The eustachian tube. Update on anatomy, development, and function

Evaluation of Eustachian tube dimensions by temporal bone computed tomography in patients with chronic otitis media

OBJECTIVE

To clarify the relationship between Eustachian tube dimensions and chronic otitis media aetiology using temporal bone computed tomography.

METHODS

The data of 231 adults who had undergone surgery for unilateral chronic otitis media were reviewed retrospectively. Diseased and healthy ears were enrolled in groups 1 and 2, respectively. Group 1A included chronic otitis media with cholesteatoma (n = 28) and group 1B included chronic otitis media without cholesteatoma (n = 203). The Eustachian tube dimensions of groups 1 and 2 were compared, to clarify the relationship between the Eustachian tube dimensions and chronic otitis media aetiology. Groups 1A and 1B were compared to assess the effect of Eustachian tube dimensions on cholesteatoma development.

RESULTS

The Eustachian tube was shorter, narrower and located more horizontally in ears with chronic otitis media. No significant difference was found between groups 1A and 1B.

CONCLUSION

Eustachian tube dimensions are closely related to chronic otitis media aetiopathology, but are not related to cholesteatoma development.

Comparative Study on Temporalis Fascia Graft Versus Tragal Cartilage in Type-1 Tympanoplasty in Paediatric Patients

The aim of the study was to compare anatomical and functional outcomes of temporalis fascia graft versus tragal cartilage graft in type 1 tympanoplasty in paediatric patients. A prospective, comparative and randomised study. A detailed history was taken from all the patients visiting the ENT OP dept after fulfilling the inclusion and exclusion criterion patients were enrolled for the study. Written and informed consent was taken for all the patients from legally acceptable guardians. Preoperative assessment was done and the patients were subjected to type1 tympanoplasty with Temporalis fascia graft or tragal cartilage graft. All the patients were followed up on the third, sixth postoperative months to assess hearing improvement. All the patients were followed up on the first and third,sixth postoperative months for graft status with otoscopic examination. In the present study out of 80 patients, 40 patients underwent type 1 tympanoplasty with temporalis fascia and the remaining 40 patients with tragal cartilage. Both groups were assessed postoperatively for anatomical and functional success with maximum follow up of six months. There was no statistical significance between the outcome and the age or site and size of tympanic membrane perforation. Both groups had comparable graft success rate and hearing improvement. The cartilage group had a higher anatomical success rate. The functional outcome was similar. However, there was no statistically significant difference found in the outcome of two groups. Tympanoplasty can be performed in a paediatric age group with a good success rate in suitable patients. It can be done at an early age,safely with good anatomical and functional outcomes. The age group, site or size of perforation, the type of graft used for tympanoplasty does not alter the anatomical or functional outcome significantly.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12070-023-03490-1.

Linking Chronic Otitis Media and Nasal Obstruction: A CFD Approach

OBJECTIVES

To investigate a possible relationship between altered nasal flow and chronic otitis media (COM) using computational fluid dynamics (CFD).

STUDY DESIGN

Retrospective case series.

METHODS

Retrospective cohort sample of CT scans from patients with COM and controls without COM to compare the results of various nasal airflow parameters determined by CFD between a group of patients with COM (N = 60) and a control group of subjects without any evidence of ear disease (N = 81). The CT were subjected to various procedures to carry out CFD studies, determining the resistance to nasal flow, the proportion of flow through the right and left nasal cavity, and two nondimensional estimators. The results of CFD studies between patients with COM and controls were compared.

RESULTS

Whereas only 12.3% of the controls had CFD alteration (10 out of 81), 43.3% of the patients suffering COM displayed alterations of our nondimensional parameters R - ϕ (26 out of 60).

CONCLUSIONS

According to our results, the incidence of alterations in nasal airflow by studying with CFD is significantly higher in patients with COM than in controls. To our knowledge, this is the first article linking nasal cavity and COM using a CFD approach. Our results support the hypothesis that nasal flow alterations could be implicated in the etiopathogenesis of the COM.

