Histomorphologic studies of the glottic region to elucidate the pathogenesis and functional significance of fibrinoid vocal cord lesions in infants and young children.

Focal lesions of the vocal cord in form of fibrinoid necrosis and thickening of the basement membrane are morphological findings in infants and young children that receive only scant attention and are also controversially valued. We discuss two causes for the pathogenesis of these findings: (1) recurrent laryngospasms and (2) a laryngeal phonotrauma resulting from frequent spells of shrill, presumably high-frequency crying. The aim of our study therefore was to gain insight into the development and functional significance of these lesions by examining their histological patterns and to draw the pertinent conclusions. In 56 deaths (natural and unnatural causes, fetal life up to 4 years, no pathological or traumatic laryngeal lesions) histological investigations were carried out on putrefaction-free material. For the histomorphological studies, horizontal sections through the region of the vocal cord were obtained and stained according to conventional and immunohistochemical staining methods. In 42 cases the thickness of the basement membrane was determined morphometrically. In 12 of the 56 cases (21%) we observed staged variations of focal lesions, ranging from fibrinoid necrosis to degenerative lesions with pronounced macrophage involvement and deposits of PAS-positive plaques. Measurements at the basement membrane revealed a thickness of 7.9 microm. Separate measurements at the anterior and posterior portions of the vocal fold showed a ratio of 1.7:1. When the cases were subdivided into those with and without fibrinoid necrosis the ratios were 2.5:1 and 1.5:1. This different pattern makes it unlikely that laryngospasm is the sole or essential cause. Pathogenetically more important might be phonatory overstraining due to maximum vibrations in only the anterior portions of the vocal fold, which is not specific for later SIDS victims. This assumption is also supported by the often observed conspicuous phonetic behavior of some later SIDS victims and the absence of these stage-like vocal cord lesions in stillborns and adults. It is presumably an age-specific, temporary finding which is completely reversible.