Radiological Anatomy of the Olfactory Fossa: Is Skull Base Anatomy Really Ever "Safe"?

Objective Computed tomography (CT) is a powerful tool for delineating the anatomy of the anterior skull base. The goal of this study is to further characterize the relevant anatomical features of this area, along with other parameters important for endoscopic sinus surgery. Design Retrospective case review. Setting Tertiary care hospital. Participants Thirty patients who had CT scans of the paranasal sinuses. Main Outcome Measures The following features were assessed using image analysis software: olfactory fossa depth, the length and angle of the lateral lamella, fovea ethmoidalis length and shape, ethmoid roof height and slope, and the position and course of the anterior ethmoid artery. Statistical analysis was performed assessing for differences in the above parameters. Results The mean olfactory fossa depth of the anterior and posterior skull base was 3.4 ± 1.1 and 2.4 ± 0.9 mm, respectively ( p < 0.05). The mean lateral lamella length was 3.6 ± 0.9 mm, which did not demonstrate significant variability. The angle of the lateral lamella varied significantly by skull base position, measuring 63.1 ± 17.8 degrees anteriorly, and 39.1 ± 17.9 degrees posteriorly ( p < 0.05). In scans classified as a Keros type I, 25.3% had lateral lamellae longer than 4 mm. Furthermore, 43.7% had lateral lamellae with angles less than 45 degrees. Moving anteriorly, the posterior skull base sloped downward in 46.7% of patients. Conclusion Thorough preoperative assessment of CT scans is crucial to understanding the inherent variability of skull base anatomy. Even "safe" anatomy can still contain features such as long and acutely angled lateral lamella, which may predispose patients to iatrogenic injury.

Quality-of-life outcomes in Graves disease patients after total thyroidectomy.

Historically, research into surgical treatment of Graves disease has assessed subtotal rather than total thyroidectomy. Most clinicians now recommend total thyroidectomy, but little information is available regarding quality-of-life (QOL) outcomes for this procedure. Our aim was to assess QOL after total thyroidectomy. This is a retrospective, pilot study of patients with Graves disease who underwent total thyroidectomy from 1991 to 2007 at a high-volume tertiary referral center in Toronto, Canada. Questionnaires addressing disease-specific symptoms and global QOL concerns were sent to 54 patients. Analyses included parametric and nonparametric tests to assess the differences between perception of symptoms and global QOL before and after surgery. Forty patients responded (response rate: 74%) at a median of 4.8 years postoperatively. On a 10-point scale, overall wellness improved from 4.1 preoperatively to 8.7 postoperatively (p < 0.001). Patients recalled missing less work or school after surgery (7.8 vs. 1.1 days/year; p = 0.001). Overall satisfaction with the procedure was high. On average, symptoms improved within 32 days of surgery, and all symptoms showed substantial improvement. This is the first North American study to assess QOL outcomes of patients with Graves disease after total thyroidectomy. Patients experienced marked and rapid improvement in QOL postoperatively. These findings suggest that total thyroidectomy is a safe and effective treatment.

Advanced airway management teaching in otolaryngology residency programs in Canada: A survey of residents.

We conducted a study to assess residents' levels of comfort with advanced airway management in Canadian otolaryngology residency programs. In October 2008, an electronic questionnaire was sent to all otolaryngology residents in Canada. Responses were voluntary and anonymous. The response rate was 64.8% (94 of 145 residents). Residents were asked about the amount of teaching they received and the amount they would like to receive each year in four areas: emergency surgical airway, pediatric airway, airway trauma, and management of complications during laryngoscopy/bronchoscopy. They were also asked how comfortable they were with their current level of knowledge in these areas. Overall, residents were not comfortable with difficult airway situations, scoring a mean of 3.08 on a 5-point Likert scale. Residents were most comfortable with the emergency airway and least comfortable with the pediatric airway. Overall, residents indicated that they had not received adequate teaching on advanced airway management, and they consistently desired more. With respect to the type of instruction, most residents requested more teaching via simulations, mannequins, and cadaver or animal models. Linear regression models revealed a positive relationship between their overall comfort with airway management and the number of airway teaching hours they received. Their consensus was that formal airway training should occur during postgraduate year (PGY) 2, with refresher courses offered every 2 years. This is the first wide-scale assessment of the status of airway teaching in otolaryngology residency programs in Canada. Overall, our findings suggest that otolaryngology residents in these programs are not comfortable with advanced airway management early in their training and feel they would benefit from a significant increase in airway teaching time. Comfort levels improved with increasing levels of training such that PGY5 residents indicated they were indeed comfortable with advanced airway management.

