Bronchiolar wall changes in sudden infant death syndrome: morphometric study of a new observation

Sudden infant death syndrome (SIDS) infants have significantly thicker and more cellular bronchiolar walls than control infants of similar age. A morphometric study of 25 SIDS and 18 control infants was undertaken to measure the bronchiolar wall thickness using a Cue-2 image analysis system. A mathematical formula (relative index) was used to compare the thickness of bronchioles of varying diameter. Data analysis using a nested design two-way analysis of variance and covariance of the measured bronchioles showed a significant difference between the SIDS and control infants with a P value less than .001. Manual counting of the cells in the bronchiolar walls and data analysis using an unpaired two-tailed t test showed that the SIDS infants had a significantly greater number of cells than control infants (P less than .01). Our preliminary results indicate that the cells in the bronchiolar wall are either peripheral nerve-derived (Schwann cells) or Langerhans cells. We postulate that these cells are increased in number in response to chronic hypoxia in SIDS infants.