Neuronavigation in endoscopic skull base surgery and the accuracy of different MRI sequences.

OBJECTIVE: Neuronavigation is common technology used by skull base teams when performing endoscopic endonasal surgery. A common practice of MRI imagining is to obtain 3D isotopic gadolinium enhanced T1W magnetisation prepared rapid gradient echo (MPRAGE) sequences. These are prone to distortion when undertaken on 3 T magnets. The aim of this project is to compare the in vivo accuracy of MRI sequences between current and new high resolution 3D sequences. The goal is to determine if geometric distortion significantly affects neuronavigation accuracy. METHODS: Patients were scanned with a 3D T1 MPRAGE sequence, 3D T1 SPACE sequence and a CT stereotactic localisation. Following general anaesthesia, patients were registered on the Stealth Station (Medtronic, USA) using a side mount emitter for Electromagnetic navigation. A variety of surgically relevant anatomical landmarks in the sagittal and coronal plane were selected with real and virtual data points measured. RESULTS: A total of 10 patients agreed be enrolled in the study with datapoints collected during surgery. The distance between real and virtual datapoints trended to be lower in SPACE sequences compared to MPRAGE. Paired t test did not demonstrate a significant difference. CONCLUSION: We have demonstrated that navigational accuracy is not significantly affected by the type of MRI sequence selected and that current corrective algorithms are sufficient. Navigational accuracy is affected by many factors, with registration error likely playing the most significant role. Further research involving real time imaging such as endoscopic ultrasound may hopefully address this potential error.

Cranial Base Measurements in Skeletal Malocclusion among Orthodontic Patients.

BACKGROUND: Facial growth and development is necessary for proper orthodontic diagnosis and treatment planning. Growth of cranial base is linked to the overall growth of facial bones, especially the maxilla and mandible. Any change in the amount and direction of growth of the cranial base can have direct or indirect effects on the developing maxilla and mandible. Thus the aim of this study was to determine the linear and angular cranial base measurements in different skeletal malocclusion in Nepalese population. METHODS: Pretreatment lateral cephalograms of 225 patients aged between 17-30 years were collected. Linear measurements Sella-Nasion (S-N), Sella-Articulare (S-Ar), Articulare-Gonion (Ar-Go), Gonion-Gnathion (Go-Gn) and angular measurements Saddle angle (N-S-Ar), Articular angle (S-Ar-Go) and Gonial angle (Ar-Go-Gn) were measured. RESULTS: In angular measurements statistically significant differences were found in the saddle and gonial angles between class I, II, and III skeletal pattern. In linear measurements, anterior and posterior cranial base lengths were not significantly different among groups however, ramal height and mandibular body length were significantly different among groups with a P value < 0.05. CONCLUSIONS: Skeletal class III has a larger gonial angle, ramal height and mandibular length. Males have larger linear measurements and females have larger angular measurements.

Transpalpebral mini-orbitozygomatic approach for nonvascular skull base lesions: a single neurosurgeon's experience.

OBJECTIVE: The authors aim to describe the advantages, utility, and disadvantages of the transpalpebral mini-orbitozygomatic (MOZ) approach for tumors of the lateral and superior orbit, orbital apex, anterior clinoid, anterior cranial fossa, middle cranial fossa, and parasellar region. METHODS: The surgical approach from skin incision to closure is described while highlighting key technical and anatomical considerations, and cadaveric dissection demonstrates the surgical steps and focuses on important anatomy. Intraoperative images were included to supplement the cadaveric dissection. A retrospective review of adults who had undergone the MOZ approach for nonvascular pathology performed by a single neurosurgeon from 2017 to 2023 was included in this institutional review board-approved study. Descriptive statistics was used to summarize the data. Four representative cases were included to demonstrate the utility of the MOZ approach. RESULTS: The study included 65 patients (46 female, 19 male), average age 54.84 years, who had undergone transpalpebral MOZ surgery. Presenting symptoms included visual changes (53.8% of cases), vision loss (23.1%), diplopia (21.8%), and proptosis (13.8%). The optic nerve and optic chiasm were involved in 32.3% and 10.8% of cases, respectively. The most common pathology was meningioma (81.5% of cases), and gross-total resection was achieved in 50% of all cases. Major complications included an infection and a carotid injury. Improvement of preoperative symptoms was reported in 92.2% of cases. Visual acuity improved in 12 patients. The mean follow-up was 8.57 ± 8.45 months. CONCLUSIONS: The MOZ approach is safe and durable. The transpalpebral incision provides better cosmesis and functional outcomes than those of standard anterolateral approaches to the skull base. Careful consideration of the limits of the approach is paramount to appropriate application on a case-by-case basis. Further quantitative anatomical studies can help to define and compare the utility of the approach to open cranio-orbital and endoscopic transorbital approaches.

