Periventricular leukomalacia ( PVL ) is a form of white skin injury, characterized by necrosis (more commonly coagulation) of white matter near the lateral ventricle. This can affect newborns and fetuses (less common); premature infants are at the greatest risk of neonatal encephalopathy that can cause this condition. Affected individuals generally show motor control problems or other developmental delays, and they often develop cerebral palsy or epilepsy later on.
These brain pathologies are described by various names ("encephalodystrophy", "ischemic necrosis", "periventricular infarction", "necrotizing coagulation", "leukomalasia", "softening of the brain", "white matter periventricular infarcts", "necrosis of white matter" "spread symmetrical periventricular leukoencephalopathy"), and more frequently by German scientists, but worldwide dissemination is the term "periventricular leukomalacia", introduced in 1962 BA Banker and JC Larroche. This term can be misleading, as there is no network softening in PVL. V. V. Vlasyuk and V. P. Tumanov in 1985 published the world's first monograph devoted to PVL. Vlasyuk (1981) first revealed the high incidence of optical radiation lesions and showed that PVL - a persistent process that the old necrosis can join the new PVL focus could be at different stages of development.
In the process of morphogenesis focuses the PVL through three stages: 1) necrosis, 2) resorption, and 3) the formation of scarred gliosis or cyst. Cysts occur when a large and confluent PVL focus, with mixed necrosis (central kolacola at the periphery and coagulation at the periphery). Around the focus are generally defined areas of other lesions of the white matter of the brain - the deaths of prooligodendrocytes, the proliferation of microgliocytes and astrocytes, swelling, bleeding, loss of capillaries, and others (so-called "PVL diffuse components"). However, diffuse lesions without necrosis are not PVL.
Video Periventricular leukomalacia
Presentations
Often it is not possible to identify PVL based on physical characteristics or patient behavior. White matter in the periventricular region is heavily involved in motor control, so individuals with PVL often exhibit motor problems. However, since healthy newborns (especially premature babies) can perform a small amount of certain motor tasks, the initial deficit is very difficult to identify. As individuals develop, the area and extent of problems caused by PVL can begin to be identified; However, this problem is usually found after an initial diagnosis has been made.
The extent of the mark depends heavily on the extent of damage to white matter: minor damage only causes slight deficits or delays, while significant white matter damage can cause severe problems with motor coordination or organ function. Some of the most frequent signs include delayed motor development, vision deficits, apnea, low heart rate, and seizures.
Pending motor development
Delayed motor development in infants exposed to PVL has been demonstrated in several studies. One of the earliest markers of developmental delay can be seen in the affected infant's leg movements, as early as one month of age. Those with white matter injuries often show "tight coupling" of the foot joint (all elongated or all flexing) longer than other infants (premature and full term). In addition, babies with PVL may not be able to take the same position to sleep, play, and breastfeed as premature or full-term children of the same age. This developmental delay can continue throughout infancy, childhood, and adulthood.
Deficit vision
Premature infants often show visual impairment and motor deficits in eye control soon after birth. However, this deficit correction occurs "in a predictable pattern" in healthy premature infants, and babies have vision comparable to term infants up to 36 to 40 weeks after conception. Infants with PVL often show a decrease in the ability to maintain a stable view of fixed objects and make coordinated eye movements. In addition, children with PVL often exhibit nystagmus, strabismus, and refractive abnormalities.
Seizures
Occurrence of seizures is often reported in children with PVL. In an Israeli-based study in infants born between 1995 and 2002, seizures occurred in 102 of 541, or 18.7%, of PVL patients. Seizures are usually seen in more severe cases of PVL, which affects patients with larger numbers of lesions and those born at low gestation and birth weight.
Maps Periventricular leukomalacia
Cause
Predisposing factors
Those generally considered to be at greatest risk for PVL are premature babies, very low birth weight babies. It is estimated that about 3-4% of infants weighing less than 1,500 g (3.3 lb) have PVL, and 4-10% of those born before 33 weeks of gestation (but who survive more than three days after delivery) have the disorder. Gestational CMV infection also produces PVL in neonates.
Path of injury
Two major factors appear to be involved in the development of PVL: (1) decreased blood or oxygen flow to the periventricular region (white matter near the cerebral ventricles) and (2) damage to glial cells, cells supporting neurons throughout the nervous system. These factors are highly likely to interact with premature infants, resulting in a series of events leading to the development of white matter lesions.
