PERIVENTRICULAR LEUKOMALACIA

Definition and Incidence

Periventricular Leukomalacia (PVL) is an ischemic lesion leading to areas of coagulation necrosis in the periventricular white matter at the external angles of the lateral ventricles in the watershed areas of the deep penetrating arteries of the middle cerebral artery.

The incidence of PVL is reported as approximately 25-75% of very low birth weight infants who die.   The incidence among surviving infants is unknown; however, ultrasound findings estimate the incidence at 5-15%.   Ultrasonography is typically used to detect cystic PVL, but MRI is more sensitive in detecting noncystic PVL. In recent correlative study of sonographic and neuropathologic studies, only 30-40% of PVL lesions were detected by cranial ultrasound prior to death. 

Infants at risk are not just preterm infants but any infant with a maternal history of possible ischemic or hypoxic associated disease (i.e. pregnancy induced hypertension,   chronic hypertension, diabetes mellitus, placental insufficiency, severe renal disease). The incidence of PVL is increased with maternal chorioamnionitis, hypocarbia, and hypotension in premature neonates.

Etiology and Pathogenesis

PVL may coexist with IVH but likely has a separate pathologic process. Generally, PVL is a focal area of ischemia with coagulation necrosis followed by macrophage and astrocytic proliferation. On occasion secondary hemorrhage occurs.   Eventually, there is thinning of the white matter with secondary dilation of the lateral ventricles. This may be followed by cystic or cavitational changes in these areas that can become evident by ultrasound or MRI

Diagnosis/Clinical Presentation

Age of Onset.  Occurrence may be intrauterine and present at birth. Most commonly, PVL is found at 7-10 days upon routine head ultrasound.

Radiographic Studies. Ultrasonography is most commonly used for diagnosis and has excellent sensitivity at detecting cystic changes >0.5 cm in diameter, but it is not sensitive in detecting decreased myelination. MRI is performed routinely at UTMB to detect PVL in ELBW infants at a corrected gestational age of 40 weeks. MRI has the advantage of detecting noncystic diffuse white matter abnormalities with higher sensitivity.

Neurologic Findings. Spastic paresis of the legs is the most common clinical sequelae. The involved area generally includes white matter through which long descending motor tracts descend from the motor cortex with the leg fibers being closest to the ventricles. With lateral extension of the lesion there may be arm involvement resulting in spastic quadriplegia.  Infants with cystic degeneration can develop hydrocephalus ex vacuo or ventricular dilation associated with diffuse cerebral atrophy. In infants showing moderate to severe white matter abnormalities on MRI at corrected age of 40 weeks, there was an increase in cognitive delay, motor delay, neurosensory impairment and cerebral palsy.

Management

Weekly head circumference to monitor for normal head growth.

After initial diagnosis a head ultrasound every 1-3 weeks, depending on the clinical specifics, may be obtained to monitor for hydrocephalus. If the PVL is associated with an IVH event, hydrocephalus may develop as a result of post hemorrhagic hydrocephalus and hydrocephalus ex vacuo.

Good neurodevelopmental follow-up.   Early referral (at the time of discharge) for childhood intervention to minimize severity of limb spasticity may be necessary.


toc | return to top | previous page | next page