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Objective: To determine alterations in the crista galli (CG) size in fetuses with advancing weeks., Methods: Skull bases of 32 fetuses (11 males/21 females) aged 17 to 32 weeks in utero were included in the study. The width (width of CG), height (height of CG), and length (length of CG) of CG were measured, and also olfactory fossa depth (OFD) was measured to determine the relation of CG with OFD., Results: Width of CG, height of CG, length of CG, and OFD were measured as 1.77 ± 0.59 mm, 5.10 ± 1.70 mm, 12.32 ± 2.25 mm, and 1.56 ± 0.56 mm, respectively. No significant difference was observed between the measurements in terms of sex and side ( P > 0.05). Apart from OFD, the parameters were greater in the third-trimester fetuses than in the second-trimester fetuses ( P < 0.001). Olfactory fossa depth was similar in both trimester fetuses ( P = 0.798). Olfactory fossa depth did not alter with advancing gestational weeks ( P = 0.077), but the others increased ( P < 0.01). Only one configuration regarding Keros types was observed. Type 1 was detected in all fetuses (100%). A linear function was calculated as y=1.442+0.455×age for the length of CG, y=-2.566+0.321×age for the height of CG, y=0.641+0.039×age for OFD, and y=-1.088+0.119×age for the width of CG., Conclusions: Crista galli size increased with advancing fetal weeks. The authors detected Keros type 1 in all fetuses. The authors' linear functions representing the growth pattern of CG and OFD in fetuses may be useful in estimating their dimensions., Competing Interests: The authors report no conflicts of interest., (Copyright © 2024 by Mutaz B. Habal, MD.)

Objective: The objective of this study is to evaluate the role of hybrid 18F-FDG PET for treatment response assessment and management guidance in patients with skull base osteomyelitis., Materials and Methods: Retrospectively, 33 patients, with at least a baseline and follow-up PET (computed tomography/MRI) scan, were included. Parameters like standardized uptake value (SUV) max, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) (initial, follow-up, percentage change) were analysed and outcomes based on 18F-FDG PET reports were classified into resolution (a), partial response (b), progression (c) and stable disease (d). The clinical course and response on anatomical imaging were also compared with 18F-FDG PET., Results: There was mild correlation between initial SUV with ESR (0.338) and CRP (0.384). Moderate correlation was seen between follow-up SUV and CRP (0.619), percentage change in SUV max (PC SUV) with percentage change in ESR (0.456) and CRP (0.668). Mean PC SUV was 70% (a), 35% (b), -40% (c) and -18% (d), respectively. 48% (16/33) (resolution, progression, stable disease) patients had clear management change with 18F-FDG PET with either escalation or stopping of antibiotics/antifungals. Management decision in partial response group (52%, 17/33) was taken clinically. On retrospective PC SUV analysis, treatment continuation group (8 patients) showed 20% decrease, whereas the group that was only monitored further (9 patients) had 48% reduction in SUV., Conclusion: 18F-FDG PET showed a moderate association with clinical markers used in follow-up of patients with skull base osteomyelitis and is a reliable investigation for assessment of disease status. This can be used as a guide along with clinical evaluation for de-escalation of treatment., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Purpose of Review: Benign bony lesions of the craniofacial complex are relatively common. However, their location close to critical neurovascular structures may render their treatment, if required, highly challenging.This article reviews the current literature on their pathophysiology, diagnosis, natural course and treatment, with a focus on most recent findings., Recent Findings: A new classification has been suggested concerning endoscopic resectability. The ratio of lateral frontal to interorbital distance can accurately and reliably predict the endoscopic reach to lateral frontal sinus, while orbital transposition can assist us in reaching lateral frontal sinus when anatomy is unfavorable. New and combined endoscopic transnasal and transorbital approaches are now in the surgical armamentarium. Prophylactic optic nerve decompression in fibrous dysplasia is absolutely contraindicated as it leads to worse visual outcomes. Radiotherapy of such lesions is of no benefit and may lead to a higher risk of malignant transformation. The presence of Guanine Nucleotide binding protein Alpha Stimulating (GNAS) mutation in chromosome 20 is universally present in fibrous dysplasia and can differentiate them from ossifying fibromas., Summary: Diagnosis and therapeutic management of benign craniofacial bone lesions remains challenging. If surgical treatment is contemplated, the morbidity of the intervention should always be weighed against the potential benefits. Evolution of extended endoscopic endonasal and transorbital surgery means that more lesions can be reached purely endoscopically with better oncological and cosmetic results., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Objectives: We describe 10 new cases of otogenic (n = 8) and nonotogenic (n = 2) skull base osteomyelitis (SBO) in previously healthy children and review the literature on SBO in the pediatric population., Methods: We retrospectively analyzed the medical records of 10 children (age range 0.9-12.8 years) discharged with a diagnosis of SBO between 2015 and 2020 in 2 children's hospitals in central Israel., Results: Five patients presented with fever and 5 with otological signs and symptoms. All 10 children underwent a comprehensive clinical evaluation, imaging studies (computerized tomography or magnetic resonance imaging) and laboratory investigations. The physical examination revealed neurologic findings, including nuchal rigidity, papilledema, and apathy, in 4 patients. All 8 otogenic patients underwent surgical intervention and the 2 nonotogenic patients, who were diagnosed as having deep neck and throat infections, responded well to treatment consisting of antibiotics without surgery., Conclusions: Early diagnosis of pediatric SBO can be challenging because the symptoms are often nonspecific. The final diagnosis relies mainly on imaging, preferably magnetic resonance imaging. Surgical intervention is usually mandatory in the otogenic patients, whereas the nonotogenic patients respond well to medical management alone., Competing Interests: Disclosure: The authors declare no conflict of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Objective: The timing for resuming continuous positive airway pressure (CPAP) postoperatively after skull base surgery remains controversial because of the risk of pneumocephalus. We determined the safety of immediate CPAP use after middle cranial fossa (MCF) spontaneous cerebrospinal fluid (sCSF) leak repair with bone cement., Study Design: Prospective cohort study., Setting: Tertiary academic medical center., Patients: Thirteen consecutive patients with CPAP-treated obstructive sleep apnea and temporal bone sCSF leaks who underwent skull base repair with hydroxyapatite bone cement between July 2021 and October 2022., Interventions: CPAP use resumed on postoperative day 1 after the confirmation of skull base reconstruction with temporal bone computed tomography (CT)., Main Outcome Measures: Postoperative skull base defects on CT, pneumocephalus, or intracranial complications., Results: The average age was 55.5 ± 8.8 years (±standard deviation), and 69.2% were female with a BMI of 45.39 ± 15.1 kg/m 2 . Multiple tegmen defects were identified intraoperatively in 53.9% of patients with an average of 1.85 ± 0.99 defects and an average defect size on preoperative imaging of 6.57 ± 3.45 mm. All patients had an encephalocele identified intraoperatively. No residual skull base defects were observed on CT imaging on postoperative day 1. No postoperative complications occurred. One patient developed a contralateral sCSF leak 2 months after repair. There were no recurrent sCSF leaks 1 month postoperatively., Conclusion: Immediate postoperative CPAP use is safe in patients undergoing MCF sCSF leak repair with bone cement because of the robust skull base repair., Competing Interests: The authors disclose no conflicts of interest., (Copyright © 2023, Otology & Neurotology, Inc.)

The facial nerve emerges out of skull through the stylomastoid foramen located between styloid process and mastoid process. Unilateral paralysis of facial nerve is known as Bell's palsy and is reported to be caused most frequently by herpes simplex virus. The herpes infection is comparatively common but Bell's palsy is not very common. So, other causes of Bell's palsy like variation in morphological forms of stylomastoid cannot be ruled. There is paucity of literature elucidating morphological shapes of this foramen and correlating these forms of foramen with Bell's palsy. Hence the study was carried out. The aim of this study is to expound varied forms of stylomastoid foramen and to bring out clinical implications. The study was conducted in the department of anatomy using undamaged 70 adult dry human skulls of unknown age and sex. The morphological shapes were observed, interpretated and compared with available literature and their clinical implications were brought out. Most common shapes observed were round and oval followed by square shapes. Round shaped foramina were observed in 40 skulls on right sides constituting 57.1% and in 36 skulls on left side constituting 51.4%. While oval shapes were found in 16 skulls on right side (22.6%) and in 12 skulls on left side (17.1%). Rare variants of the foramen include triangular, serrated and closely applied to styloid process. The rare morphological forms were mostly observed to be unilateral in occurrence. Unilateral Bell's palsy is common, so, the rare morphological forms might be responsible for Bell's palsy., Competing Interests: The author reports no conflicts of interest., (Copyright © 2023 by Mutaz B. Habal, MD.)

