Eustachian tube dysfunction in an intensive care unit: A prospective observational study.

Background: Eustachain tube (ET) dysfunction can aggravate the morbidity in ICU patients, but is often ignored. In this prospective observational study we followed a cohort of patients (without pre-existing ET dysfunction) requiring in-patient management, hospitalized either to ICU or to non ICU wards, for any development of ET dysfunction during hospitalization. Methods: Patients requiring hospitalization to ICU or non ICU wards from Dec 2018 to Jun 2019 were included. Those with pre-existing ET dysfunction, disease of ear/nose or sinuses, head neck tumours and history of radiotherapy or glucocorticoid therapy were excluded. All patients were evaluated by serial tympanometry. Type A curve was considered normal while type B, C1 and C2 were considered as ET dysfunction. Results: There were 385 patients, 258 (67.01%) males and 127 (32.99%) females in the ICU group; while non ICU group comprised 129 patients, 86 (66.67%) males and 43 (33.33%) females. ET dysfunction developed in 107 (27.79%) patients in ICU group, but only in 3 (2.3%) in non ICU group (Relative risk 11.95, 95% CI 3.86 to 36.99, P < 0.0001). Within ICU, ET dysfunction showed significant positive association with endotracheal intubation, Ramsay sedation score and number of days on tracheostomy; but not with age, male gender, number of days in ICU, mechanical ventilation or route of feeding. Conclusion: Our study demonstrates high incidence of ET dysfunction in patients admitted to ICU.

Can the negative pressures found in obstructive sleep apnea and Eustachian tube dysfunction be related?

OBJECTIVE: The association between obstructive sleep apnea (OSA) and Eustachian tube dysfunction (ETD) is well known. When both exist in a single pediatric patient, one of the expected culprits is adenoid enlargement. We hypothesize, in contrast, that the negative pharyngeal pressure found in OSA may be transmitted to the middle ear as negative middle ear pressure (MEP), which subsequently results in pathology. The objective of this study was to determine whether the degree of OSA and MEP are associated while using MEP as a quantifiable measurement of ETD. STUDY DESIGN: Retrospective chart review. SETTING: Tertiary academic center (Jan 2000-Jan 2018). SUBJECTS AND METHODS: The relationship between apnea-hypopnea index (AHI) and MEP was examined. A non-anatomic model was utilized to support causality. RESULTS: Thirty-four pediatric patients and twenty-three adult patients were included in the analysis. REM AHI showed a moderate negative correlation with MEP in children (r = -0.265), and a weak positive correlation with MEP in adults (r = 0.171). Children with an AHI in the severe OSA category had a more negative mean MEP than those in the mild category (p = 0.36). Adults with an AHI in the severe OSA category had a more positive mean MEP than those in the mild category (p = 0.11). CONCLUSION: In children, increasing severity of OSA is associated with a negative MEP, suggesting that negative pressure associated with OSA may be transmitted to the middle ear. In adults, increasing severity of OSA is associated with a more positive MEP.

Histological identification of nasopharyngeal mechanoreceptors.

The auditory tube plays a fundamental role in regulating middle ear pressure. A "system" sensitive to a pressure gradient between the middle ear and the ambient environment is necessary. The presence of mechanoreceptors in the middle ear and the tympanic membrane has been studied, but the presence of these receptors in the nasopharyngeal region remains unclear. The aim of this study is to confirm the presence of pressure sensitive corpuscles in the nasopharynx. An experimental study was conducted on five fresh and unembalded human cadavers. The pharyngeal ostium of the auditory tube and its periphery was removed in one piece by video-assisted endonasal endoscopy. Samples were fixed in formaldehyde solution, embedded in paraffin, and cut. Slides were analyzed by HES (Hematoxyline Eosine Safran) coloration, by S100 protein and neurofilament protein immunostaining. Encapsulated nerve endings were researched and identified by slides analysis. Eight samples were included in our study. On seven samples, Ruffini corpuscles were identified in the mucosa of the posterior area of the pharyngeal ostium, with a higher concentration in the pharyngeal recess and in the posterior nasopharyngeal wall. Our study identified nasopharyngeal mechanoreceptors that could detect the nasopharyngeal pressure and, by extension, the atmospheric pressure. These findings support the theory of the neuronal reflex arc of isobaric system of the middle ear, based on the existence of a "system" sensitive to a pressure gradient between the middle ear and the ambient environment. Understanding of this system has been helpful in the diagnosis and management of middle ear diseases.

