Posterior Fossa Lesions Research Articles

8220 Panhypopituitarism due to Granulomatosis with Polyangiitis - Wegener's Granulomatosis. A Very Rare Cause of Panhypopiturism: A Case Report

Abstract Disclosure: T.D. Bertolacini da Silva: None. V.S. da Silva: None. P.R. Fiorin: None. J.S. Freire: None. C.G. Braga: None. M. Canzian: None. C. Machado: None. Background: Granulomatosis with Polyangiitis (GPA) is a necrotizing granulomatous vasculitis and pituitary involvement is less than 1%. We report a case of pituitary involvement, with CDI, and later panhypopituitarism. Clinical Case: A 43-year-old man was admitted in a hospital due to a headache 3 months ago. CT showed an expansive lesion in posterior fossa and hydrocephaly. Submetted for withdrawal of a Schwannoma and peritoneal shunt, with ipsilateral peripheral facial paralysis. After 1 year, started with polyuria and polydipsia, CDI was diagnosed and DDAVP started. Pituitary MRI showed a small rounded image in the sella turcica, cystic, 0.8 x 0.5 x 0.8cm. After 6 months, readmitted on hospital after trauma in surgical scar, with abscess, accomplished debridement and started oxacillin, with good controls of electrolytes and diuresis: Na 144 mmol/L (137-145 mmol/L). Readmitted after 2 months for surgical wound infection, on that occasion hyponatremia was diagnosed. Other tests were requested: TSH < 0.0015 uIU/mL (0.49-5.58 uIU/mL/mL), free T4 0.68 ng/dL (0.89-1.53 ng/dL), repeated TSH 0.036 uIU/mL and free T4 0.63 ng/dL, central hypothyroidism has been confirmed and levothyroxine started. Pituitary MRI was repeated with enlarged adeno-pituitary: 1.9 x 1.7 x 1.1cm, extension to the suprasellar cistern, compression, and superior displacement of the optic chiasm. Other tests: GH 0.173 ng/mL (< 3 ng/mL), IGF1 66 ng/mL (58-219 ng/mL), testosterone < 7.30 ng/dL (12-59 ng/dL), LH 0.1 mIU/mL (1.9-12.5 mIU/mL), prolactin 0.66 ng/mL (2.1-17.7 ng/mL), ACTH 6.66 pg/mL (< 46.0 pg/mL), confirmed pan-hypopituitarism. After 1-month patient started with petechiae and persisted with hyponatremia, SIADH hypothesis made. Chest CT showed a solid pulmonary nodule, spiculated, 2.6 x 2.1 x 1.8cm, first biopsy was inconclusive. After repeating the chest CT there was persistence the pulmonary nodule 4.2 x 5.8 x 4.4cm. Videothoracoscopy was perfomed and anatomopathological confimed GPA and C-ANCA positive. The patient received prednisone, ivermectin, pulse therapy (methylprednisolone) and cyclophosphamide. After 8 months admitted on hospital due to pneumonia and exogenous Cushing's syndrome, new tests were requested: pituitary MRI showed a hypocontrasting and heterogeneous on the sellar cavity 0.4 x 0.7 x 1.0cm, showing reduction of the lesion after treatment of the rheumatological disease. Patient also received treatment with Rituximab and the last pituitary MRI: hypocontrasting lesion, sometimes with a cystic appearance in the sellar cavity. Currently, in use: testosterone replacement, desmopressin prednisone, levothyroxine, rosuvastatin/ezetimib, cholecalciferol, colchicin and ibandronate sodium. He presented with an improved quality of life. Conclusion: GPA should be considered in cases of CDI and hypopituitarism when sellar disorders were discarded, and if a vasculitis is suspected. Presentation: 6/1/2024

Vermian multinodular and vacuolating lesion of unknown significance discovered following syncope: a case report