Abstract: Photon-counting computed tomography (PCCT) offers better high-resolution and noise performance than energy integrating detector (EID) CT. In this work, we compared both technologies for imaging of the temporal bone and skull base. A clinical PCCT system and 3 clinical EID CT scanners were used to image the American College of Radiology image quality phantom using a clinical imaging protocol with matched CTDI vol (CT dose index-volume) of 25 mGy. Images were used to characterize the image quality of each system across a series of high-resolution reconstruction options. Noise was calculated from the noise power spectrum, whereas resolution was quantified with a bone insert by calculating a task transfer function. Images of an anthropomorphic skull phantom and 2 patient cases were examined for visualization of small anatomical structures. Across measured conditions, PCCT had a comparable or smaller average noise magnitude (120 Hounsfield units [HU]) to the EID systems (144-326 HU). Photon-counting CT also had comparable resolution (task transfer function f25 : 1.60 mm -1 ) to the EID systems (1.34-1.77 mm -1 ). Imaging results supported quantitative findings as PCCT more clearly showed the 12-lp/cm bars from the fourth section of the American College of Radiology phantom and better represented the vestibular aqueduct and oval and round windows when compared with the EID scanners. A clinical PCCT system was able to image the temporal bone and skull base with improved spatial resolution and lower noise than clinical EID CT systems at matched dose., Competing Interests: E.S. lists relationships with the following entities unrelated to the present publication: GE, Bracco, Imalogix, 12Sigma, Metis Health Analytics, Cambridge University Press, and Wiley and Sons. J.B.S. benefits from a license agreement with Sun Nuclear Corporation and is an adviser for METIS Health Analytics. Both relationships are unrelated to this work. The other authors declare no conflict of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Competing Interests: The authors disclose no conflicts of interest.

Objective: This report describes a case of a spontaneous cerebrospinal fluid leak at the jugular foramen that was surgically repaired via the infralabyrinthine approach with adjunct use of intrathecal fluorescein and stereotactic navigation., Patients: A 39-year-old woman presenting with clear otorrhea confirmed to be cerebrospinal fluid (CSF) emanating from a defect in the jugular foramen., Intervention: Surgical repair of the skull base defect using an infralabyrinthine approach to the jugular foramen. During surgery, intrathecal fluorescein and stereotactic navigation were used to localize the defect and confirm a successful repair., Main Outcome Measure: Recurrence of a CSF leak., Results: The defect was successfully repaired using the techniques described, resulting in cessation of the patient's CSF leak. There was no recurrence of the CSF leak up to a 4-month postoperative outpatient follow-up., Conclusions: Diagnosis and repair of spontaneous otogenic CSF leaks in an uncommon location like the jugular foramen are challenging. This report demonstrates the successful use of the infralabyrinthine approach for control of a CSF from the jugular foramen. In addition, use of techniques, such as intrathecal fluorescein and stereotactic navigation that are not routinely used in otology and neurotology allowed for safe, effective repair of the leak in this case., Competing Interests: The authors disclose no conflicts of interest., (Copyright © 2022, Otology & Neurotology, Inc.)

Objective: The aim of this study is to verify if the length of the nasoseptal flap is sufficient to cover the tuberculum sellae and planum sphenoidale of sphenoidal sinuses with varied degrees of pneumatization., Methods: Retrospective study of paranasal sinus computed tomography comparing the potential length of the nasoseptal flap and the length of the nasoseptal flap required for reconstruction of transtuberculum and transplanum approaches in conchal, presellar, sellar, incomplete postsellar, and complete postsellar sphenoidal sinuses., Results: The length of the nasoseptal flap required for reconstruction of transtuberculum and transplanum approaches was directly related to the degree of pneumatization of the sphenoidal sinus. The nasoseptal flap length was adequate to cover the cranial base after transtuberculum approaches of all cases from the conchal, presellar, and sellar groups and the majority of cases from postsellar pneumatization. For transplanum approaches, the nasosseptal flap was sufficient to reconstruct defects in most cases from conchal, pre-sellar, and sellar type sinuses and in 54,9% and 19,2% in incomplete and complete postsellar, respectively., Conclusions: In well pneumatized sphenoidal sinus, the nasoseptal flap may not be sufficient to cover the cranial base after transtuberculum and transplanum approaches., Competing Interests: The authors report no conflicts of interest., (Copyright © 2022 by Mutaz B. Habal, MD.)

Purpose: The anatomy and variations of the anterior ethmoidal artery (AEA) are clinically relevant. The anterior ethmoidal foramen (AEF) can be used to locate the initial site of the AEA, and the anterior nasal spine (ANS) is a constant bony marker in the anterior nasal atrium. However, there is no relevant research on AEF and ANS targeting the AEA. Hence, this study aimed to accurately locate the AEA through AEF and ANS using computed tomography., Methods: A total of 120 (240 sides) sinus computed tomography scans were retrospectively selected and studied. The AEA was classified into grades I, Ⅱ, and Ⅲ group based on the relationship between the AEA and the skull base. The distance between AEF and ANS and the angle between AEF-ANS and the axial plane were measured., Results: The average distance from AEF to ANS was 58.26±3.64 mm, and the corresponding angle was 60.05±5.93 degrees. The AEF-ANS distances and angles were negatively correlated with age. Moreover, the distances from AEF to ANS were significantly increased in the grade Ⅲ group compared with the grade Ⅱ group., Conclusion: The measurements obtained in this study add anatomic knowledge that can serve as a better intraoperative localization method of the AEA, which can help surgeons avoid relative complications during endoscopic sinus surgery., Competing Interests: The authors report no conflicts of interest., (Copyright © 2022 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of Mutaz B. Habal, MD.)

Background: Idiopathic intracranial hypertension (IIH) is a disorder characterized by elevated intracranial pressure without secondary causes on neuroimaging. IIH typically occurs in young, obese female patients and, when severe, can cause permanent and irreversible vision loss. The association between skull base thinning in patients with intracranial hypertension and obesity has been previously reported; however, no study has reported these findings in IIH. The goal of our study is to determine whether IIH is independently associated with skull base and calvarial thinning., Methods: A retrospective, matched case-control study was performed. Each patient diagnosed with IIH (case) was matched with a patient diagnosed with headache (control) by age, gender, and race. Patients were included if they underwent computed tomographic imaging of the head, maxillofacial, or orbits within 3 months of their diagnosis. Exclusion criteria were history of skull base or frontal bone pathology because of surgery or skull trauma, central nervous system infections, or incomplete radiologic data. Patient demographics, medical history, clinical examination, and skull base, calvarial, and zygoma thickness were recorded. Skull base thickness was measured by the height of the auditory canal in the coronal plane. Calvarial thickness was measured just anterior to the foramen rotundum in the coronal plane. Extracranial zygoma thickness was measured and used as an internal imaging control because the zygoma is not subject to intracranial forces., Results: One hundred twenty-six patients were included in the study, 63 cases and 63 controls. Each group comprised 61 female patients (97%), 24 (38%) Caucasian, 23 (37%) black, 1 (2%) Asian, and 15 (24%) others. The average age was 31.5 ± 8.7 years. Patients with IIH were more likely to be obese (n = 60, 95%) compared with the control patients (n = 23, 37%, P < 0.001). All patients with IIH underwent lumbar puncture (LP) with an average opening pressure (OP) of 40.5 ± 15.6 cm H2O, whereas only 13 (20%) controls underwent an LP with a mean OP of 19.5 ± 8.5 cm H2O. There was no statistical difference in mean visual acuity between the IIH and control groups (logMar 0.22 [20/30] ± 0.45 vs logMar 0.09 [20/25] ± 0.30, P = 0.093, respectively). Compared with the controls, patients with IIH were more likely to have headache (97% vs 74%, P = 0.001), pulsatile tinnitus (48% vs 7%, P < 0.001), horizontal binocular diplopia (24% vs 4%, P = 0.006), confrontational visual field deficit (23% vs 2%, P = 0.003), and papilledema (74% vs 0%, P < 0.001). Patients with IIH had thinner skull base and calvarium width compared with the controls (mean skull base thickness 4.17 ± 0.94 mm vs 5.05 ± 1.12 mm, P < 0.001 and mean calvarial width 1.50 ± 0.50 mm vs 1.71 ± 0.61 mm, P = 0.024). Zygoma thickness was similar in both groups (mean zygoma thickness 1.18 ± 0.30 mm in the IIH group vs 1.26 ± 0.35 mm in the control group, P = 0.105). In a subgroup analysis controlling for obesity (body mass index >30 kg/m2), there was no statistically significant difference in skull base, calvarial, or zygoma thickness between obese and nonobese patients., Conclusions: Patients with IIH have thinner mean skull base and calvarial thickness compared with the controls. There was no difference in the mean extracranial zygoma thickness, which was the internal imaging control. Contrary to previous reports, we did not find an association between obesity and skull base or calvarial thinning. These findings suggest that IIH is associated with skull base and calvarial thinning., Competing Interests: The authors report no conflicts of interest., (Copyright © 2022 by North American Neuro-Ophthalmology Society.)

