Caliber of the lumen of the eustachian tube pre-isthmus in infants and children.

We measured the eustachian tubes in temporal bones taken from infants and children. These specimens included eustachian tubes from 35 normal temporal bones and 13 temporal bones containing acute and secretory otitis media. All temporal bones were serially sectioned for histological studies. The lumen of the third portion of each eustachian tube (i.e., the pre-isthmus or the physiological isthmus) was measured with the aid of a grid mounted on a microscope. These measurements showed: (1) the eustachian tube lumen grows and enlarges to a small degree with age; (2) each age group has a considerable variation in the size of the lumen which is compatible with natural biological distribution; (3) no statistical differences were found in the size of the pre-isthmus lumina of those eustachian tubes from temporal bones showing acute or secretory otitis media when compared with the lumina of eustachian tubes in non-pathological ears.