Otolaryngologists' radiological assessment of nasal septum deviation symptomatology.

OBJECTIVES: Nasal Septal Deviation (NSD) is one of the most common causes of nasal obstruction. This study aims to further examine the clinical utility of imaging assessment in the workup and management of symptomatic nasal septal deviation, across all levels of medical training. STUDY DESIGN: Cross-sectional survey. METHODS: CT scans of 10 confirmed NSD patients and 36 healthy controls (HC) were mixed and emailed through anonymous REDCap surveys to otolaryngologists in the US. The HC had no reported sinonasal obstruction symptoms-NOSE (NSD: 62.2 ± 12.5; HC: 5.69 ± 5.99, p < 0.05); SNOT-22 (NSD: 31.4 ± 14.5; HC: 9.72 ± 10.76, p < 0.05). The images consisted of a coronal slice at each subject's most deviated location. Participants were instructed to choose the patients suspected to present with symptoms of sinonasal obstruction. RESULTS: 88 otolaryngologists responded to the survey. 18 were excluded due to incomplete responses. On average, they identified 64.2 ± 29.8% of symptomatic NSD subjects correctly, but misidentified 54.6 ± 34.6% of HC as symptomatic. Their decisions were strongly correlated to degree of NSD (r = 0.69, p < 0.05). There exists a significant degree of NSD among HC (38.7 ± 17.2%), which does not significantly differ from symptomatic subjects (51.0 + 18.7%, p = 0.09). Residents and fellows performed similarly, with responses correlated between levels of training (r = 0.84-0.96, p < 0.05). CONCLUSIONS: The incorporation of a substantial number of otolaryngologists, large patient sample, and blind mixing with HC gives us greater insight to the relative contribution of the extent of septal deviation to symptoms of nasal obstruction. Although NSD is a common factor contributing to nasal obstruction, the results of this study suggest that it is difficult to reliably infer obstructive symptoms based on degree of NSD on CT. LEVEL OF EVIDENCE: Three.

Nasal Structural and Aerodynamic Features That May Benefit Normal Olfactory Sensitivity.

Nasal airflow that effectively transports ambient odors to the olfactory receptors is important for human olfaction. Yet, the impact of nasal anatomical variations on airflow pattern and olfactory function is not fully understood. In this study, 22 healthy volunteers were recruited and underwent computed tomographic scans for computational simulations of nasal airflow patterns. Unilateral odor detection thresholds (ODT) to l-carvone, phenylethyl alcohol (PEA) and d-limonene were also obtained for all participants. Significant normative variations in both nasal anatomy and aerodynamics were found. The most prominent was the formation of an anterior dorsal airflow vortex in some but not all subjects, with the vortex size being significantly correlated with ODT of l-carvone (r = 0.31, P < 0.05). The formation of the vortex is likely the result of anterior nasal morphology, with the vortex size varying significantly with the nasal index (ratio of the width and height of external nose, r = -0.59, P < 0.001) and nasal vestibule "notch" index (r = 0.76, P < 0.001). The "notch" is a narrowing of the upper nasal vestibule cartilage region. The degree of the notch also significantly correlates with ODT for PEA (r = 0.32, P < 0.05) and l-carvone (r = 0.33, P < 0.05). ODT of d-limonene, a low mucosal soluble odor, does not correlate with any of the anatomical or aerodynamic variables. The current study revealed that nasal anatomy and aerodynamics might have a significant impact on normal olfactory sensitivity, with greater airflow vortex and a narrower vestibule region likely intensifying the airflow vortex toward the olfactory region and resulting in greater olfactory sensitivity to high mucosal soluble odors.

Endoscopic endonasal cranial base surgery simulation using an artificial cranial base model created by selective laser sintering.