Objectives: Information about the endonasal endoscopic approach (EEA) for the management of posttraumatic tension pneumocephalus (PTTP) remains scarce. Concomitant rhinoliquorrhea and posttraumatic hydrocephalus (PTH) can complicate the clinical course., Methods: The authors systematically reviewed pertinent articles published between 1961 and December 2020 and identified 6 patients with PTTP treated by EEA in 5 reports. Additionally, the authors share their institutional experience including a seventh patient, where an EEA resolved a recurrent PTTP without rhinoliquorrhea., Results: Seven PTTP cases in which EEA was used as part of the treatment regime were included in this review. All cases presented with a defect in the anterior skull base, and 3 of them had concomitant rhinoliquorrhea. A transcranial approach was performed in 6/7 cases before EEA was considered to treat PTTP. In 4/7 cases, the PTTP resolved after the first intent; in 2/ 7 cases a second repair was necessary because of recurrent PTTP, 1 with and 1 without rhinoliquorrhea, and 1/7 case because of recurrent rhinoliquorrhea only. Overall, PTTP treated by EEA resolved with a mean radiological resolution time of 69 days (range 23-150 days), with no late recurrences. Only 1 patient developed a cerebrospinal fluid diversion infection probably related to a first incomplete EEA skull base defects repair. A permanent cerebrospinal fluid diversion was necessary in 3/7 cases., Conclusions: Endonasal endoscopic approach repair of air conduits is a safe and efficacious second-line approach after failed transcranial approaches for symptomatic PTTP. However, the strength of recommendation for EEA remains low until further evidence is presented., Competing Interests: The authors report no conflicts of interest., (Copyright © 2021 by Mutaz B. Habal, MD.)

Background: Surgery to anterior skull base is challenging since complex structures are involved. Injury of olfactory fila and optic nerve may result in postoperative complications. In our study, the authors aim to use computer topographic image to provide a comprehensive anatomical information of anterior skull base and set up a new classification of optic canal (OC) in ethmoid sinus by the degree of bony defect, so as to help surgeons in endoscopic transnasal approach to anterior skull base., Method: Computer topographic angiography images of 112 individuals were reviewed, the measurement was performed on coronal, sagittal, and axis planes after the multiplanar reformation. Nostril and mid-sagittal lines were used to locate the anterior, middle, and posterior part of ethmoidal foramina and orbital opening of OC. Further, the authors classified OC in ethmoidal sinus into 4 types by the degree of the bony defect., Result: Distance between nostril to anterior, middle, and posterior part of ethmoidal foramina and OC are 6.23 ± 0.21, 6.62 ± 0.26, 7.29 ± 0.25, and 7.76 ± 0.41 mm, respectively. Angle between line from nostril to ethmoidal foramina and horizontal plane are 47.50° ± 1.03°, 41.67° ± 1.33°, 37.20° ± 1.34°, respectively. For the 4 types of OC, the percentage is 15.6%, 11.6%, 31.3%, and 41.5%, respectively., Conclusions: Our findings provide anatomical information of ethmoidal foramina and OC during endoscopic transnasal approach to anterior skull base, on the basis of some fixed anatomical landmarks. So as to enhance the surgical safety of this procedure and aid in the choice of the appropriate endoscopic equipment for the procedure., Competing Interests: The authors report no conflicts of interest., (Copyright © 2021 by Mutaz B. Habal, MD.)

Abstract: The purpose of this study was to investigate the effects of early spheno-occipital synchondrosis (SOS) fusion in preadolescent patients with syndromic craniosynostosis (SC) on the craniofacial skeletal patterns. Twenty preadolescent SC patients were divided into the fused SOS (FS, n = 10; 8 Crouzon and 2 Apert) and not-fused SOS groups (NFS, n = 10; 9 Crouzon and 1 Apert). Lateral cephalograms (mean age: 9.60 years, cervical vertebral maturation index: stage I and II) were used to investigate the skeletal sagittal (ANB) and vertical patterns (SN-GoMe), upward inclination of the anterior cranial base (ACB; SN-FH), degree of midface hypoplasia (MH, SNA), retrusive position of orbitale (SNO), and forward position of the condyle in relation to sella (saddle angle). Using the ordinal values calculated by ethnic norm (criteria: moderate, over ±1 standard deviation, severe, over ±2 standard deviation), statistical analysis was performed. The FS group showed a higher percentage of severe MH than the NFS group (70% versus 10%, P < 0.05). Although the 2 groups did not differ in the distribution of ANB, SN-GoMe, saddle angle, and SN-FH (all P > 0.05), the FS group showed relatively higher percentages of severe Class III (100% versus 70%), severe hyper-divergent pattern (40% versus 10%), severely forward condyle position (30% versus 0%), and moderate and severe upward anterior cranial base inclination (90% versus 50%) than the NFS group. However, the 2 groups exhibited the same distribution of moderately and severely retrusive orbitale position ([50%, 20%], P > 0.05). Early SOS fusion in preadolescent SC patients might not be related to retrusive orbitale position, but to severe MH., Competing Interests: The authors report no conflicts of interest., (Copyright © 2021 by Mutaz B. Habal, MD.)

Background: Fusion of cranial-base sutures/synchondroses presents a clinical conundrum, given their often unclear "normal" timing of closure. This study investigates the physiologic fusion timelines of cranial-base sutures/synchondroses., Methods: Twenty-three age intervals were analyzed in subjects aged 0 to 18 years. For each age interval, 10 head computed tomographic scans of healthy subjects were assessed. Thirteen cranial-base sutures/synchondroses were evaluated for patency. Partial closure in greater than or equal to 50 percent of subjects and complete bilateral closure in less than 50 percent of subjects defined the fusion "midpoint." Factor analysis identified clusters of related fusion patterns., Results: Two hundred thirty scans met inclusion criteria. The sutures' fusion midpoints and completion ages, respectively, were as follows: frontoethmoidal, 0 to 2 months and 4 years; frontosphenoidal, 6 to 8 months and 12 years; and sphenoparietal, 6 to 8 months and 4 years. Sphenosquamosal, sphenopetrosal, parietosquamosal, and parietomastoid sutures reached the midpoint at 6 to 8 months, 8 years, 9 to 11 months, and 12 years, respectively, but rarely completed fusion. The occipitomastoid suture partially closed in less than or equal to 30 percent of subjects. The synchondroses' fusion midpoints and completion ages, respectively, were as follows: sphenoethmoidal, 3 to 5 months and 5 years; spheno-occipital, 9 years and 17 years; anterior intraoccipital, 4 years and 10 years; and posterior intraoccipital, 18 to 23 months and 4 years. The petro-occipital synchondrosis reached the midpoint at 11 years and completely fused in less than 50 percent of subjects. Order of fusion of the sutures, but not the synchondroses, followed the anterior-to-posterior direction. Factor analysis suggested three separate fusion patterns., Conclusions: The fusion timelines of cranial-base sutures/synchondroses may help providers interpret computed tomographic data of patients with head-shape abnormalities. Future work should elucidate the mechanisms and sequelae of cranial-base suture fusion that deviates from normal timelines., (Copyright © 2021 by the American Society of Plastic Surgeons.)