LEVEL OF EVIDENCE

Level 4 Laryngoscope, 2021.

Diagnostic value of computed tomography in Eustachian tube dysfunction

OBJECTIVE

Investigate radiological findings on temporal bone computed tomography, which are associated with obstructive Eustachian tube dysfunction and determine its diagnostic validity.

METHODS

The present study was conducted as a prospective, cross-sectional case series study in a tertiary referral center. Forty patients with clinically diagnosed unilateral Eustachian tube dysfunction and older than 16 years old underwent pre interventional radiological assessment by temporal bone computed tomography while performing a Valsalva-maneuvre to enhance visualization of Eustachian tube lumen. The Eustachian tubes were assessed for intersite morphological differences, presence of mucus in the lumen or middle ear cleft and secretion retention or mucosal swelling in the adjacent sinuses. Image analyses and radiological statements about the side of pathology were delivered blinded to the clinical diagnoses.

RESULTS

The radiologic detection of mucus/mucosal edema in Eustachian tube or adjacent middle ear cleft structures was associated with the pathological side (t (1, N = 40) = 3.60, p = 0.001 < 0.05). On the contrary, there is no association between radiological findings of sinonasal disease and side of Eustachian tube dysfunction (x² (1, N = 40) = .00, p = 1.00 > 0.05). The diagnostic value of radiologic assessment in Eustachian tube dysfunction has a sensitivity and specificity of 52,5 and 97,5% respectively.

CONCLUSION

The sensitivity of radiologic assessment is rather low, and hence it is inappropriate as a screening tool for Eustachian tube dysfunction in routine clinical practice. In the case of present CT-scans of the temporal bone, the focus should be laid on the detection of mucus in the Eustachian tube or adjacent structures, as a predictor of disease.

Risk Factors for Multiple Tympanostomy Tube Placements in Children: Systematic Review and Meta-Analysis

OBJECTIVES/HYPOTHESIS

To determine the rate and predictors of receiving multiple tympanostomy tube (TT) placements in children.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

PubMed, EMBASE, and Cochrane Library databases were searched for studies reporting the risk factors for receiving repeat TT (r-TT) placements in children with chronic otitis media with effusion or recurrent acute otitis media. These articles were systematically reviewed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) recommendations. Data were pooled using a random-effects model.

RESULTS

Twenty-one studies involving a total of 290,897 children were included. Among all patients, 24.1% (95% confidence interval (CI), 18.2%-29.9%) underwent ≥2 TT placements and 7.5% (95% CI, 5.7%-9.4%) underwent ≥3 TT placements. Craniofacial disease (odds ratio (OR) 5.13, 95% CI, 1.57-16.74) was the strongest predictor of r-TT. Younger age at initial TT placement and shorter TT retention time were also significantly associated with r-TT. Receipt of primary adenoidectomy with initial TT placement was associated with decreased odds of r-TT (OR, 0.46; 95% CI, 0.39-0.55). Long-term tubes also significantly reduced the odds of r-TT (OR, 0.27; 95% CI, 0.17-0.44).

CONCLUSIONS

About 1 in 4 children receiving TT will receive at least one repeat set of TT and about 1 in 14 will receive multiple repeat sets. Concurrent adenoidectomy and long-term tubes reduced the incidence of r-TT. Younger patients and those with earlier extrusion of the initial set are at increased risk for repeat surgery. The identification of these risk factors may improve parental counseling and identify patients who might benefit from closer follow-up.

LEVEL OF EVIDENCE

NA Laryngoscope, 131:E2363-E2370, 2021.

Do the Angle and Length of the Eustachian Tube Affect the Success Rate of Pediatric Cartilage Type 1 Tympanoplasty?

OBJECTIVES

To investigate the relationships between the angle and length of the Eustachian tube (ET) (the ETa and the ETl) and the success rates of pediatric type 1 tympanoplasty.