Improvement of vertigo symptoms and acoustic power absorbance in cases with endolymphatic hydrops.

Objective: The pathophysiology and symptoms underlying Meniere's disease (MD) manifest as endolymphatic hydrops (EH), potentially impacting acoustic power absorbance in vestibular EH. The longitudinal effects of middle ear pressure therapy (MEPT) and conservative therapies for EH by magnetic resonance imaging (MRI) and on acoustic power absorbance on wideband acoustic immittance (WAI) were evaluated, and their changes were compared with clinical symptoms. Methods: Eleven patients with definite MD or delayed endolymphatic hydrops (DEH), resistant to conservative therapies and who continued MEPT for 1 year, were included. Vertigo scores, hearing levels, acoustic power absorbance on WAI, and degrees of EH on 3-T MRI were evaluated and compared before and after the treatments. Results: One year after the start of MEPT, all cases showed symptomatic improvement in vertigo score; however, the degrees of EH showed no improvements except in one case. In the affected ears with EH, their absorbances on WAI improved, particularly at 1580-1905 or 2400-2953 Hz (p < .05). Conclusion: Alleviation of vestibular symptoms with the therapy of MD was not necessarily associated with improved EH. Vestibular symptoms could be related to the change in the impedance of inner ear pressure, which was proven by the normalization of acoustic power absorbance. Assessments of acoustic power absorbance may provide useful information for physiological conditions and causative factors of vertigo in ears with EH. Level of evidence: 4.

Monitoring pressure changes in the inner ear induced by middle ear pressure therapy with an EFET01 device in guinea pigs.

BACKGROUND: As a low-cost, portable, handheld air pressure generation tool not requiring a ventilation tube, the EFET01 device has shown clinical effectiveness for intractable Ménière's disease (MD) patients in Japan. However, no animal studies have investigated changes in inner ear pressure (PI) when applying this device. OBJECTIVE: To determine the PI properties in response to middle ear pressure therapy (MEPT) induced by the EFET01 in guinea pigs. MATERIAL AND METHODS: In seven healthy guinea pigs, bi-phasic pressure pulses from -5 to 12 cm H2O were delivered to the external ear canal and transmitted to the middle and inner ear cavities with an intact tympanic membrane. Hydrostatic pressure change in the inner ear perilymphatic compartment was measured by a servo-controlled micropipette system. RESULTS: From eight successful ears, pressure changes in the middle ear slightly decreased and were instantly transferred to the inner ear. The EFET01 produces a bi-phasic positive/negative pressure pulse, which is approximately twice as large as the monophasic pressure pulse. CONCLUSION: Our study clarified the EFET01's ability to transmit pressure and verified its effectiveness in MD patients as observed in clinical studies. SIGNIFICANCE: The PI properties in guinea pig response to MEPT with the EFET01 device were investigated.

Long-term effects of middle ear pressure therapy with the EFET01 device in patients with Ménière's disease and delayed endolymphatic hydrops in Japan.

