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PERIVENTRICULAR LEUKOMALACIA IMAGING
Category: Child Health
Abstract : Imaging Studies: • Cranial ultrasonography: Cranial ultrasonography is the modality of choice for the initial evaluation of hypoxic-ischemic damage of the CNS in premature infants. Sonography may be performed in the NICU without the need to transport fragile infants. The earliest ultrasonographic appearance of PVL is abnormal increased echotexture in the periventricular white matter. Thi
Imaging Studies:
• Cranial ultrasonography: Cranial ultrasonography is the modality of choice for the initial evaluation of hypoxic-ischemic damage of the CNS in premature infants. Sonography may be performed in the NICU without the need to transport fragile infants. The earliest ultrasonographic appearance of PVL is abnormal increased echotexture in the periventricular white matter.
This is a nonspecific finding that must be differentiated from the normal periventricular halo and mild periventricular edema that may not result in permanent injury. The abnormal periventricular echotexture of PVL usually disappears at 2-3 weeks. Approximately 15% of infants experiencing PVL demonstrate periventricular cysts first appearing at 2-3 weeks after the initial increased echodensities. The severity of PVL is related to the size and distribution of these cysts. Cranial ultrasonographic findings may be normal in patients who go on to develop clinical and delayed imaging findings of PVL.
• CT scanning: CT scanning is not a first-line modality in evaluating these fragile premature infants in the first weeks of life. CT scanning may be helpful to better evaluate the extent and severity of PVL. Findings include ventriculomegaly involving the lateral ventricles with irregular margins of the ventricles and loss of deep white matter.
• MRI: Like CT scanning, MRI does not play a major role in the early evaluation of PVL. MRI is most helpful in monitoring infants with suspected PVL and evaluating infants who develop clinical signs suggestive of PVL. MRI demonstrates the loss of white matter, abnormal signal intensity of the deep white matter, and ventriculomegaly. MRI demonstrates thinning of the posterior body and splenium of the corpus callosum in severe cases of PVL.
Other Tests: • Electroencephalography (EEG) Histologic Findings: PVL lesions demonstrate widespread loss of oligodendrocytes and an increase in astrocytes.
Medical Care: No medical treatment currently exists for PVL. Free radical scavengers are being investigated to determine if they have a role in preventing oligodendrocyte injury in PVL. Consultations: Infants with PVL require close neurodevelopmental follow-up after discharge from the hospital. Potential consultants include pediatricians, developmental specialists, and neurologists.
Further Outpatient Care:
• Developmental follow-up: Premature infants with evidence of PVL require close developmental follow-up because of the high association with CP.
Deterrence/Prevention:
• Prevention of premature birth is the most important means of preventing PVL.
• Prior to birth, diagnosing and managing chorioamnionitis may prevent PVL. In 1999, Baud et al reported that betamethasone administered to mothers at 24-31 weeks' gestation, before delivery, significantly reduced the risk of PVL, suggesting the possible effect of steroids on fetal inflammatory response.
• Avoiding maternal cocaine abuse and avoiding maternal-fetal blood flow alterations has been suggested to minimize PVL.
• Following delivery of a premature infant, attempts to minimize blood pressure (BP) swings and hypotension may also be beneficial in preventing PVL.
• Avoidance of prolonged hypocarbia in the mechanically premature infant may be useful in the prevention of PVL.
Prognosis:
• Infants with PVL are at risk for development of neurodevelopmental deficits. Mild PVL is often associated with spastic diplegia. Severe PVL is associated with quadriplegia. Severe PVL is also associated with a higher incidence of intelligence deficiencies and visual disturbances.
Medical/Legal Pitfalls:
• Timing of initial cranial ultrasonography can be useful in determining the timing of the insult. Cystic PVL has been identified on cranial ultrasounds on the first day of life, indicating that the event was prenatal rather than perinatal or postnatal.
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