Focal changes in the brain: development, types, symptoms, dangerous or not, how to treat

© Author: A. Olesya Valerievna, candidate of medical sciences, practicing physician, teacher at a medical university, especially for SosudInfo.ru (about the authors)

Focal changes in the brain substance are areas of atrophic, dystrophic, necrotic changes that arise against the background of impaired blood flow, hypoxia, intoxication and other pathological conditions. They are recorded on MRI and cause anxiety and fear in patients, but do not always cause any symptoms or are life-threatening.

Structural changes in the brain substance are more often diagnosed in the elderly and serve as a reflection of natural aging. According to some data, more than half of people over 60 years old have signs of focal changes in the brain. If the patient suffers from hypertension, atherosclerosis, diabetes, then the severity and prevalence of dystrophy will be greater.

Focal changes in the brain substance are also possible in childhood. Thus, in newborns and infants, they serve as a sign of severe hypoxia during the prenatal period or during childbirth, when a lack of oxygen provokes the death of immature and very sensitive nervous tissue around the ventricles of the brain, in the white matter of the hemispheres and in the cortex.

The presence of focal changes in nervous tissue, established by MRI, is not yet a diagnosis. Focal processes are not considered an independent disease, so the doctor is faced with the task of finding out their cause, establishing a connection with the symptoms and determining tactics for managing the patient.

In many cases, focal changes in the brain are detected by chance, but patients tend to associate their presence with a variety of symptoms. In fact, these processes do not always disrupt brain function, provoke pain or anything else, so treatment is often not required, however, most likely, the doctor will recommend follow-up and MRI annually.

Causes of focal changes in the brain

Perhaps the main cause of focal changes in the brain substance in adults can be considered the age factor, as well as its accompanying diseases. Over the years, natural aging occurs in all tissues of the body, including the brain, which somewhat decreases in size, its cells atrophy, and in some places structural changes in neurons are noticeable due to insufficient nutrition.

Age-related weakening of blood flow and slowdown of metabolic processes contribute to the appearance of microscopic signs of degeneration in brain tissue - focal changes in the brain substance of a dystrophic nature. The appearance of so-called hematoxylin balls (amyloid bodies) is directly associated with degenerative changes, and the formations themselves are once active neurons that have lost their nucleus and accumulated the products of protein metabolism.

Amyloid bodies do not resolve; they exist for many years and are found diffusely throughout the brain after death, but mainly around the lateral ventricles and vessels. They are considered one of the manifestations of senile encephalopathy, and there are especially many of them in dementia.

Hematoxylin balls can also form in foci of necrosis, that is, after cerebral infarction of any etiology, or trauma. In this case, the change is local in nature and is detected where the brain tissue was most damaged.

amyloid plaques in the brain during natural aging or Alzheimer's disease

In addition to natural degeneration, in older patients a noticeable imprint on the structure of the brain is left by concomitant pathology in the form of arterial hypertension and atherosclerotic vascular lesions. These diseases lead to diffuse ischemia, degeneration and death of both individual neurons and their entire groups, sometimes very extensive. Focal changes of vascular origin are based on a total or partial disruption of blood flow in certain areas of the brain.

Against the background of hypertension, the arterial bed is primarily affected. Small arteries and arterioles experience constant tension, spasm, their walls thicken and become denser, and the result is hypoxia and atrophy of the nervous tissue. With atherosclerosis, diffuse brain damage is also possible with the formation of scattered foci of atrophy, and in severe cases, a stroke occurs like a heart attack, and focal changes are local in nature.

Focal changes in the brain substance of a dyscirculatory nature are precisely associated with hypertension and atherosclerosis, which almost every elderly inhabitant of the planet suffers from. They are detected on MRI in the form of scattered areas of rarefaction of brain tissue in the white matter.

Focal changes of a post-ischemic nature are caused by previous severe ischemia with necrosis of brain tissue . Such changes are typical for cerebral infarctions and hemorrhages due to hypertension, atherosclerosis, thrombosis or embolism of the cerebral vascular bed. They are local in nature, depending on the location of the site of neuronal death, and can be barely noticeable or quite large.

