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Rhinorrhoea and nasal obstruction have been described;however, more recently, sudden onset of olfactory and gustatory dysfunction has been described in up to 85 6% and 98% of patients with COVID-19, respectively 17-21 Many of these patients had no other sinonasal signs or symptoms;few, if any, had other symptoms of COVID-19 20'22 In fact, olfactory dysfunction was the presenting symptom in up to 26 6% of patients 18'20'23 In a French study, 94% of patients presenting with anosmia tested positive forSARS-CoV-2 24 Olfactory dysfunction is more common in women with COVID-19 than in men and in younger patients (median age 56 years in olfactory dysfunction group, compared with 66 years in group without olfactory dysfunction),25 and it may be associated with a milder clinical course 18'25'26 Sudden loss of smell or taste may therefore be a markerof COVID-19 and should be part of any screening protocol Olfaction usually starts to recover after 5-10 days, with the most significant improvement occurring in the first two weeks 20 Most patients recover fully 20'24 Coronaviruses are known to have neurotropic properties affecting the olfactory neurons and entering the central nervous system via the olfactory bulb 27 SARS-CoV-2 has been found to target the central nervous system and therefore has neuro invasive potential 2830 However, ACE2 has not been detected in olfactory sensory neurons or olfactory bulb neurons but, in fact, in the sustentacular cells of the olfactory epithelium and olfactory bulb vascular pericytes 31 The fact that SARS-CoV-2 infects non-neuronal cell types may explain why most patients with olfactory impairment recover Essentially, an aerosol is any liquid or solid particle suspended in air and generated when air passes over a layer of fluid 32'33 Large droplets will fall to the ground before they evaporate and transmit disease via droplet or contact spread 34 Smaller aerosols remain airborne for longer periods (potentially evaporating before they land on a surface) and transmit disease via airborne transmission 35'36 A sneeze can generate approximately 46,000 large droplets and up to 1,100,000 small droplet nuclei (the residual dried droplet), travelling at anywhere from 4 5 m/s to 100 m/s 37 40 Each droplet contains up to 200 million virus particles 41 In practical terms, aerosols

BACKGROUND Significant advances have been made in transoral robotic surgery (TORS), yet its application in anterior skull-base surgery has yet to be defined. This work explores the history of endoscopic sinus and anterior skull-base surgery, and its advantages and disadvantages. The development of robotic surgery is then discussed as well as the advantages and disadvantages of TORS as it relates to the anterior skull base. The current applications for robotic surgery to the anterior skull base are presented with details of future applications. METHODS A structured search of the current literature using MEDLINE, PubMed, and EMBASE was performed from inception to May 2019. Search terms related to topics of robotic skull-base surgery were identified and queried to identify relevant articles. RESULTS Fifty-four papers were identified from the literature search and a hand search of the references. Twenty-one other references were discovered from personal communication, websites, and books relevant to the topic. CONCLUSION Anterior skull-base surgery has the potential for significant morbidity compared to head and neck surgery, yet the application of the robot in sinus and anterior skull-base surgery has yet to be formally defined. Currently, there are certain limitations that need to be overcome; however, research to address these barriers is currently underway and promises an exciting future for robotic sinus and anterior skull-base surgery.

Background The palatine neurovascular bundle is at risk during endoscopic surgery. Injury may result in significant blood loss and anesthesia of the ipsilateral hard palate. Nonetheless, its endoscopic anatomy has not been described previously. This article strives to establish landmarks to identify the greater palatine canal; thus, avoiding injury to its contents. Methodology This study comprised 50 deidentified computed tomographic angiograms using landmarks that are immediately visible during endoscopic medial maxillectomy to calculate: the angle of the greater palatine canal to the vertical, the distance from the anteroinferior aspect of the greater palatine canal to the orifice of the nasolacrimal duct, the distance from the anteroinferior aspect of the greater palatine canal to the posterolateral free edge of the hard palate, and the distance from the anterior aspect of the greater palatine canal as it enters the hard palate to the posterior wall of the maxillary sinus. Results The mean angle of the greater palatine canal to the vertical was 23.01 degrees. The mean distance from the anteroinferior aspect of the greater palatine canal to the nasolacrimal duct was 31.52 mm. The mean distance from the anterior aspect of the greater palatine canal to the posterolateral free edge of the hard palate was 7.71 mm and the mean distance from the anterior aspect of the greater palatine canal to the posterior wall of the maxillary sinus was 7.07 mm. Conclusion Accessible anatomical landmarks help ascertain the location of the greater palatine canal intraoperatively; thus, avoiding injury to its contents.

