ABSTRACT
OBJECTIVES: To establish a mathematical model of middle ear gas pressure regulation and to discuss potential implications for pathophysiology-oriented theoretical approach to middle ear surgery, with particular attention to mastoid obliteration. BACKGROUND: Numerous studies support that small mastoid volume is associated with cholesteatoma. Latest studies show that mastoid obliteration is an effective technique to lower the recurrence rate in these ears. METHODS: A mathematical model was used to predict the development of gas pressure balance in the function of different middle ear volumes (VME), considering normal and dysfunctional Eustachian tube. Published data as gas pressure input values and our 3D CT reconstruction data in healthy and pathologic middle ears of children were applied. RESULTS: The model predicted ≤6.66 daPa pressure fluctuations in VME ≥3 ml, compared to ≥16 daPa of a VME ≤1 ml at perfect ET function, because of the different pressure change rate and pressure buffer effect of the MEs. Substantially larger fluctuations can be expected in a VME <3 ml with malfunctioning ET. Modeling mastoid obliteration predicts similar pressure fluctuations to a VME ≥3 ml resulting from elimination of gas exchange surface. CONCLUSION: Pressure change is faster in smaller MEs than in larger ones. Healthy MEs between 3 and 6 ml are very sensitive to the duration of a potential ET dysfunction to develop ME pathology. In MEs with poor mastoid pneumatization and dysfunctional ET, typical in cholesteatoma cases, mastoid obliteration as surgical reduction of mucosal surface for gas exchange can improve ME gas pressure balance resulting in better long-term outcome.
Subject(s)
Cholesteatoma, Middle Ear/surgery , Ear, Middle/physiopathology , Eustachian Tube/physiopathology , Gases , Mastoid/surgery , Models, Biological , Adolescent , Child , Child, Preschool , Cholesteatoma, Middle Ear/physiopathology , Computer Simulation , Ear, Middle/surgery , Eustachian Tube/surgery , Humans , Mastoid/physiopathology , Otologic Surgical Procedures , Partial Pressure , RecurrenceABSTRACT
OBJECTIVE: To characterize the pneumatization of the temporal bone in age-matched healthy children and in children with otitis media with effusion (OME). STUDY DESIGN: Prospective case-control study. SETTING: Tertiary hospital center. PATIENTS: This study included 40 healthy children and 56 children with OME, with age ranging from 2 to 18 years. INTERVENTION: Mastoid volume and surface determination by 3-dimensional reconstruction of axial temporal bone computed tomographic images. MAIN OUTCOME MEASURE: Mastoid volume and surface area comparison of healthy children and children with OME. RESULTS: The mastoid cell system (MCS) grows continuously up to the age of 18 years, with different intensities. The mean ± SD MCS volume and surface of children with OME are significantly lower (2.82 ± 1.51 ml and 40.45 ± 18.14 cm, respectively) than those of healthy children (10.05 ± 5.3 ml and 84.47 ± 37.95 cm, respectively). The mastoid volume and surface area of the left and right ears correlate well in healthy children. In children with bilateral OME, the ipsilateral and contralateral ears can be largely different. The ratio of surface and volume is constant in age groups. CONCLUSION: In children with OME, the functional volume of MCS acting as a pressure buffer and the surface area serving for gas exchange are small. In case of OME, 1 ear could be more seriously affected by the disease. Otitis media with effusion presumably has a negative effect on the mastoid pneumatization process. The surface-to-volume ratio is constant through chronological age and is a good indicator of a normal middle ear function.
