Gas diffusion across the tympanic membrane in chinchillas: effect of repeated perforations

OBJECTIVE

Earlier studies documented a slow diffusion of gas across the tympanic membrane (TM) in humans and animals. However, structural changes caused by repeated TM perforations could affect gas diffusion rates. This possibility was evaluated using a chinchilla model.

METHODS

In six chinchillas, the right TM was perforated four times at 2-week intervals; the left TM served as a control. Approximately 12 weeks after the fourth perforation and when the right TMs had healed, a probe was introduced into the external canal and sealed to the environment. For 120 min, pressure in the probe was continuously monitored and probe gas was sampled at 10 min intervals and analyzed for composition by online mass spectrometry. Percent compositions for CO(2) and O(2) were calculated and these data were recast as partial-pressure versus time functions. The information contained in those functions was used to estimate time-constants for transTM O(2) and CO(2) diffusion.

RESULTS

In all experiments, CO(2) percent composition in the probe increased as a curvilinear function of time while that for O(2) decreased linearly. For all animals and both gases, the rate of change in probe partial-pressure was greater for the right TM. Average values of the right and left time-constants were (6.7 +/- 2.4) x 10(-3) and (4.2 +/- 2.2) x 10(-3)min(-1)TM(-1) for CO(2), and (2.3 +/- 0.8) x 10(-3) and (1.5 +/- 0.5) x 10(-3)min(-1)TM(-1) for O(2). Between side differences in these time-constants were statistically significant (P < 0.05, 2-tailed, paired, Student's t-test). The average right/left, transTM time-constant ratio was 1.66 +/- 0.43 for CO(2) and 1.61 +/- 43 for O(2); both were significantly different from a value of 1.0 (P < 0.05, 2-tailed Student's t-test).

CONCLUSION

These results document an increased rate of diffusive gas exchange across TMs that had been repeatedly perforated. This effect may be caused by structural thinning secondary to scar formation and could have implications for middle ear pressure regulation in ears with a history of repeated myringotomies and/or tympanostomy tube insertions.

[Health aspects of diving in ENT medicine. Part I: Diving associated diseases]

There has been a steady increase in the number of recreational scuba divers in the last years, with a growing number of diving associated diseases involving ENT medicine. Disorders of the ears, sinuses and pharynx are those most common in divers. In particular, external otitis and barotrauma of the middle ear are commonly treated by every ENT specialist. They usually do not lead to any permanent complaints. Incidents involving the cochleovestibular system are less common, but can result in deafness, vertigo and tinnitus, and therefore have to be treated appropriately. To treat diving medical disorders, the physician has to have some basic understanding of the physical laws that lead to diving incidents. This article will inform the reader of the forces that are encountered by divers, and then give details of the treatment of acute ENT diseases which result from diving incidents.

A willingness-to-pay assessment of parents' preference for shorter duration treatment of acute otitis media in children

OBJECTIVE

To assess parental willingness to pay (WTP) for a shorter course of antibacterial treatment versus conventional antibacterial therapy for acute otitis media (AOM).

METHODS

The study population consisted of 562 parents of children who had been seen and treated by a paediatrician for an episode of AOM between February and November 2002 in Montreal, Quebec, Canada. At the end of the AOM treatment, a questionnaire that included demographic information about the parents and child, details of the child's AOM history, a global wellbeing (i.e. quality of life) assessment, an evaluation of treatment compliance and a scripted WTP question was administered over the telephone. Descriptive analyses were performed in addition to a multivariate analysis to estimate possible predictors of parental WTP.

RESULTS

The children with AOM were representative of the AOM patient population, with 46% being <2 years of age and the majority attending day-care or school. Parents were willing to pay a median of 31.66 Can dollars (2002 values) for a mono-dose (one dose, on 1 day) and 26.63 Can dollars for a tri-dose (one dose daily, for 3 days) antibacterial treatment. Regression analyses demonstrated that the amount parents were willing to pay was positively associated with increasing household income, increasing number of AOM episodes during the previous year and experiencing adverse effects of treatment.

CONCLUSION

Parents of children with AOM were willing to pay more for their child to benefit from a shorter duration of antibacterial treatment than for a standard course. Short duration of treatment appears to be associated with better compliance and parents' perception of better general wellbeing for their child.

