Anemia of Prematurity - Portal Neonatal

CLINICAL Section 3 of 11
History: A history of risk for hemolytic disease can be an important clue to a neonate's increased
risk of pathologic hyperbilirubinemia, particularly Rh antigen incompatibility between mother and
baby. ABO incompatibility and a family history of red blood cell (RBC) abnormalities (ie, G6PD
deficiency, hereditary spherocytosis) are also concerning.
Conversely, if the baby is breastfeeding well and appears healthy and vigorous, this can be
reassuring. The mother may have breastfed previous babies who also developed significant
jaundice. If so, she may be one of the approximately 20-40% of women who have above-average
levels of beta-glucuronidase in their breast milk, which potentiates and prolongs hyperbilirubinemia
in their breastfed babies.
Physical:
• Acute bilirubin encephalopathy: The clinical features of this diagnosis have been well
described and can be divided into 3 stages. Of babies with kernicterus, approximately 55-
65% manifest these features, 20-30% may display some neurologic abnormalities, and
approximately 15% have no neurologic signs.
o Phase 1 (first few days of life): Decreased alertness, hypotonia, and poor feeding are
the typical signs. Obviously, these are quite nonspecific and could easily be indicative
of a multitude of neonatal abnormalities. A high index of suspicion of possible bilirubin
encephalopathy at this stage that leads to prompt intervention can halt the progression
of the illness, significantly minimizing long-term sequelae. Of note, seizure is not
typically associated with acute bilirubin encephalopathy.
o Phase 2 (variable onset and duration): Hypertonia of the extensor muscles is a typical
sign. Patients present clinically with retrocollis (backward arching of the neck),
opisthotonus (backward arching of the back), or both. Infants who progress to this
phase develop long-term neurologic deficits.
o Phase 3 (infants aged >1 wk): Hypotonia is a typical sign.
• Chronic bilirubin encephalopathy: The clinical features of chronic bilirubin encephalopathy
evolve slowly over the first several years of life in the affected infant. The clinical features
can be divided into phases; the first phase occurs in the first year of life and consists of
hypotonia, hyperreflexia, and delayed acquisition of motor milestones. The tonic neck reflex
can also be observed. In children older than 1 year, the more familiar clinical features
develop, which include abnormalities in the extrapyramidal, visual, and auditory systems.
Minor intellectual deficits can also occur.
o Extrapyramidal abnormalities: Athetosis is the most common movement disorder
associated with chronic bilirubin encephalopathy, although chorea can also occur. The
upper extremities are usually more affected than the lower ones; bulbar functions can
also be impacted. The abnormalities result from damage to the basal ganglia, the
characteristic feature of chronic bilirubin encephalopathy.
o Visual abnormalities: Ocular movements are affected, most commonly resulting in
upward gaze, although horizontal gaze abnormalities and gaze palsies can also be
observed. These deficits result from damage to the corresponding cranial nerve nuclei
in the brain stem.
o Auditory abnormalities: Hearing abnormalities are the most consistent feature of
chronic bilirubin encephalopathy and can develop in patients who show none of the
other characteristic features. The most common abnormality is high-frequency hearing
loss, which can range from mild to severe. These deficits can result from damage both
to the cochlear nuclei in the brain stem and to the auditory nerve, which appear to be
exquisitely sensitive to the toxic effects of bilirubin, even at relatively low levels.
Clinically, this deficit can manifest as delayed language acquisition. Hence, auditory
function must be assessed early in any baby at risk for chronic bilirubin encephalopathy