 3 pseudotumors, 2 WHO Grade I meningiomas, and 1 clear-cell kidney cancer. Tumor resection was successful in 5 out of 6 patients; repeated surgery was required in one patient. In one case, the transorbital approach was combined with the transnasal one for treatment of supraorbital mucocele. One patient developed a persistent neurological deficit (dysfunction of the fifth and sixth nerves) after upper-lateral transorbital surgery. There were no poor cosmetic results in the series. CONCLUSION: Transorbital neuroendoscopic surgery needs an interdisciplinary approach and a sufficient amount of surgical experience. Surgical skills setting includes microsurgical and endoscopic tumor resection, harvesting and positioning of free and vascularized grafts for skull base reconstruction and prevention of postoperative enophthalmos, and facial incisions and their cosmetic closure. Implementation of new local vascularized flaps may significantly improve the results of transorbital endoscopic procedures and extend the spectrum of indications.

Post-embolization neurological syndrome after embolization for intracranial and skull base tumors: transient exacerbation of neurological symptoms with inflammatory responses.

PURPOSE: Pre-operative embolization is an effective treatment strategy for hypervascular intracranial and skull base tumors. However, neurological complications resulting from tumor swelling, cranial nerve ischemia, or hemorrhage can occur after embolization. The purpose of this study was to examine the relationship between neurological complications following pre-operative embolization and minor adverse events including fever, headache, or increasing inflammation, which are common after embolization for abdominal tumors (i.e., post-embolization syndrome, PES). METHODS: We retrospectively reviewed 39 consecutive patients with pre-operative embolization for intracranial and skull base tumors. Neurological symptoms and minor adverse events were regularly observed after embolization. The degree of devascularization was evaluated using enhanced magnetic resonance imaging. We also evaluated changes in peritumoral edema. RESULTS: Neurological complications occurred in eight cases, five of whom had exacerbation of existing neurological symptoms, which occurred concurrent with a general inflammatory response. We termed this clinical condition post-embolization neurological syndrome (PENS). The mean time to neurological symptom onset was 37.2 h after embolization. PENS was self-limiting in all cases but one, which required emergency surgery. The remaining three cases were diagnosed with cranial nerve ischemia. CONCLUSIONS: PENS is an important neurological complication after pre-operative embolization, which should be distinguished from ischemic or hemorrhagic complications. PES is a minor complication with favorable prognosis, whereas PENS should be considered as a dangerous clinical sign that may require emergency treatment. Further experiments are needed to elucidate the pathology of PENS.

Preservation of the facial and lower cranial nerves in glomus jugulare tumor surgery: modifying our surgical technique for improved outcomes.

PURPOSE: To describe the neurological results obtained in six patients with large Fisch C glomus jugulare tumors (GJT) in which a less aggressive, nerve-preserving surgical strategy was used to reduce surgical morbidity. METHODS: Prospective study of six patients with Fisch C GJT who underwent surgery in a tertiary care referral center from February 2015 to August 2017 with an average follow-up of 18 months. The intervention is the surgical technique used and the main outcome measures are recurrence and the functional preservation of the facial and lower cranial nerves. RESULTS: Gross total removal was obtained in the six patients with preservation of the medial wall of the jugular bulb protecting the lower cranial nerves. After follow-up, we obtained a House-Brackmann (H-B) grade II in three patients who were managed with an inferior facial nerve transposition. One patient managed with a facial bridge technique preserved a normal facial function and two patients who presented a H-B III before surgery went to H-B V after surgery and recovered to a H-B III after 4 months. Four patients were presented with dysphagia after surgery and required nasogastric tube placement. The average time for removal with return to normal oral feeding was 4.3 weeks. Three patients with preoperative Xth nerve dysfunction showed an adequate compensation of the opposite vocal fold in the postoperative period without dysphonia or aspiration. CONCLUSION: The surgical techniques used in these patients provided good functional preservation without recurrence after an 8-30-month follow-up.

Clinical efficacy and safety of surface imaging guided radiosurgery (SIG-RS) in the treatment of benign skull base tumors.

Frameless, surface imaging guided radiosurgery (SIG-RS) is a novel platform for stereotactic radiosurgery (SRS) wherein patient positioning is monitored in real-time through infra-red camera tracking of facial topography. Here we describe our initial clinical experience with SIG-RS for the treatment of benign neoplasms of the skull base. We identified 48 patients with benign skull base tumors consecutively treated with SIG-RS at a single institution between 2009 and 2011. Patients were diagnosed with meningioma (n = 22), vestibular schwannoma (n = 20), or nonfunctional pituitary adenoma (n = 6). Local control and treatment-related toxicity were retrospectively assessed. Median follow-up was 65 months (range 61-72 months). Prescription doses were 12-13 Gy in a single fraction (n = 18), 8 Gy × 3 fractions (n = 6), and 5 Gy × 5 fractions (n = 24). Actuarial tumor control rate at 5 years was 98%. No grade ≥3 treatment-related toxicity was observed. Grade ≤2 toxicity was associated with symptomatic lesions (p = 0.049) and single fraction treatment (p = 0.005). SIG-RS for benign skull base tumors produces clinical outcomes comparable to conventional frame-based SRS techniques while enhancing patient comfort.

