History of Management of Hydrocephalus After Intraventricular Hemorrhage in Infants
Understanding of Disease
Hemorrhagic intracranial events: Before the introduction of imaging techniques, intracranial hemorrhage in newborns could be noticed in severe symptomatic cases, and information regarding the pathology could be assessed in autopsies. Such autopsies conducted 40 to 60 years ago revealed subdural hematomas as the commonest hemorrhagic event. In the following years, the incidence of subdural hematomas declined, presumably due to the evolution of obstetrics, and the incidence of germinal matrix IVH increased because of the more advanced neonatal intensive care support of very premature newborns (16).
Terminology: IVH is a widely used term, although it doesn’t indicate the origin of the bleeding. More precise is the term germinal matrix IVH, which provides the exact location of the initial event (germinal matrix) and the subsequent extension into the ventricular system.
Parenchymal involvement: Extension of the hematoma into the periventricular white matter results in more severe damage and poses a worse prognosis (grade IV). Although the direct mechanism of this progression is not fully understood, it has become evident that it involves a sequence of venous infarction, rather than a true extension (25, 90).
Multifactorial etiology: Over the years many risk factors have been proposed as contributors to the hemorrhage. Grossly they can be classified as prenatal, intrapartum, and postnatal factors. Another scheme distinguishes vascular, respiratory, hemodynamic, and metabolic factors, while some investigators classify the causes as primary or secondary to the treatment provided.
An approach to pathophysiology: Theories regarding the formation of hydrocephalus have evolved to identification of specific substances (e.g., TGF-β1) that contribute to the formation of fibrosis which obstructs the CSF flow pathways.
Diagnosis and management: A critical point for the management of neonates after an IVH is the identification of active hydrocephalus, defined as ventriculomegaly associated with increased CSF pressure. This condition has to be distinguished from the parenchymal loss that often coexists. The first needs neurosurgical intervention, while the second doesn’t.
Neonatal Intensive Care Units: Advanced and sophisticated equipment allows excellent monitoring and ventilation that can support very premature neonates with multiple co-morbidities.
Neuroimaging: One of the landmarks for the better evaluation and understanding of PHH was the introduction of cranial ultrasonography. It forms the basis for the widely used classification system devised by Levene (47) and the close follow-up of neonates suffering from IVH. The same impact was had by the CT scan, which provided for the first time in vivo images of the exact location and progression of the hemorrhage along with details for the resulting hydrocephalus and the parenchymal injuries. Today’s gold standard for the most accurate visualization of the insulted neural tissue is the MRI. Details of the normal and abnormal anatomy can be obtained, along with accurate estimations of the extent of the parenchymal damage.
Neurosurgical implants and instruments Low profile subcutaneous reservoirs and more compatible shunts (valves, tubes) are used for the diversion of excess CSF from the ventricles. The development of small caliber endoscopes is important as well, mainly for the treatment of later complications such as the multiloculated ventricles.
CSF diversion techniques: For the last 50 years the definitive treatment of PHH in these patients has remained the insertion of a ventriculoperitoneal shunt. Ventriculoperitoneal shunts in neonates have the highest complication rate and these complications, in turn, determine to a great extent the overall outcome. Subcutaneous reservoirs, subgaleal drains, and EVDs are additional means that have contributed to the better surgical management of hydrocephalus, but they are temporary measures. Neuroendoscopy is an important advance, but its role remains restricted. ETV has proven ineffective so far in the management of neonatal PHH. Some options for neuroendoscopic applications are the ventricular washouts for the removal of blood in the ventricles and the coagulation of the choroid plexus for the limited cases of slowly progressing communicating hydrocephalus (10, 68, 77).