Changes in the lateral ventricle with the head position: Ultrasonographic observation

Ultrasonographic examination was performed in 7 preterm infants to evaluate changes in the ventricular width with the head position. An ultrasonographic scan (US) was performed in a coronal section passing through both Sylvian fissures and the foramen magnum through the anterior fontanelle. The maximum width of the frontal horn was measured in all infants, first with the infants in the prone position, the head on one side, and then 5 min, 1h, and 3h later in all infants. Thereafter, the head was turned over onto other side (Figure). As a result, in all infants, the frontal horn width was found to be clearly changed with the head position 3 hours after the head had been turned over. The lower of the horns was narrowed, and the upper side dilated. In addition, serial US examinations with the head on one side demonstrated that the grade of ventricular asymmetry decreased as the postmenstrual age increased. These changes suggest that the form of the premature brain is affected by the head position, which may be closely related to gravity, and the decrease of these changes with maturation suggests that the structure of the brain becomes firm as the maturity of the brain increases. It is important to know the width of the lateral ventricles in order to identify enlargement, but we should also be careful to determine the laterality of the frontal horns in preterm infants because any deformity as to width caused by head position is physiological.