[Fetal neurological evaluation]

To review recent advances in the procedures and techniques that have made possible to evaluate the anatomy and function of the central nervous system (CNS) in the fetus.

The neurological evaluation of the fetus can be performed at different levels: clinical, anatomical and functional. At a clinical level the analysis of body, ocular or respiratory fetal movements, as well as fetal heart rate, defines 4 behavioural states: 1F and 2F correspond to the quiet and active sleep, respectively. States 3F and 4F occur during wakefulness in the newborn, but there is no scientific evidence that the fetus is awake. Behavioral states probably play an important role in the process of CNS maturation and development. Anatomic evaluation of the CNS to rule out brain malformations can be performed with ultrasound since week 7-8 of gestational age and with magnetic resonance imaging (MRI) since week 18-20. Both techniques are also useful in the diagnosis of acquired fetal neurological diseases. Both modalities are concordant in the majority of cases, but in others each of them provides additional, different information. Computed tomography should only be used in selected cases that involve bone structures. Functional evaluation of fetal CNS can be performed with proton MR spectroscopy, which determines the cerebral content of inositol, choline, creatine and N-acetylaspartate. Other techniques to functionally study the fetal brain are functional MRI (fMRI), near infrared spectroscopy, and magnetoencephalography.

Fetal neurology is a discipline that will continue to develop fast in the immediate future. Technological advances will facilitate the possibility of a more rapid and reliable diagnosis of anatomic or functional abnormalities of the fetal CNS.