[Analysis of preoperative findings and ossicular condition in chronic suppurative otitis media]

OBJECTIVE

To discussion the relationship of preoperative findings and ossicular condition in chronic suppurative otitis media.

METHOD

The correlation between the ossicular conditions and classification of tympanic membrane perforation, ear discharge, air conduction pure tone average, air-bone gap, pneumatization, complication, and cholesteatoma in 251 patients(288 ears) with chronic suppurative otitis media was analysed.

RESULT

The air-conduction threshold and air-bone gap in patients with ossicular discontinuity are higher than that in patients with ossicular continuity. Ossicular discontinuity in patients with perforation of the pars flaccida of tympanic membrane, persistently draining ears, complications, and cholesteatoma occurred significiantly more frequently than those without these conditions.

CONCLUSION

The air-conduction threshold and air-bone gap are the more reliable indications to identify the ossicular conditions in patients with chronic suppurative otitis media. There are significiant correlation between the ossicular conditions in patients with chronic otitis media and their classification of tympanic membrane perforation, ear discharge, complication, and cholesteatoma.

Evaluation of human middle ear function via an acoustic power assessment

Measurements of middle ear (ME) acoustic power flow (power reflectance, power absorption, and transmittance) and normalized impedance (acoustic resistance, acoustic reactance, and impedance magnitude) were compared for their utility in clinical applications. Transmittance, a measure of the acoustic power absorbed by the ME, was found to have several important advantages over other measures of acoustic power flow. In addition to its simple and audiologically relevant physical interpretation (absorbed power), the normal transmittance curve has a simple shape that is visually similar to the ME transfer function. The acoustic impedance measures (resistance and reactance) provided important additional information about ME status and supplemented transmittance measurements. Together these measurements can help identify unusual conditions such as eardrum perforations. While this article is largely a review of the development of a commercial power reflectance measurement system, previously unpublished experimental results are presented.

Otorrinolaringología

The terrorist attack on 11 March caused a high percentage of patients with ear injuries. Shock waves provoke alterations to the external ear as well as to the middle and inner ear. The most frequent lesion is tympanic membrane perforation. Initial evaluation with otoscopy, acoumetry, tonal audiometry and vestibular examination was performed and was repeated after 2 and 3 months. In most patients there was a correlation between the grade of middle ear lesion and auditory damage. In most patients with tympanic rupture, the perforation was total or subtotal. Spontaneous closure can occur in some patients but is usually related to the size of the initial lesion. Thus in tympanic perforations of more than 50%, spontaneous closure is unlikely.

[Chronic otitis media]

In the presence of persistent or recurrent otorrhea with or without hearing impairment, a chronic infection of the middle ear should be suspected. Otoscopy is performed to distinguish between the less serious central perforation of the tympanic membrane and the peripheral bone-eroding infection, cholesteatoma. The diagnosis is purely clinical. Prior to an operation, a hearing test, radiography of the mastoid air cells and treatment of any infection are a must. Central perforation of the tympanic membrane is a relative indication for surgery, while in the case of a cholesteatoma complete removal of the process is mandatory to avoid potentially serious complications. Reconstruction of the ossicles takes second place in importance to complete removal of the cholesteatoma. All patients with this condition--in particular children--should be kept under surveillance over the long term.

Otologische Befunde von Erwachsenen mit isolierter Gaumenspalte oder Lippen-Kiefer-Gaumen-Spalte

BACKGROUND

Children with cleft palate often develop middle ear ventilation disorders due to chronic Eustachian tube dysfunction. This may lead to hearing loss. The insertion of ventilation tubes is a widely accepted measure to avoid sequelae of middle ear ventilation disorders and hearing loss. On the other hand, long-term therapy with ventilation tubes may inflict iatrogenic complications. The objective of the study was the evaluation of otoscopic and audiometric long-term findings in adult cleft patients who had been treated with ventilation tubes since childhood when chronic otitis media with effusion had been observed.

PATIENTS AND METHODS

Ninety-two cleft palate patients had been followed up otoscopically and audiometrically for years. The average age was 19.3 years (minimum: 14, maximum: 39 years) at the time the last status was taken.