Mastery of the expanded endoscopic endonasal approach (EEA) requires anatomical knowledge and surgical skills; the learning curve for this technique is steep. To a great degree, these skills can be gained by cadaveric dissections; however, ethical, religious, and legal considerations may interfere with this paradigm in different regions of the world. We assessed an artificial cranial base model for the surgical simulation of EEA and compared its usefulness with that of cadaveric specimens. The model is made of both polyamide nylon and glass beads using a selective laser sintering (SLS) technique to reflect CT-DICOM data of the patient's head. It features several artificial cranial base structures such as the dura mater, venous sinuses, cavernous sinuses, internal carotid arteries, and cranial nerves. Under endoscopic view, the model was dissected through the nostrils using a high-speed drill and other endonasal surgical instruments. Anatomical structures around and inside the sphenoid sinus were accurately reconstructed in the model, and several important surgical landmarks, including the medial and lateral optico-carotid recesses and vidian canals, were observed. The bone was removed with a high-speed drill until it was eggshell thin and the dura mater was preserved, a technique very similar to that applied in patients during endonasal cranial base approaches. The model allowed simulation of almost all sagittal and coronal plane EEA modules. SLS modeling is a useful tool for acquiring the anatomical knowledge and surgical expertise for performing EEA while avoiding the ethical, religious, and infection-related problems inherent with use of cadaveric specimens.

Volumetric Analysis of Nasopharyngectomy via Endoscopic Endonasal, Maxillary Transposition, and Lateral Temporal-Subtemporal Approaches.

OBJECTIVE: This project develops a computer model that allows volumetric analysis of the exposure afforded by an endonasal-endoscopic approach, maxillary transposition, and lateral temporal-subtemporal approaches during a nasopharyngectomy. The model will demonstrate idiosyncracies of these approaches, including sacrifice of normal tissues, ease of instrumentation, and gate of entry. SUBJECTS AND METHODS: Computed tomographic scans of an anatomic specimen were used to create computer simulations of the endoscopic endonasal, maxillary transposition, and lateral temporal-subtemporal approaches for T1and T4 nasopharyngeal carcinoma; therefore, allowing assessment of their surgical corridor using Intuition, a software that allows a semiautomated computerized segmented volumetric analysis. RESULTS: The smallest volumes of tissue mobilization or removal were observed during the endoscopic-endonasal nasopharyngectomy. The volumes of tissue mobilization for the maxillary transposition approach were higher than those of lateral temporal-subtemporal approaches. CONCLUSIONS: This model adds to our understanding of select surgical corridors to the nasopharynx. It suggests that an endoscopic-endonasal approach requires less manipulation or resection of smaller volumes of normal tissue to expose a nasopharyngeal tumor than the lateral temporal-subtemporal and maxillary transposition approaches. It also, however, requires instrumentation through a smaller entry gate implying greater difficulty. Nonetheless, these factors should not be construed as superiority of one approach over the other. Factors that are important in the choosing of the surgical approach, such as surgeon's training and experience, invasion of neurovascular structures and method of reconstruction are not considered in this model.

Anatomic comparison of the endonasal and transpetrosal approaches for interpeduncular fossa access.

OBJECT: The interpeduncular cistern, including the retrochiasmatic area, is one of the most challenging regions to approach surgically. Various conventional approaches to this region have been described; however, only the endoscopic endonasal approach via the dorsum sellae and the transpetrosal approach provide ideal exposure with a caudal-cranial view. The authors compared these 2 approaches to clarify their limitations and intrinsic advantages for access to the interpeduncular cistern. METHODS: Four fresh cadaver heads were studied. An endoscopic endonasal approach via the dorsum sellae with pituitary transposition was performed to expose the interpeduncular cistern. A transpetrosal approach was performed bilaterally, combining a retrolabyrinthine presigmoid and a subtemporal transtentorium approach. Water balloons were used to simulate space-occupying lesions. "Water balloon tumors" (WBTs), inflated to 2 different volumes (0.5 and 1.0 ml), were placed in the interpeduncular cistern to compare visualization using the 2 approaches. The distances between cranial nerve (CN) III and the posterior communicating artery (PCoA) and between CN III and the edge of the tentorium were measured through a transpetrosal approach to determine the width of surgical corridors using 0- to 6-ml WBTs in the interpeduncular cistern (n = 8). RESULTS: Both approaches provided adequate exposure of the interpeduncular cistern. The endoscopic endonasal approach yielded a good visualization of both CN III and the PCoA when a WBT was in the interpeduncular cistern. Visualization of the contralateral anatomical structures was impaired in the transpetrosal approach. The surgical corridor to the interpeduncular cistern via the transpetrosal approach was narrow when the WBT volume was small, but its width increased as the WBT volume increased. There was a statistically significant increase in the maximum distance between CN III and the PCoA (p = 0.047) and between CN III and the tentorium (p = 0.029) when the WBT volume was 6 ml. CONCLUSIONS: Both approaches are valid surgical options for retrochiasmatic lesions such as craniopharyngiomas. The endoscopic endonasal approach via the dorsum sellae provides a direct and wide exposure of the interpeduncular cistern with negligible neurovascular manipulation. The transpetrosal approach also allows direct access to the interpeduncular cistern without pituitary manipulation; however, the surgical corridor is narrow due to the surrounding neurovascular structures and affords poor contralateral visibility. Conversely, in the presence of large or giant tumors in the interpeduncular cistern, which widen the spaces between neurovascular structures, the transpetrosal approach becomes a superior route, whereas the endoscopic endonasal approach may provide limited freedom of movement in the lateral extension.