STUDY DESIGN

A retrospective clinical chart review.

METHODS

In total, 51 children (31 females and 20 males; average age, 11.92 ± 3.46 years; age range: 7-18 years) who underwent cartilage type 1 tympanoplasty were included. Demographics and anatomical outcomes were recorded. The patients were divided into 2 groups in terms of anatomical success. In group A, all patients had intact grafts without perforation, retraction, or lateralization, and a dry ear, at 6 months postoperatively. In group B, reperforation of the tympanic membrane was evident 6 months postoperatively. The average ETa and ETl values of each group were measured on computed tomography images using a multiplanar reconstruction technique, and compared.

RESULTS

The ETa values of diseased ears of males and females were, respectively, 26.60 ± 6.42° and 23.29 ± 6.51°, compared to 27.25 ± 5.23° and 23.32 ± 4.61° for normal male and female ears, respectively. In group A, the ETa was 26.46 ± 6.82° in males and 22.95 ± 7.50° in females. In group B, the ETa was 26.85 ± 6.12° in males and 23.90 ± 4.45° in females. In group A, the mean ETl was 41.0 mm (29.6-45.3 mm) in males and 37.9 mm (32.0-44.5 mm) in females. In group B, the mean ETl was 40.5 mm (30.5-47.1 mm) in males and 38.0 mm (32.8-45.0 mm) in females. In group A, the ETa value of diseased ears did not differ between females and males, but in normal ears, the ETa was higher in males than females (P = 0.020 and P < 0.05, respectively). In group B, no difference was evident between the ETa values of normal and diseased ears (P > 0.05). No difference in the ETl values of diseased and normal ears, in either group, was apparent between females and males (both P > 0.05).

CONCLUSIONS

Neither the ETa nor the ETl affected the success rate of pediatric cartilage type 1 tympanoplasty. Further studies with larger numbers of patients are needed to compare anatomical outcomes after placement of various graft types and the effects of anatomical features of the ET on the success rate of pediatric tympanoplasty.

Imaging of the Eustachian tube and its function: a systematic review

Introduction

The Eustachian tube is a complex and inaccessible structure, which maintains middle ear ventilation to facilitate transmission of sound from the tympanic membrane to the cochlea. A renewed interest in treatments for eustachian tube dysfunction has led to a demand for methods of imaging the Eustachian tube, and assessing tube opening non-invasively. This review aims to summarise the use of imaging in the anatomical assessment of the Eustachian tube, and to explore how radiological techniques can be used to assess tube function.

Methods

A systematic review of the literature was performed with narrative data analysis.

Results

With high-resolution images, the soft and bony anatomy of the Eustachian tube can be assessed in detail. CT and MRI are best suited to identifying features associated with obstructive or patulous Eustachian tube dysfunction, though true assessments of function have only been achieved with contrast enhanced radiographs and scintigraphy. A single modality has yet to provide a complete assessment. No test has entered routine clinical use, but further development and research is underway.

Conclusion

Significant information can be gained from imaging the Eustachian tube, and as faster acquisition techniques are developed, it is possible that dynamic imaging of tubal opening could play an important role in the assessment of patients with ET dysfunction.

Tympanometric changes and eustachian tube function in patients with hypothyroidism

OBJECTIVE

The aim of this study was to investigate the tympanometric changes and eustachian tube function (ETF) in patients with hypothyroidism.

METHODS

Automatic ETF tests were performed and tympanometric measurements were evaluated to assess ETF in 40 patients diagnosed with hypothyroidism and a 40-patient euthyroid control group. Levothyroxine sodium tablet treatment was started in patients with hypothyroidism. After achieving a euthyroid state in these patients, the tympanometric measurements and automatic ETF tests were repeated.

