The conical cartilage of the cat's middle ear

AbstractThe object of this study was to investigate the anatomy, histology, and possible function of a conical structure found in the middle ear of the cat. This conical structure lies across the dorso-caudal compartment of the middle ear. It is directly related to the course of the chorda tympani nerve in the middle ear. Its base is attached by fibrous tissue to the dorso-caudal segment of the tympanic bone adjacent to the tympanic membrane. Its apex rests on the promontory just rostral to the round window niche. Histologically, it is cartilaginous tissue enveloped by a mudous membrane with no trace of bone. Portions of some conical cartilage specimens display extensive calcification. A previous hypothesis suggests that this structure conducts high frequency sounds directly from the tympanic membrane to the round window membrane. This seems unlikely because its length is shorter than the distance between the tympanic membrane and round window membrane. The conical cartilage may be a vestigial remnant of the second arch bar (Reichert's cartilage).

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Endoscopic visualisation of the round window during cochlear implantation

The Journal of Laryngology & Otology ◽

10.1017/s0022215120000067 ◽

2020 ◽

Vol 134 (3) ◽

pp. 219-221 ◽

Cited By ~ 1

Author(s):

A Jain ◽

R Sharma ◽

J C Passey ◽

R Meher ◽

R Bansal

Keyword(s):

Middle Ear ◽

Cochlear Implantation ◽

Round Window ◽

Electrode Array ◽

Round Window Membrane ◽

Window Region ◽

Round Window Niche ◽

Window Approach ◽

Maximum Exposure

AbstractBackgroundEndoscopes provide a magnified view of the middle ear and visualisation of hidden areas. Otoendoscopes facilitate excellent visualisation of the round window niche during cochlear implantation.ObjectiveTo compare microscopic and endoscopic visualisation of the round window membrane during cochlear implantation in 20 patients.MethodsTwenty patients who underwent cochlear implantation were included in the study. After maximum exposure of the round window, the accessibility of the round window membrane was graded according to the St Thomas Hospital classification, first by microscope and then by endoscope.ResultsWith the use of the endoscope, visualisation of the round window membrane improved in all the patients as compared to the microscope. The electrode array was inserted via a round window or extended round window approach in all but two cases; the latter cases required bony cochleostomy because of unfavourable anatomy.ConclusionThe main benefit of endoscope-assisted cochlear implantation is improved visibility of the round window region.

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How body size affects middle-ear structure and function and auditory sensitivity in gekkonoid lizards.

Journal of Experimental Biology ◽

10.1242/jeb.201.4.487 ◽

1998 ◽

Vol 201 (4) ◽

pp. 487-502 ◽

Cited By ~ 5

Author(s):

Y L Werner ◽

L G Montgomery ◽

S D Safford ◽

P G Igic ◽

J C Saunders

Keyword(s):

Body Size ◽

Tympanic Membrane ◽

Middle Ear ◽

Round Window ◽

Acoustic Stimulus ◽

Round Window Membrane ◽

Auditory Function ◽

Functional Changes ◽

Eublepharis Macularius ◽

Compound Action Potentials

Gekkonoid lizards increase in body size throughout life, and the present study investigates whether changes in auditory function accompany these increases. Middle-ear structures in four groups of animals, adults and juveniles of two gekkonoid species (Eublepharis macularius and Oedura marmorata), were examined. Tympanic membrane velocity and phase were also measured in all four groups. An indication of peripheral auditory function was obtained for each group by measuring compound action potentials (CAPs) from the round window membrane. The middle-ear contribution to CAP thresholds was obtained by comparing threshold levels of the CAP response with and without an intact middle-ear system. The results from these studies indicated that significant changes occurred in middle-ear structure, tympanic membrane velocity and CAP threshold between the younger and older animals. In addition, the adults of both species exhibited better auditory function when the acoustic stimulus was delivered to the tympanic membrane than when it was delivered to the columella footplate. The findings show clearly that increased body size (or age) is accompanied by functional changes in the auditory periphery.

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Cochlear Implantation Following Explorative Tympanotomy in Patients With Sudden Sensorineural Hearing Loss: Surgical Features and Audiological Outcomes

Ear Nose & Throat Journal ◽

10.1177/01455613211009141 ◽

2021 ◽

pp. 014556132110091

Author(s):

Robin Rupp ◽

Joachim Hornung ◽

Matthias Balk ◽

Matti Sievert ◽

Sarina Müller ◽

...

