Skull Base Research Articles

Focal incidental colorectal fluorodeoxyglucose uptake: Should it be spotlighted?

Focal incidental colorectal fluorodeoxyglucose uptake: Should it be spotlighted?

Imaging characteristics and treatment strategies for carotid artery occlusion caused by skull base fracture: Three case reports

Imaging characteristics and treatment strategies for carotid artery occlusion caused by skull base fracture: Three case reports

Skull base surgery for malignant tumors: The 2nd international collaborative study (1995-2015).

The current study presents the effort of a global collaborative group to review the management and outcomes of malignant tumors of the skull base worldwide. A total of 28 institutions contributed data on 3061 patients. Analysis evaluated clinical variables, survival outcomes, and multivariable factors associated with outcomes. The median age was 56 years (IQR 44-67). The open surgical approach was used in 55% (n = 1680) of cases, endoscopic resection was performed in 36% (n = 1087), and the combined approach in 9.6% (n = 294). With a median follow-up of 7.1 years, the 5-year OS DSS and RFS were 65%, 71.7% and 53%, respectively. On multivariable analysis, older age, comorbidities, histology, dural/intracranial involvement, positive margins, advanced stage, and primary site were independent prognostic factors for OS, DSS, and RFS. Adjuvant RT was a protective prognostic factor. The progress across various disciplines may have contributed to improved OS and DSS in this study compared to previous reports.

Pilot Validation of a 3-Dimensional Printed Pituitary Adenoma, Vascular Injury, and Cerebrospinal Fluid Leak Surgical Simulator.

Endoscopic skull base surgery is a subspecialty field which would benefit significantly from high-fidelity surgical simulators. Giving trainees the opportunity to flatten their learning curve by practicing a variety of procedures on surgical simulators will inevitably improve patient outcomes. Four neurosurgeons, 8 otolarynologists, and 6 expert course faculty agreed to participate. All participants were asked to perform a transsphenoidal exposure and resection of a pituitary adenoma, repair a cerebrospinal fluid (CSF) leak, control a carotid injury, and repair a skull base defect. The content, face, and construct validity of the 3-dimensional printed model was examined. The heart rate of the participants significantly increased from baseline when starting the carotid injury simulation (mean 90 vs 121, P = .029) and significantly decreased once the injury was controlled (mean 121 vs 110, P = .033, respectively). The participants reported a significant improvement in anxiety in facing a major vascular injury, as well as an increase in their confidence in management of major vascular injury, resecting a pituitary adenoma and repair of a CSF leak using a 5-point Likert scale (mean 4.42 vs 3.58 P = .05, 2 vs 3.25 P < .001, 2.36 vs 4.27 P < .001 and 2.45 vs 4.0 P = .001, respectively). The mean Objective Structured Assessment of Technical Skills score for experienced stations was 4.4, significantly higher than the Objective Structured Assessment of Technical Skills score for inexperienced stations (mean 3.65, P = .016). We have demonstrated for the first time a validated 3-dimensional printed surgical simulator for endoscopic pituitary surgery that allows surgeons to practice a transsphenoidal approach, surgical resection of a pituitary adenoma, repair of a CSF leak in the diaphragma sellae, control of a carotid injury, and repair of skull base defect.

Development of an evaluation and treatment strategy for olfactory neuroblastoma: a review of evidence from large-scale studies, including population-based and multicenter studies, and meta-analyses.