Early hypoxia (decreased oxygen flow) or ischemia (decreased blood flow) may occur for a number of reasons. Fetal blood vessels are thin-walled structures, and the possibility of vessels providing nutrients to the periventricular region can not maintain adequate blood flow during episodes of oxygenation decline during development. In addition, hypotension resulting from fetal distress or cesarean delivery can lead to decreased blood flow and oxygen to the developing brain. This hypoxic-ischemic incident can cause damage to the blood brain barrier (BBB), the endothelial cell system and glial cells that regulate the flow of nutrients to the brain. Damaged BBBs may contribute to a greater degree of hypoxia. Alternatively, damage to the BBB may occur due to maternal infection during fetal development, fetal infection, or infection in newborns. Because their cardiovascular and immune systems are not fully developed, premature babies are particularly at risk for this initial humiliation.
Damage caused to the BBB by hypoxic-ischemic injury or infection triggers a series of responses called inflammatory responses. Immediately after the injury, the nervous system produces a "pro-inflammatory" cytokine, which is the molecule used to coordinate the response to humiliation. These cytokines are toxic to the developing brain, and their activity in an effort to respond to specific areas of damaged tissue is believed to cause "damage caused by others" to nearby areas that are not affected by genuine insults. Further damage is believed to be caused by free radicals, compounds produced during ischemic episodes. The processes that affect neurons also cause damage to glial cells, leaving neurons closest to little or no support systems.
It is estimated that other factors can lead to PVL, and researchers are studying other potential pathways. A 2007 article by Miller et al., Provided evidence that white matter injury is not a condition limited to premature infants: long-term infants with congenital heart disease also show "a very prominent incidence of white injury." In a study described by Miller, of 41 long-term newborns with congenital heart disease, 13 infants (32%) showed a white matter injury.
Diagnosis
As mentioned earlier, there are often some signs of injury to white matter in newborns. Sometimes, doctors can make preliminary observations of extreme stiffness or poor ability to suckle. The initial diagnosis of PVL is often made using imaging technology. In most hospitals, premature babies are examined with ultrasound immediately after birth to check for brain damage. Severe white matter injuries can be seen with head ultrasound; However, the low sensitivity of this technology allows some white matter damage to be missed. Magnetic resonance imaging (MRI) is much more effective in identifying PVL, but it is not unusual for premature infants to receive MRI unless they have very difficult developments (including recurrent or severe infections, or known hypoxic events during or shortly after birth). No body or regulatory body has established protocols or guidelines for screening at-risk populations, so that every hospital or physician generally makes decisions about which patients should be screened with a more sensitive MRI than a head ultrasound.
PVL is overdiagnosed by studies of neuroimaging and other white matter lesions of the underrated brain. It is important to distinguish PVL from the following major white matter lesions in the hemispheres: edematous hemorrhagic leukoencephalopathy (OGL), telentsefalny gliosis (TG), diffuse leukomalacia (DFL), subcortical leukomalasia (SL), periventricular hemorrhagic infarction (PHI), intracerebral haemorrhage (ICH ), multicystic encephalomalasia (ME), subendimia pseudocyst. Diffused white matter lesions from cerebral hemispheres, accompanied by softening and spread to central and subcortical areas are more likely DFL, PHI and ME.
Prevention
Preventing or delaying preterm delivery is considered the most important step in reducing PVL risk. Common methods to prevent premature birth include self-care techniques (diet and lifestyle decisions), bed rest, and prescribed anti-contraction medications. Avoiding premature delivery allows the fetus to develop further, strengthening the affected system during the development of PVL.
Emphasis on prenatal health and routine medical examinations of mothers may also reduce the risk of PVL. Appropriate diagnosis and treatment of maternal infection during pregnancy reduces the likelihood of a large inflammatory response. In addition, treatment of infections with steroids (especially within 24-34 weeks of gestation) has been indicated in reducing the risk of PVL.
It has also been suggested that avoiding the use of mother cocaine and any changes in maternal-fetal blood flow may reduce the risk of PVL. Episodes of hypotension or decreased blood flow to the baby can cause damage to white matter.