Endoscopic precaruncular medial transorbital and endonasal multiport approaches to the contralateral skull base: a clinicoanatomical study.

OBJECTIVE: Minimally invasive endoscopic endonasal multiport approaches create additional visualization angles to treat skull base pathologies. The sublabial contralateral transmaxillary (CTM) approach and superior eyelid lateral transorbital approach, frequently used nowadays, have been referred to as the "third port" when used alongside the endoscopic endonasal approach (EEA). The endoscopic precaruncular contralateral medial transorbital (cMTO) corridor, on the other hand, is an underrecognized but unique port that has been used to repair CSF rhinorrhea originating from the lateral sphenoid sinus recess. However, no anatomical feasibility studies or clinical experience exists to assess its benefits and demonstrate its potential role in multiport endoscopic access to the other contralateral skull base areas. In this study, the authors explored the application and potential utility of multiport EEA combined with the endoscopic cMTO approach (EEA/cMTO) to three target areas of the contralateral skull base: lateral recess of sphenoid sinus (LRSS), petrous apex (PA) and petroclival region, and retrocarotid clinoidocavernous space (CCS). METHODS: Ten cadaveric specimens (20 sides) were dissected bilaterally under stereotactic navigation guidance to access contralateral LRSS via EEA/cMTO. The PA and petroclival region and retrocarotid CCS were exposed via EEA alone, EEA/cMTO, and EEA combined with the sublabial CTM approach (EEA/CTM). Qualitative and quantitative assessments, including working distance and visualization angle to the PA, were recorded. Clinical application of EEA/cMTO is demonstrated in a lateral sphenoid sinus CSF leak repair. RESULTS: During the qualitative assessment, multiport EEA/cMTO provides superior visualization from a high vantage point and better instrument maneuverability than multiport EEA/CTM for the PA and retrocarotid CCS, while maintaining a similar lateral trajectory. The cMTO approach has significantly shorter working distances to all three target areas compared with the CTM approach and EEA. The mean distances to the LRSS, PA, and retrocarotid CCS were 50.69 ± 4.28 mm (p < 0.05), 67.11 ± 5.05 mm (p < 0.001), and 50.32 ± 3.6 mm (p < 0.001), respectively. The mean visualization angles to the PA obtained by multiport EEA/cMTO and EEA/CTM were 28.4° ± 3.27° and 24.42° ± 5.02° (p < 0.005), respectively. CONCLUSIONS: Multiport EEA/cMTO to the contralateral LRSS offers the advantage of preserving the pterygopalatine fossa contents and the vidian nerve, which are frequently sacrificed during a transpterygoid approach. This approach also offers superior visualization and better instrument maneuverability compared with EEA/CTM for targeting the petroclival region and retrocarotid CCS.

[Usefulness of Preoperative Simulation: Skull Base Approach].

Preoperative simulation images creates an accurate visualization of a surgical field. The anatomical relationship of the cranial nerves, arteries, brainstem, and related bony protrusions is important in skull base surgery. However, an operator's intention is unclear for a less experienced neurosurgeon. Three-dimensional(3D)fusion images of computed tomography and magnetic resonance imaging created using a workstation aids precise surgical planning and safety management. Since the simulation images allows to perform virtual surgery, a déjà vu effect for the surgeon can be obtained. Additionally, since 3D surgical images can be used for preoperative consideration and postoperative verification, discussion among the team members is effective from the perspective of surgical education for residents and medical students. Significance of preoperative simulation images will increase eventually.

