Austin S. Rose

Multi-material 3D Models for Temporal Bone Surgical Simulation.

Hypothesis: A simulated, multicolor, multi-material temporal bone model can be created using 3-dimensional (3D) printing that will prove both safe and beneficial in training for actual temporal bone surgical cases. Background: As the process of additive manufacturing, or 3D printing, has become more practical and affordable, a number of applications for the technology in the field of Otolaryngology–Head and Neck Surgery have been considered. One area of promise is temporal bone surgical simulation. Methods: Three-dimensional representations of human temporal bones were created from temporal bone computed tomography (CT) scans using biomedical image processing software. Multi-material models were then printed and dissected in a temporal bone laboratory by attending and resident otolaryngologists. A 5-point Likert scale was used to grade the models for their anatomical accuracy and suitability as a simulation of cadaveric and operative temporal bone drilling. Results: The models produced for this study demonstrate significant anatomic detail and a likeness to human cadaver specimens for drilling and dissection. Conclusion: Simulated temporal bones created by this process have potential benefit in surgical training, preoperative simulation for challenging otologic cases, and the standardized testing of temporal bone surgical skills.

A review of the evaluation and management of velopharyngeal insufficiency in children.

This article highlights the most common causes of velopharyngeal insufficiency (VPI), and discusses routine evaluation and treatment algorithms for the management of VPI in children. VPI is a multifactorial condition that occurs commonly in syndromic and non-syndromic children. The most common features of VPI are audible hypernasal speech, facial grimacing, decreased speech intelligibility, nasal regurgitation, and nasal emission from failure to produce oronasal separation. Work-up of VPI typically involves radiologic and endoscopic testing performed with the assistance of a speech-language pathologist. Management of VPI involves initial speech therapy followed by operative repair with sphincter or pharyngeal flap pharyngoplasty, if needed.

Immunohistochemical Localization of Nitric Oxide Synthase Activity in Upper Respiratory Epithelium

Nitric oxide (NO) production in the respiratory epithelium of the upper airways has recently been described. To better delineate the role of epithelial NO, the authors of this study attempted to identify the cell type responsible for the production of NO in rat tracheal epithelium and human nasal epithelium. They localized the activity of NO through immunohistochemical analysis with an antibody to L‐citrulline, a marker for activity of the L‐arginine‐dependent nitric oxide synthase (NOS) pathway. Using anti‐inducible NOS (iNOS) and anti‐constitutive NOS (cNOS) antibodies, they also attempted to identify the specific NO isotypes that were present.

Nitric oxide mediates mucin secretion in endotoxin-induced otitis media with effusion*

The mechanisms that regulate mucin release in chronic otitis media with effusion, a leading cause of hearing loss in children, remain largely unknown. We developed an animal model using Sprague-Dawley rats to determine the factors responsible for mucin production in chronic otitis media with effusion. N-nitro-L-arginine methyl ester (L-NAME), a competitive inhibitor of nitric oxide synthase, was used to investigate the role of nitric oxide in mucin secretion by the middle ear epithelium. All rats underwent eustachian tube obstruction. In the first set of rats, the middle ear was then injected transtympanically with 35 microl of either 300 mOsm Krebs-Ringer bicarbonate buffer (control group) or 1 mg/ml lipopolysaccharide in Krebs-Ringer (experimental group 1). In a second set of rats, the middle ear space was injected with lipopolysaccharide and then infused at a continuous rate for 7 days with either Krebs-Ringer (experimental group 2) or 1 mmol/L L-NAME in Krebs-Ringer (experimental group 3) through an osmotic infusion pump. After 7 days the volume of effusion and the quantity of mucin collected were significantly greater in lipopolysaccharide-exposed ears than in controls. In addition, antimucin immunostaining demonstrated mucous cell hyperplasia in response to lipopolysaccharide. The lipopolysaccharide-induced production of mucin and mucous cell hyperplasia was inhibited in ears treated with lipopolysaccharide and L-NAME. These results suggest that nitric oxide is a mediator in the pathway of mucin secretion in chronic otitis media with effusion.

