Multifrequency multicomponent tympanometry in children with a history of ventilation tube insertion

Abstract

Objectives

To use multifrequency multicomponent tympanometry (MF-MCT) for evaluating the middle ear mechano-acoustics of children with a history of ventilation tube (VT) insertion and to determine the effects of tube insertion sequelae on middle ear function.

Methods

A prospective case-control study in a tertiary referral center involving 26 children (51 ears) aged 3–15 years. The children had undergone VT insertion surgery at least one-year previously and had no other known ear diseases. In addition, 13 age-matched healthy controls (26 ears) with no prior history of ear disease were included. The patients and control subjects underwent an otoscopic examination, standard 226 Hz tympanometry, and MF-MCT.

Results

In 13.7% of cases, the VT was still in place in the operated ears. Post-operative myringosclerosis and/or eardrum retraction were noticed in 30% of ears with intact tympanic membranes in the patient group. While patients exhibited a great variability of tympanometric types (with standard 226 Hz tympanometry and tympanometric patterns with 1000 Hz MF-MCT), all cases in the control group had type A tympanograms and 3B1G patterns.

Conclusion

The effects of VT treatment on the mechano-acoustics of the middle ear have been revealed in this study. It has also been determined that VT application may increase the mass effect on the middle ear functions, which can be detected in the tympanometric shape and pattern.

Introduction

Chronic otitis media with effusion (COMwE) is one of the most common otologic diseases of childhood. Further, this can cause serious problems (such as cholesteatomatous chronic otitis) if the course of the disease is not followed appropriately [1]. Children with COMwE can suffer from tympanic membrane sequelae, hearing loss, and speech and language delays [2]. Ventilation tubes (VTs), also known as tympanostomy tubes or grommets, are often used to treat COMwE by balancing the pressures on each side of the tympanic membrane through ventilation of the middle ear cavity. Previous studies have investigated the effects of VT treatment on hearing [[3], [4], [5]] and revealed the presence of sequelae (such as myringosclerosis and retractions) due to treatment in children with chronic otitis media (COM) [[6], [7], [8]]. Further, VT treatment can cause conductive hearing loss or anatomical modifications of the tympanic membrane [1], similar to the disease itself. Although VT treatment is highly effective at improving hearing in the short term, longer term effects of this application on middle ear functions have seldom been reported [7,9].

In conventional 226 Hz tympanometry, the middle ear acoustic admittance (Y) is measured, which is the amount of acoustic energy that flows into the middle-ear system. This procedure provides different types of tympanograms (types A, B, and C) [10] by presenting pressure in the outer ear canal and determining the amount of acoustic energy admitted through the middle ear. Admittance has three components: mass susceptance (Bm), compliance (inverse of stiffness) susceptance (Bs), and conductance (G) [11]. Moreover, multi-frequency and multi-component tympanometry (MF-MCT) can be used to assess middle ear dynamics across a wide range of frequencies by investigating these elements as a function of probe frequency. In MF-MCT, susceptance (B) and conductance (G) tympanograms progress through a sequence classified as 1B1G, 3B1G, 3B3G, and 5B3G as the middle ear system shifts from stiffness to mass control, in which the numbers represents the peaks and troughs in the components [11].

Tympanometry is frequently used to assess the status of the tympanic membrane and the functions of the middle ear in COMwE. Moreover, a type B (flat) tympanogram with conventional 226 Hz tympanometry measures in COMwE indicates a high probability of effusion [2]. However, considering the sensitivity and specificity of a type B tympanogram for associated hearing loss and the positive predictive value of a type B tympanogram for pure tone hearing loss, it has been reported that COMwE (with a type B tympanogram findings) can be encountered without related hearing loss [2]. Although standard 226 Hz tympanometry is performed in the majority of clinics for assessing middle-ear status at a single frequency with a single component, it has been demonstrated that low probe tone single frequency tympanometry is not suitable for detecting minor changes in middle-ear mechanics caused by otitis media [12,13]. There are four diagnostic parameters in MF-MCT: tympanometric configuration (Vanhuyse Pattern), the frequency corresponding to an admittance phase angle of 45° (F45°), static admittance (SA) at multiple frequencies, and resonant frequency (RF) [14]. Accordingly, MF-MCT can provide information on the nature of the abnormality by evaluating the mass and stiffness components of the middle ear admittance [15], rendering it more sensitive to changes caused by middle ear pathologies [12,13,[16], [17], [18]].

It is known that otitis media causes abnormal increases in the mass and stiffness of the middle ear and its progress can physically interrupt the transmission of sound [19]. However, the long-term effect of VT applications in COMwE with regard to mass and stiffness is unknown. We posit that VT applications with direct intervention in the tympanic membrane (and thus middle ear ventilation) causes tympanic membrane sequelae or hearing loss and can affect the mass and stiffness components of the middle ear admittance, which could be measured with MF-MCT. Therefore, the purposes of this study were to use MF-MCT to evaluate the middle ear mechano-acoustics of children with a history of VT insertion, determine the effects of tube insertion sequelae on middle ear function, and explore the differences in mechano-acoustical properties of the middle-ear between patients and the control group.