Medical and surgical management of otic barotrauma

Overview

Otic barotrauma (OBT) is traumatic injury of the middle ear and tympanic membrane resulting from a high-pressure differential existing between the middle ear and external environment. In common daily activities (e.g., driving to different elevations, air travel), individuals may experience slight changes in pressure of the middle ear, which results in mild, self-limiting otologic symptoms (e.g., slight aural discomfort). However, it is possible for these same activities to cause OBT, which is an increasingly encountered issue by otolaryngologists and otologists given the wide adoption of air travel; Over the past 50 years, the number of passengers has increased from 310 million to 3.7 billion annually, with approximately 1 million passengers flying at any given moment ^, and this number will likely continue to grow. Estimating the overall prevalence of OBT though varies considerably by types of activities that individuals participate in (e.g., scuba diving) and risk factors such as history of otitis media and head and neck cancers. To help address this clinical issue, this chapter will provide an overview of the pathophysiology, diagnosis, and medical and surgical management of OBT.

Eustachian tube and middle ear function

As described previously, the pathophysiology of OBT is related to an imbalance of pressures between the air-filled space of the middle ear and the external environment, which are separated by the tympanic membrane. Normally, the Eustachian tube, which connects the middle ear and the nasopharynx, will open briefly while yawning or swallowing to equalize middle ear pressure via the levator and tensor veli palatini muscles. Eustachian tube dysfunction (ETD), which reduces the ability for the Eustachian tube to open, may arise from several reasons such as increased mass near the Eustachian tube's nasopharyngeal opening (e.g., tumor, enlarged adenoids) or swelling due to infections (e.g., acute otitis media). In addition, the middle ear mucosa and underlying vessels promote equalization of middle ear pressure via gas exchange. These intact physiologic processes are required to accommodate for ambient pressure changes that follow Boyle's law, which states that as the volume of a gas increases, the pressure decreases proportionally, and vice versa. If the middle ear compartment's pressure is not able to equalize properly, OBT can occur through a variety of mechanisms that are described below.

Pathophysiologic mechanisms