Angiogenesis in costal cartilage graft laryngotracheoplasty: a corrosion casting study in piglets.

OBJECTIVES/HYPOTHESIS: To investigate the timing and degree of angiogenesis following anterior costal cartilage graft laryngotracheoplasty in an animal model. STUDY DESIGN: Randomized controlled animal model. METHODS: Twelve pigs were included in this study. Three control pigs were perfused with intravascular methyl methacrylate, and overlying tissue was corroded with potassium hydroxide and hydrochloric acid, leaving only a cast of vessels. Nine pigs underwent anterior costal cartilage graft laryngotracheoplasty and were survived for various lengths of time (3 for 48 hours, 3 for 10 days, 3 for 3 weeks) prior to corrosion casting. Transition zones between trachea and cartilage graft as well as the graft itself were analyzed for signs of angiogenesis (budding, sprouting, intussusception) and hypoxic or degenerative vessel features (extravasation, corrugation, circular constriction) using scanning electron microscopy. RESULTS: Angiogenesis peaked above control levels 48 hours after laryngotracheoplasty (P < .0001) and decreased 10 days and 3 weeks following surgery (P < .001, P < .0001, respectively) while remaining elevated above control levels (P < .0001, P < .005, respectively). There was no difference in hypoxic or degenerative features across surgical and control groups. Sprouting angiogenesis dominated over intussusception preoperatively (P < .0001) and 3 weeks following surgery (P < .05). However, there was no difference in type of angiogenesis 48 hours and 10 days following surgery. CONCLUSION: Angiogenesis peaked by 48 hours following costal cartilage graft laryngotracheoplasty and persisted for at least 3 weeks (although decreased) after surgery in this animal model. Hypoxic or degenerative processes did not appear to play a role in tracheal revascularization during the first 3 postoperative weeks.

Attenuating Cardiac Pulsations within the Cochlea: Structure and Function of Tortuous Vessels Feeding Stria Vascularis.

The mammalian ear has an extraordinary capacity to detect very low-level acoustic signals from the environment. Sound pressures as low as a few µ Pa (-10 dB SPL) can activate cochlear hair cells. To achieve this sensitivity, biological noise has to be minimized including that generated by cardiovascular pulsation. Generally, cardiac pressure changes are transmitted to most peripheral capillary beds; however, such signals within the stria vascularis of the cochlea would be highly disruptive. Not least, it would result in a constant auditory sensation of heartbeat. We investigate special adaptations in cochlear vasculature that serve to attenuate cardiac pulse signals. We describe the structure of tortuous arterioles that feed stria vascularis as seen in corrosion casts of the cochlea. We provide a mathematical model to explain the role of this unique vascular anatomy in dampening pulsatile blood flow to the stria vascularis.

Corrosion casting of the subglottis following endotracheal tube intubation injury: a pilot study in Yorkshire piglets.

PURPOSE: Subglottic stenosis can result from endotracheal tube injury. The mechanism by which this occurs, however, is not well understood. The purpose of this study was to examine the role of angiogenesis, hypoxia and ischemia in subglottic mucosal injury following endotracheal intubation. METHODS: Six Yorkshire piglets were randomized to either a control group (N=3, ventilated through laryngeal mask airway for corrosion casting) or accelerated subglottic injury group through intubation and induced hypoxia as per a previously described model (N=3). The vasculature of all animals was injected with liquid methyl methacrylate. After polymerization, the surrounding tissue was corroded with potassium hydroxide. The subglottic region was evaluated using scanning electron microscopy looking for angiogenic and hypoxic or degenerative features and groups were compared using Mann-Whitney tests and Friedman's 2-way ANOVA. RESULTS: Animals in the accelerated subglottic injury group had less overall angiogenic features (P=.002) and more overall hypoxic/degenerative features (P=.000) compared with controls. Amongst angiogenic features, there was decreased budding (P=.000) and a trend toward decreased sprouting (P=.037) in the accelerated subglottic injury group with an increase in intussusception (P=.004), possibly representing early attempts at rapid revascularization. Amongst hypoxic/degenerative features, extravasation was the only feature that was significantly higher in the accelerated subglottic injury group (P=.000). CONCLUSIONS: Subglottic injury due to intubation and hypoxia may lead to decreased angiogenesis and increased blood vessel damage resulting in extravasation of fluid and a decreased propensity toward wound healing in this animal model.

Use of tissue glues in endoscopic pituitary surgery: a cost comparison.