Introduction and importance: Multinodular and Vacuolating Posterior Fossa Lesions of Unknown Significance (MV PLUS) are benign cystic lesions that, though typically asymptomatic, can present with neurological symptoms such as seizures, headaches, and syncope. These lesions are predominantly found in sub-tentorial brain structures but can also appear in supratentorial areas. MRI is crucial in detecting these lesions, characterized by small nodules with high intensity on T2-FLAIR sequences. Despite increasing awareness, the pathophysiology and classification of MV PLUS lesions remain unclear, necessitating further research and careful monitoring. Case presentation: A 52-year-old female presented with subjective dizziness and a recent syncope episode. Neurological examination showed ataxia and a positive Romberg sign. MRI revealed a multicystic and nodular lesion in the vermian and paravermian regions, with altered signal intensity on T1-weighted and FLAIR sequences. The lesion showed no pathological enhancement post-gadolinium administration, and spectroscopy revealed no significant metabolite peaks. Clinical improvement was observed following corticosteroid and antivertiginous therapy, and the patient was discharged with a recommendation for neuroradiological follow-up. Clinical discussion: MV PLUS lesions are a subset of multinodular and vacuolating lesions that present significant diagnostic challenges due to their complex radiological features. First described in 2013, these lesions have distinct MRI characteristics, including a nodular appearance with high T2-FLAIR intensity and occasional cystic components. Despite being benign and typically stable, the differential diagnosis includes various other intracranial lesions, requiring careful evaluation. The pathogenesis and optimal management strategies for MV PLUS lesions are still under investigation, emphasizing the need for continued research. Conclusion: MV PLUS lesions, although rare and benign, present unique diagnostic challenges due to their varied radiological features and potential neurological symptoms. Regular MRI monitoring is essential to track their stability, given the current lack of understanding regarding their pathophysiology and long-term implications. Further research is needed to elucidate the etiology, natural history, and optimal management of these intriguing lesions.

Intralesional epileptiform activity in a fourth ventricular hamartoma associated with epileptic hemifacial spasm in a toddler: illustrative case.

Focal epilepsy caused by a posterior fossa lesion is a rare phenomenon. In these cases, seizure onset typically occurs during the first few months of life, with episodes of epileptic hemifacial spasms and abnormal eye movements. Patients often present with drug-resistant epilepsy and often require resection for the best chance of seizure freedom. The authors present the case of a 19-month-old male with intractable epileptic hemifacial spasms and a dorsally exophytic right brainstem and middle cerebellar peduncle hamartoma, following 2 prior subtotal resections. The authors recommended a third suboccipital craniotomy with intraoperative electrocorticography, which revealed interictal spiking from an intralesional depth electrode. Near-total resection led to durable seizure freedom. Although posterior fossa lesions are rarely associated with epileptiform activity, this case demonstrates that pediatric patients with epileptic hemifacial spasms associated with a posterior fossa lesion may respond favorably to resection. Furthermore, this case demonstrates that intralesional electrocorticography can detect epileptic activity in posterior fossa lesions, which may predict postoperative seizure outcomes. https://thejns.org/doi/10.3171/CASE2452.

Posterior fossa Hodgkin's lymphoma radiographically mimicking an arteriovenous malformation: illustrative case.

Intracranial Hodgkin's lymphoma (HL) is an exceedingly rare condition that is at an increased risk of misdiagnosis and mismanagement, especially when initial radiographic evidence points to an alternative pathology. The authors describe the case of a 75-year-old female who presented with a posterior fossa lesion initially concerning for a vascular malformation on computed tomography imaging due to perilesional hypervascularity. Subsequent angiography revealed a developmental venous anomaly (DVA) but no arteriovenous shunting. The patient's clinical history combined with magnetic resonance imaging findings prompted a tissue biopsy, which demonstrated a rare case of central nervous system (CNS) HL. The neoangiogenesis of this CNS HL with an adjacent DVA contributed to the original radiographic misdiagnosis of an arteriovenous malformation. HL's angiogenic potential, coupled with the proangiogenic environment induced around DVAs, may have contributed to this rare CNS HL metastasis to the cerebellum. The potential misdiagnosis of posterior fossa CNS HL has also been seen in several prior cases reviewed herein. Hypervascular tumors, especially when associated with an adjacent DVA, should also be considered when first evaluating suspected intracranial vascular lesions. Although rare, CNS HL should be included in the differential diagnosis for patients with a prior history of HL. https://thejns.org/doi/10.3171/CASE24238.

