Preterm infants with athetoid cerebral palsy: kernicterus?

Problems with using total serum bilirubin as a criterion for phototherapy in extremely low-birthweight infants

BACKGROUND

Despite the early use of phototherapy and exchange transfusion in premature infants based on total serum bilirubin (TSB), the reemergence of kernicterus has been reported. The aim of this study was to assess the validity of using TSB as the criterion for phototherapy in extremely low-birthweight infants (ELBWI).

METHODS

We reviewed the medical charts of 43 ELBWI admitted to hospital between January 2009 and December 2010, and analyzed the relationship between TSB and unbound bilirubin (UB).

RESULTS

No infant underwent exchange transfusion or developed acute bilirubin encephalopathy. There was a significant correlation between TSB and UB measured immediately before phototherapy during the first 7 days of life (r = 0.657, P < 0.001), but none thereafter (r = 0.120, P = 0.213). Thirty-seven percent of infants who underwent phototherapy during the first 7 days of life had suprathreshold USB but subthreshold TSB, whereas this rose to 97% thereafter.

CONCLUSIONS

No correlation was observed between TSB and UB in ELBWI after the first 7 days of life, and almost all phototherapy sessions were initiated based on the UB criterion, even though TSB was below the accepted threshold. UB may be high if jaundice is evaluated solely on the basis of TSB.

Severe neonatal hyperbilirubinemia and kernicterus: are these still problems in the third millennium?

Despite efforts to eliminate permanent and irreversible brain damage due to bilirubin encephalopathy and kernicterus, these conditions continue to accompany us into the third millennium. This phenomenon occurs not only in developing countries with emerging medical systems, but in Westernized countries as well. Comprehensive guidelines to detect newborns with jaundice and treat those in whom hyperbilirubinemia has already developed have been formulated in several countries, but have not been successful in completely eliminating the problem. In this appraisal of the situation we review selected aspects of bilirubin encephalopathy and/or kernicterus. We highlight recent reports of severe hyperbilirubinemia and kernicterus, discuss some of the factors responsible for the continuing appearance of these conditions, and briefly review what can be done to decrease bilirubin-related morbidity and mortality to the minimum.

Kernicterus in preterm infants

OBJECTIVE

We sought to clarify the features of kernicterus in preterm infants.

METHODS

The subjects of this study were 8 preterm infants with athetoid cerebral palsy whose gestational ages were < or =34 weeks. We retrospectively investigated clinical, laboratory, MRI, and brainstem auditory evoked potential (BAEP) findings.

RESULTS

Gestational age was < or =26 weeks in 6 of the 8 infants, and birth weight was <1000 g in 5 infants. Serious postnatal complications with systemic deterioration were observed in 3 infants. Total bilirubin levels were measured frequently in the majority of infants; peak values of >15 mg/dL were observed in 3 infants. No infant showed neurologic symptoms characteristic of classical acute bilirubin encephalopathy during the neonatal period. Dystonic posture and abnormal muscle tone were first recognized within 6 months' corrected age in all patients. During infancy, MRI was performed in 7 infants. Abnormal high-intensity areas were observed in the bilateral globi pallidi in all 7 infants. However, MRI during the neonatal period or after 1 year's corrected age showed no abnormal findings. BAEP measurements were abnormal in 7 of the 8 infants.

CONCLUSIONS

Preterm infants with athetotic cerebral palsy showed rather homogeneous features, similar to term infants with kernicterus, with marked hyperbilirubinemia. This combination of clinical, laboratory, neuroimaging, and neurophysiological data will contribute to the increased recognition of preterm infants with kernicterus.

Serial brain MRI and ultrasound findings: relation to gestational age, bilirubin level, neonatal neurologic status and neurodevelopmental outcome in infants at risk of kernicterus

AIMS

To describe cranial ultrasound (cUS) and magnetic resonance imaging (MRI) findings in neonates at risk of kernicterus, in relation to gestational age (GA), total serum bilirubin (TSB), age at imaging and neurodevelopmental outcome.

PATIENTS AND METHODS

Neonates with peak TSB > 400 micromol/L and/or signs of bilirubin encephalopathy. Review of neonatal data, cUS, preterm, term and later MRI scans and neurodevelopmental outcome.

RESULTS

11 infants were studied, two < 31, four 34-36 and five 37-40 weeks GA. TSB levels: 235-583 micromol/L (preterms); 423-720 micromol/L (terms). Neonatal neurological examination was abnormal in 8/10. cUS showed increased basal ganglia (BG) in 4/9 infants and white matter (WM) echogenicity, lenticulostriate vasculopathy (LSV) and caudothalamic hyperechogencity/cysts (GLCs) in 5/9 infants. MRI showed abnormal signal intensity (SI) in the globus pallidum (GP) in 1/2 preterm, 8/9 term and 9/11 later scans. Abnormal WM SI occurred in 2 preterm, 7 term and 10/11 later scans. Seven infants developed athetoid/dystonic cerebral palsy (CP) and 6 hearing loss (HL). Adverse outcome was associated with abnormal BG on cUS (3/4 CP, 4/4 HL), with high SI in GP (7/9 CP, 6/9 HL) on late T2-weighted MRI (all GA) and on T1/T2-weighted term MRI, mainly in term-born infants. WM abnormalities, GLCs and LSV did not correlate with outcome.