Aims: Identify variations of skull base measurements in individuals with dentofacial deformities associated or not with cleft lip and palate and compare the results with individuals without dentofacial deformities., Methods and Results: The individuals were categorized into three different groups: dentofacial deformity without cleft malformation, dentofacial deformity associated with cleft lip and palate, and without facial deformity. The inclusion criteria were individuals over 18 years of age, without any intervention involving facial bones or structures of interest for the study and field of view encompassing from the glabella to the hyoid bone. Poor quality CT scans or lack of adequate medical records were considered exclusion criteria. In the analysis by computerized tomography using the Dolphin Imaging Software, the length determined by the Ba-S and S-N lines was evaluated, as well as the Ba-S-N angle formed by landmarks., Results: The length of S-N was not statistically different between the groups, the Ba-S length and the Ba-S-N angle demonstrated statistical difference., Conclusion: There was statistically significant difference in the morphometry of the (Ba-S) between groups (FS) and (C). This suggests that the standard values for cephalometric analyzes involving these structures, especially to determine the treatment planning, should be used with caution., Competing Interests: The authors report no conflicts of interest., (Copyright © 2021 by Mutaz B. Habal, MD.)

Purpose of Review: Skull base osteomyelitis (SBO) is a life-threatening condition. Due to an aging and increasingly multimorbid population, clinicians are more often challenged with this disease. Yet, there is no consensus on the optimal diagnostic and follow-up management. This review should aid clinicians in decision-making for their patients., Recent Findings: Treatment-resistant otalgia or headache is suspicious of SBO. Pseudomonas aeruginosa remains the most common pathogen but clinicians are challenged with increasing rates of sterile or fungal cultures due to previously applied antibiotics/steroids. No single imaging modality is able to detect the full extent of the disease. Whereas functional nuclear imaging with gallium-67 or methylene diphosphonate-technetium-99m was once advocated, its actual benefit is questionable. Newer modalities such as fluoro-D-glucose-positron emission tomography (PET)/computed tomography, PET/magnetic resonance imaging (MRI), or diffusion-weighted MRI seem to be promising in diagnosis and follow-up. Finding the causative pathogen is of utmost importance followed by long-term intravenous antibiotics until the disease has completely resolved. Surgery plays a minor role in treatment but can be helpful in selected cases., Summary: The numerous challenges in SBO render management difficult, but with a clear work-up including regular clinical, laboratory and imaging examinations, outcome can be improved., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Purpose of Review: Skull base osteomyelitis (SBO) is a challenging entity to diagnose and treat. The goal of this review is to summarize the imaging findings of SBO and present these in the context of recent studies on imaging of SBO., Recent Findings: This review discusses the clinical presentation, pathophysiology and imaging appearances of SBO. The review further emphasizes the results of latest studies on imaging of SBO, and the role of different modalities in diagnosis and evaluation of disease course and treatment response. Brief discussion on differential diagnoses from an imaging standpoint is also included., Summary: Various imaging modalities play different and complimentary roles in diagnosis and management of SBO, which are discussed in this review., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Competing Interests: The authors report no conflicts of interest.

Introduction: Crista galli is extremely important in the endoscopic transcribriform approaches and some extradural approaches. Because of its clinical significance, the morphometric properties of crista galli should be well known. In this study, it was aimed to examine the morphometry and the pneumatization incidence of the crista galli in cone beam computed tomography (CBCT) images., Material and Methods: In this retrospective study, the length and width of the crista galli were measured in CBCT images of 300 healthy individuals. Besides, the presence of crista galli pneumatization was examined., Results: The length and width of the crista galli were determined to be as 14.03 ± 2.93 mm and 3.73 ± 1.48 mm, respectively. Pneumatized crista galli was detected in 53 out of 300 individuals (17.67%). There was no statistical difference between the presence of pneumatization and both length and width values of the crista galli (P = 0.876 and P = 0.478, respectively). In addition, no relationship was determined between age and the presence of pneumatization (P = 0.167)., Conclusion: In this study, it is seen that the length (range: 6.00-23.40 mm) and width (range: 1.40-8.00 mm) of crista galli are in a very wide range. Besides, it is seen in the literature that the incidence of crista galli pneumatization is in a very wide range (2.4% to 66.6%). Based on the available data, it will not be possible to determine a specific range of values for crista galli morphometry. Therefore, the authors think that CT imaging is extremely important in preoperative evaluation., Competing Interests: The authors declare no conflict of interest., (Copyright © 2021 by Mutaz B. Habal, MD.)

Abstract: Treatment of refractory cerebrospinal fluid (CSF) leaks, particularly those associated with large skull base defects, is challenging. A variety of synthetic biomaterial-based systems have been investigated in experimental models and/or humans for reconstructing cranial base defects. A widely used dental composite (bisphenol A-glycidyl methacrylate [bis-GMA]) has been shown to be effective for reconstruction of anterior skull base defects in animal models. Here, we report 4 patients who underwent reconstruction of large anterior skull base defects (1405.8 ± 511 mm2) secondary to tumor resection and traumatic injury using the dental bis-GMA resin-based composite. A vascularized pericranial flap with fibrin glue was initially performed in all patients with concurrent use of dental bis-GMA during the primary surgery in 2 patients, and later use (in a repeat surgery) in other 2 cases. In these latter 2, CSF rhinorrhea persisted after the initial surgery (in the absence of bis-GMA use) despite external CSF drainage with lumbar drain. Following treatment with bis-GMA, rigid structural support and watertight closure of the defect were successfully achieved. At the follow-up, CSF leak did not recur and none of the patients had any complications related to the surgery or the composite. The results obtained from this series are promising, and dental bis-GMA resin seems to provide an effective and feasible material for the treatment and prevention of CSF leaks related to large-scale anterior skull base defects. However, further studies with longer clinical follow-up and larger number of patients are required to prove the safety and efficacy of this matrix in the long run., Competing Interests: The authors report no conflicts of interest., (Copyright © 2021 by Mutaz B. Habal, MD.)

Abstract: The authors report a case of a rare, large, nodular pseudogout which developed from the temporomandibular joint (TMJ).An 83-year-old female was referred to the hospital with swelling on her left cheek. Imaging studies revealed a large calcified mass surrounding the left mandibular condyle, partially destroying the adjoining bone and extending to the skull base. Magnetic resonance imaging (MRI) revealed soft tissue masses with low signal intensity on T1- and T2-weighted images and were enhanced after intravenous gadolinium injection.The mass was clinically and radiologically suspected to be a neoplastic lesion, such as chondrosarcoma or fibrous dysplasia. However, histological analysis showed that the mass contained granulomatous lesions with numerous multiple nodular rod-shaped and diamond-shaped crystal deposits, which validated the diagnosis of pseudogout. X-ray diffraction (XRD) was performed to identify the tumor's deposited materials and revealed that these were calcium pyrophosphate dihydrate (CPPD) crystals. This result confirmed the histopathological diagnosis of "tophaceous pseudogout.", Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2020 by Mutaz B. Habal, MD.)

Purpose: It is known from both anatomic and radiographic studies that the majority of cranial sutures begin fusing in early adulthood and are fused by late adulthood. However, most of the studies focus on the cranial vault rather than the cranial base. Most clinicians treating patients with craniosynostosis are interpreting the behavior of cranial sutures on CT imaging. Therefore, the purpose of this study was to further clarify the radiographic appearance of cranial base sutures over the natural human life span., Methods: Thirty CT scans of the head and face were reviewed for each decade starting at 1 year of life up to age 90. Scans were evaluated for the appearance of the occipitomastoid, petrosoocciptial, sphenosquamous, sphenopetrosal, frontosphenoidal, sphenozygomatic, petrososquamosal, frontoethmoidal, sphenoethmoidal and sphenoccipital sutures. Sutures were categorized as obliterated, present with fusion, present without fusion and unable to visualize., Results: The majority of cranial base sutures are visible up through the eighth decade, although evidence of ossification across the suture starts as early as the second decade. Some sutures such as the occipitomastoid appeared > 90% open even as late as the ninth decade. Other sutures such as the sphenosquamosal and frontozygomatic are mostly fused by that age., Conclusion: Cranial base sutures appear to behave radiographically similar, to the cranial vault sutures in that they largely remain visible throughout adulthood but show varying amounts of ossification. There are some cranial base sutures which appear to remain open throughout life although the significance of this has yet to be determined., Competing Interests: The authors report no conflicts of interest., (Copyright © 2020 by Mutaz B. Habal, MD.)