EPEN-13. PRE-IRRADIATION CHEMOTHERAPY EXPERIENCE FOR PEDIATRIC EPENDYMOMA POLISH PROTOCOL

Abstract BACKGROUND Pediatric ependymomas are aggressive central nervous system malignancies arising from the ependymal linings of ventricles and spinal canal. Despite better understanding of tumor biology ependymomas remain therapeutic challenge in pediatric neurooncology. The role of chemotherapy remains controversial. Herein, we describe the outcomes of patients treated at the largest center in Poland who underwent surgery, pre-irradiation chemotherapy and irradiation regardless of extent of surgical resection. METHODS This retrospective review includes pediatric patients with ependymoma treated according to national protocol at the Children’s Memorial Health Institute. We reviewed histology, disease extent, treatment, and report on overall survival (OS) and progression free survival rates (PFS). Descriptive statistics were analyzed using SPSS software. RESULTS Forty-nine patients were included (median age: 84 months). Most patients (96%) had cranial ependymomas (43% supratentorial and 57% posterior fossa lesions). Disseminated disease was found in 16% of cases. Complete resection was achieved in 43%. All patients received pre-irradiation chemotherapy; 6.1% had progressive disease and 41% achieved complete response (CR). All patients, except one, underwent irradiation (67% focal, 2% focal/ventricular, 29% craniospinal, and 2% whole brain). Thirty-five percent of patients relapsed. Five-year PFS and OS were 69% and 80% respectively. Comparing posterior fossa to supratentorial lesions, there was no difference in response after surgery and pre-irradiation chemotherapy (CR 37% versus 50% (p=0.51)) or irradiation (CR 42% versus 55% (p=0.37)). However, relapse was more likely in posterior fossa ependymomas (OR 0.30 IQR (0.70, 1.29), p=0.03) with lower 5-year PFS (56% versus 85%, p=0.03) and 10-year PFS (52% versus 85%, p=0.02). The benefit of chemotherapy was marked in patients with Grade 3 (5-year OS 82% versus 69%) CONCLUSIONS We describe a large cohort of pediatric ependymoma patients who received pre-irradiation chemotherapy. This strategy did not negatively impact the incidence of progression before irradiation.

A case of a cerebellar form of progressive multifocal leukoencephalopathy in a patient undergoing peritoneal dialysis.

Progressive multifocal leukoencephalopathy (PML), a severe demyelinating disease of the central nervous system, is caused by the reactivation of the polyomavirus JC virus (JCV). It favors the cerebrum and typically occurs in patients with immunodeficiencies, with a progressive course and fatal outcome in the majority of cases. However, the cerebellar form of PML, characterized by isolated posterior fossa lesions, such as those in the cerebellum or brainstem at disease onset, is rare, and reports of its occurrence in peritoneal dialysis (PD) patients are lacking. In this paper, we describe a rare case of a cerebellar form of PML in a PD patient. A 64-year-old man undergoing PD was referred to our hospital for anorexia, nausea, and vomiting in the past month. He had finger-to-nose test abnormalities, gaze-directed nystagmus, and scanning speech. He was diagnosed with the cerebellar form of PML based on his progressive cerebellar symptoms, the typical magnetic resonance imaging findings, and the presence of JCV-DNA in the cerebrospinal fluid polymerase chain reaction test. He developed nocturnal delirium, aggravated disquiet, and died of pneumonia on the 69th day. Clinicians should consider the cerebellar form of PML as a differential diagnosis if PD patients develop progressive cerebellar symptoms.

Arteriovenous malformations in the cerebellopontine angle: assessment of the "backdoor resection" technique and microsurgical results in 38 patients.

Posterior fossa arteriovenous malformations (AVMs) represent 7% to 15% of all intracranial AVMs and are associated with an increased risk of hemorrhage, morbidity, and mortality compared with supratentorial AVMs, thus prompting urgent and definitive treatment. Cerebellopontine angle (CPA) AVMs are a unique group of posterior fossa AVMs incorporating characteristics of brainstem and cerebellar lesions, which are particularly amenable to microsurgical resection. This study reports the clinical, radiological, operative, and outcome features of patients with CPA AVMs in a large cohort. The authors conducted a single-surgeon, 2-institution retrospective cohort study of all consecutive patients with CPA AVMs treated with microsurgical resection during a 25-year period. CPA AVMs represented 22% (38 of 176) of all infratentorial AVMs resected by the senior author. Overall, 38 patients (22 [58%] male and 16 [42%] female) met the study inclusion criteria and were analyzed. Most patients presented with hemorrhage (n = 29, 76%). The median age at surgery was 56 (range 6-82) years. Subtypes included 22 (58%) petrosal cerebellar AVMs, 11 (29%) lateral pontine AVMs, and 5 (13%) AVMs involving both the brainstem and cerebellum. Most AVM niduses were small (< 3 cm; n = 35, 92%) and compact (n = 31, 82%). Fourteen (37%) patients harbored flow-related aneurysms. Twenty (53%) patients underwent preoperative embolization. Complete angiographic obliteration was achieved with microsurgery in 35 (92%) patients. Five (13%) patients with poor neurological conditions at presentation died before hospital discharge. Of the 7 (18%) patients with new postoperative neurological deficits, 5 had transient deficits. The median (interquartile range) follow-up was 1.7 (0.5-3.2) years; 32 (84%) patients were alive at last follow-up, and 30 (79%) had achieved a favorable neurological outcome (modified Rankin Scale [mRS] score 0-2). The only independent predictor of unfavorable postoperative outcome (mRS score 3-6) was the preoperative mRS score (p = 0.002). CPA AVMs are unique posterior fossa lesions, including petrosal cerebellar and lateral pontine AVMs. The "backdoor resection" technique provides a safe and efficient strategy with high obliteration rates and a low risk of treatment-related morbidity. Microsurgical resection should be considered the frontline treatment for most CPA AVMs, except for those with a significant diffuse brainstem component.

