Neuroimaging and neuropathological characteristics of cerebellar injury in extremely low birth weight infants

Objective: To determine the morphological characteristics and pathogenic factors of cerebellar injury in extremely low birth weight infants (ELBWI).

Subjects and methods: Neuroimaging examination was performed on 17 eligible surviving ELBWI. Their MR images were assessed and classified its pattern of cerebellar injuries. Brain pathology was examined on 15 patients, who isolated this neuroimaging subjects. The trend of brain pathologies was revealed.

Results: Four types of morphological pattern were recognized: (i) the absence of major portions in the cerebellum (6/17 cases); (ii) focal cerebellar tissue loss (2/17); (iii) unilateral cerebellar atrophy/hypoplasia (3/17); (iv) small cerebellum with entrapped fourth ventricle (6/17). In cerebellar pathology, the most common findings were focal or widespread cerebellar subarachnoid hemorrhage (12/15) and olivocerebellar degeneration (12/15). In addition, one-third of the cases indicated remote cerebellar parenchymal hemorrhage.

Conclusion: In MRI-defined lesions, the absence of major portions or focal tissue loss was associated with cerebellar parenchymal hemorrhage and/or hemorrhagic infarction, that is destructive lesion. On the other hand, small cerebellum or unilateral atrophy/hypoplasia, that is impaired development, may be related to the cerebellar neuron loss due to hemosiderin deposits in the surface of the cerebellum. The cerebellar injury in ELBWI is probably caused by not only environmental factors such as hemorrhage, hypoxia-ischemia, or other deleterious effect, but also immaturity of the rapidly growing cerebellum in particular gestational age.