Pre-operative simulation of pediatric mastoid surgery with 3D-printed temporal bone models

OBJECTIVES As the process of additive manufacturing, or three-dimensional (3D) printing, has become more practical and affordable, a number of applications for the technology in the field of pediatric otolaryngology have been considered. One area of promise is temporal bone surgical simulation. Having previously developed a model for temporal bone surgical training using 3D printing, we sought to produce a patient-specific model for pre-operative simulation in pediatric otologic surgery. Our hypothesis was that the creation and pre-operative dissection of such a model was possible, and would demonstrate potential benefits in cases of abnormal temporal bone anatomy. METHODS In the case presented, an 11-year-old boy underwent a planned canal-wall-down (CWD) tympano-mastoidectomy for recurrent cholesteatoma preceded by a pre-operative surgical simulation using 3D-printed models of the temporal bone. The models were based on the childs pre-operative clinical CT scan and printed using multiple materials to simulate both bone and soft tissue structures. To help confirm the models as accurate representations of the childs anatomy, distances between various anatomic landmarks were measured and compared to the temporal bone CT scan and the 3D model. RESULTS The simulation allowed the surgical team to appreciate the childs unusual temporal bone anatomy as well as any challenges that might arise in the safety of the temporal bone laboratory, prior to actual surgery in the operating room (OR). There was minimal variability, in terms of absolute distance (mm) and relative distance (%), in measurements between anatomic landmarks obtained from the patient intra-operatively, the pre-operative CT scan and the 3D-printed models. CONCLUSIONS Accurate 3D temporal bone models can be rapidly produced based on clinical CT scans for pre-operative simulation of specific challenging otologic cases in children, potentially reducing medical errors and improving patient safety.

Action of histamine on eustachian tube function

INTRODUCTION: The role of allergy in eustachian tube dysfunction is controversial. In this study, allergy was simulated by exposure to histamine, and eustachian tube function testing was performed in an experimental rat model. METHODS: Ventilatory function was assessed by measuring passive opening and closing pressures of the eustachian tube after challenge with either transtympanic or intranasal histamine. The mucociliary clearance time of the tubotympanum was assessed by observing dye transport from the middle ear to the nasopharynx after challenge with either transtympanic histamine or control solution. RESULTS: There was a statistically significant increase in passive opening and closing pressures with transtympanic histamine versus intranasal histamine. In addition, mucociliary clearance times of the tubotympanum after transtympanic histamine showed a statistically significant increase when compared with those after transtympanic control solution. CONCLUSIONS: Transtympanic histamine exposure causes eustachian tube dysfunction in the rat by increasing passive opening and closing pressures of the eustachian tube and impairing mucociliary clearance time.

Systemic reactivation of otitis media with effusion in a rat model

OBJECTIVE: This study addresses the interaction of bacterial antigens, specifically peptidoglycan-polysaccharide (PG-PS) and lipopolysaccharide (LPS), in the induction and reactivation of mucoid middle ear effusions. METHODS: Twenty-seven rats underwent eustachian tube obstruction before inoculation of the middle ear bulla with PG-PS. Three weeks later, after resolution of all middle ear effusions, 6 rats were randomly selected and euthanized as the first control group (control I). The remaining 21 animals were randomly assigned to 3 groups that received intravenous injections of Krebs Ringer (control II), PG-PS, and LPS, respectively. These rats were euthanized 2 days after intravenous injection. Middle ear mucin production and histologic changes were measured in all animals. RESULTS: The mean concentrations of mucin were 0.94 ± 0.52 mg/mL, 0.41 ± 0.87 mg/mL, 16.33 ± 3.67 mg/mL, and 1.15 ± 0.41 mg/mL in the control I, control II, PG-PS, and LPS groups, respectively. Thus the mean concentration of mucin in the middle ear lavage samples was significantly greater in rats that were injected intravenously with PG-PS than in rats in other groups (P < 0.05). Histologic analyses demonstrated a greater degree of goblet cell hyperplasia in the PG-PS group than in other groups. CONCLUSIONS: This is the first animal model of recurring otitis media with effusion in which a systemic injection of PG-PS was used to reactivate a middle ear effusion in rats previously primed with a transtympanic injection of PG-PS. This study suggests that after otitis media with effusion has resolved, it may be reactivated by the presence of bacterial antigens and/or cytokines in the systemic circulation. (Otolaryngol Head Neck Surg 1999;121:7-12.)

