New scoring system for fetal neurobehavior assessed by three- and four-dimensional sonography

Four-dimensional Ultrasound Evaluation of Fetal Neurobehavioral Development

The introduction of four-dimensional (4D) ultrasound techniques would facilitate fetal behavioral assessment in three-dimensions in realtime during pregnancy. We describe the latest 4D sonographic studies on fetal behavior, especially fetal whole-body movements and facial expressions in all three trimesters of pregnancy and the continuation of behavior from the fetal to neonatal period. Moreover, we introduce a new scoring system (KANET, Kurjak Antenatal Neurological Test) for assessment of the fetal neurological status using 4D ultrasound. 4D ultrasound also facilitated the evaluation of inter-human contact in twin pregnancies in utero. This novel technique may assist in the evaluation of fetal behavior and inter-twin contact, and offer potential advantages relative to conventional two-dimensional ultrasound. 4D ultrasound should become an important modality in future research on fetal neurobehavioral development and the prenatal identification of severely brain-damaged infants. Further studies involving a larger sample size are needed to ascertain the role of 4D ultrasound in the evaluation of fetal neurobehavioral development.

Further Experience in the Clinical Assessment of Fetal Neurobehavior

Recent development of three-dimensional (3D) and four-dimensional ultrasound (4D) provided us with new possibilities to study fetal movements and behavior. Many studies have been conducted in order to provide information on specific movement pattern appearance in normal and high-risk fetus. This was the base for multicenter study on use of new scoring system for fetal neurobehavior which purpose is to recognize fetuses with increased risk for poor neurological outcome. The purpose of this paper is to give brief review on the use of 3D and 4D ultrasound in the assessment of fetal behavior.

Objectives

Define possibilities to study fetal movements and behavior by 3D and 4D ultrasound

Decribe new scoring system for neurobehavior in fetuses with increased risk for poor neurological outcome

Summarize behavioral perinatology research and potential clinical applications

Recent Advances in 3D Assessment of Various Fetal Anomalies

Recent advances of ultrasound technology including 3D/4D sonography have revealed embryonal/fetal morphology, intrauterine vascularity and fetal behavior from early gestation. Modern ‘sonoembryology’ allows the definition of in vivo anatomy including visualization of dynamic features, which cannot be characterized in fixed specimens after embryonic death in embryology. Furthermore, recent highresolutional ultrasound technologies have remarkably approached accurate prenatal diagnoses with vivid and distinct sonographic depiction. Nowadays, the antenatal diagnosis is no longer ‘maybe’ nor ambiguous, owing to progressive 3D/4D ultrasound which have contributed to the field of embryology, fetal physiology and pathology.

Advances in Visualization of the Early Human Development

The anatomy and physiology of placental and embryonic development is a field where medicine exerts its impact on early pregnancy and opens fascinating aspects of embryonic differentiation. The introduction of high frequency transvaginal transducers as well as three and four dimensional sonography has resulted in remarkable progress in ultrasonic visualization of early embryos and fetuses.

Ultrasound has been widely used in the field of early human development due to its safety, diagnostic accuracy and convenience. Normal fetal anatomy and development have been widely investigated using two-dimensional ultrasound and most of the knowledge regarding early human development were established through understanding of sectional images of fetal body and organs obtained by two-dimensional ultrasound. Usage of new techniques has produced more objective and accurate information of embryonal and early fetal development. For the first time parallel analyses of structural and functional parameters in the first 12 weeks of gestation become possible. This article deals with establishment of human life from ovum and sperm, though fertilization, detailed histological development and the establishment of the placenta, and early human development visualized by 2- and 3-dimensional ultrasonography.

An Attempt to Introduce Neurological Test for Fetus Based on 3D and 4D Sonography

Fetal neurology is a new challenging field. Brain damage often originates in fetal life. Early identification of this damage has implications for perinatal management; moreover documentation of such lesions is essential in case of litigation. In the last two decades, fetal imaging with 2-dimensional ultrasounds and conventional magnetic resonance imaging have made a major contribution in the identification of classic brain lesions and malformations. However, it is only recently with diffusion weight imaging that the whole spectrum of perinatal white matter injuries has been described in the neonate. The recent advances of 3DUS and 4DUS in exploring fetal motor behavior should support a better clinical description of the full spectrum of fetal damage. New neurological test (KANET) of the fetus recently suggested by us (Kurjak et al 2008) might be helpful in the assessment of fetal neurobehavior.