Abstract: Skull base osteomyelitis that is secondary to otitis media is extremely rare in the modern antibiotic era. The authors present an 84-year-old male with atypical skull base osteomyelitis that developed from otitis media during the COVID-19 pandemic due to delayed diagnosis and partial treatment which is blamed for development of skull base osteomyelitis. The atypical presentations of skull base osteomyelitis pose a diagnostic challenge. This case highlights that even otitis media is a potentially fatal infection in older patients with diabetes. Early diagnosis and aggressive management of skull base osteomyelitis are of upmost importance and will ensure a more favorable prognosis., Competing Interests: The authors report no conflicts of interest., (Copyright © 2021 by Mutaz B. Habal, MD.)

Background: Little is known about the detailed growth of the cranial fossae, even though they provide an important structural connection between the cranial vault and the facial skeleton. This study details the morphologic development of isolated cranial vault synostosis and associated syndromes on cranial fossa development., Methods: A total of 125 computed tomographic scans were included (nonsyndromic bicoronal synostosis, n = 36; Apert syndrome associated with bicoronal synostosis, n = 24; Crouzon syndrome associated with bicoronal synostosis, n = 11; and controls, n = 54). Three-dimensional analyses were produced using Materialise software., Results: The regional anterior and middle cranial fossae volumes of nonsyndromic bicoronal synostosis are characterized by significant increases of 43 percent (p < 0.001) and 60 percent (p < 0.001), respectively, and normal posterior cranial fossa volume. The cranial fossae depths of nonsyndromic bicoronal synostosis were increased, by 37, 42, and 21 percent (all p < 0.001) for anterior, middle, and posterior cranial fossae, respectively, accompanying the shortened cranial fossae lengths. The volume and morphology of all cranial fossae in Apert syndrome nearly paralleled nonsyndromic bicoronal synostosis. However, Crouzon syndrome had reduced depths of cranial fossae, and more restricted fossa volumes than both Apert syndrome and nonsyndromic bicoronal synostosis., Conclusions: Cranial vault suture synostosis is likely to be more influential on cranial fossae development than other associated influences (genetic, morphologic) in Apert and Crouzon syndromes. Isolated Apert syndrome pathogenesis is associated with an elongation of the anterior cranial fossa length in infants, whereas in Crouzon syndrome, there is a tendency to reduce cranial fossa depth, suggesting individual adaptability in cranial fossae development related to vault synostosis., (Copyright © 2021 by the American Society of Plastic Surgeons.)

Objective: Spontaneous cerebrospinal fluid (CSF) leaks are thought to arise due to elevated intracranial pressure which is distributed across the skull base, potentially predisposing the development of multifocal CSF leaks. The aims of this study are to evaluate the characteristics of this population at presentation and surgical outcomes., Study Design: Retrospective case series., Setting: Tertiary referral center., Patients: Patients 18 years or older with spontaneous CSF leak diagnosis were eligible for study inclusion. Multifocal spontaneous CSF leak was defined as leaks originating from more than one skull base defect at anatomically distinct subsites., Intervention: None., Main Outcome Measure: Clinical presentation and surgical outcome., Results: Two hundred ninety-three patients with diagnosis of spontaneous CSF leak were identified. Of these, 11 (3.8%) were characterized as having multifocal spontaneous CSF leaks. Mean body mass index was significantly higher in multifocal CSF leak patients (31.5 ± 8.5 vs 46.2 ± 9.9, p < 0.0001). There was also higher prevalence of women (100% vs 63.8%, p = 0.012) and African-Americans (63.6% vs 23.4%, p = 0.003). The overall success rate of CSF leak repair was 95%. Fifty percent of patients developed headaches or blurry vision after surgical repair, and two patients required ventriculoperitoneal shunting., Conclusions: Multifocal spontaneous CSF leaks are rare and occurred in 3.8% of patients with spontaneous CSF. These patients were morbidly obese and more likely to be female and African American. Surgical repair conferred excellent outcomes. However, these patients have high risk of developing symptoms suggestive of elevated intracranial pressure postoperatively and should be counseled accordingly., Competing Interests: The authors disclose no conflicts of interest., (Copyright © 2020, Otology & Neurotology, Inc.)

Abstract: Anterior skull base cerebrospinal fluid (CSF) fistulas result from skull base osteodural defects, allowing subarachnoid space CSF to escape into pneumatized cavities such as the paranasal sinuses and nasal fossa. Precise localization, characterization, and effective treatment of CSF leaks is essential to prevent meningitis, treatment failure, or recurrence. Advances in magnetic resonance imaging have improved radiologists' ability to localize and characterize anterior skull base CSF fistulas. This article reviews new imaging techniques enabling diagnostic location of CSF fistulas, with an emphasis on magnetic resonance imaging-based techniques., Competing Interests: The authors report no conflicts of interest., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Background: The trochlear nerve (the fourth cranial nerve) is the only cranial nerve that arises from the dorsal aspect of the midbrain. The nerve has a lengthy course making it highly susceptible to injury. It is also the smallest cranial nerve and is often difficult to identify on neuroimaging., Evidence Acquisition: High-resolution 3-dimensional skull base MRI allows for submillimeter isotropic acquisition and is optimal for cranial nerve evaluation. In this text, the detailed anatomy of the fourth cranial nerve applicable to imaging will be reviewed., Results: Detailed anatomic knowledge of each segment of the trochlear nerve is necessary in patients with trochlear nerve palsy. A systematic approach to identification and assessment of each trochlear nerve segment is essential. Pathologic cases are provided for each segment., Conclusions: A segmental approach to high-resolution 3-dimensional MRI for the study of the trochlear nerve is suggested., Competing Interests: The authors report no conflicts of interest., (Copyright © 2020 by North American Neuro-Ophthalmology Society.)

Background: Pfeiffer syndrome is a rare syndromic craniosynostosis disorder, with a wide range of clinical manifestations. This study aims to investigate the structural abnormalities of cranial fossa and skull base development in Pfeiffer patients, to provide an anatomic basis for surgical interventions., Method: Thirty preoperative CT scans of Pfeiffer syndrome patients were compared to 35 normal controls. Subgroup comparisons, related to differing suture synostosis, were performed., Results: Overall, the volume of anterior and middle cranial fossae in Pfeiffer patients were increased by 31% (P < 0.001) and 19% (P = 0.004), versus controls. Volume of the posterior fossa in Pfeiffer patients was reduced by 14% (P = 0.026). When only associated with bicoronal synostosis, Pfeiffer syndrome patients developed enlarged anterior (68%, P = 0.001) and middle (40%, P = 0.031) fossae. However, sagittal synostosis cases only developed an enlarged anterior fossa (47%, P < 0.001). The patients with solely bilateral squamosal synostosis, developed simultaneous reduced anterior, middle and posterior cranial fossae volume (all P ≤ 0.002). The overall skull base angulation, measured on both intracranial and subcranial surfaces, grew normally., Conclusion: Enlarged anterior cranial fossae in Pfeiffer syndrome children is evident, except for the squamosal synostosis cases which developed reduced volume in all fossae. Volume of the middle cranial fossa is influenced by associated cranial vault suture synostosis, specifically, sagittal synostosis cases develop normal middle fossa volume, while the bicoronal cases develop increased middle fossa volume. Posterior cranial fossa development is restricted by shortened posterior cranial base length. Surgical intervention in Pfeiffer syndrome patients optimally should be indexed to different suture synostosis., Competing Interests: The authors report no conflicts of interest., (Copyright © 2020 by Mutaz B. Habal, MD.)

Hypothesis: The cochlear aqueduct (CA) is subject to considerable anatomical variability. We hypothesize a topographical relationship between the CA and the internal auditory canal (IAC)., Background: The CA represents the lower limit of dissection during transcanal transpromontorial approaches to the lateral skull base due to its close relationship to the lower cranial nerves and jugular vein., Methods: Three-dimensional models from high-resolution computed tomography scans of normal human temporal bones were created using threshold-based segmentation. The CA was classified into four categories. Five points were determined on the three-dimensional models to measure the surgically relevant relationships., Results: Segmentation was performed on 26 high-resolution computed tomography scans. The average length of the virtual and visual part of the CA was 6.6 mm (SD ±1.7 mm) and 5.5 mm (SD ±1.3 mm) respectively. The mean distance between the IAC and the medial end of the visual part of the CA was 3.8 mm (±0.7 mm), while the average distance between the IAC and the lateral end was 1.4 mm (±0.6 mm). The distance between the visual part of the CA and the IAC increased by 0.25 mm per from the fundus of the IAC., Conclusion: A close relationship between the CA and the IAC could be established, despite the anatomical variability of the CA. The distance between CA and IAC increases by 0.25 per mm from the fundus to the porus of the IAC. These findings quantify the inferior limit of dissection of the transcanal transpromontorial approach to the lateral skull base., Competing Interests: The authors disclose no conflicts of interest., (Copyright © 2020, Otology & Neurotology, Inc.)