Care and management
Current care
Currently, no treatment is prescribed for PVL. All treatment provided is a response to secondary pathology that develops as a consequence of PVL. Because white matter injuries in periventricular areas can lead to a variety of deficits, neurologists should closely monitor infants diagnosed with PVL to determine the severity and extent of their condition.
Patients are usually treated with individual care. It is important for doctors to observe and maintain organ function: visceral organ failure can occur in untreated patients. In addition, motor deficits and increased muscle tone are often treated with physical therapy treatments and individual occupations.
Care challenge
The fetal and neonatal brain is a rapidly evolving and changing structure. Because nerve structures are still developing and connections still form at birth, many successful drugs for treatment and protection of adult central nervous system (CNS) are not effective in infants. In addition, some adult care actually proves toxic to the developing brain.
Next treatment
Although no treatment is approved for use in human PVL patients, a large amount of research occurs in developing treatments to protect the nervous system. Researchers have begun examining the potential of synthetic nerve protectors to minimize the number of lesions in patients exposed to ischemic conditions.
Prognosis
The prognosis of patients with PVL depends on the severity and extent of damage to white matter. Some children show relatively small deficits, while others have significant deficits and disabilities.
Small network damage
Minor damage to white matter is usually demonstrated through slight developmental delays and deficits in posture, vision systems, and motor skills. Many patients exhibit spastic diplegia, a condition characterized by increased muscle tone and elasticity in the lower part of the body. The gait of PVL patients with spastic diplegia shows an unusual flexing pattern when walking.
Progression
Patients with severe white matter injuries usually show signs of extensive brain damage. Babies with severe PVL experience very high levels of muscle tone and frequent seizures. Children and adults may be paralyzed, indicating loss of function or paralysis of all four limbs.
Cerebral palsy
Many babies with PVL eventually develop cerebral palsy. The percentage of individuals with PVL developing cerebral palsy is commonly reported with significant variability from study to study, with estimates ranging from 20% to over 60%. One reason for this difference is the great variability in the severity of cerebral palsy. This range corresponds to the severity of PVL, which can also vary greatly. More white matter damage leads to more severe cerebral palsy; Different subtypes are identified and diagnosed by neurologists.
Despite varying levels of PVL and cerebral palsy, affected babies usually begin to show signs of cerebral palsy in a predictable manner. Usually, some abnormal neurological signs (as mentioned earlier) are seen by third trimester pregnancies (28 to 40 weeks after conception), and the exact signs of cerebral palsy are seen by the age of six to nine months.
Epilepsy
Another common but severe result of PVL patients is the development of epilepsy. The relationship between the two is not entirely clear; However, it appears that both genetic and early environmental factors are involved. One study estimated that 47% of children with PVL also had epilepsy, with 78% of patients with epilepsy forms not easily managed by drugs. Many of these affected patients showed some seizures, as well as a more severe spastic diplegia or cerebral palsy form, before the diagnosis of epilepsy was made.
Frequency
Unfortunately, very few population-based studies on PVL frequencies. As mentioned before, the highest PVL frequency seen in preterm babies is very low. These babies are usually seen in NICUs in hospitals, with about 4-20% of patients in NICU affected by PVL. In large autopsy materials without choosing the PVL most often detected in boys with birth weight is 1500-2500 g., Die at 6-8 days of life. Diffuse soft brain damage with softening (diffuse leucomalacia, DFL) is found more frequently in children weighing less than 1500 g. However, PVL is not DFL.
Research
Animal research
Animal models are often used to develop better care for and a more complete understanding of PVL. A mouse model that has white matter lesions and experienced seizures has been developed, as well as other rodents used in PVL studies. These animal models can be used to examine the potential efficacy of new drugs in the prevention and treatment of PVL.
Clinical research
Current clinical research ranges from research aimed at understanding the development and pathology of PVL to develop protocols for the prevention of PVL development. Many studies have assessed the trend of individual outcomes with PVL: a recent study by Hamrick et al., Considering the role of cystic periventricular leukomalacia (a very severe form of PVL, involving cyst development) in infant development outcomes.
Other ongoing clinical studies aimed at the prevention and treatment of PVLs: clinical trials testing neuroprotectants, preventing premature births, and examining potential drugs for the damping of white matter damage are all currently supported by NIH funding.
References
Source of the article : Wikipedia
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