CONCLUSIONS

Severe CP occurred with relatively low TSB levels in preterms but only at high levels in full-terms; HL was difficult to predict. Early scans did not reliably predict motor deficits whilst all children with CP had abnormal central grey matter on later scans. Abnormal WM was seen early suggesting primary involvement rather than change secondary to grey matter damage. Why characteristic central grey matter MRI features of kernicterus are not seen early remains unexplained.

Single photon emission computed tomography and serial MRI in preterm infants with kernicterus

Single photon emission computed tomography was performed in three preterm infants with athetoid cerebral palsy due to kernicterus. No clinical signs and symptoms of kernicterus, or ultrasonographic abnormalities were seen during the neonatal period in any patients. Although MRI during infancy revealed high intensity areas in bilateral globi pallidi in all of them, MRI abnormalities were mild in two of them. On later MRI, subtle high intensity areas in the globi pallidi were recognized in only one of them. Single photon emission computed tomography demonstrated hypoperfusion in the basal ganglia regions in all patients. Regions of interest analyses showed decreased blood flow in the basal ganglia related to the cortical areas. Single photon emission computed tomography will be useful for the diagnosis of kernicterus, whereas MRI abnormalities become less clear beyond infancy.

Hyperbilirubinemia and kernicterus

This article describes new findings concerning the basic science of bilirubin neurotoxicity, new considerations of the definition of clinical kernicterus, and new and useful tools to diagnose kernicterus in older children, and discusses treatments for kernicterus beyond the newborn period and why proper diagnosis is important.

Clinical (video) findings and cerebrospinal fluid neurotransmitters in 2 children with severe chronic bilirubin encephalopathy, including a former preterm infant without marked hyperbilirubinemia VIDEO

Chronic bilirubin encephalopathy, characterized clinically by extrapyramidal movement abnormalities, vertical gaze abnormalities, and hearing loss, results from neuronal injury after marked hyperbilirubinemia in term and preterm infants. In premature infants, bilirubin staining of specific brain structures has been described at autopsy after only moderate hyperbilirubinemia, but classic chronic bilirubin encephalopathy without marked hyperbilirubinemia has been reported only rarely. We report a case of a 7-year-old, former 29-weeks' gestation, gravely ill premature infant with a peak bilirubin level of 13.3 mg/dL in the neonatal period. We compare this case with a 12-year-old, former term infant with a peak bilirubin level of 49.4 mg/dL on day 10 of life. Both children have dystonia, athetosis, upward gaze palsy, and sensorineural hearing loss, with MRIs showing characteristic abnormal signal in the globus pallidus. We add previously unreported cerebrospinal fluid neurotransmitter levels that show a mild decrease in the dopamine metabolite homovanillic acid in the former premature infant only.

Changes in globus pallidus with (pre)term kernicterus

OBJECTIVE

We report serial magnetic resonance (MR) and sonographic behavior of globus pallidus in 5 preterm and 3 term infants with kernicterus and describe the clinical context in very low birth weight preterm infants. On the basis of this information, we suggest means of diagnosis and prevention.

METHODS

Charts and MR and ultrasound images of 5 preterm infants and 3 term infants with suspected bilirubin-associated brain damage were reviewed. Included were preterm infants with severe hearing loss, quadriplegic hypertonia, and abnormal hypersignal of globus pallidus on T2-weighted MR imaging (MRI). In 1 infant who died on day 150, the diagnosis was confirmed during the neonatal period. The others were picked up as outpatients and scanned at 12 or 22 months' corrected age. Three instances of term kernicterus were included for comparison of serial MRI in the neonatal period and early infancy: they were caused by glucose-6-phosphate dehydrogenase deficiency, urosepsis, and dehydration plus fructose 1-6 biphosphatase deficiency.

RESULTS

Five preterm infants of 25 to 29 weeks' gestational age presented with total serum bilirubin (TSB) levels below exchange transfusion thresholds commonly advised. Mixed acidosis was present in 3 infants around the TSB peak. The bilirubin/albumin molar ratio was >0.5 in all, in the absence of displacing drugs. All failed to pass bedside hearing screen tests and had severe hearing loss on auditory brain response testing. Symmetrical homogeneous hyperechogenicity of globus pallidus was the alerting feature in 1 infant. Globus pallidus was hyperintense on T1-weighted MR images in this child. The other infants presented with severe developmental delay as a result of dyskinetic quadriplegia and hearing loss. Globus pallidus was normal on T1- but hyperintense on T2-weighted MR images at 12 or 22 months' corrected age. Subthalamic involvement was documented in coronal fluid attenuated inversion recovery MRI in 2 infants. The term infants with classical clinical presentation in the neonatal period had MR behavior similar to the preterms, but pallidal injury was not recognized with targeted sonographic examination. Their neonatal MR images demonstrated pallidal T1 hyperintensity and mild T2 hyperintensity.

CONCLUSION

Acidotic very low birth weight preterm infants with low serum albumin levels develop MR-confirmed pallidal injury and hearing loss facing "accepted" TSB levels. Serial MRI documents a shift from acute mainly T1 hypersignal to permanent T2 hypersignal in globus pallidus within the late neonatal period. Subthalamic and not thalamic involvement helps to differentiate from ischemic or metabolic disorder. As newborns, these infants are rigid and have severe apnea, before developing hypertonic quadriplegia in infancy.