Olfactory neuroblastoma is a rare sinonasal malignancy arising from the olfactory epithelium that is characterized by skull base involvement and a modest natural history. Because of its rarity and long course, identification of independent prognostic factors is dependent on multivariate analysis of large, long-term data. In this review, we outline evidence for the evaluation and treatment of olfactory neuroblastoma obtained from recent large-scale population-based studies, meta-analyses and multicenter studies. Hyams grade is currently the only pathological grade system for olfactory neuroblastoma. The modified Kadish staging and Dulguerov classification are available for clinical staging. The results of large-scale studies have confirmed Hyams, the modified Kadish and Dulguerov as independent prognostic factors. Surgery followed by radiotherapy provides the best overall survival and recurrence-free survival for resectable disease. The question of whether postoperative radiotherapy should be administered for all cases or only for those at risk of recurrence remains unanswered. Exclusively endoscopic resection is indicated for modified Kadish A/B cases without any increase in the risk of death or recurrence, and is also indicated for modified Kadish C cases if a negative surgical margin is ensured. For more advanced cases, such as those with extensive brain infiltration, the open approach is indicated. Elective nodal irradiation prevents late nodal recurrence of N0 patients. Chemotherapy has failed to show a benefit in survival or disease control. Current needs for olfactory neuroblastoma include the development and validation of refined staging systems suitable for current practice; expansion of indications for endoscopic surgery; less invasive surgery; definitive radiotherapy and novel systemic therapy.

Meningocele in the Parapharyngeal Space: A Case Report and Review of the Literature.

The parapharyngeal space has been described as an inverted pyramid shape with the base of the skull and the great cornu of the hyoid bone at the top. Tumors of the parapharyngeal space account for 0.5% of head and neck tumors and a wide range of tumor types can occur in this area, 80% of which are benign, the most common being pleomorphic adenomas of the salivary glands and neurogenic tumors. We present a 39-year-old woman who was hospitalized due to left-sided neck pain with a feeling of blockage in the left ear and hearing loss for 10 months. Imaging showed that the mass was not connected to the cranium and the patient underwent surgical resection via a transoral approach, where the contents of the mass were found to be cerebrospinal fluid, and meningocele in the parapharyngeal space is a rare occurrence. The patient presented mainly with painful symptoms, which were eventually relieved by nerve block therapy.

Reconstruction methods for large cranial-nasal communications: surgeons’ concerns about proper anterior skull base reconstruction

Purpose: Skull base reconstruction is one of the most difficult reconstructive surgical procedures. Due to its complexity, most surgeons have modified the reconstruction methods to minimize the postoperative complications and mortality rate. In the past, flap surgery was not usually performed, but it has recently become more common due to advances in medicine. In this study, we analyzed successful flap surgery methods in skull base reconstruction for large cranial-nasal communications.Methods: Patients who underwent skull base reconstruction from April 2015 to January 2024 were eligible for this study. Of these patients, we included those who underwent reconstruction using a volumetric flap. Reconstructions that only used the conventional galeal flap, allograft skin, or bone substitute were excluded. The reconstruction methods used local flaps and free flaps.Results: In total, 22 patients underwent skull base reconstruction. The most frequently used local flap was the bilateral reverse temporalis muscle flap (seven of 11 cases), and the most frequent free flap was the anterior lateral thigh flap (10 of 11 cases). Other local flap operations used the modified temporalis muscle flap and scalp flap. A rectus myocutaneous flap was also used. There were no cases of flap necrosis.Conclusion: Flap surgery is needed for skull base reconstruction in patients with large cranial-nasal communications. As long as the flap volume is large enough to block and fill the defect, either a local flap or a free flap can be used for reconstruction.

The endaural subtemporal keyhole: a novel minimally invasive approach to the middle cranial fossa.

The goal of this study was to evaluate the feasibility of a minimally invasive approach to the middle cranial fossa using a novel endaural keyhole. The charts of all patients who underwent this novel minimally invasive approach to the middle cranial fossa were retrospectively reviewed. In addition, cadaveric dissection was performed to demonstrate the feasibility of the endaural keyhole to the middle cranial fossa. Six patients (5 female and 1 male; age range 47-77 years) who underwent craniotomy for CSF leak (n = 3), intracerebral hematoma evacuation (n = 2), and tumor resection (n = 1) via the endaural subtemporal approach were identified. There were no approach-related complications noted. Representative imaging from cadaveric dissection is provided with a stepwise discussion of the procedure. The endaural subtemporal keyhole craniotomy provides a novel approach to middle fossa skull base pathology, as well as a minimally invasive approach to intra-axial pathology of the temporal lobe and basal ganglia. Further research is needed to establish the limitations and potential complications of this novel approach.