Surgical Navigation in the Anterior Skull Base Using 3-Dimensional Endoscopy and Surface Reconstruction.

Importance: Image guidance is an important adjunct for endoscopic sinus and skull base surgery. However, current systems require bulky external tracking equipment, and their use can interrupt efficient surgical workflow. Objective: To evaluate a trackerless surgical navigation system using 3-dimensional (3D) endoscopy and simultaneous localization and mapping (SLAM) algorithms in the anterior skull base. Design, Setting, and Participants: This interventional deceased donor cohort study and retrospective clinical case study was conducted at a tertiary academic medical center with human deceased donor specimens and a patient with anterior skull base pathology. Exposures: Participants underwent endoscopic endonasal transsphenoidal dissection and surface model reconstruction from stereoscopic video with registration to volumetric models segmented from computed tomography (CT) and magnetic resonance imaging. Main Outcomes and Measures: To assess the fidelity of surface model reconstruction and accuracy of surgical navigation and surface-CT model coregistration, 3 metrics were calculated: reconstruction error, registration error, and localization error. Results: In deceased donor models (n = 9), high-fidelity surface models of the posterior wall of the sphenoid sinus were reconstructed from stereoscopic video and coregistered to corresponding volumetric CT models. The mean (SD; range) reconstruction, registration, and localization errors were 0.60 (0.24; 0.36-0.93), 1.11 (0.49; 0.71-1.56) and 1.01 (0.17; 0.78-1.25) mm, respectively. In a clinical case study of a patient who underwent a 3D endoscopic endonasal transsphenoidal resection of a tubercular meningioma, a high-fidelity surface model of the posterior wall of the sphenoid was reconstructed from intraoperative stereoscopic video and coregistered to a volumetric preoperative fused CT magnetic resonance imaging model with a root-mean-square error of 1.38 mm. Conclusions and Relevance: The results of this study suggest that SLAM algorithm-based endoscopic endonasal surgery navigation is a novel, accurate, and trackerless approach to surgical navigation that uses 3D endoscopy and SLAM-based algorithms in lieu of conventional optical or electromagnetic tracking. While multiple challenges remain before clinical readiness, a SLAM algorithm-based endoscopic endonasal surgery navigation system has the potential to improve surgical efficiency, economy of motion, and safety.

Imaging of congenital anomalies and defects of the skull base and calvarium.

Congenital anomalies and defects of the skull base and calvarium encompass a broad and complex spectrum of pathologies. The clinical presentation is highly variable, and these anomalies may be discovered incidentally in asymptomatic individuals. Radiological assessment plays a pivotal role in precisely characterizing these abnormalities, facilitating the diagnostic process, and assisting in any preoperative preparation.

Topographic Anatomy and Pneumatization of the Posterior Clinoid Process in Chiari Type I Malformation.

OBJECTIVE: This study aimed to examine pneumatization and topographic location of the posterior clinoid process (PCP) in Chiari type I malformation (CIM) for skull base approaches. METHODS: Computed tomography images of 52 (23 males/29 females) CIM subjects aged 23.87 ± 16.09 years and 71 (26 males/45 females) healthy subjects aged 42.48 ± 21.48 years constituted the study universe. RESULTS: The distances of PCP to the foramen magnum (P = 0.037), superior orbital fissure (P < 0.001), foramen rotundum (P < 0.001), and foramen ovale (P < 0.001) were smaller, but the distance of PCP to the crista galli (P = 0.038) was greater in CIM patients, compared with normal subjects. In CIM, the fusion between PCP and the anterior clinoid process was observed in 9 sides (8.70%), while in controls it was observed in 12 sides (8.50%). PCP pneumatization was observed in 40 sides (38.50%) in CIM patients, while it was observed in 28 sides (19.70%) in normal subjects. These data displayed that PCP pneumatization was affected by CIM (P < 0.001). CONCLUSIONS: The distances of PCP to the crista galli and foramen magnum indicate the anterior fossa length and the posterior fossa depth, respectively; thus CIM patients have a longer anterior fossa and a shallow posterior fossa. In addition, the distances of PCP to the superior orbital fissure, foramen rotundum, and foramen ovale indicate the middle fossa width; hence CIM patients have less middle fossa width than normal individuals. CIM patients have an approximately 50% higher PCP pneumatization rate, and this may increase the risk of complications such as cerebrospinal fluid fistula during the application of posterior clinoidectomy.