Objectives The pedicled nasoseptal flap (NSF) has dramatically reduced postoperative cerebrospinal fluid leakage following endoscopic endonasal approach (EEA) surgery. Although rare, its arterial supply may be damaged during harvest or may be preoperatively damaged for numerous reasons. Early recognition permits harvesting a contralateral flap before sacrificing its pedicle as part of the surgical exposure or use of an alternative flap. Design Technical feasibility study and case series. Setting Tertiary care university-associated medical center. Participants Five patients requiring an EEA with NSF reconstruction. Main Outcome Measures During NSF harvest, intravenous indocyanine green (IVICG) was administered, and a customized endoscopic system was used to visualize the emerging fluorescence. At the end of each case, just before final positioning of the NSF, additional IVICG was administered, and the custom endoscope was again introduced to evaluate fluorescence. Results In four patients, the entire NSF fluoresced brightly with IVICG on initial harvest and before final positioning. One patient showed heterogeneous fluorescence of the pedicle and distal parts of the NSF at both stages. All NSFs healed well without complication. Conclusion IVICG facilitates real-time evaluation NSF's arterial supply. This may provide early recognition of arterial compromise, allowing the harvest of alternate flaps or modification of surgery.

Objectives The purpose of this study is to demonstrate the potential contribution of positron emission tomography (PET)/computed tomography (CT) to help differentiate olfactory neuroblastoma (ONB) from sinonasal undifferentiated carcinoma (SNUC). Methods Following approval by the institutional review board at the Wexner Medical Center at the Ohio State University, Columbus, Ohio, a pilot study with retrospective review of patients with biopsy-proven diagnosis of ONB s and SNUC s was conducted. Staging PET/CT scans were reviewed to document the maximum standardized uptake value (SUVmax). A statistical comparison of SUVmax was performed. Results We identified 13 patients (7 with ONBs and 6 with SNUCs) with mean age 60.2 years who had undergone staging F-18 fluorodeoxyglucose (18F-FDG) PET/CT of the primary tumor at the time of their diagnosis. Mean SUVmax was found to be five-fold higher in SNUC patients (35.63, range 10.8–77.9) than in ONB patients (7.24, range 4.6–10.7) (P ≤ 0.00169). Conclusion Maximum standardized uptake value of 18F-FDG PET/CT can be used to initially discriminate between ONB and SNUC. This finding may prove helpful to guide diagnostic and treatment planning when the histopathologic diagnosis is inconclusive. Level of Evidence 4. Laryngoscope, 2016

Chondrosarcomas of the skull base are rare, locally invasive tumors that typically arise in the petroclival region, from degenerated chondroid cells located within the synchondrosis. Given their usually slow growth rate, they are capable of reaching sizable dimensions, promoting bone erosion and significant displacement of neurovascular structures before causing symptomatology that will eventually lead to diagnosis; cranial neuropathies and headaches are common complaints. This article discusses the pertinent surgical anatomy, patient selection criteria, technical nuances and complication management of the endonasal resection of skull base chondrosarcomas.

Purpose of review The purpose of this review is to provide an update on the use and risks of long-term corticosteroids in the management of chronic rhinosinusitis (CRS). Recent findings Long-term use of systemic corticosteroids is not indicated in the management of CRS due to the associated side effects and potential complications. Therefore, recent research has focused on the safety and efficacy of topical corticosteroid, particularly second-generation corticosteroids, and their modes of administration. Second-generation corticosteroids are more potent and have less systemic bioavailability than their first-generation counterparts. However, caution must be taken with concomitant use of more than two types of corticosteroids (topical, systemic, inhaled etc.) and also with their dosage and frequency of administration to avoid adrenal suppression, growth suppression in children, elevated intraocular pressure or epistaxis. Research is ongoing into therapies that may reduce corticosteroid resistance which has been demonstrated in some nasal polyps. Summary Corticosteroids play an essential role in the management of CRS; however, use must be tailored to the patient-specific disease and requires ongoing review and regular reevaluation by their physician.

The posterior pedicle nasoseptal flap, also named the Hadad-Bassagaisteguy flap, was developed at the University of Rosario, Argentina by Hadad and Bassagaisteguy, and modified by Carrau with the aim to design a better intranasal vascular pedicled flap for skull base reconstruction (1,2). The posterior pedicle nasoseptal flap provides an ample surface area with a superior arc of rotation and is therefore a reliable flap, especially for the reconstruction of large skull base defects.