Immediate complications associated with high-flow cerebrospinal fluid egress during endoscopic endonasal skull base surgery.

Endoscopic expanded endonasal approaches (EEAs) to the skull base are increasingly being used to address a variety of skull base pathologies. Postoperative CSF leakage from the large skull base defects has been well described as one of the most common complications of EEAs. There are reports of associated formation of delayed subdural hematoma and tension pneumocephalus from approximately 1 week to 3 months postoperatively. However, there have been no reports of immediate complications of high-volume CSF leakage from EEA skull base surgery. The authors describe two cases of EEAs in which complications related to rapid, large-volume CSF egress through the skull base surgical defect were detected in the immediate postoperative period. Preventive measures to reduce the likelihood of these immediate complications are presented.

Endoscopic endonasal surgical management of chondrosarcomas with cerebellopontine angle extension.

OBJECT: Skull base chondrosarcomas are slow-growing, locally invasive tumors that arise from the petroclival synchondrosis. These characteristics allow them to erode the clivus and petrous bone and slowly compress the contents of the posterior fossa progressively until the patient becomes symptomatic, typically from cranial neuropathies. Given the site of their genesis, surrounded by the petrous apex and the clival recess, these tumors can project to the middle fossa, cervical area, and posteriorly, toward the cerebellopontine angle (CPA). Expanded endoscopic endonasal approaches are versatile techniques that grant access to the petroclival synchondrosis, the core of these lesions. The ability to access multiple compartments, remove infiltrated bone, and achieve tumor resection without the need for neural retraction makes these techniques particularly appealing in the management of these complex lesions. METHODS: Analysis of the authors' database yielded 19 cases of skull base chondrosarcomas; among these were 5 cases with predominant CPA involvement. The electronic medical records of the 5 patients were retrospectively reviewed for age, sex, presentation, pre- and postoperative imaging, surgical technique, pathology, and follow-up. These cases were used to illustrate the surgical nuances involved in the endonasal resection of CPA chondrosarcomas. RESULTS: The male/female ratio was 1:4, and the patients' mean age was 55.2 ±11.2 years. All cases involved petrous bone and apex, with variable extensions to the posterior fossa and parapharyngeal space. The main clinical scenario was cranial nerve (CN) palsy, evidenced by diplopia (20%), ptosis (20%), CN VI palsy (20%), dysphagia (40%), impaired phonation (40%), hearing loss (20%), tinnitus (20%), and vertigo/dizziness (40%). Gross-total resection of the CPA component of the tumor was achieved in 4 cases (80%); near-total resection of the CPA component was performed in 1 case (20%). Two patients (40%) harbored high-grade chondrosarcomas. No patient experienced worsening neurological symptoms postoperatively. In 2 cases (40%), the symptoms were completely normalized after surgery. CONCLUSIONS: Expanded endoscopic endonasal approaches appear to be safe and effective in the resection of select skull base chondrosarcomas; those with predominant CPA involvement seem particularly amenable to resection through this technique. Further studies with larger cohorts are necessary to test these preliminary impressions and to compare their effectiveness with the results obtained with open approaches.

Salpingopharyngeus myomucosal flap.

OBJECTIVES: Improvements in the efficacy of extended endonasal approaches to resect skull base pathologies have created the need for new reconstructive alternatives. Hereby, we describe a novel pedicled myomucosal flap that allows the reconstruction of dural defects in the lower clivus and craniovertebral junction or to cover the paraclival and petrous segments of the internal carotid artery. STUDY DESIGN: Anatomic description. Technical report. Feasibility. METHODS: We describe a myomucosal flap with a cephalic pedicle based on the salpingopharyngeus muscle and its vessels. Subsequently, using a cadaveric model, we harvested the flap and explored its potential for the reconstruction of various dural defects or to cover the internal carotid artery. RESULTS: Our study confirmed the feasibility of harvesting and transposing the myomucosal salpingopharyngeus (Dicle flap) flap for the reconstruction of inferior clival and craniovertebral junction defects or to cover the petrous and paraclival segments of the internal carotid artery. CONCLUSIONS: The Dicle flap is a feasible, reconstructive alternative for the reconstruction of select small- to medium-sized defects of the posterior and inferior aspects of the ventral skull base.