RESULTS

Otoscopy revealed a perforation of the tympanic membrane in 3.8% of the 184 ears. 12% of the patients developed cholesteatoma, however three quarters of these occurred after age 11. 86.4% of the 92 patients had normal hearing in pure tone audiometry.

CONCLUSION

Compared with adult cleft patients who did not receive ventilation tubes, our patients had a similar low incidence of eardrum perforations but a higher incidence of cholesteatomas while hearing loss occurred less often. Whether the higher incidence of cholesteatomas is caused iatrogenically or due to a longer follow-up period remains unclear. Whether the use of long-lasting ventilation tubes affects the incidence of cholesteatomas must be proved in further studies.

Cochlear implantation in the chronically diseased ear

PURPOSE OF REVIEW

The presence of chronic ear disease in patients with profound SNHL presents a challenge to the otologic surgeon and was considered, in the past, a contraindication to cochlear implantation. This review discusses options for cochlear implantation in patients with chronically diseased ears.

RECENT FINDINGS

Several management options are available for cochlear implantation in patients with chronic suppurative otitis media (CSOM) and severe to profound sensorineural hearing loss (SNHL).

CONCLUSION

Cochlear implantation can be safely achieved in patients with CSOM. The approach chosen should be individualized based on clinical findings.

Cost-effectiveness of audiometric screening of first-year preparatory pupils in Dhofar Region, Oman

Audiometric screening was conducted in Dhofar region to study the magnitude of ear problems and cost-effectiveness of screening first-year preparatory-school children in Oman. None of the 1894 pupils had otitis media with effusion or sensory neuronal hearing loss. Six children (0.32%) had impacted wax, 4 (0.21%) chronic suppurative otitis media and 2 (0.11%) dry perforation of eardrum. In all, 14 children (0.74%) with suspected hearing impairment were referred to a specialist but only 2 attended. Physicians and nurses spent 8-10 minutes for ear examination per child for a yield of less than 1%. The screening expenditure was US$ 5 per pupil. As the prevalence of serious ear conditions was low, we conclude that expanding the audiometric screening of schoolchildren to first-year preparatory pupils is not cost-effective.

[Selective stimulation of the equilibrium organ using monochromatic near infrared]

BACKGROUND

The aim of this study was, to establish, if a selective thermal warm-stimulation using monochromatic near infrared radiation (NIR) in healthy persons, patients with chronic otitis media (chronic mucosal inflammation) and after radical surgery of one ear shows quantitative or qualitative changes of the nystagmus reaction.

PATIENTS AND METHODS

Healthy persons (n = 3), patients with a large central defect of the tympanic membrane (n = 5) and after radical ear surgery (n = 6) were examined. In healthy persons a stimulation with monochromatic NIR (lambda = 980 nm) of several areals of the external auditory canal was performed. In patients with large defects of the tympanic membrane the promontorium was stimulated. In patients with a radical cave of the ear a selective NIR-stimulation of the region of the vertical and the anterior semicircular canal was performed. The horizontal semicircular canal was visible as a landmark. Registration of the nystagmus was performed by means of videonystagmography.

RESULTS

In healthy persons the mean slow phase velocity of the nystagmus depended on the stimulated region. But there was no qualitative change of three dimensional eye movement. Stimulation of the promontorium showed a strong directional horizontal nystagmus. In patients with a radical cave the stimulation of the regions of the three semicircular canals showed a qualitative difference in three dimensional eye movement. NIR-stimulation showed in all cases a nystagmus into the stimulated ear.

CONCLUSIONS

The method of monochromatic near infrared stimulation can be used for selective stimulation of several regions of the external auditory canal, the promontorium and the regions of the semicircular canals in a radical cave of the ear as well as to prove the warm reaction of the equilibrium organ. A specific nystagmus after stimulation of the semicircular canal-region in a radical cave of the ear could be an indication for a normal semicircular canal function.

[Near infrared stimulation of the equilibrium organ--first clinical experiences]

BACKGROUND

A new method for the stimulation of the organ of equilibrium by means of a broad-scale and monochromatic near infrared emission was developed. This method should be examined within the framework of a pilot study, evaluated and its clinical possible applications examined.

