Uneven Distribution of Purkinje Cell Injury in the Cerebellar Vermis of Term Neonates with Hypoxic-Ischemic Encephalopathy

In term neonates with hypoxic-ischemic encephalopathy (HIE), cerebellar injury is becoming more and more acknowledged. Animal studies demonstrated that Purkinje cells (PCs) are especially vulnerable for hypoxic-ischemic injury. In neonates, however, the extent and pattern of PC injury has not been investigated. The aim of this study was to characterize the morphology and distribution of PCs in the cerebellar vermis of term born neonates with HIE. Twenty-two term born neonates with severe HIE, several of which received therapeutic hypothermia, who underwent post-mortem autopsy of the brain including cerebellar vermis within three to five days after birth were included. Haematoxylin & Eosin (H&E) stained sections of the vermis were used to determine total PC count and morphology (normal, abnormal or non-classified) at the bases and crowns of the folia and of the lobules in both the anterior and posterior lobes. Differences in PC count and PC morphology between the anterior and posterior lobe and between the bases and crowns were compared. The total number of PCs was significantly higher at the crowns compared to the bases (p < 0.001) irrespective of the precise location. Besides, PCs at the bases more often had an abnormal morphology. Also, a significant difference between the injury in the anterior and posterior lobe was observed, notably at specific microscopic locations with more abnormal PCs in the posterior lobe. The number of PCs scored as abnormal was increased in the bases compared to the crowns, which might resemble supratentorial ulegyria.