The leukoencephalopathy is the name given to any disorder that affects the white matter of the brain, regardless of its causes. The white matter or white matter, is a part of the central nervous system whose nerve cells are covered with a substance called myelin.
Myelin is made up of layers of lipoproteins that promote the transmission of nerve impulses throughout neurons. That is, it causes information to travel much faster through our brain..
It may happen that, due to hereditary factors, myelin once developed, begins to degenerate (what is called leukodystrophies). Whereas, those conditions in which problems occur in the formation of myelin are called demyelinating diseases..
However, despite scientific advances, it appears that more than 50% of patients with inherited leukoencephalopathy remain undiagnosed. That is why new types and more accurate ways of diagnosing them are currently being discovered..
Leukoencephalopathies can also arise from acquired causes such as infections, neoplasms or toxins; and can appear at any time in life, from neonatal stages to adulthood.
Whatever its cause, this leads to a wide variety of symptoms such as cognitive deficits, seizures, and ataxia. In addition, these can remain static, improve over time, or worsen little by little..
As for the prevalence of leukoencephalopathy, due to the various types it encompasses, it is not yet established. Depending on the type of condition we treat, it may be more or less frequent. Although in general, these diseases are not very widespread.
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As leukoencephalopathies are any condition in which part of the white matter is affected, acquired or inherited, the causes are very numerous.
In addition, there are different types of encephalopathies depending on their causes and the characteristics of the damage. Thus, each causative factor generates a different type of white matter damage, which, as a consequence, produces different symptoms..
There are authors who divide the causes of leukoencephalopathies into 5 groups: non-infectious inflammatory, infectious inflammatory, toxic-metabolic, hypoxic ischemic and traumatic (Van der Knaap & Valk, 2005).
However, sometimes certain diseases do not fit into specific categories, as they can have several different causes at the same time.
The conditions that can cause a leukoencephalopathy are very diverse:
There are a series of genetic mutations that can be inherited from parents to children and that facilitate the appearance of leukoencephalopathies. Autosomal dominant cerebral arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) would be an example, since it is produced by the involvement of the Notch3 gene.
There are authors who call "leukodystrophies" to the degeneration of the white matter due to genetic factors. However, sometimes the distinction between which conditions have genetic causes and those with acquired causes is not absolutely clear. In fact, there are conditions in which a disease can arise from both types of causes..
It has been found that leukoencephalopathies can develop if the body is not able to fight a certain virus, due to an abnormality or weakness of the immune system.
This is what happens in progressive multifocal leukoencephalopathy, which appears due to the presence of the JC virus. There are also cases in which the measles virus appears to be the cause of deterioration of the white matter, such as Van Bogaert's sclerosing leukoencephalopathy.
Some strokes, hypertension or hypoxia ischemic encephalopathy (lack of oxygen or blood flow in the newborn's brain), can affect the integrity of the white matter of the brain.
Chemotherapy treatments, such as radiation therapy, can cause progressively increasing white matter lesions. These are: cisplatin, 5-fluorourcil, 5-florauracil, levamisole and Ara-C.
- In children, a characteristic pattern of the development of skills and abilities. It consists of a period of normal development followed by a stagnation in the acquisition of skills, and finally, a decline or regression. Another sign is that this occurs after injuries, infections, or any brain damage..
- Seizures or epileptic seizures.
- Progressive spasticity, or increasingly stiff and tense muscles.
- Ataxia or difficulties in coordinating movements that have a neurological origin.
- Lack of balance causing trouble walking.
- Cognitive deficits or cognitive slowness in processes of attention, memory, and learning.
- Visual difficulties They often affect the cornea, retina, lens, or optic nerve.
- In some children with leukoencephalopathy, the circumference of the skull is larger than normal, something called macrocephaly..
- Successive episodes of stroke or cerebral hemorrhage.
- Irritability.
There are many diseases that can be classified under the term leukoencephalopathy. Some of them are:
It is a hereditary disease that produces multiple strokes in the minor arteries, affecting part of the white matter of the brain. The first symptoms appear around the age of 20 and consist of migraines, psychiatric disorders and frequent strokes..
It is also called infantile ataxia with central nervous system hypomyelination (CACH). It is an autosomal recessive inherited condition. This means that it appears when both parents pass the same genetic mutation to their child. The mutation can be found in any of these 5 genes: EIF2B1, EIF2B2, EIF2B3, EIF2B4, or EIF2B5.
It is usually diagnosed in childhood between 2 and 6 years of age, although there have been cases of onset in adulthood.