Background: Geometric morphometric analysis with Procrustes superimposition is an advanced computational tool that can be used to quantify dynamic changes in complex three-dimensional structures. The present study couples high resolution CT imaging with a Geometric Morphometric approach in order to further understand the complex dysmorphology that occurs in unilateral coronal synostosis (UCS)., Methods: Forty-one UCS patients and 41 age- and sex-matched controls received high-resolution CT imaging. Thirty-one anatomical landmarks were identified on each imaging set. A geometric morphometric workflow was used to perform a Procrustes superimposition to register landmarks into a common space. Procrustes-aligned landmarks were used to derive angle calculations, lengths, and other anatomical measurements. Three-dimensional coordinates were also used to perform a principal components analysis (PCA)., Results: Unilateral coronal synostosis patients exhibited significant angular deviation at the levels of the inferior skull base, mid-posterior fossa, and vertex. Both left- and right-sided UCS patients showed increased lengthening in the transverse (left-right) dimension, exhibiting increased length between the left and right EAC (P = 0.047). Conversely, UCS patients revealed shortening in the midline AP dimension as evidenced by the decreased Nasal root-Lambda (P < 0.0001) and Nasal root-superior dorsum sellae (P = 0.01) distances compared with controls. PCA revealed that 25.26% of variation in shape among the patients sampled to be driven by flattening of the skull and that18.93% of variation was driven by right-sided deformity and mediolateral expansion., Conclusions: Significant dysmorphology between UCS patients and controls was quantified using Geometric Morphometric approach, which may be useful in further characterizing the dynamic craniofacial changes in UCS., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2020 by Mutaz B. Habal, MD.)

Objective: Report the details of an unusual case of initially unilateral intradural spontaneous otogenic pneumocephalus in which the patient developed contralateral pneumocephalus after surgical repair of temporal bone and dural defects on the initial side. Discuss the lessons learned concerning management and pathophysiology of this rare case., Patient: A 73-year-old male presenting with bilateral retro-orbital pain and headache was found to have unilateral intradural pneumocephalus in the temporal lobe with an adjacent defect in the temporal bone., Intervention: Surgical repair of the initial defect in the temporal bone and dura via a middle cranial fossa approach with obliteration of the mastoid cavity., Results: The patient's symptoms and degree of pneumocephalus on first affected side decreased initially after surgery. Two weeks after surgery he developed worsening pneumocephalus on the contralateral side in the temporal and frontal lobes with weakness and mild somnolence. This side was repaired via a similar technique without mastoid obliteration. Two weeks after surgery the patient recovered to normal level of consciousness with mild residual weakness., Conclusions: Spontaneous otogenic intradural pneumocephalus is an extremely rare but serious condition related to defects in the temporal bone and dura. The precise mechanism by which this occurs is poorly understood. This unusual case where there were bilateral defects presenting with spontaneous otogenic pneumocephalus in sequence illustrates that it represents a rare sequelae of processes which thin the skull base. These processes should be addressed in addition to acute management of the defect and intracranial air.

Three-dimensional (3D) technology including 3D reconstruction and 3D printing technology, has been widely used in clinical treatment, especially in surgical planning, and image navigation technology, which can make surgical procedures more accurate, now is also increasingly favored by surgeons. But the combination of those 2 technologies was rarely reported. Thus, this study will preliminarily investigate the feasibility and the effect of the combination of 2 technologies in endonasal skull base surgery. Eight patients were involved in this study (from October 2016 to July 2017 at The Affiliated Hospital of Qingdao University), 5 cases of nasal skull base tumors and 3 cases of foreign body perforation. All operations were done under the assistance of 3D technology and image guidance system. Surgical discussion with patient, preoperative planning and clinical teaching were investigated between 2D images and 3D models by voting. For all cases, 3D reconstruction model and 3D printed model were deemed to be more helpful than CT/MRI images in surgical discussion with the patient; surgical simulation on 3D model in preoperative planning was largely deemed to be helpful and very helpful; and in clinical teaching, 3D models combined with image guidance system were deemed to be more helpful in understanding the disease than using 2D images. Besides, all patients recovered well after surgery, no recurrence and complications were found in the follow-up. The combination of 3D technology and electromagnetic image guidance system could improve surgical efficiency and the quality of clinical teaching.

Background: The association of isolated craniosynostosis and the influence of syndromic forms confound the understanding of craniofacial morphologic development. This study attempts to clarify the individual influences of isolated bicoronal synostosis, Apert syndrome, and Crouzon syndromes on skull base morphology., Methods: One hundred seventeen computed tomographic scans were included (nonsyndromic bicoronal synostosis, n = 36; Apert syndrome with bicoronal synostosis, n = 25; Crouzon syndrome with bicoronal synostosis, n = 11; controls, n = 45). Cephalometric measurements were analyzed using Materialise software., Results: Nonsyndromic bicoronal synostosis patients developed a shortened cranial base length, with a significantly shortened distance between nasion and sella (p = 0.005). The cranial base angles of nonsyndromic bicoronal synostosis in both the cranial side (N-S-BA) and facial side (N-SO-BA) increased significantly, by 17.04 degrees (p < 0.001) and 11.75 degrees (p < 0.001), respectively. However, both the N-S-BA and N-SO-BA angles of Apert syndrome and Crouzon syndrome were narrowed more than that of nonsyndromic bicoronal synostosis [by 12.11 degrees (p < 0.001) and 12.44 degrees (p < 0.001), respectively, in Apert syndrome; and by 11.66 degrees (p = 0.007) and 13.71 degrees (p = 0.007), respectively, in Crouzon syndrome]. However, there is no statistically significant difference of these two angles between Apert syndrome and Crouzon syndrome, when they were only associated with bicoronal synostosis. Contrary to the relatively normal subcranial space of nonsyndromic bicoronal synostosis, both Apert and Crouzon syndromes developed a reduced subcranial space., Conclusions: Isolated bicoronal synostosis resulted in a flattened cranial base, whereas Apert syndrome and Crouzon syndrome developed a normal cranial base angle when only associated with bicoronal synostosis. The syndromic skulls had additional significantly reduced subcranial space.

Objective: To determine the feasibility of a patient-specific, three-dimensionally (3D)-printed reconstruction plate for repair of lateral skull base defects., Study Design: Prospective case series and cadaveric study., Setting: A university-based, tertiary care hospital., Patients: Three patients with lateral skull base defects and five cadavers., Main Outcome Measure(s): Caliper gauge fit testing was performed in the cadaver temporal bones to determine the fit of the tegmen plate in engaging the tegmen defect. Additionally, three patients underwent standard of care reconstruction of their middle fossa floor using autografts or allografts. Temporary plate insertion during standard operative repair was performed to gauge feasibility and fit. Operative time required for standard grafting compared with placement of the tegmen plate was examined., Results: Real-time, intraoperative placement of the tegmen plate in our patients under 1 minute compared with nearly 60 minutes for standard surgical repair. Tegmen plates covered the defects and locked into place from contour matching without impinging on critical structures. Fit testing revealed flush-fitting plates to the cadaveric temporal bone surface with all gaps less than 500 μm., Conclusions: Computer modeling and 3D printing can design custom fitted tegmen reconstruction plates for temporal bone defects. Versatility in prefabrication and 3D modeling shows potential in allowing the construct to avoid critical structures and adequately cover defects with high precision to the tegmen surface.

Petrous apex cephalocel, also called arachnoid cyst or meningocele, is a rare cephalocele caused by protrusion of the posterolateral wall of the Meckel cave to the petrous apex. Increased intracranial pressure is thought to play a role in etiopathogenesis and is generally asymptomatic. Radiologically, they are expansile lesions with the same density or intensity as cerebrospinal fluid and may mimic cystic masses. The diagnosis is made by showing the continuity with Meckel cave on magnetic resonance imaging. No intervention is required in asymptomatic patients; surgical treatment is applied in symptomatics.