Endoscopic Third Ventriculostomy versus Cerebrospinal Fluid Shunting in Hydrocephalus associated with Posterior Fossa Lesions in Adults; Comparative study

Endoscopic Third Ventriculostomy versus Cerebrospinal Fluid Shunting in Hydrocephalus associated with Posterior Fossa Lesions in Adults; Comparative study

Predictors of Acute Cerebellar Bulge Prior to Posterior Fossa Lesion Resection

ObjectiveA cerebellar bulge prior to posterior fossa resection is an emergency condition during surgery. Intraoperative cerebellar bulging not only increases the difficulty of lesion resection but also brings additional postoperative complications. Currently, there are few systematic reports on this topic. The predictors of cerebellar bulge and how to effectively prevent intraoperative cerebellar bulge are discussed in this article. MethodsThe clinical and imaging data of 527 patients with posterior fossa lesions who underwent resection at our hospital were retrospectively collected and analyzed. Perioperative clinical and imaging data were assessed. Variables were analyzed using univariate and multivariate regression analyses. ResultsOverall, 10.4% (55/527) of patients had intraoperative acute bulges. Multivariate analysis revealed that age <60 years, BMI ≥24, lesion size ≥30 (mm), cerebellar tonsillar herniation and/or hydrocephalus, and perilesional edema (moderate-severe) were predictors of cerebellar bulging. Relief of the cerebellar bulge can be accomplished by excising the lesion, releasing cerebrospinal fluid, and removing the cerebellum (the outer 1/3). Obvious cerebellar-related complications occurred in 4 patients postoperatively, and the symptoms disappeared after 6 months of follow-up. ConclusionsCerebellar bulging during intraoperative posterior fossa resection deserves attention. Through the analysis of multiple factors related to cerebellar bulge, comprehensive evaluation and early intervention during the perioperative period are necessary. The incidence of cerebellar bulges can be reduced, and surgical complications related to cerebellar bulges can be avoided.

Purely endoscopic subtemporal keyhole anterior transpetrosal approach to access the petrous apex region: surgical techniques and early results.

The anterior transpetrosal approach using a microscope to provide wider access to the petrous apex region has been described for radical resection of lesions of the middle and posterior skull base. The microscopic anterior transpetrosal approach (mATPA) requires a wide craniotomy and meticulous epidural procedures to minimize temporal lobe retraction. Recently, the clinical application of transcranial endoscopic keyhole approaches for minimally invasive surgery has been steadily expanding. In this study, the details of the purely endoscopic subtemporal keyhole ATPA (eATPA) for petrous apex lesions are described and its initial results are reported. Between May 2022 and May 2023, the authors performed eATPA in 10 patients with petrous apex lesions, of which 6 were meningiomas, 3 were trigeminal schwannomas, and 1 was epidermoid cyst. The surgical procedure of the purely eATPA is as follows. After a small temporal craniotomy, the endoscopic procedure is started. The anterior rim of the petrous bone and Meckel's cave are exposed via an intradural subtemporal approach. The lesion is removed with additional drilling of Kawase's triangle, cutting the superior petrosal sinus, opening Meckel's cave, and cutting the tentorium. The authors also compared the outcomes of mATPA versus eATPA for consecutive cases of petrous apex lesions. Gross-total resection was achieved in 8 of the 10 patients. The average operative time was 4 hours 13 minutes. There were 3 cases of transient abducens nerve palsy and 1 case of trochlear nerve palsy in the postoperative period. No new-onset motor deficits or CSF leakage was noted in any of these patients. Only 1 patient exhibited postoperative asymptomatic temporal lobe edema. The Karnofsky Performance Scale (KPS) scores remained unchanged or improved for all patients postoperatively. Compared with mATPA, eATPA achieved a similar extent of resection and comparable postoperative KPS scores with a significantly shorter mean operative time, much smaller temporal craniotomy, and thus less mean blood loss during surgery with lower rates of new-onset temporal lobe edema in the postoperative period. An eATPA allows a direct route to access Meckel's cave and posterior cranial fossa lesions similar to conventional mATPA, with shortening the operative time and reducing the risk of postoperative temporal lobe edema. This eATPA is considered one of the new surgical techniques that can be expected to develop in the future.