NITRIC OXIDE IS A MEDIATOR OF NEUROGENIC VASCULAR EXUDATION IN THE NOSE

Rhinorrhea is a troublesome symptom of rhinitis seen commonly by otolaryngologists. The sources of nasal fluid production are glandular secretions and exudation from submucosal blood vessels. This study was designed to investigate the role of nitric oxide in neurogenically mediated vascular exudation in the nose. A rat model of the nasonasal reflex was developed in which one nasal cavity was challenged with histamine while albumin exudation was measured on the contralateral side. Histamine challenge was associated with a significant rise in albumin leakage, indicating an increase in vascular permeability. Perfusion with a nitric oxide synthase inhibitor ( N -nitro-l-arginine methyl ester [l-NAME]) in the nasal cavity contralateral to nasal challenge was found to block albumin exudation on that side. This inhibition was overcome by the addition of L-arginine, the natural substrate of nitric oxide synthase, to the perfusate. Treatment of the ipsilateral nasal cavity with l-NAME did not significantly decrease the contralateral response. These findings indicate that NO is an important mediator of the effector arm of the nasonasal reflex that increases vascular permeability but is not involved in the sensory nerve afferent pathway. Further elucidation of the role of NO in nasal physiology may lead to novel pharmacotherapeutic approaches to the treatment of allergic and nonallergic rhinorrhea.(Otolaryngol Head Neck Surg 1997;116:294-300.)

Expression of protease-activated receptors in allergic fungal rhinosinusitis

The etiology of the intense inflammatory response showed by patients with allergic fungal rhinosinusitis (AFRS) remains a mystery. Potential sources of this inflammation may include fungal proteases. Protease‐activated receptors (PARs) are components of the innate immune response that are modulated by proteolytic activity and are involved in potentiating T helper 2 (Th2) responses. The objective of the study was to determine whether there is differential expression of PARs in patients with AFRS compared to controls.

High-Resolution Ultrasound in the Evaluation of Pediatric Recurrent Respiratory Papillomatosis

OBJECTIVES To characterize the ultrasonographic appearance of laryngeal papillomatosis and to compare ultrasound with direct laryngoscopy and bronchoscopy, the criterion standard, for airway evaluation. DESIGN Prospective, nonrandomized analysis of preoperative and postoperative airway ultrasound images. SETTING Tertiary, university-based medical center. PARTICIPANTS Eight patients (4 females and 4 males) with recurrent respiratory papillomatosis, with a mean age of 10.25 years and a mean of 14 surgical papilloma resections (range, 3-35). INTERVENTION The patients underwent planned papilloma resections with ultrasound evaluation before formal endoscopic resection. Preresection ultrasound images of respiratory papillomas were evaluated. MAIN OUTCOME MEASURES The ultrasonographic appearance of respiratory papillomas and pediatric airway anatomy. RESULTS Respiratory papillomas appeared as discrete, hyperechoic lesions on the relatively hypoechoic background of the true vocal folds. CONCLUSIONS Recurrent respiratory papillomas have a characteristic ultrasonographic appearance that seems to correlate with endoscopic findings. It seems that this modality holds promise for identifying pedunculated papillomas. Although direct laryngoscopy and bronchoscopy are the criterion standard, airway ultrasound may have a role in the early diagnosis of, surveillance of, and operative planning for recurrent respiratory papillomatosis. To our knowledge, this is the first study to describe the ultrasonographic appearance of papillomas and the first comparison of ultrasonographic and endoscopic airway images. This modality merits further study, and further investigation is ongoing.