RESULTS

When the patient groups (hypothyroid and control) were compared in terms of ETF, a statistically significant ET dysfunction was observed in the hypothyroid patient group (P < 0.01).When hypothyroid patients were evaluated in terms of ETF before and after treatment, whereas 61.3% of cases had ET function before treatment, this ratio increased to 78.8% after treatment. Furthermore, according to pressure and compliance measurements, statistically significant increases were found in the after treatment measurements (P < 0.05).

CONCLUSIONS

As a result of this study, we have come to the opinion that hypothyroidism can change tympanometric measurements and also cause ET dysfunction. However, more comprehensive and detailed studies researching the effects of hypothyroidism on tympanometric measurements are needed.

Do the angle and length of the eustachian tube influence the development of chronic otitis media?

OBJECTIVES/HYPOTHESIS

To compare the eustachian tube (ET) angle (ETa) and length (ETl) of ears with and without chronic otitis media (COM), and to determine the relationship between ET anatomy and the development of COM.

STUDY DESIGN

A retrospective case-control study.

METHODS

The study group comprised 125 patients (age range, 8-79 years; 64 males and 61 females) with 124 normal ears and 126 diseased ears, including ears with chronic suppurative otitis media (CSOM) with central perforation, intratympanic tympanosclerosis (ITTS), cholesteatoma, and a tympanic membrane with retraction pockets (TMRP). ET angle and length were measured using computed tomography employing the multiplanar reconstruction technique.

RESULTS

The ETa was significantly more horizontal in diseased versus normal ears of all study groups (P = .030), and there was no group difference in ETl (P = .160). ETl was shorter in CSOM versus ITTS ears and normal ears (P = .007 and P = .003, respectively) and in cholesteatoma versus TMRP ears (P = .014). In the unilateral COM group, there were no significant differences in the ETa or ETl of diseased versus contralateral normal ears (P = .155 and P = .710, respectively). The ETa was significantly more horizontal in childhood-onset diseased versus normal ears (P = .027), and there was no group difference in ETl (P = .732). The ETa (P = .002) and ETl (P < .001) were significantly greater in males than females.

CONCLUSIONS

A more horizontal ETa and shorter ETl could be contributory (though not significantly) etiological factors in the development of COM.

LEVEL OF EVIDENCE

3b.

Transtympanic balloon dilatation of eustachian tube: a human cadaver pilot study

Objective:

To determine the feasibility and safety of transtympanic balloon dilatation of the eustachian tube.

Methods:

Transtympanic eustachian tube dilatation was performed on six cadaver heads using balloon catheters. Catheters were placed in each eustachian tube and the head scanned by computed tomography. Randomised, blinded dilatation of one balloon in each head was performed, followed again by a second computed tomography scan. The scans were reviewed by a neurotologist and neuroradiologist who were blinded to previous treatment, and measurable dilatation and incidental damage noted.

Results:

There was adequate placement of the balloon catheter beyond the bony isthmus in 6 of 10 eustachian tubes. There was one insufficient catheter placement and three adverse placements (one into the petrous carotid canal and two into the vidian canal). Only one dilated tube showed a measurable increase in diameter.

Conclusion:

This experiment revealed serious safety issues with transtympanic eustachian tube dilatation. Therefore, this approach should not be considered feasible at this time.

