Mechanisms in middle ear effusion production caused by irritation of the external auditory canal.

In an animal model, a stream of chilled air blown into the external auditory canal evoked an edematous pars flaccida and accumulation of a serous effusion in the attic. The degree of inflammatory changes depended on the temperature of the stimuli. The nervous system appears to mediate the observed changes, as the vagus nerve, representing the parasympathetic system, potentiates vascular leakage, and the sympathetic nerves inhibit leakage.