Acute and Chronic Kernicterus: MR Imaging Evolution of Globus Pallidus Signal Change during Childhood

Abstract

Background and purpose: Despite its rarity in Western countries, kernicterus resulting from severe neonatal hyperbilirubinemia and its associated neurologic consequences still persists. Subtle MR imaging patterns may be overlooked, leading to diagnostic and prognostic uncertainties. The study systematically analyzes MR imaging pattern over time.

Materials and methods: A retrospective MR imaging study was conducted in Departments of Pediatric Neurology at the University Children's Hospitals in Leipzig, Germany, or Tübingen, Germany, between 2012 and 2022 in patients who presented beyond the neonatal period suspected of having chronic kernicterus.

Results: Eight patients with a total of 15 MR images were identified. The clinical diagnosis of kernicterus was confirmed in all cases on the basis of typical MR imaging findings: Bilateral, diffuse hyperintensity of the globus pallidus was observed in the neonatal period on T1WI (1 MR imaging, at 2 weeks), in infancy on T2WI (4 MR images, at 9-26 months). In children 2 years of age and older, bilateral hyperintensity on T2WI was limited to the borders of the globus pallidus (8 MR images, at 20 months -13 years). Notably, 2 children exhibited normal initial MR imaging findings at 2 months of age. Hence, MR imaging depiction of kernicterus pathology evolves with time, first evident on T1WI, subsequently on T2WI, with a "blind window" during early infancy. The T2WI signal change initially involves the entire globus pallidus and later is limited to the borders. Kernicterus had not been diagnosed in any except 2 patients by previous investigators.

Conclusions: All patients presented with a characteristic clinical history and signs and an evolving MR imaging pattern. Nonetheless, the diagnosis of kernicterus was frequently missed. Abnormalities on later MR images appear to be underrecognized.

FIG 1.

Examples illustrating the various patterns observed with respect to bilateral signal change in the GP in kernicterus. The upper row displays pattern I, characterized by a diffuse signal increase on T1WI (arrows), while T2WI shows no abnormalities (sample case one, 2 weeks). The middle row represents pattern IIa, where T1WI appears normal, but there is a diffuse signal increase on T2WI (arrows) and FLAIR (arrows), (sample case three, 11 months of age). The lower row shows pattern IIb, featuring normal T1WI findings and a signal increase on T2WI (arrows) and FLAIR (arrows), limited to the borders (sample case two, 2 years 10 months of age).

FIG 2.

The temporal progression of the GP signal changes in 8 patients. A bilateral signal change in the GP is the characteristic sign of kernicterus. In the neonatal period, hyperintensity is observed on T1WI (arrows). However, at approximately 2 months of age, a “blind diagnostic window” is encountered, where neither T1WI nor T2WI/FLAIR show abnormal findings. Subsequently, during infancy, there is signal hyperintensity of the entire GP on T2WI/FLAIR (arrows). After around 2 years, the signal hyperintensity on T2/FLAIR is limited to the borders of the GP (arrows). IR indicates inversion recovery; corr., corrected age related to gestational age.

FIG 3.

Case 2 demonstrates the typical temporal sequence in a single patient (patient 2). The initial MR imaging was performed at approximately 2 months of age, revealing no abnormalities (illustrated on T1WI, left). At 9 months of age (middle), the entire GP exhibited a diffuse signal increase on T2WI (pattern IIa, arrows). At 34 months of age (right), a signal increase on T2WI was observed solely at the borders of the GP (pattern IIb, arrows).

FIG 4.

Hippocampal volume loss is illustrated in patient 8 at the age of 11.5 years. The coronal T1WI (left) displays the head of the hippocampus only as filiform structures (arrows), resulting in enlarged temporal horns, as also depicted in the axial T2WI (arrows, middle). Both the external and internal spaces are globally enlarged (axial T2WI, right). The right images highlights the bilateral signal changes in the GP (arrows), indicative of pattern IIb.