The rat eustachian tube: Anatomical, histological, and radiological features

Purpose

This study investigated the anatomical and histological characteristics of the rat Eustachian tube (E-tube) and the feasibility of Eustachian tubography in a rat model.

Materials and methods

Fifteen male Wistar rats were used in this study, and the bilateral E-tubes of each rat were examined. Ten E-tubes were used for anatomical studies, another ten for histological analysis, and the other ten for Eustachian tubography. Five rats were euthanized and decapitated, and ten E-tubes were dissected to describe the anatomy of the E-tube. Ten E-tube specimens obtained from five other rats were sectioned to investigate E-tube histology. Eustachian tubography was performed on the bilateral E-tubes of the other five rats using the trans-tympanic approach.

Results

The rat E-tubes consisted of bony and membranous parts. Cartilage and bone tissue covered only the bony part. The E-tubes' mean diameter and overall length were 2.97 ​mm and 4.96 ​mm, respectively. The tympanic orifices' mean diameter was 1.21 ​mm. The epithelium of E-tubes was mainly composed of pseudostratified ciliated and goblet cells. Eustachian tubography was successfully performed on both sides of the E-tube for each rat. The technical success rate was 100%, the average running time was 4.9 ​min, and no procedure-related complications occurred. On tubography images, the E-tube, tympanic cavity, and nasopharynx could be identified because of the visualization of bony landmarks.

Conclusion

In this study, we described the anatomical and histological features of rat E-tubes. With the aid of these findings, E-tube angiography was successfully performed using a transtympanic approach. These results will facilitate further investigation of E-tube dysfunction.

Endoscopic Treatment of Otitis Media with Effusion

Myringotomy with grommet insertion is considered the standard of care for patients with unresolved otitis media with effusion and is traditionally performed under the operating microscope. The introduction of endoscopic ear surgery has provided otologists a tool for minimally invasive ear surgery with a panoramic view. We have described the use of endoscope for myringotomy and grommet insertion. The technique was found to be safe and effective and has the added advantage of being an excellent tool for teaching. The advantages and disadvantages of this technique vis a vis the traditional otomicroscopic technique have been discussed.

A three-dimensional printed myringotomy, tympanostomy and ventilation tube placement simulator

OBJECTIVE

Tympanostomy is one of the most commonly performed surgical procedures in otolaryngology, and its complexity is challenging for trainee surgeons. Investing in medical education is a cornerstone of good patient safety practices. For trainees, use of simulators before operating on actual patients helps mitigate risks. This study aimed to develop a three-dimensional printed model simulator for myringotomy, tympanostomy and ventilation tube placement.

METHODS

An articulated model with a detachable portion, base and plastic bag to simulate the external auditory canal, middle ear and tympanic membrane, respectively, was modelled and printed.

RESULTS

The final simulator was made from acrylonitrile butadiene styrene polymer and measured 4 × 4 × 12 cm. It was designed to mimic the angulation of patient anatomy in the myringotomy position and simulate the texture and colour of the tissues of interest. The cost was low, and testing with an operating microscope and endoscope yielded satisfactory results. The advent of three-dimensional printing technology has made surgical simulation more accessible and less expensive, providing several advantages for medical education.

CONCLUSION

The proposed model fulfilled expectations as a safe, inexpensive, reproducible, user-friendly and accessible surgical education tool that can be improved and reassessed for further research.

Investigating the learning curve in endoscopic compared to microscopic myringotomy and ventilation tube insertion

OBJECTIVE

Rate of learning is often cited as a deterrent in the use of endoscopic ear surgery. This study investigated the learning curves of novice surgeons performing simulated ear surgery using either an endoscope or a microscope.

METHODS

A prospective multi-site clinical research study was conducted. Seventy-two medical students were randomly allocated to the endoscope or microscope group, and performed 10 myringotomy and ventilation tube insertions. Trial times were used to produce learning curves. From these, slope (learning rate) and asymptote (optimal proficiency) were ascertained.

RESULTS

There was no significant difference between the learning curves (p = 0.41). The learning rate value was 68.62 for the microscope group and 78.71 for the endoscope group. The optimal proficiency (seconds) was 32.83 for the microscope group and 27.87 for the endoscope group.

CONCLUSION

The absence of a significant difference shows that the learning rates of each technique are statistically indistinguishable. This suggests that surgeons are not justified when citing 'steep learning curve' in arguments against the use of endoscopes in middle-ear surgery.

Transnasal Placement of a Balloon-Expandable Metallic Stent: Human Cadaver Study of the Eustachian Tube

PURPOSE

To investigate the technical feasibility of stent placement in the cartilaginous portion of the Eustachian tube (ET).

MATERIALS AND METHODS

Twelve ETs of 6 cadavers were used. Two different-sized stents were placed on either the right (2.5 mm in diameter) or left (3.5 mm in diameter) side of the ET. The procedural feasibility was assessed by subtraction Eustachian tubography, computed tomography before and after the procedure, and fluoroscopic and endoscopic images. The stent location, inner luminal diameter of the stented ET, radiation dose, procedural time, and fluoroscopy time were analyzed.

RESULTS

Stent placement was successful in 11 of 12 cadaveric specimens without procedure-related complications. In the 1 specimen, the balloon catheter with crimped stent was passed into the bony canal of the ET without any resistance. The distal end of the stent was located in the middle ear cavity. Stents were located within the cartilaginous portion of the ET (n = 1), the proximal tip bridging the nasopharyngeal orifice of the ET (n = 5), or the proximal end of the stent protruded from the tubal orifice (n = 5). The mean luminal diameter in the outer segment was significantly smaller than in the middle (P < .001) and inner (P < .001) segments. The mean procedure time was 128 ± 37 seconds. The mean radiation dose and fluoroscopy time of each cadaver were 3235.4 ± 864.8 cGy/cm² and 139 ± 49 seconds, respectively.

CONCLUSIONS

Stent placement of the ET under endoscopic and fluoroscopic guidance is technically feasible in a human cadaver model.

Comparison of endoscopic and microscopic tympanoplasty

Tympanoplasty was conventionally performed using a microscope for decades. However, since the endoscope began to be used in middle ear surgery in the 1970s, endoscopic tympanoplasty has gained increasing attention. The main objective of this study was to compare endoscopic and microscopic tympanoplasty with and without ossiculoplasty, demonstrating the potential advantages, disadvantages, and outcomes of each. This retrospective study included 126 patients with chronic otitis media who received tympanoplasty from 2013 to 2015 in our hospital. The clinical follow-up continued for at least 3 months postoperatively. Otoscopy and audiometry were conducted before and after the procedure. The different variables affecting surgical outcomes were thoroughly documented in each case. A total of 126 patients (131 ears) were included in this retrospective study. Moreover, 74 and 57 ears underwent endoscopic and microscopic tympanoplasty, respectively. The overall endoscopic tympanoplasty graft uptake rate was 97.7% (128/131). The operation time was significantly shorter in the endoscopic group statistically. A paired t test was used to compare pre- and postoperative audiometry results and showed significant differences between the endoscopic and microscopic groups. However, no statistically significant difference was observed in audiometry improvement between the two groups. No major complications were observed in any of the patients. Our study demonstrated that endoscopic tympanoplasty can be feasibly applied in middle ear surgery. The success rate, audiometry improvement, and complication rate are comparable between endoscopic tympanoplasty and conventional microscopic tympanoplasty. Moreover, the endoscopic group had smaller operation wounds and lower medical expenditures.