How Does Oxymetazoline Change Nasal Aerodynamics and Symptomatology in Patients with Turbinate Hypertrophy?

OBJECTIVES: Oxymetazoline relieves nasal obstructive symptoms via vasoconstriction, however, the changes in nasal structures and aerodynamics that impact symptoms the most remain unclear. METHODS: This prospective, longitudinal, and single blinded cohort study applied Computational Fluid Dynamic (CFD) modeling based on CT scans at baseline and post-oxymetazoline on 13 consecutive patients with chronic nasal obstruction secondary to inferior turbinate hypertrophy from a tertiary medical center. To account for placebo effect, a sham saline spray was administered with subject blindfolded prior to oxymetazoline, with 30 min rest in between. Nasal Obstruction Symptom Evaluation (NOSE) and unilateral Visual Analogue Scale (VAS) scores of nasal obstructions were collected at baseline, after sham, and 30 min after oxymetazoline. RESULTS: Both VAS and NOSE scores significantly improved from baseline to post-oxymetazoline (NOSE: 62.3 ± 12.4 to 31.5 ± 22.5, p < 0.01; VAS: 5.27 ± 2.63 to 3.85 ± 2.59, p < 0.05), but not significantly from baseline to post-sham. The anatomical effects of oxymetazoline were observed broadly throughout the entire length of the inferior and middle turbinates (p < 0.05). Among many variables that changed significantly post-oxymetazoline, only decreased nasal resistance (spearman r = 0.4, p < 0.05), increased regional flow rates (r = -0.3 to -0.5, p < 0.05) and mucosal cooling heat flux (r = -0.42, p < 0.01) in the inferior but not middle turbinate regions, and nasal valve Wall Shear Stress (WSS r = -0.43, p < 0.05) strongly correlated with symptom improvement. CONCLUSION: Oxymetazoline broadly affects the inferior and middle turbinates, however, symptomatic improvement appears to be driven more by global nasal resistance and regional increases in airflow rate, mucosal cooling, and WSS, especially near the head of the inferior turbinate. LEVEL OF EVIDENCE: 3: Well-designed, prospective, single blinded cohort trial. Laryngoscope, 134:1100-1106, 2024.

Surgical management of craniopharyngioma with third ventricle involvement.

Craniopharyngiomas are notorious for their ability to invade the hypothalamus and third ventricle. Although several transcranial approaches have been proposed for their treatment, the endonasal route provides direct access to the tumor with no need for cerebral retraction or manipulation of the optic apparatus. After the lesion is debulked, the unique angle of approach achieved with this technique enables the surgeon to perform an extra-capsular dissection and visualize the walls of the third ventricle, the foramina of Monro, and the anterior comissure. Moreover, the enhanced magnification and lighting afforded by the endoscope facilitate safe tumor removal, particularly in areas where there is loss of clear lesion delimitation and greater infiltration of the surrounding structures. Herein we present the case of a 68-year-old female patient with a 3-month history of visual deterioration accompanied by worsening headaches. Investigation with magnetic resonance imaging revealed a heterogeneous mass in the suprasellar region, extending into the third ventricle and displacing the pituitary gland and stalk inferiorly. Hormonal profile was within expected range for her age. An endonasal, fully endoscopic, transplanum transtuberculum approach was performed. Gross-total removal was achieved and pathology confirmed the diagnosis of craniopharyngioma. Postoperative recovery was marked by transient diabetes insipidus. Closure was achieved with a pedicled nasoseptal flap; despite exploration of the third ventricle, there was no cerebrospinal fluid leakage. Pituitary function was preserved. Visual function has fully recovered and the patient has been uneventfully followed since surgery. The video can be found here: http://youtu.be/it5mpofZl0Q. (http://thejns.org/doi/abs/10.3171/2013.V1.FOCUS12330)

3D Printing as a Planning Tool to Optimize Sinonasal Irrigation.