Stereotactic frame-based biopsy of infratentorial lesions via the suboccipital-transcerebellar approach with the Zamorano-Duchovny stereotactic system—a retrospective analysis of 79 consecutive cases

ObjectiveLesions of the posterior fossa (brainstem and cerebellum) are challenging in diagnosis and treatment due to the fact that they are often located eloquently and total resection is rarely possible. Therefore, frame-based stereotactic biopsies are commonly used to asservate tissue for neuropathological diagnosis and further treatment determination. The aim of our study was to assess the safety and diagnostic success rate of frame-based stereotactic biopsies for lesions in the posterior fossa via the suboccipital-transcerebellar approach.MethodsWe performed a retrospective database analysis of all frame-based stereotactic biopsy cases at our institution since 2007. The aim was to identify all surgical cases for infratentorial lesion biopsies via the suboccipital-transcerebellar approach. We collected clinical data regarding outcomes, complications, diagnostic success, radiological appearances, and stereotactic trajectories.ResultsA total of n = 79 cases of stereotactic biopsies for posterior fossa lesions via the suboccipital-transcerebellar approach (41 female and 38 male) utilizing the Zamorano-Duchovny stereotactic system were identified. The mean age at the time of surgery was 42.5 years (± 23.3; range, 1–87 years). All patients were operated with intraoperative stereotactic imaging (n = 62 MRI, n = 17 CT). The absolute diagnostic success rate was 87.3%. The most common diagnoses were glioma, lymphoma, and inflammatory disease. The overall complication rate was 8.7% (seven cases). All patients with complications showed new neurological deficits; of those, three were permanent. Hemorrhage was detected in five of the cases having complications. The 30-day mortality rate was 7.6%, and 1-year survival rate was 70%.ConclusionsOur data suggests that frame-based stereotactic biopsies with the Zamorano-Duchovny stereotactic system via the suboccipital-transcerebellar approach are safe and reliable for infratentorial lesions bearing a high diagnostic yield and an acceptable complication rate. Further research should focus on the planning of safe trajectories and a careful case selection with the goal of minimizing complications and maximizing diagnostic success.

Anaesthetic Challenges in a Pediatric with Solitary Fibrous Tumour in the Neck Posted for Resection -A Case Report

Context: Hemangiopericytoma and Solitary fibrous tumor in infant are more vascular involving head and neck region. Juvenile form have better prognosis compared to adult form , so surgical excision offers benefit at this age. Case Report: Ten year old female child had presented with a soft tissue mass in the right temporal region behind ears , which was progressive in growth. In further evaluation, MRI showed heterogenicity enhancing lesion in posterior fossa in right cerebellar region with extracranial extension into subcutaneous space . Histologically, a hypercellular spindle cell mesenchymal neoplasm seen. Conclusion: Solitary Fibrous Tumour of head and neck can grow rapidly during the paediatric age group period. Complete excision without mutilating surgery should be curative.

Usefulness of Opening the Diaphragma Sellae Before Transecting Interclinoidal Ligament for Endoscopic Endonasal Transoculomotor Triangle Approach: Technical Nuances and Surgical Outcomes