BACKGROUND: Long-term efficacy of middle ear pressure therapy (MEPT) with the EFET01 device in patients in Japan with definitive Ménière's disease (MD) and delayed endolymphatic hydrops (DEH) was evaluated. OBJECTIVE: To examine the effects of reducing vertigo attacks and improving hearing of MD and DEH patients by using MEPT with the EFET01 device for two years after treatment. MATERIAL AND METHODS: A retrospective study was conducted of 32 MD patients and 2 DEH patients treated by MEPT with the EFET01 device from December 2018 to April 2021. According to Japan Society for Equilibrium Research (JSER) guidelines, patients were investigated for the frequency of vertigo attacks and change in hearing levels during a period of 6 months before to 18-24 months after start of treatment. RESULTS: The frequency of vertigo attacks significantly decreased in both MD and DEH patients, and hearing level has remained stable in the majority of our patients after treatment. CONCLUSION: Our study clarified that MEPT with the EFET01 device was effective in controlling vertigo symptoms of MD and DEH. It should be considered a safe option for patients failing medical treatment. SIGNIFICANCE: The efficacy of MEPT with the EFET01 was shown over a 2-year follow-up period.

Evaluation of changes in endolymphatic volume after middle ear pressure therapy for intractable meniere's disease using 3D magnetic resonance imaging.

BACKGROUND: Nowadays, the endolymphatic space size can be evaluated by 3D-analysis of 3 T-MRI after intravenous injection of gadolinium enhancement. AIMS/OBJECTIVES: In the present study, to elucidate the relationships between vertigo and endolymphatic hydrops (EH) volume after middle ear pressure therapy (MEPT), we investigated changes in EH volume after MEPT for intractable Meniere's disease (MD) by means of the inner ear MRI (ieMRI) in relation to clinical results. MATERIALS AND METHODS: We enrolled 202 successive definite MD cases with intractable vertiginous symptoms from 2015 to 2020, assigning Group-I of MEPT, and Group-II of endolymphatic sac drainage (ELSD). Ninety patients completed the planned 2-year-follow-up, which included assessment of vertigo frequency and changes in EH volume using ieMRI (Group-I/MEPT: n = 40; Group-II/ELSD: n = 50). RESULTS: Two years after surgery, vertigo was completely controlled in 77.5% of patients in Group-I and 90.0% in Group-II. Hearing improved by >10 dB in 7.5% of patients in Group-I and 24.0% in Group-II. ELS ratios were significantly reduced after treatments of Group-I and Group-II only in the vestibule. CONCLUSIONS: The obtained results indicate that MEPT as well as ELSD could be a good treatment option for patients with intractable MD.

A Case Report on Ground-Level Alternobaric Vertigo Due to Eustachian Tube Dysfunction With the Assistance of Conversational Generative Pre-trained Transformer (ChatGPT).

Alternatenobaric vertigo (ABV) develops when the middle ear pressure (MEP) is not equal at the same height in the sea or the air. This is possible when the altitude changes. Eustachian tube dysfunction (ETD) is a common cause of ABV. In this case report, we discuss a patient who experienced repeated bouts of ground-level alternobaric vertigo (GLABV) due to ETD. We also discuss how Conversational Generative Pre-trained Transformer (ChatGPT) might be used in the creation of this case report. A 41-year-old male patient complained of vertigo at ground level on several occasions. His medical history included chronic sinusitis, nasal congestion, and laryngopharyngeal reflux (LPR). During the physical exam, his tympanic membranes were dull and moved less. Tympanometry showed that he had an asymmetric type A and that both of his middle ears had negative pressure. The results of the audiometry test were normal, and the laryngoscopy revealed LPR. The patient was found to have GLABV because of ETD, and different treatment options, such as Eustachian tube catheterization (ETC), were thought about. This case study demonstrates how ChatGPT can be used to assist with medical documentation and the treatment of GLABV caused by ETD. Even though ChatGPT did not provide specific diagnostic or treatment recommendations for the patient's condition, it did assist the doctor in determining what was wrong and how to treat it while writing the case report. It also aided the doctor in writing the case report by allowing them to discuss it. The use of artificial intelligence (AI) tools such as ChatGPT has the potential to improve the accuracy and speed of medical documentation, thereby streamlining clinical workflows and improving patient care. Nonetheless, it is critical to consider the ethical implications of using AI in clinical practice This case study emphasizes the importance of understanding that ETD is a common cause of GLABV and how ChatGPT can aid in the diagnosis and treatment of this condition. More research is needed to fully understand how long-term AI interventions in medicine work and how reliable they are.

