Cranial Ultrasound in Preterm Neonates : Screening of at Risk Infants for Long Term Neurodevelopmental Impairments

Background: Preterm birth is associated with variable degree of brain injury and adverse neurodevelopmental outcomes. Therefore, screening of these infants is required to assess further neurodevelopmental abnormalities. Cranial ultrasound finding has been a predictor of outcome in this population. Objective: The present study was carried out to find cranial ultrasound abnormalities in preterm neonates to aid in screening at risk infants for long term neurodevelopmenal impairment. Materials and Methods: This observational study was conducted in Dhaka Shishu (Children) Hospital from October 2011 to March 2012. Total 103 preterm neonates who met the inclusion criteria were enrolled in the study. The neonates underwent cranial ultrasound (cUS) scan just after admission and before discharge for screening at risk infants. Results: Total 103 neonates were enrolled with mean age of 7.67 days in neonates with normal cUS findings and 7.23 days in neonates with abnormal cUS findings. Mean gestational age was 31.94 weeks in neonates with normal cUS and 31.85 weeks in neonates with abnormal cUS findings with mean weight 1.83 and 1.81 kg respectively. Among the neonates, 64 (62.1%) were males and 39 (37.9%) were females. Before discharge, out of 103 preterm neonates, 56 (54.3%) had normal cUS and 47 (45.7%) had abnormal cUS findings of which 22 (21.4%) had cerebral edema, 17 (16.5%) IVH and 8 (7.8%) had ventricular dilatation. Conclusion: Routine cranial ultrasound scanning of preterm neonates may aid in identifying at risk infants for long term neurodevelopmental impairments.

Despite being mild in degree individually, in combination, such deficits often lead to school difficulties, with a need for remedial assistance or speech education. 6 estimated 20% infants are born prematurely in Bangladesh, and 30% have low birth weight (LBW) (<2500 g). 7With a total population of >146 million people including >20 million children <5 years of age 8 , large unrecognized populations may be at risk for neurodevelopmental morbidity, particularly considering that 85% of deliveries occur at home, often with no skilled care; only 7% births are ever registered and primary health care services do not include screening for the developmentally delayed child. 9thodical issues remain regarding how to identify younger children with impairments and disabilities.Yet, there is awareness among parents of the presence of developmental problems early in the child's life.Recognizing impairments earlier might have improved their chances of catch-up development. 10Recent reviews of early intervention studies in high risk populations have demonstrated the potential to improve long term development in children across low and high income countries. 11o main imaging techniques have been used for prediction of neurodevelopmental outcome in the neonatal period: cranial ultrasound (cUS) and MRI. 6he major benefits of testing are to direct families of preterm infants toward the most appropriate follow-up facilities to promote early diagnosis and intervention for chronic neurodevelopmental sequel of hemorrhagic or ischemic brain injury and to faster ongoing research activities that are aimed at ensuring the best possible outcomes for all infants.The major advantages of cUS are: it is relatively inexpensive and safe compared to other neuroimaging techniques, can be performed bedside with little manipulation of the infant.It can be repeated as often as necessary and thereby enables visualizations of ongoing brain maturation and the evaluation of brain lesion in addition to assessing the timing of brain damage. 12When cUS is used repeatedly, its sensitivity and specificity can be very high. 13nce the late 1970s, cUS examinations have been performed on preterm infants to provide information about perinatal brain injury for the prediction of longterm outcomes. 14Classic studies by Pape et al 15