A Tailored Combined Petrosal Approach for the Resection of a Petroclival Meningioma With Pneumatized Apex: Checkmate to the Trigeminal Nerve: 2-Dimensional Operative Video.

Petroclival meningiomas are a challenge in skull base surgery, despite the advances in the knowledge of this pathology, there are still many controversies regarding their optimal treatment.1 The proximity and adherence to cranial nerves, major vessels such as the basilar artery, and brainstem compression explain the significant surgical risk.2,3 We present the case of a woman with a petroclival meningioma (WHO grade I) and pneumatization of the petrous apex. A tailored combined petrosal approach with a wide pedicled flap was performed for reconstruction of the pneumatized petrous apex. The decision to choose an appropriate surgical approach in this type of tumor depends on multiple factors including the surgeon's skill. We believe that in this particular case the pneumatization of the petrosal apex and the involvement of the trigeminal nerve by the tumor demanded a surgical approach that allowed a 360-degree view of the trigeminal nerve and at all angles of attack on the site of tumor implantation, we call this a checkmate of the trigeminal nerve. Transposition of the trigeminal nerve may be necessary in cases such as the one we present for adequate visualization of the petroclival region. This surgical video discusses the nuances of technique, surgical pearls, and anatomic landmarks in the combined petrosal approach. The patient consented to the procedure and to the publication of her image, and appropriate consent was obtained for publication of the cadaver's image.

Body fat and circulating leptin levels in the captive short-beaked echidna (Tachyglossus aculeatus).

It is possible that the reproductive strategy of the short-beaked echidna is related to seasonal changes in fat deposition and energy availability, regulated by seasonal changes in endocrine function. We predicted that circulating leptin levels would be directly proportional to adiposity during most of the year, but that a change in this relationship would occur during the pre-breeding season to allow increased fat deposition. To test this hypothesis, we made use of a captive colony of echidnas to describe and quantify changes in fat distribution and the adipostatic hormone leptin. First we assessed seasonal changes in circulating leptin levels, body mass and adiposity for three male and three female adult echidnas maintained on a standard diet. Second, we explored the relationship between circulating leptin levels and increased caloric intake for an additional five adult female echidnas that were provided with supplemented nutrition. Third we visualised fat distribution in male and female adult echidnas using magnetic resonance imaging (MRI) before and after the breeding season, to determine where fat is deposited in this species. For echidnas maintained on the standard diet, there were no seasonal changes in body mass, body fat or plasma leptin levels. However, female echidnas provided with supplemented nutrition had significantly elevated plasma leptin levels during the breeding season, compared to the pre-and post- breeding periods. MRI showed substantial subcutaneous fat depots extending dorso-laterally from the base of the skull to the base of the tail, in both sexes. Pre-breeding season, both sexes had considerable fat deposition in the pelvic/rump region, whilst the female echidna accumulated most fat in the abdominal region. This study shows that male and female echidnas accumulate body fat in the pelvic/rump and the abdominal regions, respectively and that circulating leptin may promote fattening in female echidnas during the breeding season by means of leptin resistance. However, further research is required to evaluate the precise relationship between seasonal changes in leptin and adiposity.

Comparative Cross Sectional Prospective Study of Anterior Skull Base Thickness in Spontaneous Cerebrospinal Fluid Rhinorrhoea vs Matched Controls

Comparative Cross Sectional Prospective Study of Anterior Skull Base Thickness in Spontaneous Cerebrospinal Fluid Rhinorrhoea vs Matched Controls

SMARCA4(BRG1)-deficient carcinoma invading the skull base: report of two cases and literature review

SMARCA4(BRG1)-deficient carcinoma invading the skull base: report of two cases and literature review

Diabetes Insipidus After Endoscopic Endonasal Pituitary Macroadenoma Resection, Correlation of Patient and Surgery-Related Risk Factors

