KERNICTERUS IMAGING STUDIES
Category: Child Health
Abstract : kernicterus imaging studies : • In the acute phase of bilirubin
encephalopathy, neuroimaging has no major diagnostic benefit. However, it can
help rule out other diagnoses, particularly in the absence of profound
hyperbilirubinemia. • Head ultrasonography (HUS): This modality is
particularly well suited to the neonate because it is painless, portable, and
noninva
kernicterus imaging studies :
• In the acute phase of bilirubin
encephalopathy, neuroimaging has no major diagnostic benefit. However, it can
help rule out other diagnoses, particularly in the absence of profound
hyperbilirubinemia.
• Head ultrasonography (HUS):
This modality is
particularly well suited to the neonate because it is painless, portable, and
noninvasive; also, the neonatal brain is easily imaged through the fontanelles.
Sonographic imaging is not helpful in diagnosing acute bacterial encephalopathy;
however, other entities, such as intraventricular hemorrhage or parenchymal
abnormalities, can be ruled out.
• CT scanning:
Computed tomography
scanning has little place in the evaluation of the neonatal brain. It is
difficult to perform because the baby must be transported to the radiology
department and must be heavily sedated for the procedure. The subtle
abnormalities often present in the neonatal period are not well visualized by CT
scanning, and false-negative findings are not uncommon.
•
MRI:
Previously, the neuronal damage characteristic of kernicterus was
thought to only be identifiable on histologic examination postmortem. However,
experience has revealed that MRI can be used to depict characteristic bilateral
symmetric high-intensity signals in the globus pallidus on both T1- and
T2-weighted images in patients surviving with chronic bilirubin encephalopathy.
The usefulness and cost-effectiveness of this modality in the diagnosis of more
subtle forms of bilirubin toxicity remains to be fully elucidated.
Other
Tests:
• Brainstem auditory evoked response (BAER): Hearing impediment is the
most common sequela of bilirubin toxicity. Impairment may be subtle and may not
be clinically apparent until the baby manifests delayed language acquisition. To
maximize the baby's long-term neurologic functioning, early identification of
any degree of hearing loss is important so that early developmental assessment
and intervention can be initiated in a timely fashion. Serial assessments of
hearing function may be necessary.
Histologic Findings
(kernicterus):
On macroscopic examinations, characteristic yellow staining
can be readily observed in fresh or frozen sections of the brain obtained within
7-10 days after the initial bilirubin insult. The regions most commonly involved
include the basal ganglia, particularly the globus pallidus and subthalamic
nucleus; the hippocampus; the substantia nigra; cranial nerve nuclei, including
the oculomotor, cochlear, and facial nerve nuclei; other brainstem nuclei,
including the reticular formation and the inferior olivary nuclei; cerebellar
nuclei, particularly the dentate; and the anterior horn cells of the spinal
cord.
Neuronal necrosis occurs later and results in the clinical findings
consistent with chronic bilirubin encephalopathy. Histologically, this appears
as cytoplasmic vacuolation, loss of Nissl substance, increased nuclear density
with haziness to the nuclear membrane, and pyknotic nuclei.
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