Efficiency of a novel middle ear pressure device for intractable definite Meniere's disease and delayed endolymphatic hydrops after certification by the public health insurance system in Japan.

BACKGROUND: Middle ear pressure therapy (MEPT) is effective in treating intractable vertigo in patients with definite Meniere's disease (MD) and delayed endolymphatic hydrops (DEH) refractory to conservative treatment. A novel middle ear pressure device, the EFET01®, which requires no transtympanic ventilation tubes, was developed in Japan, approved by the Japanese Ministry of Health, Labour and Welfare, and has been used under Japanese national health insurance since September 2018. OBJECTIVES: To examine short-term therapeutic effect of MEPT using the ETET01® compared with previous clinical trial results. METHODS: Patients selected according to Japan Society for Equilibrium Research (JSER) guidelines underwent MEPT using the EFET01 from September 2018 to July 2021, and 44 patients were enrolled in this retrospective study. Clinical data analysed at 4 months after the start of MEPT were compared with those of the previous clinical trial for the EFET01. RESULTS: MEPT using the EFET01 showed the same therapeutic efficacy as that of the previous clinical trial, i.e. improvement in the intensity and frequency of vertigo with no effect on hearing, even under JSER guidelines for proper use of MEPT. CONCLUSION: MEPT using the EFET01 provided an effective treatment option for intractable vertigo in patients with definite MD and DEH.

12-month effect of middle ear pressure therapy with the EFET01 device for intractable definite Meniere's disease and delayed endolymphatic hydrops after certification by the public health insurance system in Japan.

BACKGROUND: Middle ear pressure therapy (MEPT) is effective for intractable vertigo in patients with definite Meniere's disease (MD) and treatment-refractory delayed endolymphatic hydrops (DEH). Four-month MEPT with the EFET01®, an MEPT device developed in Japan and covered by national health insurance since September 2018, has shown efficacy. However, efficacy and safety after 12 months of treatment, which is appropriate for determining the therapeutic effect of MEPT devices, is unclear. OBJECTIVES: Examine the therapeutic effect of 12-month MEPT using the ETET01®. MATERIAL AND METHODS: Patients underwent MEPT using the EFET01® from September 2018 to July 2021. Thirty-three patients followed for >12 months were enrolled in this retrospective study. Clinical data were evaluated in the first and second 6-month treatment periods. Data from the second 6-month period were compared with data from an MEPT study using a different device. RESULTS: MEPT with the EFET01® significantly improved vertigo in the first period, with further improvement in the second period. The efficacy and safety were comparable to MEPT with other devices. CONCLUSIONS: MEPT with the EFET01® is effective for intractable vertigo in patients with definite MD and DEH, and 12-month follow-up is recommended. SIGNIFICANCE: The efficacy of 12-month MEPT with the EFET01® was demonstrated.

Forward and Reverse Middle Ear Transmission in Gerbil with a Normal or Spontaneously Healed Tympanic Membrane.