Purpose: To identify patient and surgery related factors that could predict the development of postoperative central diabetes insipidus (CDI). Methods: This is a retrospective case-control study conducted at a single-institution tertiary referral center. Patients undergoing endoscopic endonasal skull base surgery for pituitary adenoma between November 2018 and April 2023 were recruited. The main outcome measures collected include age, gender, comorbidities, tumor type, postoperative diabetes insipidus, intraoperative and postoperative cerebrospinal fluid (CSF) leak, flow of CSF leak, number of layers required for repair, the use of nasal packing, and hospital length of stay. Results: A total of 20 patients developed DI postoperatively. Patients demographic and comorbidity profile did not correlate with DI development. The encounter of an intraoperative CSF leak was correlated with post-op DI (X2(1) =18.35, p&lt;0.001) with a RR of 2.7 (CI=1.37-5.28). The use of nasal packs was also correlated with post-op DI (X2(1) =10.17, p=0.001) with a RR of 1.8 (CI=1.15-2.87). Defects requiring a two or more layers for reconstruction also correlated with post-op DI compared to single layer repairs (X2(1) =12.15, p&lt;0.001) irrelevant of the materials used. Development of DI post-op correlated with an increased hospital length of stay (t(64) = -3.35, p =0.001). Conclusion: The physician should be careful when evaluating patients with pituitary adenomas in the postoperative period, particularly those with intraoperative CSF leak, nasal packing, and those who underwent multilayer reconstruction of the surgical defect.

Anatomical Step-by-Step Dissection of Complex Skull Base Approaches for Trainees: Surgical Anatomy of the Translabyrinthine and Transcochlear Approaches

Abstract Introduction Skull base neuroanatomy is traditionally learned through two-dimensional anatomical atlases, which while are of unquestionable value, lack the nuanced association of three-dimensional relationships between fundamental anatomical structures relevant to surgical approaches. Surgically focused step-by-step anatomical dissections can augment trainee learning of complex skull base techniques, particularly multistep and nuanced techniques such as translabyrinthine and transcochlear approaches. Methods Translabyrinthine and transcochlear approaches were performed on six sides of three formalin-fixed latex-injected specimens. The study objective was the completion and photo documentation of the steps involved in the approach in order to provide a comprehensive, intelligible, and anatomically oriented resource for multilevel trainees. Illustrative case examples were prepared to supplement approach dissections. Results The translabyrinthine and transcochlear approaches offer unique lateral windows through the temporal bone into the posterior fossa, providing excellent access to pathology at the petrous apex, internal auditory canal, Meckel's cave, and anterolateral brainstem. The transcochlear approach, which is an anterior extension of the translabyrinthine, particularly provides excellent exposure of the prepontine region and clivus. Important surgical considerations include patient position, temporal bone drilling and identification of critical landmarks, dural opening and identification of neurovascular structures, and reconstruction/closure techniques. Conclusion The translabyrinthine and transcochlear approaches are fundamental techniques for lateral skull base and posterior fossa pathologies. Both approaches are hearing-sacrificing but often require minimal to no cerebellar retraction and deliver unique visualization of prepontine neurovascular structures. This step-by-step approach guide provides a unique practical and high-yield surgically oriented learning resource for neurosurgery and otolaryngology trainees.

Primary Extraskeletal Falcine Myxoid Chondrosarcoma—A Case Report and Review of Literature

AbstractIntracranial chondrosarcomas are rare malignant lesions. Both skull base and dural-based extraosseous chondrosarcomas have been reported to occur intracranially. Dural-based chondrosarcomas arising from the falx cerebri are rare lesions with only 19 cases reported till date. Although conventional, mesenchymal, and myxoid variants of chondrosarcomas have been reported intracranially, myxoid variant are the rarest with only 17 cases reported till date, among which only 2 were falcine. We are reporting the third case of falcine myxoid chondrosarcoma in a 32-year-old man who presented with seizures and subtle lower limb weakness. Radiological findings were suggestive of an atypical meningioma in the falcine region. Macroscopically total resection of the tumor was done. Histopathological examination confirmed myxoid chondrosarcoma, grade 1. Postoperative period was uneventful, and the patient remains asymptomatic 34 months after the surgery without the application of any adjuvant therapy. Falcine myxoid chondrosarcomas are extremely rare lesions with variable aggressiveness as suggested by the three cases reported till now including the present case.

