Learning Objectives:
Background: Gas pressure balance is substantial for normal middle ear (ME) function, however, mechanisms involved in the ME pressure control are still not fully understood. In vivo examination of the ME gas pressure (MEP) regulation is difficult, therefore mathematical models are developed to describe and test hypotheses concerning ME gas exchange function.
Objective: To examine the role of ET function and mastoid pneumatization in MEP balance, and to interpret the possible clinical relevance of the mathematical model predictions.
Method of approach: A mathematical description and MatLab® modeling of the MEP development is presented in the function of different ME volumes (VME ), considering normal and malfunctioning ET. Published data as input values and our 3D CT reconstruction data of healthy and pathological MEs of children are applied.
Results: The model predicted larger MEP fluctuations in VME < 3 ml than in VME ≥ 3 ml considering normal ET function due to the different pressure change rate and pressure buffer effect of the MEs. Substantially larger MEP fluctuations can be expected in a VME < 3 ml with malfunctioning ET. Modeling mastoid obliteration predicts similar MEP fluctuations to a VME ≥ 3 ml resulting from elimination of gas exchange surface. The 5-year follow-up study in children with persistent OME indicates lower ME growth rate as compared to healthy children and decrease in ME volume over time in 40% of cases.
Conclusions: Results support that the ME volume, the ME surface area/volume ratio along with the duration of ET dysfunction influence the extent of ME pathological changes. These parameters can be important to consider for a pathophysiology-oriented approach to the ME surgery that may improve the long-term outcome.