Continuity between Fetal and Neonatal Neurobehavior

As the development of the brain is unique and continuing process throughout the gestation and after birth, it is expected that there is also continuity of fetal and neonatal movements which are the best functional indicator of developmental processes of the brain. Understanding the relation between fetal and infant behavior and developmental processes of the brain in different periods of gestation may make achievable the distinction between normal and abnormal brain development. Epidemiological studies revealed that many neurologically impaired infants belong to low risk population, which means that they seemed to be developmentally normal as fetuses and as infants, while later childhood neurological disability was diagnosed. Which methods of neurological assessment are available for that purpose? Prenatally we have not many possibilities for neurological assessment, while postnatally the repertoire of diagnostic possibilities is increasing. Among the postnatally available methods for neurological assessment, the most important are: clinical neurological assessment, neuroimaging methods, assessment of general movements (GMs) and combinations. Postnatal neurological assessment is probably easier to perform than prenatal, by using a simple and suitable for everyday work screening clinical test with good reliability, specificity and sensitivity.

There is a possibility for the early and simple neurological assessment of the term and preterm newborns with the aim to detect associated risks and anticipate long-term outcome of the infant, and to establish a possible causative link between pregnancy course and neurodevelopmental outcome. The evaluation of infant's developmental optimality should be assessed in order to investigate whether the infant is neurologically normal or damaged. Neurological assessment at term by Amiel-Tison (ATNAT) is taking into account neurological maturation exploring so called lower subcortical system developing earlier from the reticular formation, vestibular nuclei and tectum, and upper cortical system developing from the corticospinal pathways.

Conventional acquisition neuroimaging techniques together with modern diffusion neuroimaging techniques can identify typical patterns of brain injury, even in the early course of the disease. However, even though highly suggestive, these patterns cannot be considered as pathognomonic. Nevertheless neuroimaging methods alone are not sufficient to predict the neurological outcome in neonates from highrisk population.

Prechtl stated that spontaneous motility, as the expression of spontaneous neural activity, is a marker of brain proper or disturbed function. The observation of unstimulated fetus or infant which is the result of spontaneous behavior without sensory stimulation is the best method to assess its central nervous system capacity. All endogenously generated movement patterns from un-stimulated central nervous system could be observed as early as from the 7-8 weeks of postmenstrual age, with developing a reach repertoire of movements within the next two or three weeks, continuing to be present for 5 to 6 months postnatally. This remarkable fact of the continuity of endogenously generated activity from prenatal to postnatal life is the great opportunity to find out those high-risk fetuses and infants in whom development of neurological impairment is emerging. The most important among those movements are GMs involving the whole body in a variable sequence of arm, leg, neck and trunk movements, with gradual beginning and the end. They wax and wane in intensity, force and speed being fluent and elegant with the impression of complexity and variability. Assessment of GMs in high-risk newborns has significantly higher predictive value for later neurological development than neurological examination. Kurjak and co-workers conducted a study by 4D ultrasound and confirmed earlier findings made by 2D ultrasonography, that there is behavioral pattern continuity from prenatal to postnatal life. Assessment of neonatal behavior is a better method for early detection of cerebral palsy than neurological examination alone.

Are we approaching the era when there will be applicable neurological test for fetus and assessment of neonate will be just the continuation? This is still not easy question to answer, because even postnatally there are several neurological methods of evaluation, while in utero we are dealing with more complicated situation and less mature brain. Could neonatal assessment of neurologically impaired fetuses bring some new insights into their prenatal neurological status is still unclear and to be investigated. New scoring system for prenatal neurological assessment of the fetus proposed by Kurjak et al will give some new possibilities to detect fetuses at high neurological risk, although it is obvious that dynamic and complicated process of functional CNS development is not easy to investigate.

The aim of this review is to present continuity of the functional central nervous system assessment from prenatal to postnatal life.