Tympanic membranes (TM) that have healed spontaneously after perforation present abnormalities in their structural and mechanical properties; i.e., they are thickened and abnormally dense. These changes result in a deterioration of middle ear (ME) sound transmission, which is clinically presented as a conductive hearing loss (CHL). To fully understand the ME sound transmission under TM pathological conditions, we created a gerbil model with a controlled 50% pars tensa perforation, which was left to heal spontaneously for up to 4 weeks (TM perforations had fully sealed after 2 weeks). After the recovery period, the ME sound transmission, both in the forward and reverse directions, was directly measured with two-tone stimulation. Measurements were performed at the input, the ossicular chain, and output of the ME system, i.e., at the TM, umbo, and scala vestibuli (SV) next to the stapes. We found that variations in ME transmission in forward and reverse directions were not symmetric. In the forward direction, the ME pressure gain decreased in a frequency-dependent manner, with smaller loss (within 10 dB) at low frequencies and more dramatic loss at high frequency regions. The loss pattern was mainly from the less efficient acoustical to mechanical coupling between the TM and umbo, with little changes along the ossicular chain. In the reverse direction, the variations in these ears are relatively smaller. Our results provide detailed functional observations that explain CHL seen in clinical patients with abnormal TM, e.g., caused by otitis media, that have healed spontaneously after perforation or post-tympanoplasty, especially at high frequencies. In addition, our data demonstrate that changes in distortion product otoacoustic emissions (DPOAEs) result from altered ME transmission in both the forward and reverse direction by a reduction of the effective stimulus levels and less efficient transfer of DPs from the ME into the ear canal. This confirms that DPOAEs can be used to assess both the health of the cochlea and the middle ear.

In vivo study measuring middle ear pressure during various stages of Eustachian tube balloon dilation.

OBJECTIVE: Documentation of middle ear pressure at different stages of balloon Eustachian tuboplasty and assessing risk of barotrauma with this procedure. MAIN OUTCOME MEASURES: Middle ear pressure measurements in patients undergoing balloon Eustachian tuboplasty at the time of pre-insertion, catheter insertion, inflation, one minute post inflation, deflation, and catheter withdrawal, as well as documentation of pressure change in the middle ear between different stages. RESULTS: A total of 24 patients and 45 Eustachian tubes, 11 females and 13 males, with an average age of 55.6 years were included in this study. Middle ear pressure values during the active stages of the procedure varied from -356 to +159 daPa. The overall greatest negative pressure change measured was -515 daPa from catheter insertion to immediately post balloon inflation. The overall greatest positive pressure change measured was +418 daPa from immediate catheter inflation to one minute post inflation. CONCLUSIONS: There was no consistent pattern of middle ear pressure change noted during the different stages of balloon Eustachian tuboplasty as both positive and negative middle ear pressure changes were noted at the time of balloon dilation. Dangerous levels of middle ear pressure raising concern for barotrauma were not identified during the procedure. LEVEL OF EVIDENCE: Level IV.

Eustachian tube dysfunction in sleep apnea patients and improvements afforded by continuous positive airway pressure therapy.

INTRODUCTION: Upper airway resistance may accompany eustachian dysfunction and alter middle ear pressure in patients with obstructive sleep apnea syndrome. OBJECTIVE: To investigate effects of obstructive sleep apnea syndrome and continuous positive airway pressure treatment on eustachian tube functions. METHODS: Forty-two mild obstructive sleep apnea syndrome patients, 45 moderate obstructive sleep apnea syndrome patients, 47 severe obstructive sleep apnea syndrome patients with continuous positive airway pressure therapy, 32 severe obstructive sleep apnea syndrome patients without continuous positive airway pressure therapy, and 88 individuals without sleep apnea (controls) were included. Tympanometric parameters of groups were compared. RESULTS: Right middle ear pressures in mild and moderate obstructive sleep apnea syndrome groups did not differ significantly from that of control group (p = 0.93 and p = 0.55), as was also true of the left middle ear pressures (p = 0.94 and p = 0.86). Right middle ear pressure was significantly higher in severe obstructive sleep apnea syndrome groups than in the control group, as was the left middle ear pressure (p < 0.001). Middle ear pressure (negative) was significantly lower in severe obstructive sleep apnea syndrome patients with continuous positive airway pressure therapy compared to those without (p < 0.001). Right ear type B and C tympanogram frequencies were significantly higher in patients with severe obstructive sleep apnea syndrome without continuous positive airway pressure therapy (12.4%) than in the controls (0%) (p = 0.02). Left ear type B or C tympanogram frequencies were significantly higher in patients with severe obstructive sleep apnea syndrome without continuous positive airway pressure therapy (21.9%) than in the controls (0%) (p = 0.002). CONCLUSION: Mild and moderate obstructive sleep apnea syndrome did not affect middle ear pressure but severe obstructive sleep apnea syndrome may increase the (negative) middle ear pressure. In severe obstructive sleep apnea syndrome patients, long-term continuous positive airway pressure therapy may normalize middle ear pressure.

