Ear infections are the most common clinical complain in the pediatrician office. Most cases are seen in children ages 6 month to 24 month of age. The prevalence of the ear infections decreases as the child matures and are infrequent in school-age children, adolescents, and adults.
The biggest culprit of ear infections is usually a common cold. To understand better how a common cold leads to an ear infection, let us go back to basic physiology. Our nose and throat connected with middle ear through the Eustachian tube. The Eustachian tube is positioned at the angle to prevent reflex of the secretions from the nose and throat getting into the middle ear.
The other responsibility of the Eustachian tube is to keep the air pressure inside the middle are same as outside. Normally middle ear compartment is filled with air only, but when patient has a cold it begins to accumulate fluid. During viral process an increase amount of mucus produced inside in the nose. The viral particles cause inflammation inside the nose and later in the Eustachian tube.
The obstruction of the Eustachian tube in turn causes poor ventilation and leads to the accumulation of secretions in the middle ear. This fluid is sterile, but nasal secretions are not and when the Eustachian tube temporarily relaxed virus particles/bacterial particles get in. Microbial growth inside the secretions in the middle ear, cause the clinical symptoms of the ear infection.