Objective: This paper proposes a virtual reality (VR) haptic simulator with realistic instruments, an exchangeable patient-specific three-dimensional (3D)-printed external nostril and a caudal septum model to facilitate real surgical motion for training in endoscopic sinus and skull-base surgery., Study Design and Setting: industry-academy cooperation development model METHODS:: The VR simulator consists of the main simulator body, a monitor, an endoscope device, 2 haptic devices, an endoscope holder support fixture, and a pair of pedals. The location of the endoscope device is determined by an electromagnetic sensor. Two haptic devices are located so as to prevent mutual interference during application of the two-nostrils/four-hands technique for endoscopic skull-base surgery. The pedals were used for select surgical instrument and endoscopes, and operate microdebriders or microdrill. An exchangeable patient-specific external nostril and caudal septum model was created using material that mimics the texture of human tissue and a 3D printer. Graphics were rendered using Unity 3D, to which the Simulation Open Framework Architecture (SOFA) physics engine can be bolted on using the Unity3d plug-in., Results: This VR haptic simulator enables performance of basic endoscopic sinus surgeries (eg, maxillary sinus antrostomy, ethmoidectomy, and frontostomy), as well as endoscopic endonasal transsphenoidal (including sphenoidotomy) and transclival approaches., Conclusion: VR haptic simulators can improve the skill and confidence of surgical trainees by allowing them to accrue experience in various tasks under different conditions. The simulator introduced here comprises novel technologies and provides a realistic training environment for endoscopic sinus and skull-base surgery.

Objectives: To evaluate the interobserver agreement and the diagnostic performance in F-sodium fluoride (F-NaF) PET/computed tomography (CT) for the detection of skull-base bone invasion (SBBI) and osseous metastases in patients with newly diagnosed nasopharyngeal carcinoma (NPC)., Methods: One hundred seventeen patients with newly diagnosed NPC between 2017 and 2019 who underwent F-NaF PET/CT was in included. Two experienced observers independently evaluated the F-NaF PET/CT of SBBI and osseous metastases on a patient level using a two-category scale present on a dichotomous scale, respectively. On a patient level, the diagnostic performance was calculated using a sensitivity analysis., Results: The interobserver agreement on a patient level of SBBI and osseous metastases were perfect on a patient-level (κ: 0.85), (κ: 0.808), respectively. On a lesion level of detection of osseous metastases, the observers agreed on the number as well as the location of osseous metastases in 101 (86.3%) patients. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of detection of SBBI and osseous metastases were ranged 0.911-0.962, 0.921-0.974, 0.932-0.957, 0.962-0.986, and 0.841-0.923, and ranged 0.917-0.958, 0.899-0.957, 0.906-0.949, 0.863-0.936, and 0.939-0.970, respectively., Conclusion: The interobserver agreement of F-NaF PET/CT for the detection of SBBI and osseous metastases in patients with NPC were both very high among trained observers. Moreover, the diagnostic performance of NaF PET/CT was satisfactory, rendering NaF PET/CT a robust tool in the diagnostic armamentarium.

Hypothesis: An augmented reality (AR) platform using a head mounted display (HMD) can successfully display and register virtual computerized tomography (CT) data to corresponding real world anatomy using fiducial markers., Background: AR is a growing field in surgical planning, and has been used by this group to aide in orthopedic surgery applications. Intraoperative AR registration of preoperative CT images could improve identification of critical anatomical structures during lateral skull base surgery., Methods: An AR based HMD platform was created to allow for virtual display and real time manipulation of a temporal bone phantom model. Four fiducial markers were incorporated into this model and used to allow manual alignment of surface markers in real-time. To test the accuracy of this platform virtual lines were created in the AR environment running through the visualized real-world fiducial marker points. Target registration error (TRE) was calculated by measuring the orthogonal distance between these virtual lines and the corresponding virtual fiducial marker for each of the four markers from varying angles. Ten consecutive experiments were performed., Results: The AR based platform successfully displayed CT renderings in the AR environment and allowed real time translation and rotation for manual alignment. A TRE of 10.62 ± 5.90 mm was found., Conclusions: Our results suggest that AR visualization of CT imaging can be registered to patient surface landmarks, but current limitations of AR hardware resulted in TREs too large to be used in the lateral skull base. Future advancements in AR technology will hopefully allow for reduction of registration error.

The anterior skull base undergoes a progressive ossification after birth. This has implications on the epidural dissection of early trans-craniofacial osteotomy procedures such as monobloc advancements. Our purpose was to determine the rate of ossification in syndromic synostosis patients relative to a normal cohort to establish when maturation of the anterior skull base is complete. The authors analyzed CT scans from 35 patients with Crouzon, Apert or Pfeiffer syndrome, and 84 patients without any craniofacial anomaly between the ages of 0 and 6 years. The non-ossified anterior skull base area was measured using 3D Slicer. The authors compared the sizes of the defects at different ages between the three syndromes and with the control group using Mann-Whitney test. Significance was set at P < 0.05. All patients less than 12 months of age had a measurable defect anterior to the cribriform whereas patients greater than five years of age had full ossification of the anterior skull base with no evidence of defect. The relationship of defect size and age at scan was non-linear, with most defects closing rapidly in the first six months. The temporal closure pattern of the defect was similar between the three syndromes and the control group with no significant difference. Our findings indicate that syndromic children undergo skull base maturation at the same rate as non-syndromic cases, with the majority ossified by three years of age. Anterior skull base surgeries performed before three years should optimize visualization of this area during dissection.

Purpose: To evaluate the diagnostic performance of regional fluorine-18 fluorodeoxyglucose (F-FDG) positron emission tomography-computed tomography (PET-CT) in patients with skull base osteomyelitis (SBO) and to compare with magnetic resonance imaging (MRI) whenever available., Materials and Methods: A total of 77 patients (male:female = 56:21; mean age 66.4 ± 9.4 years) with clinically suspected SBO, who underwent regional F-FDG PET-CT were included in this retrospective study. F-FDG PET-CT images were analyzed for presence, localization and intensity of FDG uptake. Diagnostic performance of F-FDG PET-CT was analyzed based on histopathology, culture, and clinical/imaging follow-up. The agreement analysis between F-FDG PET-CT and MRI findings was performed in 56 patients., Results: The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of F-FDG PET-CT for diagnosing SBO were 96.7, 93.3, 98.3, 87.5, and 96.1%, respectively. The average SUVmax of the lesions was 5.9 ± 3.5. The SUVmax of the fungal lesions was lower than that of bacterial lesions with P-value of <0.001. On comparing variables like C-reactive protein, erythrocyte sedimentation rate, and SUVmax for prediction of recurrence/progression, by plotting an ROC curve, the SUVmax was found to be an independent prognostic marker. 56 out of 77 patients had undergone both F-FDG PET-CT and MRI. The agreement analysis between the modalities showed almost perfect agreement for delineation of soft tissue and bony involvement with κ values of 0.82 and 0.81, respectively., Conclusion: F-FDG PET-CT is a sensitive tool in evaluation of patients with SBO. It shows a very good agreement with the MRI. It plays a critical role in treatment response evaluation.

Purpose: How different from "normal" are the cranial base and vault of infants with nonsyndromic, single-suture sagittal synostosis (NSSS)? This study quantitatively addresses this question utilizing computed tomography (CT) analytic technology., Method: Head CT scans of infants with NSSS and normocephalic controls were analyzed using Mimics to calculate craniometric angles, distances, and segmented volumes. Craniometric measurements and asymmetry indices were compared between NSSS and control groups using linear regressions controlling for age. Ratios of anterior-, middle-, and posterior-to-total cranial vault volume were compared between groups using beta regressions controlling for age., Results: Seventeen patients with NSSS and 19 controls were identified. Cranial index and interoccipital angle were significantly smaller in NSSS compared with controls (P = 0.003 and <0.001, respectively). Right-but not left-external acoustic meatus angle and internal acoustic meatus-to-midline distance were significantly greater in NSSS than in controls (P = 0.021 and 0.016, respectively). NSSS patients and controls did not significantly differ in any asymmetry indices, except for the articular fossa angle asymmetry index (P = 0.016). Anterior vault volume proportion was greater in NSSS relative to controls (proportion ratio = 1.63, P < 0.001). NSSS trended toward a smaller posterior vault volume proportion (P = 0.068) yet did not differ in middle vault volume proportion compared with controls., Conclusion: In this small study, patients with nonsyndromic, single-suture sagittal craniosynostosis had relatively similar cranial base measurements, and larger anterior vault volumes, when compared with controls. Further work is needed to confirm the possibility of rightward asymmetry of the anterior cranial base.