Opening the oculomotor triangle and removing the posterior fossa lesion by endoscopic endonasal approach (EEA) is challenging for even an experienced endoscopic neurosurgeon. We summarize the treatment experience and technical nuances with EEA for resection of pituitary neuroendocrine tumors and cavernous sinus (CS) meningiomas invading through the oculomotor triangle (OT). Between 2018 and 2022, eight cases, including five pituitary neuroendocrine tumors (PitNET) including three nonfunctioning and two somatotroph tumors with elevated growth hormone, and 3 CS meningiomas were treated using an endoscopic endonasal transoculomotor triangle approach. The critical surgical technique is continuously opening the diaphragma sellae from medial to lateral towards the interclinoidal ligament (ICL) and transecting it to enlarge the OT. We evaluated preoperative tumor size, previous surgical history, preoperative symptoms, extent of tumor resection, histopathology, and postoperative complications for all patients. The GTR(gross total resection)- defined as complete removal in 3 patients (38%), near-total resection(NTR) - defined as >95% removal in 4 patients (50%), and subtotal resection (STR)- defined as up to 90 % removal in one patient (12%)and gross-total resection of tumor invading through the OT was achieved in all patients through pure EEA. Two of three patients with visual deficit in Non-Functioning-PitNET improved, and the other remained stable postoperatively. One patient showed transient oculomotor nerve palsy. The Growth Hormone level of the two patients with somatotroph tumors declined to normal. For three patients with CS meningiomas, cranial nerve palsy improved in two patients, while the other patient developed increased facial numbness after surgery. Endoscopic endonasal transoculomotor triangle approach is an efficient surgical option for the tumor with CS invasion and OT penetration.

Is two-staged gamma knife surgery a reasonable management option for very large cerebellar metastases? A case series of three patients.

Two-staged gamma knife surgery (GKS) is a method that may extend the upper tumor volume limit for using GKS in the management of brain metastases. However, the safety of treating very large posterior fossa lesions with this technique has not been well demonstrated. Therefore, we analyzed our experience in treating cerebellar metastases larger than 12 cm3 with two-staged GKS. Four consecutive patients harboring 12 to 30 cm3 cerebellar metastases scheduled two-staged GKS were included in the study, and all but one patient completed the treatment. The treatment doses were 10-13Gy. All patients were followed with regular MR imaging and clinical assessments, and the tumor volumes were measured on all treatment and follow-up images. Tumor progression was not demonstrated in any of the patients. Tumor volumes decreased by, on average, more than half between the two stages. The median survival was 22months, and no patient died due to intracranial tumor progression. Peritumoral edema at the first GKS resolved in all patients, replaced by asymptomatic mild T2 changes in two of them not requiring any treatment. No radiation-induced complication has developed thus far. Staged GKS seems to be a feasible management option for very large cerebellar metastases.

Outcomes of Extended Middle Fossa Approach for Petroclival Tumors in the Elderly.

Objective The aims of the study are (1) to evaluate the extended middle fossa approach (eMCF) for resection of tumors in the petroclivus and anterior cerebellopontine angle (CPA) and (2) to compare surgical outcomes between elderly (≥65 years) and nonelderly patients. Design Retrospective cohort. Setting Tertiary referral center. Participants Adults with petroclival, anterior CPA, or posterior fossa lesions who underwent an eMCF approach from 2012 to 2021 were included in the study. Main Outcome Measure Demographics, symptoms, cranial nerve (CN) function, and postoperative outcomes. Results Twenty-nine patients (mean age of 55 years, 59% females) were identified. Eleven (38%) were ≥65 years (65-79 years). The most common pathology was meningioma ( n = 13, 45%), followed by vestibular schwannoma ( n = 4, 14%) and squamous cell carcinoma ( n = 3, 10%). Nineteen tumors (65.5%) were located in the petroclivus, 7 (24%) involved the cavernous sinus, and 10 (34%) were located in the posterior fossa. The mean tumor maximal diameter was 3.4 cm (range: 1.3-7.9 cm). Gross total tumor resection was accomplished in 15 (52%) patients. Most patients ( n = 23, 79%) did not develop new CN deficits postoperatively. Of the 13 patients who had complete pre- and postoperative audiometric data, 69% ( n = 9) maintained their hearing. Comparing the elderly versus nonelderly patients, there were no significant differences in the development of new CN palsies ( p = 0.14), length of stay ( p = 0.91), or incidence of postoperative complications ( p = 0.30). Conclusions The eMCF approach provides exposure to the petroclival region, anterior CPA cistern, and posterior fossa for a variety of pathologies. It has a favorable safety profile in the elderly (≥65 years) population with low morbidity.