Keyword(s):

Hearing Loss ◽

Connective Tissue ◽

Sensorineural Hearing Loss ◽

Cochlear Implantation ◽

Round Window ◽

Sudden Sensorineural Hearing Loss ◽

Sensorineural Hearing ◽

Round Window Membrane ◽

Hearing Results ◽

Round Window Niche

Objective: To investigate the anatomical status of the round window niche and hearing outcome of cochlear implantation (CI) after explorative tympanotomy (ExT) with sealing of the round window membrane in patients with sudden sensorineural hearing loss at a tertiary referral medical center. Methods: Between January 1, 2007, and July 30, 2020, 1602 patients underwent CI at our department. Out of these, all patients previously treated by ExT with sealing of the round window membrane because of unilateral sudden hearing loss were included in the study. A retrospective chart review was conducted concerning method of round window membrane sealing, intraoperative findings during CI, postoperative imaging, and hearing results. Results: Twenty one patients (9 females; 8 right ears; 54.3 years [± 12.9 years]) underwent ExT with sealing of the round window membrane with subsequent CI after 26.6 months (± 32.9 mo) on average. During CI, in 76% of cases (n = 16), the round window niche was blocked by connective tissue due to the previous intervention but could be removed completely in all cases. The connective tissue itself and its removal had no detrimental effects on the round window membrane. Postoperative computed tomography scan showed no electrode dislocation. Mean postoperative word recognition score after 3 months was 57.4% (± 17.2%) and improved significantly to 73.1% (± 16.4%, P = .005) after 2 years. Conclusion: Performing CI after preceding ExT, connective tissue has to be expected blocking the round window niche. Remaining tissue can be removed safely and does not alter the round window membrane allowing for a proper electrode insertion. Short- and long-term hearing results are satisfactory. Consequently, ExT with sealing of the round window membrane in patients with sudden sensorineural hearing loss does not impede subsequent CI that can still be performed safely.

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Role of the Round Window Membrane in Middle Ear Immune Responses

Acta Oto-Laryngologica ◽

10.3109/00016488809138897 ◽

1988 ◽

Vol 105 (sup457) ◽

pp. 139-143 ◽

Cited By ~ 3

Author(s):

E. M. Keithley ◽

A. F. Ryan ◽

J. P. Harris

Keyword(s):

Immune Responses ◽

Middle Ear ◽

Round Window ◽

Round Window Membrane

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Anatomical Effects of Sudden Middle Ear Pressure Changes

Annals of Otology Rhinology & Laryngology ◽

10.1177/000348947908800313 ◽

1979 ◽

Vol 88 (3) ◽

pp. 368-376 ◽

Cited By ~ 5

Author(s):

A. Axelsson ◽

J. Miller ◽

M. Silverman

Keyword(s):

Tympanic Membrane ◽

Middle Ear ◽

Round Window ◽

Applied Pressure ◽

Positive Pressure ◽

Air Bubbles ◽

Scala Tympani ◽

Middle Ear Pressure ◽

Contralateral Ear ◽

Pressure Changes

Acute middle ear (ME) and inner ear changes following brief unilateral phasic ME pressure changes (up to ± 6000/mm H2O) were studied in the guinea pig. Middle ear findings included perforation of the tympanic membrane, serous and serosanguinous exudate and hemorrhage of tympanic membrane and periosteal vessels. Changes were related to magnitude of applied pressure. Perforation and hemorrhage were more commonly seen with negative rather than positive pressure. Air bubbles behind the round window were seen with positive pressures. Occasional distortion, but never perforation of the round window, was noted. Hemorrhage of the scala tympani was observed with both positive and negative pressures; scala vestibuli hemorrhage was found with negative ME pressure. In some instances pressure direction and magnitude related changes were seen in the contralateral ear.

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Comparison of Round Window Anatomy between Pediatric and Adult Population: A Perspective from Cochlear Implantation Surgery

Journal of Institute of Medicine ◽

10.3126/jiom.v42i3.37573 ◽

2020 ◽

Vol 42 (3) ◽

pp. 23-25

Author(s):

Rabindra B Pradhananga ◽

Bigyan R Gyawali ◽

Pabina Rayamajhi

Keyword(s):

