Epidemiology of Hydrocephalus After Intraventricular Hemorrhage In Infants
Incidence and Prevalence
40–50% of patients with IVH: The average incidence of ventriculomegaly in the entire IVH population (all grades) is 40–50% (2, 71) .
Risk increases with extent of IVH: The respective mortality rates and risks for progressive ventriculomegaly in the various hemorrhage grades are as follows: grade I hemorrhage, 5% and 5%; grade II hemorrhage, 10% and 20%; grade III hemorrhage, 20% and 55%; and grade IV hemorrhage, 50% and 80% (18, 46, 54, 56).
None: There is no statistically significant sex predilection for IVH.
Incidence not related to geographic distribution: Among various countries, the degree of socioeconomic development that allows more premature babies to be born and survive in sophisticated pediatric Intensive Care Units contributes to the increased incidence and prevalence (38, 82).
Germinal matrix hemorrhage (IVH)
40–50% incidence of PHH: The average incidence of ventriculomegaly in the entire IVH population (all grades) is 40–50%. In cases of grades II-IV IVH, the incidence of ventriculomegaly is 55–80%, and clinically significant PHH will develop in 26–80% of these cases (67, 71, 98).
Decreased incidence of germinal matrix IVH: The incidence of germinal matrix IVH has decreased in the past 40 years. Improved treatment and survival rates of preterm infants have, however, resulted in a larger at-risk group for IVH. Thus, while the incidence has decreased, the prevalence of IVH remains high. Additionally, there is a possible underestimation bias since many cases of IVH are asymptomatic, and detection depends on screening and imaging criteria (58, 103, 113).
Decline in IVH in very-low-birth-weight subgroup (<1500 g) to 7–30%: The incidence of IVH declined from 35–50% in the 1980s to 15–30% in the 1990s in very-low-birth-weight infants (76, 87). Series from institutions around the world show a wider range of IVH from 20–64% in the subgroups of very-low-birth-weight and extremely-low-birth-weight (<700 g) infants (40, 53).
Severity of IVH correlates with age: The incidence of grade III IVH is 32% for infants born at 24–26 weeks and 11% for those born at 31–32 weeks. The incidence of grade IV IVH is 19% for infants born at 24–26 weeks and 5% for those born at 31–32 weeks (100).
Relationships to Other Disease States and Syndromes
Respiratory distress syndrome: A strong relationship between IVH and respiratory distress syndrome became evident in the 1960s. Respiratory distress syndrome occurs frequently in premature infants, and results in hypoxia. Infants with more severe cases of respiratory distress syndrome need mechanical ventilation, so numerous questions were raised regarding the impact of this ventilation (fluctuating blood pressure) and its complications (pneumothorax, hypercapnia) on the initiation and evolution of hemorrhage (6, 43, 57).