10159-STMO-7 INTRAOPERATIVE MRI SURGERY FOR POSTERIOR FOSSA LESIONS

Abstract Background: Intraoperative MRI (iMRI) is an important modality in brain tumor surgery to identify residual tumors, however, it is problematic due to patient positional limitations. In this study, we investigated the usefulness of iMRI for posterior fossa lesions. Materials and Methods: Of 320 cases of brain tumors removed using iMRI from June 2016 to April 2023, 24 cases of posterior fossa lesions were included. Tumor type, approach method, imaging availability, tumor removal rate, and complications were examined retrospectively. Results: Tumor types included 8 gliomas, 5 epidermoid cysts, 4 meningiomas, 3 metastatic brain tumors, 1 schwannoma, and 3 others. Eleven patients underwent midline suboccipital approach in the supine position, 8 patients underwent lateral suboccipital approach, 2 patients underwent occipital transtentorial approach, and 2 patients underwent anterior transpetrosal approach in the supine position. transpetrosal approach in 2 cases and subtemporal approach in 1 case. iMRI showed residual lesion in 14 of 24 patients. More than half of the gliomas and epidermoid cysts had intraoperative residual disease, whereas only one meningioma did. Total resection was achieved except for one case of intentional residual schwannoma and two cases of glioma. Discussion: iMRI requires the upper body to fit within a gantry, and it is difficult to image in the park bench position. However, various approaches is possible by using a supine-lateral or semi-prone position. In the concorde position, where the fourth ventricle and upper cerebellum are approached, it is useful to insert a mat in the anterior thoracic and raise the upper body. For tumors in the dorsal brainstem and upper cerebellum, the occipital transtentorial approach was used. iMRI is effective in the removal of all tumors, including gliomas in intramedullary tumors and epidermoid cysts in extramedullary tumors. Conclusion: iMRI can be used in posterior cranial fossa lesions.

10022-MET-2 CLINICAL FEATURES OF RENAL CELL CARCINOMA BRAIN METASTASES COMPARED WITH OTHER CARCINOMAS

Abstract INTRODUCTION In recent years, the positioning of surgical treatment for metastatic brain tumors has changed. To extract conditions suitable for surgical treatment, the background factors for each primary lesion were verified by retrospective analysis of our case. SUBJECTS AND METHODS From 2014 to 2022, 425 patients with metastatic brain tumors diagnosed and treated at our university were included. There were 219 lung cancers, 46 breast cancers, 64 gastrointestinal cancers, 26 renal cell carcinomas, and 70 others. First, the tumor volume and edema volume were measured, and the ROC curve was drawn for the presence or absence of symptoms to determine the cutoff value. After that, statistical analysis was performed on the following items for each primary lesion. The items were tumor volume (T), edema volume (E), tumor edema ratio (E/T), age, KPS, hemorrhage, cyst formation, meningitis, metastasis to other organs, posterior fossa, simultaneous detection, and single tumor. RESULTS The symptomatic cutoff was 1514mm3 for tumor volume (sensitivity 0.86 specificity 0.74) and 15616 mm3 for edema volume (sensitivity 0.85 specificity 0.85). The tumor edema ratio was significantly higher in renal cell carcinoma. Factors with significant differences were older age and multiple lesions in lung cancer, younger age and posterior fossa in breast cancer, lower KPS in gastrointestinal cancer, and solitary cases and bleeding in renal cell carcinoma. DISCUSSION/CONCLUSION In this analysis, many cases of brain metastasis from renal cell carcinoma are solitary, and because they exhibit extensive edema that seems to be affected by VEGF, they tend to develop symptoms while they are small, and they are characterized by hemorrhage easily during the course. These findings suggest that patients with brain metastases from renal cell carcinoma should be given priority for surgical treatment.

Clinical significance of morphological and morphometrical analysis of foramen magnum

Introduction: The foramen magnum is a transitional zone between cranial cavity and spinal canal, and it is related with the very important neuro-vascular structures like vertebral arteries, spinal accessory nerves and spinal arteries and terminal part of medulla oblongata. Therefore, thorough knowledge of morphometric and morphological variation of foramen magnum is important for authentic radiological diagnosis and surgeries in the area of cranio-cervical junction. Materials and Methods: This study was done on 70 dried human skulls taken from the Department of Anatomy, TS Misra Medical College &amp; Hospital, Era’s Lucknow Medical College &amp; Hospital, and KGMU, Lucknow. The shape of foramen magnum was observed and transverse and antero-posterior (AP) diameters of foramen magnum (FM) were measured with the help of vernier caliper. Foramen magnum index (FMI) and foramen magnum area (FMA) were also calculated. Results: The study showed six types of shapes of foramen magnum. The oval shaped foramen magnum was found in 47% (in 33 skulls), round 30% (in 30 skulls), tetragonal 10 % (in 10 skulls), triangular &amp; irregular 10% (in 5-5 skulls), pentagonal 2% (in 2 skulls), and hexagonal 1% (in single skull). The mean anteroposterior and transverse diameter were 34.3±2.90mm and 28.9±2.80 mm respectively. The mean foramen magnum index and Foramen magnum area were 77.80±27.80 and 845.90±87.50 mm2 respectively. Conclusions: The data obtained from the present study will be useful to the neurosurgeons prior to the surgeries in the area of cranio-cervical junction and posterior cranial fossa. The morphometric and morphological knowledge of the foramen Magnum has important clinical implications in the prognosis and treatment of various neurological pathologies like Arnold Chiari syndrome, Achondroplasia and posterior cranial fossa lesions. Keywords: Foramen magnum, Transcondylar approach, Foramen magnum index, Foramen magnum area, Transverse diameter (TD), Anteroposterior diameter, Trigonal.