Cochlear Implantation ◽

Adult Population ◽

Round Window ◽

Round Window Membrane ◽

Institute Of Medicine ◽

Statistical Association ◽

Complex Anatomy ◽

Wide Range ◽

Posterior Tympanotomy ◽

Round Window Niche

Introduction The round window is thought to be an ideal port for inserting electrodes during cochlear implantation. Considering its complex anatomy with an individual variation, this study aims to review the anatomy of round window based on the visibility of round window niche and round window membrane via posterior tympanotomy in pediatric and adult population who underwent cochlear implantation. MethodsThis was a retrospective observational study conducted at the Department of ENT-HNS, Institute of Medicine, Kathmandu, Nepal. Surgical notes of adult (>15 years) and pediatric cases (<15years) who underwent primary cochlear implantation from January 2015 to January 2018 were assessed for different grading of round window niche and round window membrane visibility via posterior tympanotomy. Cases with revision surgery and with incomplete documentation of intra-operative findings were excluded from the study. Statistical analysis was done using SPSS software version 25. We used Chi-square and Fisher’s exact tests to analyze the statistical association. ResultsType B round window niche (partially visible) was the most common variant seen in the pediatric group while in adults, both Type B (partially visible) and Type C (fully visible) round window niche were common. Compared to the adults, the pediatric group had good visibility of RWM. However, there was no statistical association between these observations. ConclusionThe round window has a wide range of anatomical variations with different levels of visibility of RWN and RWM in the different age groups. Although statistically insignificant, RWM visibility seemed to be better in pediatric cases compared to adults.

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Common drugs used in ENT

Oxford Handbook of ENT and Head and Neck Surgery ◽

10.1093/med/9780199550791.003.21 ◽

2009 ◽

pp. 347-350

Author(s):

Rogan Corbridge ◽

Nicholas Steventon

Keyword(s):

Inner Ear ◽

Tympanic Membrane ◽

Middle Ear ◽

Otitis Externa ◽

Round Window ◽

Acid Reflux ◽

Tympanic Membrane Perforation ◽

Active Infection ◽

Middle Ear Mucosa ◽

Membrane Perforation

Drugs used in the ear 348 Drugs used in the nose 349 Drugs used in the treatment of acid reflux 350 This group of drugs is widely used for the treatment of otitis externa. Otitis externa 2 drops tds for 10 days Presence of grommet or tympanic membrane perforation due to aminoglycoside ototoxicity in the inner ear. Risk thought to be low in the presence of active infection where the middle-ear mucosa is swollen and the antibiotic is unlikely to reach the inner ear via the round window...

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‘Soft reinforcement’ of the round window for superior semi-circular canal dehiscence syndrome

The Journal of Laryngology & Otology ◽

10.1017/s0022215120000353 ◽

2020 ◽

Vol 134 (4) ◽

pp. 366-368 ◽

Cited By ~ 1

Author(s):

A Gona ◽

J S Phillips

Keyword(s):

Case Report ◽

Round Window ◽

Invasive Technique ◽

Round Window Membrane ◽

Spatial Disorientation ◽

Migraine Headaches ◽

Vestibular Symptoms ◽

Round Window Niche ◽

Canal Syndrome ◽

Canal Dehiscence

AbstractBackgroundIndividuals with superior semi-circular canal syndrome often describe vestibular symptoms elicited by loud sounds, as well as other pressure-induced symptoms. They also often report other symptoms, including autophony, hyperacusis, cognitive dysfunction, spatial disorientation, anxiety and migraine headaches. Symptoms occur due to the presence of a ‘third window’ created by the dehiscence of the superior semi-circular canal. This case report describes a minimally invasive technique to provide soft reinforcement of the round window.Case reportOur patient underwent a permeatal procedure whereby the tympanic membrane was raised to allow inspection of the middle ear. The round window niche was identified and the round window membrane was reinforced with fat. The mucosa of the bony meatus leading to the round window was then disrupted before the application of a double layer of perichondrium to allow further reinforcement.ConclusionThe case provides support for the use of ‘soft reinforcement’ as a simple and effective technique to treat the symptoms of superior canal dehiscence syndrome.

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Rupture of the round Window Membrane

Annals of Otology Rhinology & Laryngology ◽

10.1177/000348947608500119 ◽

1976 ◽

Vol 85 (1) ◽

pp. 105-110 ◽

Cited By ~ 9

Author(s):

P. H. Taylor ◽

P. G. Bicknell

Keyword(s):

Middle Ear ◽

Surgical Intervention ◽

Round Window ◽

Oval Window ◽

Round Window Membrane ◽

Physical Effort ◽

Cochlear Aqueduct ◽

Definite Improvement ◽

History Of ◽

Pressure Changes

A case of sudden deafness due to rupture of the round window membrane is presented. Nineteen similar cases have previously been reported in the literature. In a review of these twenty patients, it is noted that a history of concurrent physical effort or barotrauma was present in eighteen. This supports the view that the injury is produced by pressure changes acting either along the cochlear aqueduct (the explosive route) or, directly on the middle ear structures (the implosive route). At operation, the rupture may be difficult to see, and a separate leak from the oval window may be present. The timing of any surgical intervention is important. The authors recommend that this should be deferred for one week after the onset of symptoms, as the fistula may heal spontaneously. If no definite improvement has occurred at the end of this time, then tympanotomy should be undertaken during the next week.

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