Effect of amniotic fluid cellular content on attic aeration pathways: histologic observations of infants aged 2 to 4 months.

HYPOTHESIS: The tissue-fixed amniotic fluid cellular content (AFCC) in the middle ear and mastoid antrum causes foreign body type reactions that may later severely restrict the aeration pathways to the main attic and to Prussak's space.

BACKGROUND: It was shown by Aschoff 100 years ago that AFCC remained in the neonate ears and caused sterile otitis media. Recent data show that children born through thick meconium are at risk for large quantities of AFCC entering the middle ear cleft, the ensuing inflammatory reaction being related to the amount of AFCC. Spread of AFCC in the neonate occurred along the aeration pathways with corresponding tissue fixation but further systematic data in young infants are lacking.

METHODS: Five temporal bones of three infants aged 2 to 4 months were embedded in celloidin, serially sectioned at 20 microns, and every 10th section stained with Hematoxylin and eosin and mounted on slides. All slides were studied and relevant details of aeration pathways and all compartments photographed.

RESULTS: The histologic changes were characterized by the development of masses of pseudocystic granulation tissue, with some remnants of the original AFCC, mainly in the form of fragments of hair. The tympanic isthmus was involved to varying extent, maximally to half of its size. Posterior tympanum and the stapes region had masses of fresh granulation tissue, the maturing of which might cause marked indrawing of the posterior pars tensa and further reduction of the tympanic isthmus. Aeration of Prussak's space was severely involved in two bones, favored by the narrow pathway through the posterior pouch. Features of recent acute or secretory otitis media were associated with the early changes caused by AFCC.

CONCLUSIONS: The granulation tissue in this age group is immature and its final fate is decided by the nature of the future ear disease. If the AFCC contamination is slight, the granulation tissue after maturing may appear only in the form of thin cords and sheets, a frequent chance finding in ear surgery. Large amount of AFCC may lead to chronic inflammation, which may predispose the child to recurring middle ear infections during infancy. Further histologic and clinical studies in older infants and young children are needed to find out the final outcome after a massive AFCC contamination of the new-born middle ear.