and
Slovis & Kuhn 16 reported on the use of real-time linear array and sector scanning to detect intraventricular and parenchymal hemorrhage, ventricular enlargement and other abnormalities.Major abnormalities on cUS predict the development of cerebral palsy (CP), neuromotor delay and cognitive outcome. 17 cranial ultrasound, images are interpreted normal if there is no hemorrhage, no evidence of dilatation.Some studies showed that a normal ultrasound scan provides considerable confidence that an infant will have normal neurodevelopment. 18The best predictor for outcome was a simple cranial ultrasound classification according to the presence or absence of ventriculomegaly and intraparenchymal damage of any cause.Infants with normal neonatal cerebral scan or abnormal scan without ventriculomegaly almost had a normal neurological outcome.In infants with cerebral lesions with ventriculomegaly, the incidence of normal neurological outcome decreased to less than 50%.Intraparenchymal damage was associated with cerebral palsy as well as other (mental and sensory) handicaps in over 85% of the cases. 19e major clinical outcomes that are important to preterm infants and their families are survival and normal long term neurodevelopment.Regular follow-up assessments of children at risk of neurodevelopmental impairment may allow the early detection of problems and the provision of medical, social and educational support if required.It is recognized that support and active management of the at risk group of preterm infants may resolve or ameliorate potential later problems.The purpose of this study was to find cranial ultrasound findings in preterm neonates which may be utilized in counseling families about prognosis and the need for early intervention.This study may be of paramount importance in early identification and intervention to mitigate neurodevelopmental impairments in large populations that live in developing countries where professional expertise is sparse.

Materials and Methods
This observational study was carried out in Dhaka Shishu (Children) Hospital (DSH) from October 2011 to March 2012.Preterm neonates (<37 weeks of gestational age) who were admitted in the neonatal unit of DSH were enrolled for the study.Neonates having perinatal asphyxia, congenital malformations especially of brain and spinal cord and neonatal conditions like respiratory distress syndrome (RDS), birth trauma were excluded from the study.
A structured questionnaire was used for recording all the information after taking written consent.All the preterm neonates underwent cranial ultrasound (cUS) imaging after admission and again before discharge for evaluation.Results are presented in tables.Statistical analysis was done by using software SPSS version 6.0 for Windows.

Results
In this study, 103 preterm neonates who were admitted in the neonatology unit of Dhaka Shishu (Children) Hospital during the study period from October 2011 to March 2012 were selected.All the preterm neonates underwent cranial ultrasound immediately after admission and before discharge.The findings from the data analysis are documented below.Among the 103 preterm infants 62.1% (64 infants) were male and 37.9% (39 infants) were female.Table II shows cranial ultrasound (cUS) findings of the neonates immediately after admission.Table III shows cranial ultrasound (cUS) findings of the neonates (n=103) before discharge.

Discussion
Preterm birth is associated with variable degree of brain injury and adverse outcomes.Prediction of outcome after preterm birth is critical but remains difficult, particularly in the early postnatal period.The ability to predict outcome improves parental counseling and selection of infants for early therapeutic strategies aiming at preventing or ameliorating cerebral injury. 21ood prediction is usually achieved for major functional disabilities in early childhood.Cranial ultrasound (cUS) is a simple bedside tool which has very high sensitivity and specificity in predicting neurodevelopmental outcome when it is used repeatedly.Grazing & Stainley 24 showed that ultrasound abnormalities were more strongly associated with delayed psychomotor development and the findings of ventriculomegaly and the diagnosis of periventricular hemorrhage were associated with more modest increased risk at 2 years of age.
Some other studies [25][26][27] also found that ultrasound abnormalities are associated with a two to fourfold increase in the risk of low Bayley Scales of Infant Development (BSID)-II score and mental retardation.Another study 28 revealed that major abnormalities on cUS predict the development of cerebral palsy (CP) and neuromotor delay at variable ages of follow-up.
Data from this study states that a substantial number of preterm neonates have abnormal cranial ultrasound findings and when repeated may identify the at risk infants.Long term follow-up and subsequent therapeutic intervention may ameliorate the severity of neurodevelopmental impairment.However, future studies in early months of life are recommended for routine screening of preterm neonates with cUS to detect risk infant.Finally, this study reveals that routine cranial ultrasound scan of preterm neonates may aid in identification of at risk infants for long term neurodevelopmental impairment.

28 1 .
Assistant Professor, Department of Infectious Diseases and Community Pediatrics, Dhaka Shishu Hospital, Dhaka 2. Registrar, Department of Infectious Diseases and Community Pediatrics, Dhaka Shishu Hospital, Dhaka 3. Professor, Department of Critical Care Unit, Dhaka Shishu Hospital, Dhaka

Table I :
Distribution of subjects according to age,

Table II
13