BACKGROUND: Topical sinus irrigation plays a critical role in the management of sinonasal diseases. Yet, the penetration of irrigant to targeted sinuses may be highly variable and difficult to predict. Here, we investigate the use of 3D printing as a planning tool to optimize outcomes. METHODS: Eight post-operative models were 3D printed with a FormLabs Form3 printer based on individual CT scans. Irrigations were performed and video recorded with a squeeze bottle attached via silicon water-tight seal, in 4 head positions: 45° to-the-side, 90° to-the-side, 45° forward and 45° to-the-side, and 90° forward, with irrigation fluid entering the upper (conventional) or lower (backfill) nostrils. RESULTS: Significant individual variations were observed in sinus penetration as a function of head position. In general, the maxillary sinus was the easiest to irrigate in most head positions (P < .05), followed by frontal and ethmoid, with sphenoid being the most difficult. Both the 90°-to-the-side and the 90°-forward positions were significantly more effective than the others (P < .05), with 90°-forward better for frontal sinuses and 90°-to-the-side superior for all other sinuses. The backfill was significantly superior to conventional technique in head positions involving a side tilt (P < .05). CONCLUSION: Variations in technique and position significantly impacted irrigation outcome. Backfill irrigation that pushes fluid against gravity to pool around the ostium, seems to provide overall better outcomes. This study demonstrates the advantage of 3D printing as a rapid planning tool to guide irrigation strategies.

Intraoperative Predictor of Remission in Cushing Disease.

BACKGROUND: Cushing disease represents a challenge for neurosurgeons, with high recurrence rates reported. Characteristics associated with remission are incompletely understood; thus, an intraoperative predictor for outcome would be valuable for assessing resection of adrenocorticotropic hormone (ACTH) secreting tissue. OBJECTIVE: To evaluate whether intraoperative ACTH measurement could predict outcome after surgery for Cushing disease. METHODS: Retrospective cohort study of 55 consecutive encounters with Cushing disease who had peripheral plasma ACTH levels measured intraoperatively before, during, and after tumor resection. The primary outcome measure was remission, defined by either 2 negative 24-hour urine free cortisol or 2 negative midnight salivary cortisol measurements. A logistic regression machine learning model was generated using recursive feature elimination. RESULTS: Fifty-five operative encounters, comprising 49 unique patients, had a mean follow-up of 2.73 years (±2.11 years) and a median follow-up of 2.07 years. Remission was achieved in 69.1% (n = 38) of all operations and in 78.0% (n = 32) of those without cavernous sinus invasion. The final ACTH level measured intraoperatively correctly predicted outcome (area under the curve = 0.766; P value = .002). The odds ratio of remission in patients with the lowest quartile vs highest quartile final intraoperative ACTH was 23.4 ( P value = .002). Logistic regression machine learning model resulted in incorporating postoperative day 1 morning cortisol, final intraoperative ACTH that predicted outcome with an average area under the curve of 0.80 ( P = .0027). CONCLUSION: Intraoperative ACTH may predict outcome after surgery in Cushing disease; furthermore, investigation is warranted.

Spontaneous rhinorrhea: a possible concealing initial symptom of ecchordosis physaliphora. Illustrative case.

BACKGROUND: Spontaneous rhinorrhea may be the initial manifestation of ecchordosis physaliphora (EP). There are currently 47 published cases of symptomatic EP, with spontaneous rhinorrhea being one of the most prevalent symptoms. The authors report 1 case as a cause of cerebrospinal fluid (CSF) fistula. OBSERVATIONS: A 46-year-old woman presented to the authors' clinic with meningitis secondary to nasal CSF leakage. The computed tomography (CT) scan indicated an imperceptibly thin/dehiscent focus along the posterior wall of the sphenoid air cell's midline. A tumor was identified during endoscopic endonasal CSF repair surgery. EP was diagnosed in the frozen and final pathology. LESSONS: EP should be considered as a potential cause of spontaneous rhinorrhea. This initial clinical manifestation accounts for 35% of symptomatic EP cases. The prepontine and posterior sphenoid sinus wall appear to be the locations with the highest susceptibility. Surgical therapy of the fistula without excision of the lesion may result in insufficient issue resolution and recurrence.

Complications after 1002 endoscopic endonasal approach procedures at a single center: lessons learned, 2010-2018.

