ASTROCYTES IN THE HYPOGLOSSAL NUCLEI OF SUDDEN-INFANT-DEATH-SYNDROME (SIDS) INFANTS - A QUANTITATIVE STUDY

It has been suggested that brain stem hypoxia or ischaemia underlies t he sudden infant death syndrome (SIDS)I but previous reports of astroc ytosis in the brain stems of SIDS infants have been contradictory. A v olumetric quantitative technique was, therefore, developed to compare astrocyte numbers and sizes in the hypoglossal nuclei of SIDS and cont rol infants. In 12 SIDS and eight control infants, serial sagittal sec tions were talten through the hypoglossal nucleus and every tenth sect ion was stained for glial fibrillary acidic protein. Astrocytes were c ounted in the central 4% of a grid stepped throughout the hypoglossal nucleus, and the heights of 100 astrocyte nuclei were measured with a microcator, Astrocyte number, corrected for section thickness and nucl ear height, was divided by the volume of the hypoglossal nucleus to ca lculate astrocyte density, Numbers of astrocytes did not differ signif icantly between SIDS (mean number 44 7291 so 12 096) and control (mean number 46 562, so 11000) infants, Astrocyte nuclear height did not di ffer significantly between groups (SIDS: mean height 3.98 mu m, so 0.2 2: control: mean height 3.84 mu m, so 0.31). Astrocyte density was sim ilar in SIDS (mean density 24 378 astrocytes/mm(3), so 6155) and contr ol (mean density 23 978 astrocytes/mm(3), so 4031) infants, No quantit ative evidence of astrocytosis was found in the hypoglossal nuclei of SIDS infants, This implies that SIDS infants die without previous epis odes of hypoxia/ischaemia severe enough to damage the brain stem.