Effects of General Anaesthesia on the Middle Ear Pressure.

OBJECTIVE: Inhalation agents can have different effects on the middle ear pressure (MEP). We aimed to investigate the effect of sevoflurane and desflurane, the agents used in patients who do not have any ear pathology and who undergo surgery under general anaesthesia, on MEP. METHODS: Fifty adult patients who were scheduled to undergo inguinal hernia and lower extremity surgery were included in our study. All patients were aged between 20 and 60 years and belonged to the American Society of Anesthesiologists (ASA) I-III class. Patients were divided into two groups, according to the inhalation agent administered for the surgery: sevofluran, Group S (n=25); and desfluran, Group D (n=25). Anaesthetic agents, intraoperative end tidal carbon dioxide and airway pressures were recorded. The MEP was measured for both ears preoperatively, at the intraoperative 5th, 10th, 15th minutes, and at the postoperative 10th and 30th minutes. RESULTS: The MEP at the intraoperative 10th minute was significantly higher in Group D compared to Group S. In Group D, the MEP increased significantly at the intraoperative 10th and 15th minutes, and postoperative 30th minute, compared to preoperative values. In Group S, the MEP increased significantly at the postoperative 10th minute, compared to preoperative values. CONCLUSION: We found that desflurane increases the MEP during the intraoperative and postoperative period, compared to sevoflurane.

Recovery from tympanic membrane perforation: Effects on membrane thickness, auditory thresholds, and middle ear transmission.

Sounds delivered to the ear move the tympanic membrane (TM), which drives the middle-ear (ME) ossicles and transfers the acoustic energy to the cochlea. Perforations of the TM result in hearing loss because of less efficient sound conduction through the ME. The patterns of TM motions, and thus ME sound transmission, vary with frequency and depend on many factors, including the TM thickness. In this study, we measured TM thickness, auditory brainstem responses (ABR), and ME transmission immediately following a controlled pars tensa perforation and after 4 weeks of spontaneous recovery in a gerbil model. It is found that after recovery, the hearing thresholds showed a sloping pattern across frequencies: almost back to normal levels at frequencies between 2 and 8 kHz, sloping loss in the low (<2 kHz) and mid-frequency (8-30 kHz) range, and little restoration at frequencies above 30 kHz. This pattern was confirmed by the measured ME pressure gains. The thickness of the healed TM did not return to normal but was 2-3 times thicker over a significant portion of the membrane. The increased thickness was not limited to the perforated area but expanded into intact regions adjacent to the perforation, which led to an increased thickness in general. Combined, these results suggest that TM thickness is an important factor in determining its vibration patterns and efficiency to transfer sounds to the ossicles and thus influencing ME sound transmission, especially for high-frequency sounds. The results provided both structural and functional observations to explain the conductive hearing loss seen in patients with abnormal TMs, e.g., caused by otitis media, spontaneously healed post-perforation, or repaired via tympanoplasty in the clinic.

Effects of tympanic membrane perforation on middle ear transmission in gerbil.

