Disruption of cerebellar development: potential complication of extreme prematurity

Abstract

Background and purpose: Infants with very low birth weight are at high risk for cerebral lesions. Although supratentorial brain damage is a common radiologic finding, posterior fossa pathologies are rare. We studied the morphology of cerebellar involvement in a large series of 28 premature infants born before the 30th week of gestation to define typical patterns and identify possible risk factors for this pathology.

Methods: Cranial sonograms were obtained in the early neonatal period. MR imaging was performed between the 2nd month and the 6th year of life. Morphologic patterns of cerebellar involvement were evaluated.

Results: Three morphologic patterns of cerebellar involvement were recognized: (1) symmetric volume reduction of the cerebellar hemispheres, which were floating immediately beneath the tentorium, and a small vermis with preserved shape; (2) symmetrical reduction in hemispheric volume with an enlarged, balloon-shaped fourth ventricle and a small, deformed vermis; and (3) normal overall cerebellar shape with extensive reduction of its dimensions. A small brain stem with flattened anterior curvature of the pons and loss of supratentorial white matter was present in all patients.

Conclusion: Symmetric cerebellar volume reduction was found as a consequence of extreme prematurity. Selective vulnerability of the developing cerebellum in the window of 24-30 weeks of gestation, combined with several additive perinatal risk factors (eg, hemosiderin deposits) seems to lead to destruction of immature structures and developmental arrest. Therefore, the resulting condition is the consequence of disrupted cerebellar development.

Fig 1.

Coronal sonograms in a preterm neonate born at 27 + 5 gestational weeks. A, Scan on day 1 of life shows normal cerebellar hemispheres. B, Scan at 3 weeks shows reduced cerebellar volume.

Fig 2.

Type 2 disrupted cerebellar development in a preterm infant born at 26 + 3 gestational weeks. A–C, Sagittal follow-up sonograms obtained on days 57 (A), 86 (B), and 106 (C) of life show a vanishing cerebellar vermis with successive enlargement of the fourth ventricle. D, MR image obtained at 15 weeks.

Fig 3.

Type 1 disrupted cerebellar development in a preterm infant born at 29 gestational weeks. T1-weighted MR imaging was performed at 7 months. A, Sagittal image shows normal configuration of the fourth ventricle, a thin corpus callosum, and an inclined tentorium. The vermis is small but normally shaped. Dimensions of the brain stem are reduced. B and C, Parasagittal (B) and (C) frontal images demonstrate small cerebellar hemispheres immediately beneath the tentorium.

Fig 4.

Type 2 disrupted cerebellar development. A, Sagittal T2-weighted image shows a balloon-shaped fourth ventricle; a longitudinal, small vermis; and remarkable kinking of the brainstem. B and C, Parasagittal T2-weighted (B) and frontal T1-weighted (C) images show small cerebellar hemispheres laterally located in the posterior fossa.

Fig 5.

Type 3 disrupted cerebellar development in a preterm infant born at 26 + 4 gestational weeks. T2-weighted images show a skeletonized appearance of the cerebellum. A, Sagittal image. B, Parasagittal image.

Fig 6.

Unclassified pattern in a preterm infant (patient 26) born at 24 + 6 gestational weeks. Images show different blood breakdown products in the posterior fossa, shrunken cerebellar hemispheres, and cystic pontine (arrow) and vermian lesions. A, Sagittal T1-weighted image. B, Axial T2-weighted image. C, Axial T2*-weighted image. D, Coronal T1-weighted image.