Quality of general movements: A valuable tool for the assessment of neurological integrity in young infants

Abstract

Development of brain is fascinating because of the multitude and complexity of the processes involved in it. It starts with primary neurulation in the third and fourth week of gestation. Primary neurulation refers to formation of the neural tube. This is followed by prosencephalic development in the second and third months of gestation. Development of prosencephalon is considered best in terms of three sequential events, i.e., prosencephalic formation, prosencephalic cleavage, and midline prosencephalic development.1 This development is followed by proliferation of the brain’s total complement of neurons. At a microscopic level, the first process to occur is neuronal proliferation and generation of radial glia. This takes place during the first half of gestation. In addition, cortical neurons will move from their sites of origin in the ventricular and subventricular zones to the loci within central nervous system where they will reside the rest of their life and start to differentiate. Neuronal differentiation and organization processes include establishment and differentiation of sub plate neurons, attainment of proper alignment, orientation and layering of cortical neurons, elaboration of dendritic and axonal ramifications, synapse formation, cell death, selective elimination of neuronal processes ,synapses, proliferation and differentiation of glia.1 Organizational events occur in a peak time period from approximately the fifth month of gestation to several years after birth. The glia cells take care of axonal myelination. Myelination occurs especially between the second trimester of gestation and end in the first postnatal year. However, it is first completed around 30 years.2 Brain development consists of the creation of components and the elimination of elements. Approximately half of the created neurons die (apoptosis), in particular during mid gestation. Similarly, axons and synapses are eliminated, the later especially between 18 months of age and puberty. The shaping of the nervous system by these regressive phenomena is guided by neural chemical processes and neural activity. The neural elements that fit the environment persist, thus allowing for adaptation of the brain to its own environment.2 This indicates that not only a substantial part of brain development occurs before term age, but alsothat throughout childhood the brain is in a continuous process of remodeling. The presence of continuous neurobiological changes during childhood has major clinical consequences such as age specific vulnerability of the nervous system with age specific signs and symptoms. Due to the age specific differences, it is difficult to predict nervous system development outcome during early infancy. Age specific neurological assessment is required.2,3