An Unknown Foreign laryngeal Object: an exotic complication of skull base osteoradionecrosis.

BACKGROUND: Osteoradionecrosis (ORN) of the skull base is a rare complication after head and neck radiation with a broad variety of subsequent complications. METHODS: A 68-year-old woman with a complex oncological history (right-sided sphenoid meningioma; left-sided neck metastasis of a Cancer of Unknown Primary-CUP) was admitted with a right-sided epi-/ oropharyngeal mass and severe pain exacerbations for further evaluation. CT scan revealed an advanced ORN of the skull base with subsequent abruption of the ventral part of the clivus. This dislocated part of the clivus wedged in the oropharynx for 48 h and then moved towards the larynx, resulting in dyspnea and almost complete airway obstruction. RESULTS: Due to the dangerous airway situation, an urgent exploration and removal of the dislocated clivus was necessary. After a potential cervical spine instability was ruled out, the patient's airway was initially secured with an awake tracheotomy and the clivus was removed transorally. The tracheostomy tube was removed during the ongoing inpatient stay, and the patient was discharged with significant pain relief. CONCLUSIONS: The present case illustrates an orphan complication of skull base ORN resulting in a major airway emergency situation.

Reconstructive endovascular treatment of petrous ICA pseudoaneurysm in skull base osteomyelitis: a hidden catastrophe.

Skull base osteomyelitis can be more life-threatening in immunocompromised patients and patients with diabetes. Here, we present a case of a petrous internal carotid artery pseudoaneurysm resulting from skull base osteomyelitis in a diabetic male in his 50s. This case report highlights the need to be conscious of the various complications associated with skull base osteomyelitis, be proficient in detecting them and treat them as early as possible for better outcomes. After adequate control of the disease process with medical treatment, immediate management of the aneurysm with balloon angioplasty and stenting was done. Acknowledging the trivial nasal and ear bleed, radiological evaluation is necessary to rule out rare complications like pseudoaneurysms in a diagnosed case of skull base osteomyelitis. In the discussion, we have cited the various treatment methods and similar cases of pseudoaneurysm caused by osteomyelitis. Currently, the patient continues to live a disease and disability-free life.

Association of cranial base suture/synchondrosis fusion with severity of increased intracranial pressure in Crouzon syndrome.

This study investigated how the fusion states of the cranial base is related to the degree of increased intracranial pressure (ICP) in patients with Crouzon syndrome. This retrospective cohort study enrolled patients who were diagnosed with Crouzon syndrome between May 2007 and April 2022. We categorized the patients into three groups: A, B, and C, according to the severity of increased ICP and the number of cranial vault remodeling procedures for corrective operation. The preoperative fusion states of the cranial base sutures/synchondroses were examined using facial bone computed tomography and compared between groups. Overall, 22 patients were included in Groups A, B, and C, including 8, 7, and 7 patients, respectively. The preoperative average grades of the total cranial base suture/synchondrosis fusion appeared to significantly increase with severity, except for the frontoethmoidal suture, which showed the opposite tendency. In the subgroup analysis, frontosphenoidal, sphenoparietal, sphenosquamosal, parietomastoid, and occipitomastoid suture and petro-occipital synchondrosis were associated with earlier fusion in the more severe group. Premature closure of the cranial base sutures/synchodroses seems to be associated with increased ICP severity in patients with Crouzon syndrome. Precise evaluation of minor sutures/synchondroses at the first visit might help build subsequent operative plans and predict disease prognosis.

Measurement of the intersiphon distance for normal skull base development and estimation of the surgical window for the endoscopic transtuberculum approach in children.