OBJECTIVE: The endoscopic endonasal approach (EEA) has evolved into a mainstay of skull base surgery over the last two decades, but publications examining the intraoperative and perioperative complications of this technique remain scarce. A prior landmark series of 800 patients reported complications during the first era of EEA (1998-2007), parallel to the development of many now-routine techniques and technologies. The authors examined a single-institution series of more than 1000 consecutive EEA neurosurgical procedures performed since 2010, to elucidate the safety and risk factors associated with surgical and postoperative complications in this modern era. METHODS: After obtaining institutional review board approval, the authors retrospectively reviewed intraoperative and postoperative complications and their outcomes in patients who underwent EEA between July 2010 and June 2018 at a single institution. RESULTS: The authors identified 1002 EEA operations that met the inclusion criteria. Pituitary adenoma was the most common pathology (n = 392 [39%]), followed by meningioma (n = 109 [11%]). No patients died intraoperatively. Two (0.2%) patients had an intraoperative carotid artery injury: 1 had no neurological sequelae, and 1 had permanent hemiplegia. Sixty-one (6.1%) cases of postoperative cerebrospinal fluid leak occurred, of which 45 occurred during the original surgical hospitalization. Transient postoperative sodium dysregulation was noted after 87 (8.7%) operations. Six (0.6%) patients were treated for meningitis, and 1 (0.1%) patient died of a fungal skull base infection. Three (0.3%) patients died of medical complications, thereby yielding a perioperative 90-day mortality rate of 0.4% (4 deaths). High-grade (Clavien-Dindo grade III-V) complications were identified after 103 (10%) EEA procedures, and multivariate analysis was performed to determine the associations between factors and these more serious complications. Extradural EEA was significantly associated with decreased rates of these high-grade complications (OR [95% CI] 0.323 [0.153-0.698], p = 0.0039), whereas meningioma pathology (OR [95% CI] 2.39 [1.30-4.40], p = 0.0053), expanded-approach intradural surgery (OR [95% CI] 2.54 [1.46-4.42], p = 0.0009), and chordoma pathology (OR [95% CI] 9.31 [3.87-22.4], p < 0.0001) were independently associated with significantly increased rates of high-grade complications. CONCLUSIONS: The authors have reported a large 1002-operation cohort of EEA procedures and associated complications. Modern EEA surgery for skull base pathologies has an acceptable safety profile with low morbidity and mortality rates. Nevertheless, significant intraoperative and postoperative complications were correlated with complex intradural procedures and meningioma and chordoma pathologies.

Evidence of Nasal Cooling and Sensory Impairments Driving Patient Symptoms With Septal Deviation.

OBJECTIVES/HYPOTHESIS: About 260,000 septoplasties are performed annually in the US to address nasal septal deviation (NSD). Yet, we do not consistently understand what aspects of NSD result in symptoms. STUDY DESIGN: Blinded cohort study. METHODS: Two fellowship-trained surgeons blindly reviewed computerized tomography (CTs) of 10 confirmed NSD patients mixed with 36 healthy controls. All patients were correctly identified, however, 24/36 controls were falsely identified by both surgeons as patients (33.3% specificity), which were grouped as asymptomatic NSD (aNSD), while the remaining controls as non-NSD (healthy). Acoustic rhinometry, rhinomanometry, individual CT-based computational fluid dynamics and nasal sensory testing were applied to address the puzzling questions of why these aNSD had no symptoms and, more fundamentally, what caused symptoms in sNSD patients. RESULTS: aNSD reported no nasal symptoms - Nasal Obstruction Symptom Evaluation score (sNSD: 60.50 ± 13.00; aNSD: 5.20 ± 5.41; non-NSD: 6.66 ± 7.17, P < .05); 22-item Sino-Nasal Outcome Test score (sNSD: 32.60 ± 14.13; aNSD: 10.04 ± 10.10; non-NSD: 9.08 ± 12.42, P < .001). No significant differences in measured nasal resistance, minimum cross-sectional area (MCA), degree of septal deviation, and nasal airflow distributions were found between sNSD and aNSD groups. Only three variables differentiate sNSD versus aNSD: anterior averaged heat flux on deviated side, inferior turbinate peak heat flux on non-deviated side, and nasal cool sensitivity measured by menthol lateralization threshold, with no significant differences among these variables found between the two healthy groups (aNSD vs. non-NSD). These variables by themselves or combined can differentiate sNSD from controls with higher specificity than the physicians (ROC area under the curve = 0.84 with 70% sensitivity and 91.6% specificity). CONCLUSIONS: This study sheds light on the potential mechanisms of NSD symptomatology: distorted nasal cooling due to NSD exacerbated by poorer nasal mucosal sensitivity. It further supports our previous hypothesis that nasal obstruction complaints do not result directly from obstruction, rather from the capacity of our nose to subjectively sense airflow cooling. LEVEL OF EVIDENCE: 3 Laryngoscope, 132:509-517, 2022.

