Sonographic and Doppler Sonographic Diagnosis of Posthemorrhagic Hydrocephalus

Severe intracranial hemorrhages occur especially in very immature premature infants born with a gestational age under 28 weeks of gestation and a birth weight below 1000 g. Severe hemorrhages are often complicated by a post-hemorrhagic hydrocephalus (PHH). PHH can be caused by a blockage of the cerebro-spinal fluid pathways or by obliterative arachnoiditis of the posterior cranial fossa. Cerebral sonography can differentiate between both entities. In cases of obstruction of the cerebro-spinal fluid circulation the parts of the ventricular system infront of the obstruction are dilated. Color coded Doppler sonography can display the patency or obstruction of the physiologic constrictions of the ventricular system. Increased intracranial pressure can noninvasively be detected by spectral Doppler: The increase of the peak systolic flow velocity in the intracranial section of the internal carotid artery in comparison with the extra-cranial part is an early indication of a raised intracranial pressure. The decrease of the end-diastolic flow velocity during fontanel compression is indicative of abolished cranial compliance and increased intracranial pressure. In the case of raised intracranial pressure diastolic amplitudes and end-diastolic flow velocities are decreased and the resistive-indices are increased.