OBJECTIVE: Due to the underdeveloped skull base in children, it is crucial to predict whether a sufficient surgical window for an endoscopic endonasal approach can be achieved. This study aimed to analyze the presumed surgical window through measurement of the intersiphon distance (ISD) and the planum-sella height (PSH) on the basis of age and its correlation with the actual surgical window for the endoscopic transtuberculum approach. METHODS: Twenty patients of each age from 3 to 18 years were included as the normal skull base population. ISD and PSH were measured and compared among consecutive ages. Additionally, 42 children with craniopharyngiomas or Rathke's cleft cysts who underwent treatment via the endoscopic transtuberculum approach were included. ISD and PSH were measured on preoperative images and then correlated with the dimensions of the surgical window on postoperative CT scans. The intraoperative endoscopic view was classified as narrow, intermediate, or wide based on operative photographs or videos, and relevant clinical factors were analyzed. RESULTS: In the normal skull base population, both ISD and the estimated area of the surgical window increased with age, particularly at 8 and 11 years old. On the other hand, PSH did not show an incremental pattern with age. Among the 42 children who underwent surgery, 24 had craniopharyngioma and 18 had Rathke's cleft cysts. ISD showed the strongest correlation with the actual area of the surgical window [r(40) = 0.69, p < 0.001] rather than with age or PSH. The visual grade of the intraoperative endoscopic view was narrow in 17 patients, intermediate in 21, and wide in 4. Preoperative ISD was 14.58 ± 1.29 mm in the narrow group, 16.13 ± 2.30 mm in the intermediate group, and 18.09 ± 3.43 mm in the wide group (p < 0.01). There were no differences in terms of extent of resection (p = 0.41); however, 2 patients in the narrow group had postoperative complications. CONCLUSIONS: Normal skull base development exhibited age-related growth. However, in children with suprasellar lesions, the measurement of the ISD showed a better correlation than age for predicting the surgical window for the endoscopic transtuberculum approach. Children with a small ISD should be approached with caution due to the limited surgical window.

Safety and histopathologic yield of percutaneous CT-guided biopsies of the skull base, orbit, and calvarium.

PURPOSE: Although CT-guided biopsies of the calvarium, skull base, and orbit are commonly performed, the best approaches, efficacy, and safety of such procedures remain scantly described in the literature. This retrospective review of percutaneous biopsies illustrates several approaches to challenging biopsy targets and provides a review of procedural planning considerations and histopathologic yield. METHODS: A retrospective review of CT-guided biopsies of the skull base, calvarium, and orbit between 1/1/2010 and 10/30/2020 was conducted. Patient demographics and procedural factors were recorded, including lesion size and location, biopsy approach, and needle gauge. Outcomes were also noted, including CT dose length product, complications, and histopathologic yield. RESULTS: Sixty-one CT-guided biopsies were included in the final analysis: 34 skull base, 23 calvarial, and 4 orbital lesions. The initial diagnostic yield was 32/34 (94%) for skull base lesions, with one false-negative and one non-diagnostic sample. Twenty-one of twenty-three (91%) biopsies in the calvarium were initially diagnostic, with one false-negative and one non-diagnostic sample. In the orbit, 4/4 biopsies were diagnostic. The total complication rate for the cohort was 4/61 (6.6%). Three complications were reported in skull base procedures (2 immediate and 1 delayed). A single complication was reported in a calvarial biopsy, and no complications were reported in orbital biopsies. CONCLUSION: Percutaneous CT-guided core needle biopsies can be performed safely and with a high diagnostic yield for lesions in the skull base, calvarium, and orbit.

Diagnosis of skull-base invasion by nasopharyngeal tumors on CT with a deep-learning approach.