PATIENTS AND METHODS

Healthy probands (n = 15), patients with a radical cave of the ear (n = 5), patients with a defect of the tympanic membrane (n = 5) and spontaneous nystagmus (n = 5) were examined. In healthy probands an irritation with broad-scale as well as monochromatic near infrared (NIR) was performed and compared with a water irrigation (44 degrees, 50 ml in 30 seconds). The subjective, local feelings during the application and the appearance of giddiness according to irritation were recorded and the nystagmus was registered by means of videonystagmography. In patients with radical cave of the ear and tympanic membrane defects, a broad-scale NIR-irritation before a comparative irritation with warm air (44 degrees) was performed exclusively.

RESULTS

In all healthy probands, a nystagmus reaction could be seen with broad-scale and monochromatic NIR. Compared to the hot water irritation slow phase velocity (SPV) was decreased however registrable by means of Frenzel glasses and electronystagmography during the culmination stage. In patients with radical cave (n = 4) and tympanic membrane defects (n = 3) showing paradoxical nystagmus reaction during hot air irritation, a nystagmus to the site of stimulation resulted by means of light calorisation. In patients with a spontaneous nystagmus an attenuation (n = 1) or inversion (n = 2) could be achieved by NIR-radiation.

CONCLUSIONS

The method of the NIR-radiation is suitable in clinical practice for the caloric test proofing warm reaction. Vaporization cold does not occur. The application of heat charm is better proportionable and steerable than during air irritation. The procedure is sterile, noiseless and non-contact. Difficulties in interpretation of results of vestibular tests because of evaporation coldness do not occur.

Pressures of the porcine tympanic membrane

The mean rupture pressure of the porcine tympanic membrane (TM) was measured in 9 specimens. Pressure was delivered gradually into the external ear canal of an excised piece of temporal bone, via a syringe and polyurethane tubing attached to the canal. Tympanometry was used to ascertain the structural integrity of the TM before pressure delivery. Rupture pressure was defined to be that point at which a sudden drop occurred in the overpressure in the ear canal, as measured by a pressure gauge. From the results, we concluded that the mean rupture pressure for the porcine TM is 1.2 +/- 0.3 atm. This is of the same order of magnitude as and slightly less than pressures obtained for the human TM.

Tragal cartilage in tympanic membrane reconstruction

INTRODUCTION

Management of chronic perforation and severe posterior and/or attic Retraction Pocket (RP) or atelectasis of the tympanic membrane continues to be one of the most difficult problems for otologists.

AIM OF THE STUDY

To analyse the usefulness of the tympanic membrane reconstruction with tragal cartilage.

MATERIALS AND METHODS

The study included 27 patients with chronic perforation or severe RP operated by the same surgeon, using tragal cartilage tympanoplasty. Seven supplementary procedures were required for recurrent cholesteatoma (second-look surgery).

RESULTS

There has been no recurrence of the retraction and the perforation. Nineteen ossicular reconstructions were necessary with acceptable hearing results.

CONCLUSIONS

Tragal cartilage has made a significant improvement in the tympanic membrane reconstruction procedure. A large thin cartilage combined with a titanium prosthesis can provide an excellent anatomical result, perfect stability and good functional outcome. When the eardrum is intact, we still use allografts of costal cartilage for the management of the retraction pocket or titanium prosthesis.

Inner ear damage in children due to noise exposure from toy cap pistols and firecrackers: a retrospective review of 53 cases

This retrospective study presents the findings of inner ear damage documented in 53 children exposed to impulsive sound emitted by toy weapons and firecrackers. There were 49 boys and four girls aged between four and fourteen years. Thirty-nine children were affected unilaterally while fourteen had bilateral hearing loss (total of 67 ears). Most of the hearing loss (>70%) was sensorineural high frequency hearing loss, while only nine out of the 67 injured ears had sensorineural mid frequency hearing loss. Seven children sustained a traumatic ear drum perforation. Dizziness or tinnitus was reported by twenty children, with pathological ENG findings in four of them. This paper re-emphasizes the possibility of inner ear damage in children from exposure to noisy toys.