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Purpose of the Review This manuscript reviews the current management of sinonasal malignancies based on their histology.

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

PURPOSE OF REVIEW In this manuscript, we will provide a panorama of the current status of skull base reconstruction following endoscopic endonasal or open resection of malignant lesions, focusing on novel options and recent modifications of previously described techniques. RECENT FINDINGS New developments in skull base reconstruction continue to arise, mostly as in the form of vascularized pedicled flaps that can be used following endoscopic and open resections of the skull base. SUMMARY Resection of skull base tumors, often creating large dural defects that couple with extensive intradural dissection, involving multiple cisterns or the third ventricle, may lead to high-flow cerebrospinal fluid leaks. Reconstruction of the skull base is paramount to achieve an uncomplicated postoperative course. Repair of small dural defects can be reliably achieved using a multilayer grafting technique, which yields a high success rate (>90%). Repair of larger defects associated with a high-flow cerebrospinal fluid leak, or defects in previously irradiated fields, often requires a local or regional pedicled vascularized graft as the first reconstructive choice. When these are unavailable, free microvascular tissue transfer remains an option.

Objective: Report of a patient with rapidly progressive maxillary atelectasis documented by sequential imaging. Clinical Report: A 51-year-old man, presented with left periorbital and retro-orbital pain associated with left nasal obstruction. An initial computed tomographic (CT) scan of the paranasal sinuses failed to reveal any significant abnormality. A subsequent CT scan, indicated for recurrence of symptoms 11 months later, showed significant maxillary atelectasis. An uncinectomy, maxillary antrostomy, and anterior ethmoidectomy resulted in a complete resolution of the symptoms. Conclusion: Chronic maxillary atelectasis is most commonly a consequence of chronic rhinosinusitis. All previous reports have indicated a chronic process but lacked documentation of the course of the disease. This report documents a patient of rapidly progressive chronic maxillary atelectasis with CT scans that demonstrate changes in the maxillary sinus (from normal to atelectatic) within 11 months.

Small scale slider crank mechanisms are used in many sophisticated applications, where the accuracy and precision of the mechanisms function are their main performance criteria. The input-output of the mechanism are the main criteria to define its characteristics and hence its capabilities to achieve specific application requirements. The tolerance analysis for the mechanism components are a key element for studying and improving mechanism characteristics and its transmission quality. In this paper kinematics contact approach models for small scale slider crank mechanism are presented. The models consider the mechanism characteristic range, sensitivity and input-output relations. The effect of mechanism manufacturing and assembly errors such as; components tolerances, revolute joints clearances and assembly deviations were investigated. The investigations are applied for the inline and offset types mechanisms. The study elaborates the effect of these errors on the mechanism characteristic, position errors and uncertainty. The effect of revolute joints clearances and offset on the mechanism hysteresis errors, position uncertainty, and dead zones are presented. The results of the proposed contact models are compared with those applying Ting rotatability method. The study is further condensed to define the most appropriate design parameters and manufacturing tolerance according to the permissible system errors.

Resection of skull base chordomas and chondrosarcomas can create large dural defects that involve multiple cisterns or the third ventricle leading to high-flow cerebrospinal fluid leaks. Reconstruction of the skull base is essential to an uncomplicated postoperative course. In general, small dural defects can be repaired successfully with multilayer graft in at least 90% of cases. However, repair of larger defects with high-flow cerebrospinal fluid leakage, or of defects in the petroclival area, is more challenging and often requires a local or regional pedicled vascularized graft. When these are unavailable, free microvascular tissue transfer is an option. In this chapter, we discuss all available options to reconstruct skull base defects following endoscopic endonasal or open resection of petroclival chordomas and chondrosarcomas.

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.