PURPOSE: To develop a convolutional neural network (CNN) model to diagnose skull-base invasion by nasopharyngeal malignancies in CT images and evaluate the model's diagnostic performance. MATERIALS AND METHODS: We divided 100 malignant nasopharyngeal tumor lesions into a training (n = 70) and a test (n = 30) dataset. Two head/neck radiologists reviewed CT and MRI images and determined the positive/negative skull-base invasion status of each case (training dataset: 29 invasion-positive and 41 invasion-negative; test dataset: 13 invasion-positive and 17 invasion-negative). Preprocessing involved extracting continuous slices of the nasopharynx and clivus. The preprocessed training dataset was used for transfer learning with Residual Neural Networks 50 to create a diagnostic CNN model, which was then tested on the preprocessed test dataset to determine the invasion status and model performance. Original CT images from the test dataset were reviewed by a radiologist with extensive head/neck imaging experience (senior reader: SR) and another less-experienced radiologist (junior reader: JR). Gradient-weighted class activation maps (Grad-CAMs) were created to visualize the explainability of the invasion status classification. RESULTS: The CNN model's diagnostic accuracy was 0.973, significantly higher than those of the two radiologists (SR: 0.838; JR: 0.595). Receiver operating characteristic curve analysis gave an area under the curve of 0.953 for the CNN model (versus 0.832 and 0.617 for SR and JR; both p < 0.05). The Grad-CAMs suggested that the invasion-negative cases were present predominantly in bone marrow, while the invasion-positive cases exhibited osteosclerosis and nasopharyngeal masses. CONCLUSIONS: This CNN technique would be useful for CT-based diagnosis of skull-base invasion by nasopharyngeal malignancies.

Early Displacement of Reconstruction Material is a Predictor of Cerebrospinal Fluid Leak Post Endoscopic Skull Base Surgery.

BACKGROUND: The reconstruction technique and materials used for endoscopic skull base surgery (ESBS) are important factors in preventing cerebrospinal fluid (CSF) leak, a notable complication following this surgery. Visualizing the status of reconstruction early in the postoperative course can help determine the risk of postoperative CSF leak. Here, we aimed to determine if the radiological status of reconstruction post endonasal endoscopic surgery can predict postoperative CSF leak. METHODS: This retrospective study included patients who had undergone ESBS between 2015 and 2020. An early computed tomography (CT) scan (obtained within 24 hours of surgery) was utilized to evaluate the reconstruction and postoperative radiological changes, and its findings were correlated with the occurrence of postoperative CSF leaks. RESULTS: Our study included 11 (12.7%) out of 86 patients with CSF leaks. The type of reconstruction, construction material, and type of nasal packing were not identified as significant risk factors for CSF leaks. The location of the fat graft (placed properly vs. displaced out of the surgical cavity) was significantly associated with CSF leak (P = 0.001). All patients with a displaced solid reconstruction (n = 5), displaced septal flap (n = 6), signs of air continuation (n = 2), or significantly increased amount of air (n = 5) presented with a CSF leak (P < 0.001). CONCLUSIONS: Early postoperative CT scan is predictive of CSF leak. Displacement of the fat graft in early postoperative CT was the most important factor in predicting CSF leak. In this patient group, paying attention to radiological predictors of CSF leaks is important, supported by clinical findings.

Three-dimensional changes in the cranial base associated with soft-diet feeding.

BACKGROUND: Masticatory activity affects the morphology of the maxillo-mandibular complex, however, its influence on the cranial base remains to be elucidated. The recent integration of quantitative morphometric analysis with 3D imaging enabled a comprehensive and high-resolution morphological characterization of the craniofacial complex. We aimed to investigate the influence of masticatory activity on the morphology of the growing cranial base by three-dimensional (3D) geometric morphometric approach using micro-CT. METHODS: The micro-CT data was reanalyzed to illustrate the 3D shape of the cranial base, and wireframe models were generated by connecting landmarks on the images. In the original study, mice were fed a soft diet (SD) of powdered pellets or a conventional hard diet (HD) for 6 weeks from 3 to 9 weeks of age, immediately after weaning. A principal component (PC) analysis analyzed shape variations and assessed their significance, while canonical variate (CV) analysis facilitated the comparison and differentiation of groups based on shape, unveiling meaningful shape distinctions. RESULTS: Three PCs were extracted that significantly separated the SD and HD groups among those explaining variations in shape. These PCs were related to the length of the sphenoid bone, the width of the anterior part of the sphenoid bone, and the length of the cranial base. Furthermore, one CV effectively distinguished SD from HD, and CV analysis showed that the sphenoid was shortened in the length and narrowed at the border of the temporal bone in SD mice. CONCLUSIONS: Masticatory loading affects the skeletal development of the cranial base. The morphology of the sphenoid bone was affected in both the sagittal and transverse axes.

Aspergillus infections of lateral skull base: a case series.