Use of computational fluid dynamics (CFD) to model observed nasal nitric oxide levels in human subjects.

BACKGROUND: Upper airway nitric oxide (NO) is physiologically important in airway regulation and defense, and nasal NO (nNO) levels typically exceed those in exhaled breath (fractional exhaled NO [FeNO]). Elevated concentrations of NO sampled from the nose, in turn, reflect even higher concentrations in the paranasal sinuses, suggesting a "reservoir" role for the latter. However, the dynamics of NO flux within the sinonasal compartment are poorly understood. METHODS: Data from 10 human subjects who had previously undergone both real-time nNO sampling and computed tomography (CT) scanning of the sinuses were analyzed using computational fluid dynamics (CFD) methods. Modeled and observed nNO values during the initial 2-s transient ("spike") during nasal exhalation were then compared. RESULTS: Examining the initial 2-s transient spike for each subject (as well as the pooled group), there was a statistically significant correlation between modeled and observed nNO levels, with r values ranging from 0.43 to 0.89 (p values ranging from <0.05 to <0.0001). Model performance varied between subjects, with weaker correlations evident in those with high background (FeNO) levels. In addition, the CFD simulation suggests that ethmoid sinuses (>60%) and diffusion process (>54%) contributed most to total nasal NO emissions. CONCLUSION: Analysis of this dataset confirms that CFD is a valuable modeling tool for nNO dynamics, and highlights the importance of the ethmoid sinuses, as well as the role of diffusion as an initiating step in sinonasal NO flux. Future model iterations may apply more generally if baseline FeNO is taken into account.

Soft Gasket Seal Reconstruction After Endoscopic Endonasal Transtuberculum Resection of Craniopharyngiomas.

BACKGROUND: The expanded endoscopic endonasal approach (EEA) is currently well accepted for a variety of ventral skull base tumors. Such an approach often results in a transdural defect and intraoperative cerebrospinal fluid (CSF) leak, and adequate reconstruction is necessary to prevent postoperative CSF leak and its complications. Reconstruction is usually performed using a variety of materials along with the nasoseptal flap. OBJECTIVE: This work's aim is to describe a new reconstructive technique called the "soft gasket seal" (SGS) in detail and compare it with the standard reconstructive technique at our institution for craniopharyngiomas operated via transtuberculum EEA. METHODS: A retrospective chart review was achieved to identify patients who underwent transtubercular EEA for craniopharyngioma between 2010 and 2018, by the same neurosurgical and otolaryngology team using either the SGS or standard reconstructive technique. RESULTS: Of 36 patients who met criteria and were considered for analysis, 15 of them underwent SGS reconstruction and 21 had standard reconstruction. There were 16 female (44%) and 20 male (56%) patients. The median age was 42.2 ± 20.9 years. The rate of postoperative CSF leak in the group of patients treated with the standard technique was 14.2% and 6.6% in the SGS group (odds ratio 0.43 [confidence interval 95% 0.007-6.15], P = 0.62). CONCLUSIONS: The SGS technique provides a simple reconstructive technique in conjunction with the nasoseptal flap, showing a tendency of lower complications when compared with our standard technique while avoiding donor site morbidity. Such results are encouraging, but further studies are necessary to confirm these findings.

Machine Learning-Based Analysis and Prediction of Unplanned 30-Day Readmissions After Pituitary Adenoma Resection: A Multi-Institutional Retrospective Study With External Validation.