Background: Apert syndrome causes normal or enlarged intracranial volume overall as patients grow. This study aimed to trace the segmental anterior, middle, and posterior cranial fossae volume and structural morphology in these patients, to help discern a more focused and individualized surgical treatment plan for patients with Apert syndrome., Methods: This study included 82 preoperative computed tomographic scans (Apert, n = 32; control, n = 50) divided into five age-related subgroups. The scans were measured using image processing and three-dimensional modeling software., Results: The middle cranial fossa volume was increased and was the earliest change noted. It was increased by 45 percent (p = 0.023) compared with controls before 6 months of age and remained increased into adulthood (161 percent, p = 0.016), with gradually increasing severity. The anterior and posterior cranial fossae volumes also increased, by 35 percent (p = 0.032) and 39 percent (p = 0.007), respectively. Increased depth of cranial fossae contributed most to the increase in volumes of patients with Apert syndrome, with correlation coefficients of 0.799, 0.908, and 0.888 for anterior, middle, and posterior cranial fossa, respectively. The intracranial volume was increased 12 percent (p = 0.098) across the entire test age range (0 to 26 years old), but only had statistical significance during the age range of 6 to 18 years (22 percent, p = 0.001)., Conclusions: Malformation of the middle cranial fossa is an early, perhaps the initial, pivotal cranial morphologic change in Apert syndrome. Increased cranial fossae depth is an inherent characteristic of the maldevelopment. Normalization of cranial volume and circumference overall may not achieve a normal skull structure, as it does not correct regional craniocerebral disproportion.

Background: During skull base tumor surgery, temporomandibular joint (TMJ) dissection is commonly performed. The impact of this procedure on patients' postoperative diet and TMJ function is a matter of concern to surgeons., Methods: We reviewed the Craniomandibular Index (CMI) for 32 patients (15 men and 17 women) who underwent TMJ dissection during surgery for skull base tumors between August 2015 and May 2018., Results: Fifteen patients underwent removal of the mandibular condyle, and 17 had the condyle preserved. Twenty-one patients mainly underwent infratemporal fossa approach, and 11 underwent extended temporal bone resection. No significant difference between pre- and postoperative diet was observed in any group. Significant differences in CMI index were seen in all groups. The highest score was 0.115 of Dysfunction Index, observed postoperatively in the group that underwent condyle removal., Conclusions: For skull base tumor surgery, TMJ dissection has no significant impact on postoperative diet. Patients who underwent removal of the mandibular condyle have significantly worse postoperative TMJ function.

Purpose of Review: To review the presenting signs and symptoms of spontaneous cerebrospinal fluid (CSF) leaks of the lateral skull base., Recent Findings: Research continues to demonstrate that CSF leaks from the lateral skull base are insidious, and present with subtle signs and symptoms. Patients commonly present with symptoms of aural fullness, middle ear effusion, and otorrhea following tympanostomy tube insertion that can be confused for chronic otitis media. More recently headache, pulsatile tinnitus, and dizziness/vertigo are being recorded as symptoms at presentation, which is likely a reflection of the association of spontaneous CSF leak with obesity, intracranial hypertension, and superior canal dehiscence. The presence of these less common symptoms in the setting of middle ear effusion should raise suspicion for CSF leak. The rate of meningitis in spontaneous CSF leak is not negligible, and patients should be counseled on this life-threatening risk., Summary: Spontaneous CSF leak from the lateral skull base presents with subtle signs and symptoms and remains a diagnostic challenge. Less common symptoms may represent associations with underlying comorbidities, and awareness of the increasing coincidence of diseases that accompany spontaneous CSF leak is essential to prompt diagnosis and management.

Background: Posterior vault distraction osteogenesis (PVDO) has been demonstrated to effectively increase intracranial volume, treat increased intracranial pressure, and improve head shape in syndromic patients. The purpose of this study is to compare changes along the posterior cranial base before and after distraction., Methods: A retrospective review was completed of subjects who underwent PVDO with computed tomography scans at 2 time-points: within 3 months preoperatively and 1 to 6 months postoperatively. Using Mimics software, craniometric landmarks were identified and surface area of the foramen magnum was calculated. A comparison of pre- to postoperative measurements was completed using Wilcoxon matched-paired signed rank tests and linear regression., Results: A total of 65 PVDO subjects were identified, 12 subjects met inclusion criteria. Mean operative age was 3.0 ± 4.0 years. The cranial vault was distracted on average 25.0 ± 6.0 mm, with those < 12 months of age distracted 29.5 ± 4.9 mm and >12 months of age distracted 22.0 ± 4.9 mm (P = 0.0543). There was a significant increase in pre- to postoperative foramen magnum surface area (52.1 ± 63.2 mm, P = 0.002), length (0.9 ± 1.4 mm, P = 0.050), and width (0.6 ± 1.0 mm, P = 0.050). Similarly, linear distances between nasion and posterior cranial base landmarks such as foramen magnum (3.4 ± 4.2 mm, P = 0.010), and occipital protuberance (9.1 ± 9.6 mm, P = 0.003) were increased. Subjects under 12 months had a greater percentage increases in posterior vault length than those over 12 months., Conclusion: Posterior vault distraction osteogenesis is associated with an increase in size of the foramen magnum, and lengthening of the posterior cranial base, both of which may be beneficial in patients with turribrachycephaly.

Objectives: The primary objective of the present study was to find the gold-standard accuracy of voxel-based superimposition of cone-beam computed tomography (CBCT) datasets with a protocol developed for the Dolphin Imaging 3D software. The secondary objectives were to analyze reproducibility and efficiency of this protocol., Study Design: Twenty-five CBCT datasets of patients with dental implants present were selected. Each Base Volume dataset was duplicated to create a second volume. Subsequently, both volumes were superimposed with a voxel-based protocol consisting of 3 successive steps "Side-by-side Superimposition"; "Overlay Superimposition"; and "Export Orientation to 2nd Volume". The protocol's accuracy was evaluated by measuring the mean distance between the apex of each dental implant on the Base Volume and second volume datasets. Efficiency was given by the mean time needed to complete all superimposition steps. Reproducibility was analyzed by calculating the intraclass correlation coefficients., Results: Mean time needed to complete the protocol was 198 seconds. The protocol had a rotational accuracy of 0.10° to 019° and a translational accuracy of 0.20 to 0.24 mm. Intra-observer and inter-observer reproducibility were 1 and 0.921 to 1, respectively., Conclusions: The protocol is accurate, precise, reproducible, and efficient. The validation of this method enables unbiased analysis of surgical outcomes based on a single, user-friendly software product that is widely available in academic and clinical settings.

Objective: Determine if patients with increased opening pressure (OP) on lumbar puncture (LP) have thinner calvaria and skull bases., Study Design: Retrospective cohort study., Setting: Tertiary referral center., Patients: Patients (≥18 yr of age) who had a recorded OP on LP and high-resolution computed tomography imaging of the head. Patient age, sex, body mass index were calculated. Intracranial hypertension (IH) was defined with an OP≥25 cm-H2O and low intracranial pressure with an OP<15 cm-H2O., Intervention: Measurement of calvarial, zygoma, and skull base thickness when blinded to OP with three-dimensional slicer and radiologic calipers., Main Outcome Measures: Association of calvarial, skull base, and zygoma thickness with OP and age., Results: Fifty-eight patients were included with a mean (SD) age of 53.1 (16.2) years and average (SD) body mass index of 30.1 (9.1) kg/m. Patients with IH had thinner mean (SD) calvaria (3.01 [0.81] versus 2.70 [0.58] mm; p = 0.036) and skull bases (5.17 [1.22] versus 4.60 [1.42] mm; p = 0.043) when compared with patients without IH. The mean (SD) extracranial zygoma thickness was similar between the two groups (5.09 [0.76] versus 5.00 [0.73] mm; p = 0.56). General linear model regression demonstrated advancing age was associated with increasing calvarial thickness in patients without IH and calvarial thinning in patients with IH (p = 0.038)., Conclusion: IH is independently associated with intracranial bone (calvaria and skull base) thinning and not extracranial (zygoma) thinning. Skull thinning occurs with IH and advancing age. These findings support a possible role of increased ICP in the pathophysiologic development of spontaneous cerebrospinal fluid leaks.