PURPOSE: While extensive research with accurate classification has been done in mycoses of the paranasal sinuses and anterior skull base, a similar understanding of lateral skull base fungal pathologies is lacking due to relative rarity and diagnostic difficulties. We introduce a series of eleven cases and two different invasive entities of Aspergillus temporal bone diseases-fungal skull base osteomyelitis (SBO)/malignant otitis externa (MOE) and chronic invasive granulomatous fungal disease (CIGFD). METHODOLOGY: A retrospective observational study was conducted at the neuro-otology unit of a tertiary care referral center between July 2017 and November 2022. Diagnosed cases of lateral skull base osteomyelitis with atypical symptoms and lack of response to culture-directed antibiotics were evaluated for fungal origin. Patient data, including history, laboratory findings, serum galactomannan assay, CT and MRI imaging findings, clinical examination findings, and co-morbidities, were analyzed. The treatment course and response were assessed. RESULTS: A total of 11 cases were included in the study. Of these, 9 were cases of Aspergillus-induced skull base osteomyelitis (SBO) and 2 of Aspergillus-induced chronic invasive granulomatous fungal disease (CIGFD). CIGFD presented with persistent ear discharge and slowly progressive post-aural swelling, while all patients of fungal SBO had lower cranial nerve palsies. CIGFD responded to excision and antifungals, while SBO responded well to conservative anti-fungal treatment. CONCLUSION: In cases of lateral SBO not responding to antibiotic therapy, the possibility of fungal etiology should be considered. Aspergillus spp. seems to be the major fungal pathogen.

CSF-Venous Fistula of the Clival Skull Base: A Unique Case Study and Literature Review.

An adolescent male presented with orthostatic headaches following head trauma. MRI showed cerebellar tonsil displacement and a bony defect in the clival skull base. Digital subtraction myelography (DSM) confirmed a cerebrospinal fluid-venous fistula (CVF). This was repaired endoscopically. CVFs cause uncontrolled flow of CSF into the venous system resulting in symptoms of intracranial hypotension. They're often difficult to identify on initial imaging. This is the first reported CVF originating in the central skull base, and the first treated via endoscopic trans-nasal approach. CVFs may elude initial imaging, making DSM crucial for unexplained spontaneous intracranial hypotension. Laryngoscope, 134:645-647, 2024.

Reliability of High-resolution Gadolinium-enhanced MR Cisternography and Gasket-seal Technique for Management of Anterior Skull Base Defects.

PURPOSE: Precise preoperative localization of anterior skull base defects is important to plan surgical access, increase the success rate and reduce complications. A stable closure of the defect is vital to prevent recurrence of cerebrospinal fluid (CSF) rhinorrhea. The purpose of this retrospective case series was to evaluate the reliability of a new high-resolution gadolinium-enhanced compressed-sensing SPACE technique (CS T1 SPACE) for magnetic resonance (MR) cisternography to detect cerebrospinal fluid leaks of the anterior skull base and to assess the long-term success rate of the gasket-seal technique for closure of skull base defects. METHOD: All patients with spontaneous or postoperative cerebrospinal fluid rhinorrhea and defects of the anterior skull base presenting to the Departments of Otorhinolaryngology and Neurosurgery between 2019 and 2020, receiving a computed tomography (CT) cisternography and MR cisternography (on a 3T whole-body MR scanner using a 64-channel head and neck coil) with CS T1 SPACE sequence and closure of the defect with the gasket-seal technique, were enrolled in the study. For the cisternography, iodinated contrast agent (15 ml Solutrast 250 M®), saline (4 mL) mixed with a 0.5 mL of gadoteridol was injected into the lumbar subarachnoid space. RESULTS: A total of four patients were included in the study and MR cisternography with CS T1 SPACE sequence was able to precisely localize CSF leaks in all patients. The imaging results correlated with intraoperative findings. All defects could be successfully closed with the gasket-seal technique. The mean follow-up was 35.25 months (range 33-37 months). CONCLUSION: MR cisternography with CS T1 SPACE sequence could be a promising technique for precise localization of CSF leaks and the gasket-seal technique resulted in good closure of the CSF fistula in this case series.