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Intraventricular hemorrhage in the premature infant--current concepts. Part I
1Department of Pediatrics, Washington University School of Medicine, St Louis, MO 63110.
Insights
Periventricular-intraventricular hemorrhage (IVH) remains a significant concern in neonatal intensive care, particularly for premature infants. Understanding its neuropathology and multifactorial pathogenesis is crucial for improving neurological outcomes.
Area of Science:
- Neonatal Neurology
- Pediatric Pathology
- Neuroscience
Background:
- Periventricular-intraventricular hemorrhage (IVH) is a serious neonatal brain injury, especially in premature infants.
- Despite decreased incidence, increasing survival rates of extremely premature infants maintain IVH as a critical neonatal intensive care unit problem.
- The primary lesion involves bleeding into the subependymal germinal matrix, often rupturing into the ventricles.
Purpose of the Study:
- To detail the neuropathology of IVH and its consequences.
- To explore the multifactorial pathogenesis of IVH, encompassing intravascular, vascular, and extravascular factors.
- To highlight the significance of periventricular hemorrhagic infarction in determining neurological outcomes.
Main Methods:
- Review of neuropathological characteristics of IVH.
- Analysis of contributing factors to IVH pathogenesis.
- Correlation of neuropathological findings with clinical outcomes.
Main Results:
- Key neuropathological consequences include germinal matrix destruction, posthemorrhagic hydrocephalus, and periventricular hemorrhagic infarction.
- Periventricular hemorrhagic infarction, a venous infarction, is a critical determinant of neurological outcome.
- Associated neuropathological findings include periventricular leukomalacia and pontine neuronal necrosis.
- Pathogenesis involves intravascular factors (blood flow/pressure), vascular factors (matrix microcirculation integrity), and extravascular factors (glial support, fibrinolysis).
Conclusions:
- IVH pathogenesis is complex, involving a interplay of vascular and systemic factors.
- Understanding these factors is essential for developing strategies to prevent or mitigate IVH and its long-term neurological sequelae.
- Continued research is needed to address the challenges posed by IVH in neonatal care.
Abstract:
Although the incidence of periventricular-intraventricular hemorrhage (IVH) has decreased in recent years, the increasing survival rates for the smallest premature infants indicate that the lesion will continue to be a major problem in neonatal intensive care facilities. The neuropathology is characterized by an elemental lesion, bleeding into the subependymal germinal matrix, with subsequent rupture into the lateral ventricle. Important neuropathological consequences are germinal matrix destruction, posthemorrhagic hydrocephalus, and periventricular hemorrhagic infarction. The last of these appears to be a venous infarction and is a critical determinant of neurological outcome. Neuropathological accompaniments, not caused by the IVH, include periventricular leukomalacia and pontine neuronal necrosis. The pathogenesis of IVHs is related to intravascular, vascular, and extravascular factors. Intravascular factors involve primarily control of blood flow and pressure in the microcirculation of the germinal matrix. Particular pathogenetic importance can be attached to fluctuations in cerebral blood flow, abrupt increases in flow, decreases in flow with injury to matrix vessels, increases in cerebral venous pressure, and, in selected infants, disturbances of platelet function and coagulation. Vascular factors relate to the microcirculation of the matrix, the site of the initial bleeding. A maturation-dependent alteration in vascular integrity and a vulnerability of matrix vessels to ischemic injury appear important. Extravascular factors include those relevant to mesenchymal and glial support for matrix vessels and to local fibrinolytic activity in the germinal matrix. The latter may be a manifestation of the proteolytic activity now recognized to be of general importance in developmental remodeling of the mammalian central nervous system.