A potential mechanism of pathogenesis for early posthemorrhagic hydrocephalus in the premature newborn.

Ventricular dilation is common following intraventricular hemorrhage. Neuropathologic studies have demonstrated that chronic posthemorrhagic hydrocephalus most commonly is a result of an obliterative arachnoiditis in the posterior fossa or is due to obstruction of flow of CSF within the ventricular system. Recent use of ultrasound scanning has demonstrated the occurrence of ventricular dilation within days of intraventricular hemorrhage (prior to the expected time of development of arachnoiditis). In the case described, serial real-time ultrasound scans demonstrated small mobile particles within dilated ventricles seven days following intraventricular hemorrhage. There was no obstruction of CSF flow within the ventricular system. Thus, in this case, ventricular dilation may have been secondary to plugging of arachnoid villi by the small particulate matter and, as a consequence, decrease in CSF reabsorption.