Is there a role for conventional MRI and MR diffusion-weighted imaging for distinction of skull base chordoma and chondrosarcoma?

BACKGROUND: Chordoma and chondrosarcoma are locally invasive skull base tumors with similar clinical symptoms and anatomic imaging features as reported in the literature. PURPOSE: To determine differentiation of chordoma and chondrosarcoma of the skull base with conventional magnetic resonance imaging (cMRI) and diffusion-weighted MR imaging (DWI) in comparison to histopathological diagnosis. MATERIAL AND METHODS: This retrospective study comprised 96 (chordoma, n = 64; chondrosarcoma, n = 32) patients with skull base tumors referred to the Paul Scherrer Institute (PSI) for proton therapy. cMRI signal intensities of all tumors were investigated. In addition, median apparent diffusion coefficient (ADC) values were measured in a subgroup of 19 patients (chordoma, n = 11; chondrosarcoma, n = 8). RESULTS: The majority 81.2% (26/32) of chondrosarcomas displayed an off-midline growth pattern, 18.8% (6/32) showed clival invasion, 18.8% (6/32) were located more centrally. Only 4.7% (3/64) of chordomas revealed a lateral clival origin. Using cMRI no significant differences in MR signal intensities were observed in contrast to significantly different ADC values (subgroup of 19/96 patients examined by DWI), with the highest mean value of 2017.2 × 10(-6 )mm(2)/s (SD, 139.9( )mm(2)/s) for chondrosarcoma and significantly lower value of 1263.5 × 10(-6 )mm(2)/s (SD, 100.2 × 10(-6 )mm(2)/s) for chordoma (P = 0.001/median test). CONCLUSION: An off-midline growth pattern can differentiate chondrosarcoma from chordoma on cMRI in a majority of patients. Additional DWI is a promising tool for the differentiation of these skull base tumors.

A neurosurgical simulation of skull base tumors using a 3D printed rapid prototyping model containing mesh structures.

BACKGROUND: Deep regions are not visible in three-dimensional (3D) printed rapid prototyping (RP) models prepared from opaque materials, which is not the case with translucent images. The objectives of this study were to develop an RP model in which a skull base tumor was simulated using mesh, and to investigate its usefulness for surgical simulations by evaluating the visibility of its deep regions. METHODS: A 3D printer that employs binder jetting and is mainly used to prepare plaster models was used. RP models containing a solid tumor, no tumor, and a mesh tumor were prepared based on computed tomography, magnetic resonance imaging, and angiographic data for four cases of petroclival tumor. Twelve neurosurgeons graded the three types of RP model into the following four categories: 'clearly visible,' 'visible,' 'difficult to see,' and 'invisible,' based on the visibility of the internal carotid artery, basilar artery, and brain stem through a craniotomy performed via the combined transpetrosal approach. In addition, the 3D positional relationships between these structures and the tumor were assessed. RESULTS: The internal carotid artery, basilar artery, and brain stem and the positional relationships of these structures with the tumor were significantly more visible in the RP models with mesh tumors than in the RP models with solid or no tumors. CONCLUSIONS: The deep regions of PR models containing mesh skull base tumors were easy to visualize. This 3D printing-based method might be applicable to various surgical simulations.

Review of carbon ion radiotherapy for skull base tumors (especially chordomas).

AIM: To review the clinical feasibility of carbon ion radiotherapy (C-ion RT) for skull base tumors, especially for chordomas which are often seen in the skull base area. BACKGROUND: Skull base tumors treated by C-ion RT consist of primary chordomas and chondrosarcomas, and enormously extended head and neck cancer with a histology of adenoid cystic carcinomas, adenocarcinomas and malignant melanomas. These tumors are located on anatomically complex sites where they are close to important normal tissues and therefore demand better physical dose distribution to avoid unnecessary doses for surrounding normal tissues. These tumors are also known as radio-resistant tumors for low linear energy transfer (LET) radiotherapy and show favorable results after treatment by high LET carbon ion radiotherapy. MATERIALS AND METHODS: Biological reports of C-ions for the chordoma cell line, clinical results of C-ion RT for skull base tumors, dose comparative studies between two representative facilities and tumor control probability (TCP) of chordomas by C-ion RT were reviewed. RESULTS: C-ion RT for skull base tumors, especially for chordomas, shows favorable results of tumor control and acceptable complications. The C-ion dose of 57.36 gray equivalent (GyE)/16 fractions/4 weeks will deliver 90% of local control for chordomas. The limiting doses for surrounding normal tissues are clearly revealed. The dose difference between institutes was assumed within 10%. CONCLUSIONS: C-ion RT is recommended for skull base tumors because of high LET characteristics and clinical results.