Perforations of the tympanic membrane (TM) alter its structural and mechanical properties, thus resulting in a deterioration of sound transmission through the middle ear (ME), which presents itself clinically as a conductive hearing loss (CHL). The resulting CHL is proposed to be due to the loss of the pressure difference across the TM between the outer ear canal space and the ME cavity, a hypothesis which has been tested with both theoretical and experimental approaches. In the past, direct experimental observations had been either from the ME input (umbo) or the output of the stapes, and were focused mainly on the low frequency region. However, there was little documentation providing a thorough picture of the influence of systematically increasing sizes of TM perforations on ME sound transmission from the input (i.e., pressure at the TM or motion of the umbo) to the output (pressure produced by the motion of the stapes). Our study explored ME transmission in gerbil under conditions of a normal, intact TM followed by the placement of mechanically-induced TM perforations ranging from miniscule to complete removal of the pars tensa, leaving the other parts of ME intact. Testing up to 50 kHz, variations of ME transmission were characterized in simultaneously measured tone induced pressure responses at the TM (PTM), pressure responses in the scala vestibuli next to the stapes (PSV), and velocity measurements of the umbo (Vumbo), as well as by detailed descriptions of sound transmission from the TM to the stapes, i.e., the umbo transfer function (TF), the transfer of the sound stimulus along the ossicular chain as found from the ratio of cochlear pressure to umbo motion, and ME pressure gain (MEPG). Our results suggested that increasing the size of TM perforations led to a reduction in MEPG, which appeared to be primarily due to the reduction in the effective/initial mechanical drive to the umbo, with a relatively smaller decrease of sound transfer along the ossicular chain. Expansion of the perforation more than 25% appeared to drastically reduce sound transmission through the ME, especially for the higher frequencies.

Distortion product otoacoustic emissions: Sensitive measures of tympanic -membrane perforation and healing processes in a gerbil model.

Distortion product otoacoustic emissions (DPOAEs) evoked by two pure tones carry information about the mechanisms that generate and shape them. Thus, DPOAEs hold promise for providing powerful noninvasive diagnostic details of cochlear operations, middle ear (ME) transmission, and impairments. DPOAEs are sensitive to ME function because they are influenced by ME transmission twice, i.e., by the inward-going primary tones in the forward direction and the outward traveling DPOAEs in the reverse direction. However, the effects of ME injuries on DPOAEs have not been systematically characterized. The current study focused on exploring the utility of DPOAEs for examining ME function by methodically characterizing DPOAEs and ME transmission under pathological ME conditions, specifically under conditions of tympanic-membrane (TM) perforation and spontaneous healing. Results indicated that DPOAEs were measurable with TM perforations up to ∼50%, and DPOAE reductions increased with increasing size of the TM perforation. DPOAE reductions were approximately flat across test frequencies when the TM was perforated about 10% (<1/8 of pars tensa) or less. However, with perforations greater than 10%, DPOAEs decreased further with a low-pass filter shape, with ∼30 dB loss at frequencies below 10 kHz and a quick downward sloping pattern at higher frequencies. The reduction pattern of DPOAEs across frequencies was similar to but much greater than, the directly measured ME pressure gain in the forward direction, which suggested that reduction in the DPOAE was a summation of losses of ME ear transmission in both the forward and reverse directions. Following 50% TM perforations, DPOAEs recovered over a 4-week spontaneously healing interval, and these recoveries were confirmed by improvements in auditory brainstem response (ABR) thresholds. However, up to 4-week post-perforation, DPOAEs never fully recovered to the levels obtained with normal intact TM, consistent with the incomplete recovery of ABR thresholds and ME transmission, especially at high-frequency regions, which could be explained by an irregularly dense and thickened healed TM. Since TM perforations in patients are commonly caused by either trauma or infection, the present results contribute towards providing insight into understanding ME transmission under pathological conditions as well as promoting the application of DPOAEs in the evaluation and diagnosis of deficits in the ME-transmission system.

Eardrum and columella displacement in single ossicle ears under quasi-static pressure variations.