Combined Deficit of the Four Lower Cranial Nerves also Known as the Syndrome of Collet-Sicard: A Systematic Review and Meta-analysis

AbstractCombined deficit of the four lower cranial nerves (CN IX, X, XI, and XII) was originally described by French physicians Collet (1915) and Sicard (1917) during World War I. To date though, this rare neurological clinical picture lacks systematic evidence regarding its epidemiology, clinical presentation, treatment strategies, and outcome. We conducted a systematic review and meta-analysis concerning Collet-Sicard syndrome (CSS) on Medline database in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The research yielded 84 articles among which 73 individual case reports were eventually retained. Mean age was 53.7 (± 16) years old and the male-to-female ratio was 1.8/1. CSS was firstly caused by tumors (38.4%), following by vascular etiologies (28.8%), trauma (16.4%), and infection (6.8%), among others. Temporary enteral nutrition was required for 17 patients (23.3%). The four CN presented significant chances of complete or partial recovery: 52.1% for CN IX (p &lt; 0.001), 46.6% for CN X and CN XII (p &lt; 0.001), and 39.7% for CN XI (p = 0.002). Tumoral causes presented significantly lower chances of favorable CN recovery (7.1%) compared to infection (60%), vascular (52.4%), and trauma (41.7%) (p &lt; 0.001). Older age (&gt; 53 years old) was not associated with a dismal CN prognostic (p = 0.763). Most patients (71.2%) presented a favorable outcome (Glasgow Outcome Scale score ≥ 4). All the patients who died (6.8%) suffered from skull base tumors. CSS is a rare condition requiring prompt clinical and radiologic diagnostic and multidisciplinary management. Vascular or infectious-related CSS seem to present a rather good prognostic, closely followed by trauma, whereas tumoral-related CSS seem to suffer from a more dismal prognostic.

Patterns of virtual reality and Fitbit wearable activity device use after skull base surgery.

Virtual reality (VR) and Fitbit devices are well tolerated by patients after skull base surgery. Postoperative recovery protocols may benefit from incorporation of these devices. However, challenges including patient compliance may impact optimal device utilization.

Synthetic MRI and diffusion-weighted imaging for differentiating nasopharyngeal lymphoma from nasopharyngeal carcinoma: combination with morphological features.

To investigate the feasibility of synthetic MRI (syMRI), diffusion-weighted imaging (DWI) and their combination with morphological features for differentiating nasopharyngeal lymphoma (NPL) from nasopharyngeal carcinoma (NPC). Sixty-nine patients with nasopharyngeal tumors (NPL, n = 22; NPC, n = 47) who underwent syMRI and DWI were retrospectively enrolled between October 2020 and May 2022. syMRI and DWI quantitative parameters (T1, T2, PD, ADC), and morphological features were obtained. Diagnostic performance was assessed by independent sample t-test, chi-square test, logistic regression analysis, receiver operating characteristic curve (ROC), and DeLong test. NPL has significantly lower T2, PD, and ADC values compared to NPC (all P < 0.05), whereas no significant difference was found in T1 value between these two entities (P > 0.05). The morphological features of tumor type, skull-base involvement, Waldeyer ring involvement, and lymph nodes involvement region were significantly different between NPL and NPC (all P < 0.05). The syMRI (T2+PD) model has better diagnostic efficacy, with AUC, sensitivity, specificity, and accuracy of 0.875, 77.27%, 89.36%, and 85.51%. Compared with syMRI model, syMRI+Morph (PD+Waldeyer ring involvement+lymph nodes involvement region), syMRI+DWI (T2+PD+ADC), and syMRI+DWI+Morph (PD+ADC+skull base involvement+Waldeyer ring involvement) models can further improve the diagnostic efficiency (all P < 0.05). Furthermore, syMRI+DWI+Morph model has excellent diagnostic performance, with AUC, sensitivity, specificity, and accuracy of 0.986, 95.47%, 97.87%, and 97.10%, respectively. syMRI and DWI quantitative parameters were helpful in discriminating NPL from NPC. syMRI+DWI+Morph model has the excellent diagnostic efficiency in differentiating these two entities. syMRI+DWI+morphological feature method can differentiate NPL from NPC with excellent diagnostic performance.