BACKGROUND: Unplanned readmission after transsphenoidal resection of pituitary adenoma can occur in up to 10% of patients but is unpredictable. OBJECTIVE: To develop a reliable system for predicting unplanned readmission and create a validated method for stratifying patients by risk. METHODS: Data sets were retrospectively collected from the National Surgical Quality Improvement Program and 2 tertiary academic medical centers. Eight machine learning classifiers were fit to the National Surgical Quality Improvement Program data, optimized using Bayesian parameter optimization and evaluated on the external data. Permutation analysis identified the relative importance of predictive variables, and a risk stratification system was built using the trained machine learning models. RESULTS: Readmissions were accurately predicted by several classification models with an area under the receiving operator characteristic curve of 0.76 (95% CI 0.68-0.83) on the external data set. Permutation analysis identified the most important variables for predicting readmission as preoperative sodium level, returning to the operating room, and total operation time. High-risk and medium-risk patients, as identified by the proposed risk stratification system, were more likely to be readmitted than low-risk patients, with relative risks of 12.2 (95% CI 5.9-26.5) and 4.2 (95% CI 2.3-8.7), respectively. Overall risk stratification showed high discriminative capability with a C-statistic of 0.73. CONCLUSION: In this multi-institutional study with outside validation, unplanned readmissions after pituitary adenoma resection were accurately predicted using machine learning techniques. The features identified in this study and the risk stratification system developed could guide clinical and surgical decision making, reduce healthcare costs, and improve the quality of patient care by better identifying high-risk patients for closer perioperative management.

Endoscopic Endonasal Transtubercular Approach for Resection of Giant Pituitary Adenomas With Subarachnoid Extension: The "Second Floor" Strategy to Avoid Postoperative Apoplexy.

BACKGROUND: Giant pituitary adenomas (GPAs) with subarachnoid extension can be challenging to achieve a gross total resection through a single endonasal or transcranial approach, and any residual tumor is at risk for postoperative apoplexy. Intraoperative venous congestion of the suprasellar tumor can occur following resection of the sellar tumor, limiting tumor descent, and leading to suprasellar residual. We propose a technique for resecting the suprasellar component first, which we call the "second floor" strategy (SFS) for GPA. METHODS: A retrospective review of cases from 2010-2020 identified 586 endoscopic endonasal approaches (EEAs) for pituitary adenoma resection. We report the rate of postoperative apoplexy and describe the SFS technique used in 2 cases. RESULTS: Of 586 cases, 2 developed symptomatic postoperative apoplexy (0.3%), and a third transferred to our care after undergoing postoperative apoplexy. All 3 cases had subarachnoid extension of a pituitary adenoma, underwent EEA, and had residual suprasellar tumor. All 3 had permanent morbidity due to the postoperative apoplexy including blindness, stroke, or death, despite undergoing reoperation. The SFS was used for reoperation on 1 of these patients and as a primary strategy in a fourth patient who presented with a GPA with subarachnoid extension. We describe the SFS technique and demonstrate it with a 2-dimensional operative video. CONCLUSIONS: Postoperative apoplexy of residual adenoma is a rare but serious complication after GPA resection. The proposed SFS allows early access to the suprasellar tumor and may improve the ability to safely achieve a gross total resection without need for additional procedures.

Computational modeling of nasal nitric oxide flux from the paranasal sinuses: Validation against human experiment.

BACKGROUND: Nitric oxide (NO) is important in respiratory physiology and airway defense. Although the paranasal sinuses are the major source of nasal NO, transport dynamics between the sinuses and nasal cavities are poorly understood. METHODS: Exhaled nasal NO tracings were measured in two non-asthmatic subjects (one with allergic rhinitis, one without) using NO analyzer connected via face mask. We subsequently performed computational fluid dynamics NO emission simulations based on individual CT scans and compared to the experimental data. RESULTS: Simulated exhaled NO tracings match well with experimental data (r > 0.84, p < 0.01) for both subjects, with measured peaks reaching 319.6 ppb in one subject (allergic-rhinitis), and 196.9 ppb in the other. The CFD simulation accurately captured the peak differences, even though the initial sinus NO concentration for both cases was set to the same 9000 ppb based on literature value. Further, the CFD simulation suggests that ethmoid sinuses contributed the most (>67%, other sinuses combined <33%) to total nasal NO emission in both cases and that diffusion contributes more than convective transport. By turning off diffusion (setting NO diffusivity to ~0), the NO emission peaks for both cases were reduced by >70%. CONCLUSION: Historically, nasal NO emissions were thought to be contributed mostly by the maxillary sinuses (the largest sinuses) and active air movement (convection). Here, we showed that the ethmoid sinuses and diffusive transport dominate the process. These findings may have a substantial impact on our view of nasal NO emission mechanisms and sinus physiopathology in general.