Symptoms are cerebellar ataxia (loss of muscle control due to deterioration in the cerebellum), spasticity (abnormal tightness of the muscles), epilepsy, vomiting, coma, movement problems, and even fever..
It appears in people with significant deficiencies in their immune system, since it is not able to stop the JC virus. Its activity causes a large number of tiny progressive lesions that produce brain demyelination.
As the name suggests, symptoms appear progressively, and consist of cognitive impairment, visual loss due to involvement of the occipital lobe (part of the brain that participates in vision), and hemiparesis. It is also commonly associated with optic neuritis.
It is an inherited condition that comes from mutations in the CSF1R gene. Symptoms associated with it are tremors, seizures, rigidity, gait ataxia, progressive impairment of memory and executive functions, and depression..
It is the demyelination of the cerebral cortex that appears a few years after the measles virus. Symptoms consist of slow, progressive neurological deterioration leading to eye problems, spasticity, personality changes, sensitivity to light, and ataxia..
In this case, the loss of white matter is due to the ingestion, inhalation or intravenous injection of certain drugs or drugs, as well as exposure to environmental toxins or chemotherapy treatments..
It can also appear from carbon monoxide poisoning, ethanol poisoning, ingestion of methanol, ethylene, or ecstasy..
Symptoms depend on each poison, the amount received, the time of exposure, medical history, and genetics. Generally they tend to be difficulties in attention and memory, balance problems, dementia and even death.
In many of these cases, the effects can be reversed when the poison causing the problem is removed..
It is an autosomal recessive genetic condition produced by mutations in the MLC1 and HEPACAM genes. It stands out for macrocephaly (overly developed skull) at a young age, progressive mental and motor deterioration, seizures and ataxia.
It is the degeneration of the white matter due to a sudden increase in blood pressure. It causes an acute confusional state, in addition to headaches, seizures and vomiting. Bleeding into the retina of the eye is common.
Can be effectively treated with antihypertensive medications.
Symptoms associated with this syndrome are loss of vision, seizures, headaches, and confusion..
A wide variety of causes can produce it, such as malignant hypertension (a very rapid and sudden increase in blood pressure, systemic lupus erythematosus, eclampsia (seizures or coma in pregnant women associated with hypertension), or certain medical treatments that suppress the activity of the immune system (such as immunosuppressive drugs, such as cyclosporine).
A brain scan may show edema, that is, unusual fluid accumulation in the tissues..
Symptoms tend to go away after a while, although vision problems can be permanent.
If symptoms such as seizures, motor difficulties or lack of coordination of movements occur, the healthcare professional will likely decide to perform a brain scan..
One of the best neuroimaging techniques is magnetic resonance imaging, from which high-quality images of the brain can be obtained thanks to exposure to magnetic fields.
If in these images certain patterns of localized damage are observed in the white matter of the brain, the specialist may conclude that there is a leukoencephalopathy.
It is advisable to carry out an ophthalmological exam, since, as they say, the eyes are a window into our brain. It should be remembered that ophthalmological abnormalities or changes are very common in leukoencephalopathies.
A neurological examination is also necessary to detect the existence of spasticity or excessive muscular tension, and hypotonia may also occur (quite the opposite).
Under certain conditions, such as progressive multifocal leukoencephalopathy, a cerebrospinal fluid analysis may be performed. The technique is called PCR (Polymerase Chain Reaction), and it is performed to detect the JC virus; what is the cause of this disease.
Treatment will focus on the underlying causes of white matter damage. As the causes are very diverse, the different treatments are too.
Thus, if the factors that have caused the disease have vascular origins or are related to hypertension, keeping this at bay could be of great help..
For leukoencephalopathies caused by immunodeficiency, treatment will focus on reversing this state, such as the use of antiretroviral drugs in HIV.
If, on the contrary, it is due to exposure to toxins, medications or drugs; the best way to recover is to stop contact with these substances.
It is also advisable to complement the treatment of the causes of leukoencephalopathy with other symptomatic ones that serve to alleviate the existing damage. That is, neuropsychological rehabilitation to work on cognitive deterioration, psychological assistance to help the patient to emotionally cope with their situation, physical training to improve muscle tone, etc..
If leukoencephalopathy appears due to inherited genetic mutations, the treatments will be focused on preventing the progression of the disease, improving the quality of life of the person and other preventive methods.
A form of prevention can be to have a genetic test if other relatives have suffered from any of these conditions. To check if you are a carrier of any genetic abnormality related to leukoencephalopathies that can be transmitted to future children.
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