Although most birds encounter large pressure variations during flight, motion of the middle ear components as a result of changing ambient pressure are not well known or described. In the present study, motion of the columella footplate and tympanic membrane (extrastapedius) in domestic chickens (Gallus gallus domesticus) under quasi-static pressure conditions are provided. Micro-CT scans were made of cadaveric heads of chickens under positive (0.25 kPa, 0.5 kPa, 1 kPa, and 1.5 kPa) and negative (-0.25 kPa, -0.5 kPa, -1 kPa, and -1.5 kPa) middle ear pressure. Both extrastapedius and columella footplate displacements show a non-linear S-shaped curve as a function of pressure indicating non-linear response characteristics of the middle ear components. The S-curve is also seen in mammals, but unlike in mammals, the lateral piston-like displacement of both the columella footplate and extrastapedius, which is caused by an increased middle ear pressure are smaller than the medial piston-like displacements, caused by a decreased middle ear pressure of the same magnitude. Columella footplate piston displacements are always smaller than the extrastapedius piston displacements, indicating the flexibility of the extracolumella. The cone-shape of the avian tympanic membrane with inverted apex in comparison to the mammalian tympanic membrane can cause the inverted shape of the pressure response curve.

Contrasting Effects of Pressure Compensation on TEOAE and DPOAE in Children With Negative Middle Ear Pressure.

In children with normal cochlear acuity, middle ear fluid often abolishes otoacoustic emissions (OAEs), and negative middle ear pressure (NMEP) reduces them. No convincing evidence of beneficial pressure compensation on distortion product OAE (DPOAE) has yet been presented. Two studies aimed to document effects of NMEP on transient OAE (TEOAE) and DPOAE. In Study 1, TEOAE and DPOAE pass/fail responses were analyzed before and after pressure compensation in 50 consecutive qualifying referrals having NMEP from -100 to -299 daPa. Study 2 concentrated on DPOAE, recording both amplitude (distortion product amplitude) and signal-to-noise ratio (SNR) before and after pressure compensation. Of the 20 participants, 5 had both ears qualifying. An effect of compensation on meeting a pass criterion was present in TEOAE for both left and right ear data in Study 1 but not demonstrable in DPOAE. In Study 2, the distortion product amplitude compensation effect was marginal overall, and depended on recording frequency band. SNR values improved moderately after pressure compensation in the two (overlapping) sets of single-ear data. In the five cases with both ears qualifying, a stronger compensation effect size, over 3 dB, was seen. The absolute dependence of SNR on frequency was also strongly replicated, but in no analysis, the frequency × compensation interaction was significant. Independent of particular frequency range, the data support a limited SNR improvement in 2 to 3 dB for compensation in DPOAE, with slightly larger effects in ears giving SNRs between 0 dB and +6 dB, where pass/fail cutoffs would generally be located.

Measurement of middle ear pressure changes during balloon eustachian tuboplasty: a pilot study.

CONCLUSION: The middle ear pressure changes detected during BET can be directly attributed to the balloon inflation and may represent a second, immediate, mechanism of action of BET. BET seems to be safe with respect to the risk of a barotrauma. Further human studies are now necessary to confirm the results and gain more insight into the mechanism of action of BET. OBJECTIVE: Since the introduction of Balloon Eustachian Tuboplasty (BET) as a treatment of chronic Eustachian tube dysfunction, the precise mechanism of action is unknown. Long-term effects of BET may be related to observed microfractures of the Eustachian tube cartilage. However, clinical observations indicate a second, immediate mode of action. Therefore, this study investigated and characterized middle ear pressure changes occurring directly during BET procedure. METHODS: Using a micro-optical pressure sensor, pressure changes during BET were monitored transtympanically in a cadaveric animal study using heathland sheep. RESULTS: Middle ear pressure amplitudes during BET are dependent on the speed of balloon inflation as well as the maximum inflation pressure. A 10-bar inflation pressure yielded a mean middle ear pressure of 5.34 mmHg (71.0 daPA). Negative pressure amplitudes occurring on withdrawal of the balloon catheter are influenced by the speed of withdrawal. No pressure amplitudes capable of causing barotrauma to membranous ear structures could be detected.