Management and Outcomes of Facial Nerve Hemangiomas: A Systematic Review of the Literature

Abstract Objectives To conduct a systematic review of facial nerve hemangiomas (FNH), focusing on patient characteristics, management options, and treatment outcomes. Design A systematic review was performed following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, utilizing PubMed, EMBASE, Scopus, and Cochrane databases from inception to December 31, 2022. Setting Literature sourced from various databases providing information on FNH cases. Participants A total of 176 patients with FNH were included in the study, identified from 40 articles meeting inclusion criteria. Main Outcome Measures Patient demographics, lesion characteristics, preoperative symptoms, surgical approaches, and postoperative outcomes, including House-Brackmann (HB) grades. Results Among the 1,682 initially identified articles, 40 were included in the final review. From these, a total of 176 patients (mean age = 42.7 ± 12.8, 51.1% male) were included for analysis. Bivariate analysis showed that patients with longer preoperative symptom duration and facial nerve sacrifice had significantly greater postoperative HB Grades (p &lt; 0.001). Additionally, a strong positive correlation was observed between pre- and postoperative HB Grades (Spearman's rho = 0.649). Multivariable linear regression analysis showed that both facial nerve sacrifice (β = 0.86, 95% confidence interval [CI]: 0.38–1.34; p &lt; 0.001) and greater preoperative HB Grades (β = 0.36, 95% CI: 0.20–0.53; p &lt; 0.001) were associated with significantly greater postoperative HB Grades, but preoperative symptom duration did not persist as a significant predictor of postoperative HB Grades. Conclusions FNHs are rare lesions of the skull base affecting the temporal bone. Our findings highlight the role of preoperative facial nerve function and intraoperative preservation of the facial nerve in predicting postoperative outcomes. Timely resection of lesions that prioritizes facial nerve preservation is critical to achieving optimal patient outcomes.

Anomalies of the Mesenchyme (Meninges and Skull)—Defects of Neural Tube Closure: Cephalocele and Other Calvarial and Skull Base Defects; Intracranial Lipomas; Arachnoid Cysts; Nonsyndromic and Syndromic Craniosynostoses

AbstractWithin the embryonic head, a layer of mesenchyme envelops the brain beneath the surface ectoderm. This cranial mesenchyme is responsible for the formation of the meninges, the calvaria (upper portion of the skull), and the scalp's dermis. Irregular development of these structures, particularly the meninges and the calvaria, is associated with notable congenital defects in humans, such as defects in neural tube closure. Anencephaly is the most common neural tube defect (NTD) and one of the most severe malformations of the central nervous system; it consists in the complete or partial absence of the brain, associated with the absence of the bones of the cranial vault. Iniencephaly is an uncommon congenital NTD characterized by abnormalities in the occipital region, including rachischisis of the cervicothoracic spine and a fixed retroflexion deformity of the head. Unlike anencephaly, in iniencephaly, there is a skull cavity and a normal-looking skin that entirely covers the head and the medullary retroflex area. Cephaloceles are congenital abnormalities distinguished by the protrusion of meninges and/or brain tissue through a naturally occurring defect in the skull bone. This anomaly is typically covered by skin or mucous membrane. Intracranial lipoma is a relatively uncommon and generally benign tumor that occurs in an abnormal location within the brain; it probably represents a disturbance of the differentiation of the primordial meninges: for unknown causes, the meningeal mesenchyme can differentiate into adipose tissue. Arachnoid cysts are sacs filled with cerebrospinal fluid (CSF) situated between the brain or spinal cord and the arachnoid membrane. Typically, these cysts originate within CSF cisterns and gradually expand their boundaries. Craniosynostosis is the early fusion of one or more cranial sutures. It can occur spontaneously, be associated with a syndrome, or have a familial connection. It can involve one or multiple cranial sutures. Pfeiffer's, Crouzon's, and Apert's syndromes are among the more prevalent syndromic craniosynostoses.