Evaluation of nasal airways by objective methods in chronic otitis media

Otitis media (OM) is a common health problem. Nasal airways play an important role in etiopathogenesis of OM. The aim of this study is to evaluate nasal airways by objective methods in chronic otitis media (COM) cases. The relationship between the course of the disease and nasal parameters is also investigated. Fifty-six patients who had chosen an operation for chronic otitis media were included in the study. The control group was composed of 30 healthy patients. Patients were subjected to acoustic rhinometry and rhinomanometry. Nasal airway resistance and cross-sectional area measurements were taken. The results of the COM group and the control group were compared. Cases were classified by the course of the disease such as suppurative/progressive/active and non-suppurative/inactive and the nasal parameters of these sub-groups were compared. In cases with unilateral COM, nasal cavity results from both sides were compared. The nasal airway resistance of the COM group was statistically significantly higher than the control group (p < 0.05). However, there was no difference in cross-sectional area measurements. There was no significant difference between the suppurative/progressive/active and non-suppurative/inactive groups. However, the suppurative group had higher nasal resistance (p > 0.05). There was no statistical difference between the measurements of each side in unilateral COM cases. This study found that COM cases have greater nasal airway resistance. No significant difference was found in cross-sectional area measurements so the increase in resistance may be linked to mucosal rather than structural changes. There was no evidence for a relationship between the course of the OM and nasal airway parameters.

Klippel-Feil syndrome and associated ear anomalies

BACKGROUND AND PURPOSE

Klippel-Feil syndrome (KFS) is a congenital segmentation anomaly of the cervical vertebrae that manifests as short neck, low hair line, and limited neck mobility. Various systemic malformations may also accompany the syndrome including wide variety of otopathologies affecting all 3 compartments of the ear (external, middle, and inner ear) as well as internal acoustic canal and vestibular aqueduct. We aimed to investigate these involvements and their clinical correlates in a group of patients with KFS.

MATERIALS, METHODS, AND RESULTS

We present 20 KFS cases, of which 12 (% 60) displayed most of the reported ear abnormalities such as microtia, external ear canal stenosis, chronic ear inflammations and their sequels, anomalies of the tympanic cavity and ossicles, inner ear dysplasies, deformed internal acoustic canal, and wide vestibular aqueduct, which are demonstrated using the methods of otoscopy, audiologic testing, and temporal bone computed tomography.

CONCLUSIONS

This series represents one of the highest reported rate of ear involvement in KFS. We found no correlation between the identified ear pathologies and the skeletal and extraskeletal malformations. The genetic nature of the syndrome was supported by the existence of affected family members in 4 (20%) of the cases.

[Treatment of chronic tube dysfunction. Use of the tube conductor]

BACKGROUND

Chronic tube dysfunction plays a major part in the development of chronic otitis media. Owing to the complex structure of the Eustachian tube, the development of successful therapeutic approaches to the treatment of tube function disorders is still difficult even today. The application of a gold tube wire (tube conductor) was reported in 1991, but no studies have yet been performed on the postoperative success rates achieved with tube conductors.

MATERIAL AND METHODS

In a retrospective study, the data relating to 125 patients who were operated on from 1996 to 1999 for treatment of different forms of chronic otitis media and also underwent transtympanic tube conductor implantation to improve tube ventilation disorder were evaluated. Data on pre- and postoperative tube function were available for 96 patients after a mean follow-up period of 18 months.

RESULTS

All tube implantations were achieved without complications. Tube function normalized in 8 patients (8.3%), while the tube ventilation disorder remained unaffected in 88 patients (91.7%). A total of 23 (18.4%) tube conductors have so far been removed. The reasons for removal include persistent tube ventilation disorder, dislocation of the tube conductor in 7 patients (5.6%) and granulation around the tube wire in 7 cases (5.6%).

CONCLUSIONS

The chronic tube ventilation disorder was improved by implantation of a tube conductor in only 8.3% of the patient population investigated. We are therefore of the opinion that this is not a suitable treatment for chronic tube ventilation disorders. The development of new, effective therapeutic approaches to the treatment of chronic tube ventilation disorders remains a priority.

The evaluation of the tensor veli palatini muscle function with electromyography in chronic middle ear diseases

Although there are several factors affecting the pathogenesis of chronic otitis, the pathological process has not been entirely defined yet. One of the theories suggested for the development of middle ear diseases is tubal dysfunction. The aim of the study is to analyze the function of the tensor veli palatini (TVP) muscle electromyographically in chronic middle ear pathologies and to evaluate the role of this muscle in eustachian tube dysfunction and pathogenesis of associated middle ear diseases by comparing with the results of healthy individuals.

