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Chronic hypoventilation and development of brain stem gliosis.

Chronic hypoventilation is important in the pathogenesis of congenital hypoventilation syndromes and sudden infant death syndrome. Cases of hypoventilation can be divided clinically into those with a defective respiratory drive and those with mechanical impairment of either the lungs or the chest wall. To determine the relationship between chronic hypoventilation and brain stem gliosis, the development of astrocytes in the brain stem of normal and abnormal cases with either type of chronic hypoventilation was studied morphometrically. The glial fibrillary acidic protein immunoperoxidase method of staining astrocytes showed a transient increase of astrocytes in some parts of the brain stem during early infancy in thirty-five normal cases. The astrocytosis was even greater in both types of chronic hypoventilation including subjects with myopathy, Ondine's curse, and sudden infant death syndrome. Gliosis in these subjects may have resulted from "asphyxia" of the brain stem, as seen in cases with myopathies involving respiratory muscles. However, the involvement of brain stem respiratory centers may suggest a failure of neural respiratory control that further compromises respiratory function.