[Sonographic screening of basilar arteries reduces the risk of sudden infant death].

Sudden infant death syndrome (SIDS) is the most frequent cause of death in the first year of life. The causes of SIDS remain unclear although multiple theories have been published in recent decades. However, some important risk factors associated with SIDS, such as prone sleeping have been validated. Over 85% of all SIDS victims were found in a prone position but it is unclear why the prone sleeping position is more dangerous than the supine sleeping position. A possible cause of SIDS is hypoperfusion of the brain stem during head rotation. Some infants show compression of the vertebral arteries at the craniocervical junction during head rotation, especially in the prone position and this may lead to a subsequent decrease of brain stem perfusion. If compression lasts for a longer time hypoperfusion of the brainstem and central apnea and bradycardia result, which can lead to SIDS. The decrease in brainstem perfusion occurs more often and is more pronounced in the prone position as the head is more rotated in the prone than in the supine position. Doppler sonographic flow measurements of the flow in the basilar artery through the open fontanel, allow the detection of patients at risk of position-dependent hypoperfusion of the brain. Flow measurements are obtained in a neutral position (head in midline) and during head rotation. In the vast majority of infants (98.7%) the flow in the basilar artery is independent of head rotation and body position. In rare cases (1.3%) flow velocities drop to below 50% of the initial value during head rotation. A pathological biphasic or even retrograde flow can be found during head rotation in only 0.3% of infants and these infants may have an increased risk for SIDS. To prevent SIDS head rotation which leads to an abnormal or pathological flow decrease during head rotation should be avoided. Additionally these infants should be monitored until blood flow in the basilar artery has returned to normal, which usually occurs during the first year of life. This approach reduced the incidence of SIDS in our patients from 1% to 0.04‰.