Link between both infratentorial and supratentorial intracranial pressure burdens and final outcome in patients with infratentorial brain injury.

Increased intracranial pressure (ICP) is most likely not being transmitted uniformly within the cranium. The ICP profiles in the supra- and infratentorial compartments remain largely unclear. Increased ICP in the cerebellum, however, is insufficiently captured by supratentorial ICP (ICPsup) monitoring due to compartmentalization through the tentorium. The authors hypothesized that additional infratentorial ICP (ICPinf) monitoring can be clinically valuable in selected patients. The aims of this study were to demonstrate the safety and feasibility of ICPinf monitoring and to investigate the influence of the ICPinf on clinical outcome in a real-world setting. Fifteen consecutive patients with posterior fossa (PF) lesions requiring surgery and anticipated prolonged neurointensive care between June 2019 and December 2021 were included. Simultaneous ICPsup and ICPinf were recorded. ICP burden was defined as a 15-minute interval with a mean ICP > 22 mm Hg. The Glasgow Outcome Scale score was assessed after 3 months. The mean ICPinf was substantially higher compared with ICPsup throughout the entire period of ICP recording (16.08 ± 4.44 vs 10.74 ± 3.6 mm Hg, p < 0.01). ICPinf was significantly higher in patients with unfavorable outcome when compared with those with favorable outcome (mean 17.2 ± 4.1 vs 11.4 ± 3.5 mm Hg, p < 0.05). Patients with unfavorable outcome showed significantly higher ICPinf burden compared with those with favorable outcome (mean 40.6 ± 43.8 vs 0.3 ± 0.4 hours, p < 0.05). Neither absolute ICPsup nor ICPsup burden was significantly associated with unfavorable outcome (p = 0.13). No monitoring-associated complications occurred. Supplementary ICPinf monitoring is safe and reliable. There is a significant transtentorial pressure gradient within the cranium showing elevated ICPs in the PF. Elevated ICP levels in the PF were strongly associated with unfavorable neurological outcome irrespective of ICPsup values.

The Use of the Suboccipital Transtentorial Approach to the Posterior Inferior Incisural Space.

Objective To describe our experience with the microsurgical technique of the suboccipital transtentorial (SOTT) approach in the removal of posterior fossa lesions located in the posterior incisural space. Method Between 2002 and 2020 we reviewed all patients who underwent microsurgical resection of lesions of the posterior incisural space at the Department of Neurosurgery, Essex Neuroscience Centre, London, England (eight patients, male to female 3:5, mean age: 51, range 35-69). We describe the preoperative symptoms, radiological findings, surgical techniques, histologyand postoperative outcomes in this cohort of patients. Results Eight patients with tumours located in the posterior incisural space underwent surgery during the study period including four meningiomas (50%), two haemangioblastomas (25%), one metastasis (13%) and one giant prolactinoma (13%). Gross or near total resection was achieved in six patients (75%): the giant prolactinoma could not be radically removed and one of the meningiomas required a small fragment to be left in place to protect the Vein of Galen.No patient developed a visual field deficit due to occipital lobe retraction.One patient developed a temporary trochlear nerve palsy (13%). Five patients had mild disability (Glasgow Outcome Scale (GOS) = 5), and four had moderate disability (GOS = 4). Conclusion In our series, the SOTT approach provided excellent access for all cases of tumours in the posterior incisural space. The tumour's size and relationship to the deep venous system contributed to the choice of approach and in one patient who had previously undergone surgery via the supracerebellar route, the SOTT approach enabled the avoidance of gliotic scar tissue. Success is dependent on careful case selection, though from our series of 8 patients, we conclude that this approach allows safe access to the posterior incisural space, with acceptable outcomes with regard to postoperative disability and cranial nerve palsy. As such, the approach should be in the armamentarium of any neurosurgeon who regularly deals with posterior fossa pathology.