What Is PVL?
Periventricular leukomalacia (PVL) is an injury to the white matter of the brain that consists of focal necrosis and cyst formation as well as more widespread cerebral white matter injury. Periventricular leukomalacia is often seen in babies and infants who have suffered oxygen deprivation or a hypoxic injury during labor and delivery or shortly after birth. PVL also affects premature infants. PVL is a major predictor of intellectual impairment and the subsequent development of cerebral palsy.
Prevalence Of PVL
The greatest risk for PVL occurs in premature infants and the risk increases as the gestational age decreases. Premature infants with a gestational age under 32 weeks have a higher risk for the development of periventricular leukomalacia. Although PVL occurs more frequently in preterm infants, term infants are also at risk. For term infants who have suffered a significant period of oxygen deprivation either during labor or immediately after birth, the risk of developing PVL increases as a result of ischemic injury to the brain. Periods of asphyxia, hypercarbia, hypotension and hypoxemia can impair the autoregulatory functions of the brain resulting in decreased cerebral blood flow, vasoconstriction and brain damage.
Prior to a baby’s birth, there are factors that increase the risk of PVL. In mothers who suffer from chorioamnionitis, antepartum hemorrhage, vaginal infections or a premature rupture of the membrane, the prevalence of periventricular leukomalacia increases. If there is evidence of umbilical cord inflammation (also called funisitis) or infection in the baby (i.e.: sepsis), then the risk of PVL is also increased.
Clinical And Radiographic Diagnosis Of PVL
Neurologic deficits are sometimes the first signs of PVL in an infant. If suspected, periventricular leukomalacia (PVL) can be confirmed by radiologic brain imaging via ultrasound, computed tomography (CT), or magnetic resonance imaging (MRI). The first line of imaging utilized is normally ultrasound since it is portable and less expensive than CT or MRI. Ultrasound images in PVL will normally show cysts and/or echodensities. A routine examination normally includes both coronal and sagittal views. As repeat ultrasound scans are performed, the findings usually reveal evolving brain injuries or damage. Within 1-3 weeks after the initial insult on the brain, approximately half of the echodensities will reveal small cysts. It is not uncommon for the cysts to disappear after one to three months and ventriculomegaly (dilation of the lateral ventricles) to develop. It must be noted that ultrasound is limited in its sensitivity and specificity to detect lesions less than .05 cm. In one study, ultrasound was reported to have identified only 26 percent of those brain hemispheres with evidence of hypoxic ischemic injury.1 The sensitivity of ultrasound is increased when repeated or serial ultrasounds are performed. Not only is an ultrasound of a baby’s brain highly reliable in detecting cystic PVL, it is also reliable in detecting germinal matrix hemorrhage and intraventricular hemorrhage (IVH). However, brain ultrasounds are not very sensitive in detecting PVL without cysts. For noncystic PVL, MRI is the radiology method of choice.
When MRI is used in the diagnosis of PVL, the images reveal hypointense periventricular lesions on T1-weighted images and as hyperintensity on T2-weighted images. Unlike ultrasound, MRI is able to detect periventricular changes early in the neonate baby before cystic changes have time to occur. Thus, MRI is useful in detecting diffuse white matter injury with no cystic changes. Such ability is useful in extremely premature infants.
It was recently reported that a low arterial cord pH is significantly associated with neonatal mortality, hypoxic ischemic encephalopathy, intraventricular hemorrhage or periventricular leukomalacia and cerebral palsy.2 Thus, medical evidence that a baby is suffering from a metabolic acidosis appears to be an important risk factor for the development of PVL.
Click here to read more regarding the timing of cyst formation.
Outcomes Of PVL
There are no known cures for periventricular leukomalacia (PVL). Care of a baby or individual with PVL is geared toward teaching parents and other caregivers to feed, dress, and deal with the child’s physical needs. Physical therapy is a mainstay in helping PVL sufferers deal with the physical deformities and limitations they may suffer from. As the baby ages, evidence of developmental delay, spastic cerebral palsy, cognitive impairment, and vision problems quickly become apparent.
It is recognized that the best way to prevent periventricular leukomalacia (PVL) is to maintain cerebral perfusion (oxygen delivery to the brain). Thus, medical personnel should avoid or correct conditions involving oxygen deprivation. Such conditions include hypoxemia (low oxygen), increased CO2, systemic hypotension (low blood pressure) or cerebral vasoconstriction (narrowing of the blood vessels).
In babies at risk for premature birth, it has been proven that the administration of corticosteroids (ie: betamethasone or dexamethasone) is associated with a decreased risk of cystic PVL. With respect to preterm babies, it has been reported that rate of cystic PVL was lower in those babies whose mothers received corticosteroids within 24 hours prior to birth.
If Your Child Has Periventricular Leukomalacia
If your child has been diagnosed with periventricular leukomalacia, it is important that you have his or her medical records reviewed and evaluated by an attorney experienced in handling birth injury cases. When gathering the medical records, the attorney will also need to see the labor and delivery records for the mother. These records may contain valuable information about labor and delivery events that could have played a part in depriving the unborn child of oxygen or in depleting the baby’s oxygen reserves prior to delivery. Medical malpractice that causes or results in an anoxic brain injury and PVL may go undetected until the pertinent records are reviewed by a professional. The birth injury attorneys at Hixson & Brown, P.C., are available to consult if you have a child that suffers from PVL or cerebral palsy.
1 Hope, et al. (“Precision of ultrasound diagnosis of pathologically verified lesions in the brains of very preterm infants”, Dev. Med Child Neurology, 1988; 30(4): 457)
2 Malin, et al (“Strength of association between umbilical cord pH and perinatal and long term outcomes: systematic and meta-analysis“; BMJ, 2010; 340:c1471)