STUDY DESIGN

A prospective, controlled, clinical trial. We enrolled 24 patients with chronic middle ear pathologies into our study and 18 controls without any previous ear problem. Electromyographic (EMG) needle was inserted into the TVP muscles in all patients transnasally. Functions of the TVP muscle were analyzed by using the amplitudes of the motor unit potential (MUP) and MUP durations detected on EMG. MUP amplitudes and MUP durations were compared statistically in all groups. When the mean MUP amplitudes and durations obtained from TVP muscles of all ears from the patient group were compared to the mean MUP amplitudes and durations obtained from healthy individuals, no statistically significant difference was observed between sick ears and control ears. Values obtained from the sick ears needed to be compared with mean values obtained from the control group separately, since absence of statistically significant difference cannot mean that we should ignore individual muscle dysfunction. The results we obtained from our study support that in the formation of different middle ear pathologies, myogenic defects in the eustachian tube have limited effects, except for existence of a predisposing factor like palate pathology. In all patients with chronic middle ear disease it is not appropriate to expect functional muscle dysfunction, however evaluation of TVP muscle function correctly may be helpful for bringing up the underlying possible muscle and nerve pathologies not in all patients.

Sectional anatomy of auditory tube

BACKGROUND AND PURPOSE

The auditory tube connects the tympanic cavity with nasopharynx. Due to its structure and position it is difficult to demonstrate the auditory tube in its whole length, and to study its topography on anatomical specimens. The purpose of our study was to present sectional anatomy of auditory tube in order to facilitate understanding of its structure and topography.

MATERIALS AND METHODS

We utilised serial sections of cadaveric head in four planes: transverse, oblique, frontal and sagittal.

RESULTS

The osseous part of the auditory tube was demonstrated on transverse sections, and most of the cartilaginous part on oblique sections of head and neck. The tensor veli palati muscle was found to consist of bilaminar muscle sheet: the outer part originating from the skull base and the inner part originating from lateral cartilaginous lamina and membranous part of the tube. Topographic relations seen on four section planes were described in detail.

CONCLUSION

The structure, course and topography of auditory tube are well demonstrated on sectional images. Detailed knowledge of sectional anatomy of the auditory tube is important for interpretation of corresponding computerised tomographic and magnetic resonance images, and in understanding the disorders and diseases affecting middle ear and mastoid.

Finite element analysis of active Eustachian tube function

The inability to open the collapsible Eustachian tube (ET) has been related to the development of chronic otitis media. Although ET dysfunction may be due to anatomic and/or mechanical abnormalities, the precise mechanisms by which these structural properties alter ET opening phenomena have not been investigated. Previous investigations could only speculate on how these structural properties influence the tissue deformation processes responsible for ET opening. We have, therefore, developed a computational technique that can quantify these structure-function relationships. Cross-sectional histological images were obtained from eight normal adult human subjects, who had no history of middle ear disease. A midcartilaginous image from each subject was used to create two-dimensional finite element models of the soft tissue structures of the ET. ET opening phenomena were simulated by applying muscle forces on soft tissue surfaces in the appropriate direction and were quantified by calculating the resistance to flow (Rv) in the opened lumen. A sensitivity analysis was conducted to determine the relative importance of muscle forces and soft-tissue elastic properties. Muscle contraction resulted in a medial-superior rotation of the medial lamina, stretching deformation in the Ostmann's fatty tissue, and lumen dilation. Variability in baseline Rv values correlated with tissue size, whereas the functional relationship between Rv and a given mechanical parameter was consistent in all subjects. ET opening was found to be highly sensitive to the applied muscle forces and relatively insensitive to cartilage elastic properties. These computational models have, therefore, identified how different tissue elements alter ET opening phenomena, which elements should be targeted for treatment, and the optimal mechanical properties of these tissue constructs.