BACKGROUND: Post-operative cerebrospinal fluid (CSF) leaks are a common complication of endoscopic pituitary surgery and account for a significant proportion of hospital costs associated with this procedure. Tisseel® is a tissue glue commonly used as an adjunct in dural repair but is not optimal for this purpose. DuraSeal® has several properties advantageous for dural repair but is not widely accepted in Canada partly due to its increased cost. OBJECTIVE: A cost analysis of DuraSeal® versus Tisseel® in endoscopic pituitary surgery. METHODS: A cost analysis was performed based on typical endoscopic pituitary surgery cases performed at our tertiary care institution. Operating room, hospital admission, and surgical sealant costs were obtained directly while estimates of patient recovery time and post-operative CSF leak rates were based on consensus values reported in the literature. Outcomes were reported for various possible clinical scenarios of sealant use. RESULTS: In a model where surgical sealant is employed only in high-risk cases, use of DuraSeal® allows for a yearly cost savings of at least $4486.72. If surgical sealant is used in all cases, regular use of DuraSeal® versus Tisseel® either marginally reduces yearly costs or increases them by a maximum of $7619.25, depending on the case volume and estimated post-operative CSF leak rate. CONCLUSION: In most clinical scenarios, use of DuraSeal® in endoscopic pituitary surgery may reduce overall yearly hospital costs compared to Tisseel®.

Use of duraseal in repair of cerebrospinal fluid leaks.

OBJECTIVE: The purpose of our article is to review the use of the DuraSeal Sealant System (Confluent Surgical Inc., Waltham, MA) in the repair of complex cerebrospinal fluid (CSF) leaks in endoscopic skull-base surgery. DESIGN: Retrospective chart review. SETTING: London Health Sciences Centre. METHODS: A database of endoscopic skull-base cases between 2007 and 2009 that involved CSF leakage repaired with DuraSeal was created. Demographic data and operative reports were collected and analyzed qualitatively. MAIN OUTCOME MEASURES: Recurrence of CSF leak after repair. RESULTS: Five cases were identified that met study criteria. In four of the five cases, the repair was successful. There were no complications related to DuraSeal use. Comparison to a subset of patients using Tisseel Fibrin Sealant (Baxter, Toronto, ON) for repair did not show a significant difference in failure rate (χ2 = 0.029, p = .858). CONCLUSIONS: There are a variety of techniques described to repair CSF rhinorrhea, with various studies demonstrating the advantages of using tissue glues in CSF leak repairs. We used DuraSeal in five patients to enhance graft strength and form a watertight seal. The system was effective in the majority of patients. Our study is the first to report on endoscopic endonasal repair of CSF leaks using DuraSeal.

Thyroid cancer outcomes in Filipino patients.

OBJECTIVE: To compare the outcomes of patients having thyroid cancer among Filipinos vs non-Filipinos. DESIGN: Retrospective medical record review. SETTING: High-volume tertiary referral center in Toronto, Ontario, Canada. PATIENTS: A total of 499 patients with thyroid cancer (36 Filipino and 463 non-Filipino) treated at Mount Sinai Hospital from January 1, 1984, to August 31, 2003, with a minimum 5-year follow-up period and a minimum 1.0-cm tumor size. Patients were identified from a thyroid cancer database. Data on patient, tumor, and treatment factors were collected along with outcomes. MAIN OUTCOME MEASURES: The presence of thyroid cancer recurrence, the rate of death from disease, and the time to recurrence. RESULTS: The 2 groups were similar for sex, age, history of head and neck radiation exposure, family history of thyroid cancer, follow-up time, tumor size, tumor pathologic findings, presence of tumor multifocality, stage of primary disease, type of thyroid surgery, use of postoperative radioactive iodine therapy, and use of external beam radiation therapy. Filipino patients experienced a thyroid cancer recurrence rate of 25% compared with 9.5% for non-Filipino patients (odds ratio, 3.20; 95% confidence interval, 1.23-7.49; P = .004). On multivariate analysis, the increased risk of thyroid cancer recurrence persisted for Filipino patients (odds ratio, 6.99; 95% confidence interval, 2.31-21.07; P < .001). No significant differences were noted between Filipino patients and non-Filipino patients regarding the rate of death from disease (5.6% vs 1.9%) and the time to recurrence (52.6 vs 53.1 months). CONCLUSIONS: Filipino patients have a significantly higher risk of thyroid cancer recurrence compared with non-Filipino patients. However, no significant difference was noted in the time to recurrence or the rate of death from disease. These findings justify a more aggressive initial management and follow-up regimen for Filipino patients with thyroid cancer.