Objectives Sinonasal cancers with neuroendocrine features share similar clinical, radiological, and histopathological features; however, these tumors often exhibit varying degrees of aggressive behavior presenting significant treatment challenges. The objective of this study was to report our experience with these rare malignancies and to present a review of current literature. Methods Following institutional review board approval, the records of all patients with biopsy-proven sinonasal malignancies over a 5-year period were reviewed. Results The study included 14 patients with olfactory neuroblastomas (ONBs), 7 patients with sinonasal undifferentiated carcinomas (SNUC), and 2 patients with sinonasal neuroendocrine carcinomas (SNEC). Histopathologic markers aided in final diagnosis, but showed variable specificity. In patients with sufficient follow-up, the 2-year disease-free survival rate was 81% (9/11) for ONB and 75% (3/4) for SNUC. Three patients developed a regional or distant recurrence (two with ONBs and one with SNUC). Two patients, one with SNEC and one with ONB, succumbed to brain radionecrosis related to proton radiation therapy. Conclusions Overlapping clinical and histopathological features in poorly differentiated sinonasal cancers with neuroendocrine features continue to present a diagnostic challenge. Individualized assessment and treatment strategies can improve the accuracy of the initial assessment and the treatment outcomes.

Objective Advancements in endoscopic endonasal approaches have increased the extent and complexity of skull base resections, in turn demanding the development of novel techniques for skull base defect reconstruction. The objective of this pilot study was to investigate the effect of leukocyte–platelet-rich fibrin (L-PRF) on the postoperative healing after endoscopic skull base surgery. Methods Between January and May of 2015, 47 patients underwent endoscopic endonasal resection of sellar, parasellar, and suprasellar lesions with the application of L-PRF membranes during the skull base reconstruction at two surgical centers. Early postoperative records were retrospectively reviewed. Results We found that 21 days following the surgery, 17/41 patients (42%) demonstrated improvement in the crusting score as compared with their 7 day postoperative examination. Ten of these patients (23%) showed no crusting. Fourteen (34%) patients had no change in the crusting score. Six patient records were incomplete. A total of 4/47 cases (8.5%) had postoperative cerebrospinal fluid leak requiring surgical repair. Conclusion This study demonstrates the potential utility of L-PRF membranes for skull base defect reconstruction. Future studies will be conducted to better assess the role of L-PRF in endoscopic skull base surgery.

Surgical approaches may be classified according to specific anatomic target areas, which in turn are associated with specific reconstructive idiosyncrasies. In addition, each approach creates a corridor with adjacent structures that may have different functions and significance. In the median skull base, EEAs can extend caudally to the level of C2 and anteriorly to the level of the posterior wall of the frontal sinus [1, 2]. Consequently, EEAs to the median skull base (i.e., sagittal plane) can be classified into six distinct corridors: transfrontal, transcribiform, transplanum, transsellar, transclival, and transodontoid [3]. Use of specific reconstructive techniques is contingent upon many factors aside from the corridor and target area: size and shape of the skull base defect, the condition of the surrounding bone and remaining dura, whether a CSF leak was encountered intraoperatively or not, the nature of the CSF leak encountered (high or low flow), extent of communication between the nasal and intracranial cavities, anticipated postoperative intracranial pressure (ICP), the nature of any lesion resected, patient comorbidities (e.g., diabetes mellitus, Cushing’s disease, immunosuppression), prior sinonasal surgery, status of the nasal septum and lateral nasal wall, history of previous surgery or radiation therapy, and the anticipated need for adjuvant therapies (i.e., irradiation or chemotherapy).

Purpose of review Clival chordomas are rare malignant tumors associated with a poor prognosis. In this article, we review the current literature to identify a variety of strategies that provide guidelines toward the optimal management for this aggressive tumor. Recent findings Molecular disease, particularly, the development of characterized chordoma cell lines, has become one of the new cornerstones for the histological diagnosis of chordomas and for the development of effective chemotherapeutic agents against this tumor. Brachyury, a transcription factor in notochord development, seems to provide an excellent diagnostic marker for chordoma and may also prove to be a valuable target for chordoma therapy. Aggressive cytoreductive surgery aiming for gross total resection with maintenance of key neurovascular structures, followed by proton beam or hadron radiation, provides the best local recurrence and overall survival rates. Summary Clival chordomas are locally aggressive tumors that are challenging to treat because of their unique biology, proximity to key neurovascular structures and poor prognosis. Currently, chordomas are optimally managed with aggressive surgery, whilst preserving key structures, and postoperative radiation in a multidisciplinary setting with an experienced team. The advancement of molecular techniques offers exciting future diagnostic and therapeutic options in the management of chordomas.