Tumors of the anterior skull base

Endoscopic Surgery for Sinonasal and Skull Base Cancer

The field of endoscopic endonasal surgery is in a constant state of advancement, with an expanding range of applications. Improvement in the diversity of instruments available, along with the increasing proficiency of surgical teams, has enabled the successful endoscopic treatment of complex sinonasal and skull base malignancies. Not only is the overall complication rate reduced by endoscopic approaches, but survival outcomes have also shown promising results when compared to traditional open approaches.

Surgical Anatomy and Approaches of the Anterior Cranial Fossa from a Transcranial and Endonasal Perspective

The anterior cranial fossa (ACF) is a complex anatomical region that can be affected by a broad spectrum of pathology. For the surgical treatment of these lesions, many approaches have been described, each of them with different scope and potential surgical complications, often associated with significant morbidity. Traditionally, tumors involving the ACF have been operated by transcranial approaches; however, in the last two decades, endoscopic endonasal approaches (EEAs) have been gaining popularity. In this work, the authors review and describe the anatomical aspects of the ACF and the technical nuances of transcranial and endoscopic approaches for tumors located in this region. Four approaches were performed in embalmed cadaveric specimens and the key steps were documented. Four illustrative cases of ACF tumors were selected to demonstrate the clinical application of anatomical and technical knowledge, which are essential in the preoperative decision-making process.

Quality of Life Considerations in Endoscopic Endonasal Management of Anterior Cranial Base Tumors

Considering quality of life (QOL) is critical when discussing treatment options for patients undergoing endoscopic endonasal skull base surgery (EESBS) for cancers at the base of the skull. Several questionnaires have been developed and validated in the last 20 years to explore QOL in this patient population, including the Anterior Skull Base Questionnaire, Skull Base Inventory, EESBS Questionnaire, and the Sino-Nasal Outcome Test for Neurosurgery. The Sino-Nasal Outcomes Test-22 and Anterior Skull Base Nasal Inventory-12 are other tools that have been used to measure sinonasal QOL in anterior cranial base surgery. In addition to pathology-related perturbations in QOL endoscopic surgical options (transsellar approaches, anterior cranial base surgery, and various reconstructive techniques) all have unique morbidities and QOL implications that should be considered. Finally, we look ahead to new and emerging techniques and tools aimed to help preserve and improve QOL for patients with anterior cranial base malignancies.

Anatomical Study of Ethmoidal Foramina and Optic Canal in Endoscopic Trans-Nasal Approach to Anterior Skull Base

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.

Limited utility of 5-ALA optical fluorescence in endoscopic endonasal skull base surgery: a multicenter retrospective study

OBJECTIVE

Incomplete resection of skull base pathology may result in local tumor recurrence. This study investigates the utility of 5-aminolevulinic acid (5-ALA) fluorescence during endoscopic endonasal approaches (EEAs) to increase visibility of pathologic tissue.

METHODS

This retrospective multicenter series comprises patients with planned resection of an anterior skull base lesion who received preoperative 5-ALA at two tertiary care centers. Diagnostic use of a blue light endoscope was performed during EEA for all cases. Demographic and tumor characteristics as well as fluorescence status, quality, and homogeneity were assessed for each skull base pathology.

RESULTS

Twenty-eight skull base pathologies underwent blue-light EEA with preoperative 5-ALA, including 15 pituitary adenomas (54%), 4 meningiomas (14%), 3 craniopharyngiomas (11%), 2 Rathke's cleft cysts (7%), as well as plasmacytoma, esthesioneuroblastoma, and sinonasal squamous cell carcinoma. Of these, 6 (21%) of 28 showed invasive growth into surrounding structures such as dura, bone, or compartments of the cavernous sinus. Tumor fluorescence was detected in 2 cases (7%), with strong fluorescence in 1 tuberculum sellae meningioma and vague fluorescence in 1 pituicytoma. In all other cases fluorescence was absent. Faint fluorescence of the normal pituitary gland was seen in 1 (7%) of 15 cases. A comparison between the particular tumor entities as well as a correlation between invasiveness, WHO grade, Ki-67, and positive fluorescence did not show any significant association.

CONCLUSIONS

With the possible exception of meningiomas, 5-ALA fluorescence has limited utility in the majority of endonasal skull base surgeries, although other pathology may be worth investigating.

Machine-Learning Classifiers in Discrimination of Lesions Located in the Anterior Skull Base

Purpose: The aim of this study was to investigate the diagnostic value of machine-learning models with radiomic features and clinical features in preoperative differentiation of common lesions located in the anterior skull base.

Methods: A total of 235 patients diagnosed with pituitary adenoma, meningioma, craniopharyngioma, or Rathke cleft cyst were enrolled in the current study. The discrimination was divided into three groups: pituitary adenoma vs. craniopharyngioma, meningioma vs. craniopharyngioma, and pituitary adenoma vs. Rathke cleft cyst. In each group, five selection methods were adopted to select suitable features for the classifier, and nine machine-learning classifiers were employed to build discriminative models. The diagnostic performance of each combination was evaluated with area under the receiver operating characteristic curve (AUC), accuracy, sensitivity, and specificity calculated for both the training group and the testing group.

Results: In each group, several classifiers combined with suitable selection methods represented feasible diagnostic performance with AUC of more than 0.80. Moreover, the combination of least absolute shrinkage and selection operator as the feature-selection method and linear discriminant analysis as the classification algorithm represented the best comprehensive discriminative ability.

Conclusion: Radiomics-based machine learning could potentially serve as a novel method to assist in discriminating common lesions in the anterior skull base prior to operation.

A retrospective study of skull base neoplasia in 42 dogs

This study describes the prevalence and distribution of 42 cases of skull base neoplasia in dogs between 2000 and 2014. The average age of affected individuals was 9.5 years, and there was no sex or breed predisposition. The most common skull base neoplasms were meningioma (25 cases) and pituitary adenoma (9 cases). Less common tumors included craniopharyngioma (2 cases), nerve sheath tumor (2 cases), and 1 case each of pituitary carcinoma, meningeal oligodendrogliomatosis, presumed nasal or sinonasal carcinoma, and multilobular tumor of bone. All neoplasms caused some degree of compression of adjacent structures. The distribution of the tumors was greatest in the sellar region ( n = 18), followed by the paranasal region ( n = 12), caudal cranial fossa ( n = 10), central cranial fossa ( n = 1), and rostral cranial fossa ( n = 1).