Clinical and prognostic significance of neurosonography of lateral ventricles for infants treated with therapeutic hypothermia during the early neonatal period

Abstract

Background. Currently, therapeutic hypothermia (TH) is the only approved method for treating hypoxic-ischemic encephalopathy (HIE) that helps improve outcomes. However, it also has significant drawbacks, including the necessity for expensive equipment and treatment technologies, poorly understood pathophysiological mechanisms, and, most importantly, not always well-understood long-term results. Numerous scientific studies report the potential benefits of TH, but the actual risk/benefit ratio is still unknown. The results of long-term follow-up of children who underwent TH and did not have serious neuromotor or intellectual disorders are variable. It is believed that the correlation between neonatal neuroimaging and the degree of nervous system impairment remains poorly defined. Chronic brain injuries diagnosed after the neonatal period, such as parenchymal volume loss, appear to be more prognostically significant, which may be reflected by moderate enlargement of the ventricular system of the brain. The method for determining the size of the ventricular system using ultrasound can be accessible for infants of the first year of life who had HIE but do not have direct indications for magne­tic resonance imaging. Therefore, this study aimed to explore the characteristics of the cerebral ventricular system in infants of the first year of life who suffered severe asphyxia at birth, depen­ding on the method of post-resuscitation care (with or without TH). Materials and ­methods. The study examined the results of neurosonographic examinations of 309 infants during their first year of life. Inclusion criteria were gestational age at birth ≥ 36 weeks and birth weight ≥ 2000 g, manifestations of HIE in the early neonatal period without adverse short-term outcomes (at the time of discharge from the neonatal hospital, the children showed no signs of destructive hypoxic-ischemic lesions of the central nervous system (CNS), seizures, or pathological muscle tone, and had full oral feeding). Exclusion criteria were diagnosed congenital CNS abnormalities, neuroinfections, psychomotor development delay of more than 3 months during the first years of life, progressive obstructive ventriculomegaly or ventriculomegaly associated with non-atrophic subarachnomegaly. The children were divided into three groups: hypothermia group — 19 infants who underwent TH after birth; normothermia group — 14 children who conditio­nally had indications for TH but did not undergo it; comparison group — 276 children in their first year of life who did not require TH (Apgar score > 5 at 10 minutes of life, manifestations of mild or moderate HIE (according to the Sarnat scale) during the first days of life). Neurosonographic examinations were conducted at the age of 2–7 months (mean of 2.12 ± 0.07 months). The sizes of the lateral ventricles were assessed in comparison with the results from the control group of infants of the same age (34 healthy children with no recorded factors of complicated perinatal period, no signs of neurological dysfunction during the neonatal period, and the seven-month observation). Enlargement of the lateral ventricles was recorded when the size of the anterior horn or body of the ventricle in the parasagittal projection exceeded the 95th percentile of the corresponding measurements from the control group. Results. Enlargement of the lateral ventricles during the neurosonographic examination was detected in 36.8 % of children in the hypothermia group, 14.3 % in the normothermia group, and 8.0 % of children in the comparison group. Significant differences were registered only when comparing the results of the hypothermia group with the comparison group (p < 0.05, Fisher’s exact test). Significant correlations (p < 0.05) were found between the size of the lateral ventricles and clinical signs such as sleep disturbances, decreased muscle tone in the arms, increased tendon reflexes, delayed motor development, increased muscle tone in a pyramidal pattern, and diffuse muscle hypotonia. Conclusions. Thus, infants who had severe asphyxia at birth and underwent TH significantly more often had enlargement of the cerebral ventri­cular system (versus the comparison group). Therefore, although therapeutic hypothermia improves outcomes for the development of the nervous system in children who have moderate and severe hypoxic-ischemic encephalopathy, brain morphology (particularly the state of the ventricular system) may still be altered in infants during the first year of life. And the presence of significant correlations between the size of the lateral ventricles and clinical signs of neurological dysfunction argues for further clinical monitoring of children after therapeutic hypothermia throughout the first years of life and in the absence of short-term adverse outcomes of HIE or significant delays in psychomotor development during the first year of life.