Atherosclerosis is the cause of decreased blood flow to the brain. In the chronic process, small focal/diffuse changes in brain tissue develop. In case of acute blockage, an ischemic stroke may develop with the subsequent formation of a necrotic focus in the surviving patient

In addition to natural aging and vascular changes, other causes may lead to focal damage to brain tissue:

• Diabetes mellitus and amyloidosis - cause degeneration of predominantly vascular origin due to hypoxia and metabolic disorders;

• 
  examples of demyelination foci in multiple sclerosis

  Inflammatory processes and immunopathology - multiple sclerosis, sarcoidosis, vasculitis in rheumatic diseases (systemic lupus erythematosus, for example) - both demyelination (loss of cell membranes) and microcirculation disorder with ischemia occur;

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• Infectious lesions - toxoplasmosis, “slow infections” (Creutzfeldt-Jakob disease, Kuru), herpesvirus encephalomyelitis, borreliosis, tick-borne viral encephalitis, HIV infection, etc. - focal changes are based on the direct cytopathic effect of pathogens, the death of neurons with the formation of diffuse scattered lesions, inflammation and necrosis;
• Osteochondrosis and congenital pathology of the spine and blood vessels, leading to ischemic changes and decreased blood flow;

• 
  examples of foci of brain leukoaraiosis

  Acute and chronic intoxication with narcotic substances, alcohol, carbon monoxide - diffuse irreversible degeneration and death of neurons occurs;

• Brain injuries - focal changes of a local nature at the site of application of the traumatic factor or diffuse areas of demyelination and microinfarctions in severe bruises;
• Metastatic brain damage from tumors of other organs;
• Congenital changes and perinatal severe hypoxia are considered in the context of the pathology of early childhood and represent multiple focal changes in the nervous tissue mainly around the lateral ventricles (leukoaraiosis and leukoencephalomalacia).

Features of MRI diagnostics of focal changes in the brain substance

As a rule, the presence of focal changes in the brain substance becomes known after the patient has undergone an MRI. To clarify the nature of the lesion and differential diagnosis, the study can be performed with contrast.

Multiple focal changes are more typical for infections, congenital pathology, vascular disorders and dysmetabolic processes, multiple sclerosis, while single focal changes occur after strokes, perinatal lesions, certain types of injuries, and tumor metastasis.

Natural degeneration during aging

Focal changes in the brain substance of a dystrophic nature against the background of age-related involution are represented by MRI signs:

1. Periventricular (around the vessels) “caps” and “stripes” - found outside the lateral ventricles, arising due to the breakdown of myelin and expansion of the perivascular spaces, proliferation of glial cells under the ependyma of the ventricles;
2. Atrophic changes in the hemispheres with expansion of the grooves and the ventricular system;
3. Single focal changes in the deep white matter.

Multiple focal changes of a discirculatory nature have a characteristic deep location in the white matter of the brain. The described changes will be more pronounced, and the symptoms of encephalopathy will progress with age-related hypertension.

changes in the brain with age (younger → older): leukoaraiosis around the ventricles of the brain, atrophy, focal changes

Depending on the prevalence of age-related changes, the following are distinguished:

• Mild degree - single focal changes in the white matter of point sizes in the deep parts of the brain;
• Middle - drainage pockets;
• Severe - large confluent, scattered foci of damage to nervous tissue, mainly in deep sections against the background of vascular disorders.

Diagnostics

The most informative, comprehensive examination that can objectively assess the functioning of neurons and blood vessels in the brain and their destruction is MRI.

Depending on where the MRI detected foci of destruction of the brain substance of a dystrophic nature, the following features of the disease can be assumed:

1. Pathologies in the cerebral hemispheres may be accompanied by blockage of the vertebral arteries (due to congenital defects or atherosclerosis). This deviation also occurs with an intervertebral hernia.
2. Focal changes in the white matter of the brain in the forehead are associated with hypertension and experienced hypertensive crises. Fine-focal changes found here may also be congenital; they are not life-threatening if they do not increase over time.
3. Multiple lesions detected on an MRI image indicate serious pathology. Such results occur if dystrophy develops in the substance of the brain, which is typical for pre-stroke conditions, epilepsy, and the progression of senile dementia.

If an MRI reveals such a brain pathology, the person will have to regularly repeat the examination in the future, approximately once a year. In this way, it is possible to establish the rate of progression of destructive changes and the optimal plan of action to prevent a rapid deterioration of the patient’s condition. Other methods, in particular CT, can only provide information about traces of previous heart attacks, thinning of the cortex, or accumulation of fluid (CSF).

Discirculatory changes

Focal changes in the white matter of the brain due to impaired vascular trophism are the most common occurrence when analyzing MRI scans in older patients. They are considered to be caused by chronic hypoxia and dystrophy due to damage to small arteries and arterioles.

decreased blood flow is one of the main causes of age-related changes in the brain

MRI signs of vascular lesions:

1. Multiple focal changes in white matter, mainly in the deep structures of the brain, not involving the ventricles and gray matter;
2. Lacunar or border areas of necrosis;
3. Diffuse lesions in the deep sections.

foci of lacunar microstrokes in the brain

The described picture may resemble that of age-related atrophy, therefore it can be associated with dyscirculatory encephalopathy only if the corresponding symptoms are present. Lacunar infarctions usually occur against the background of atherosclerotic lesions of cerebral vessels. Both atherosclerosis and hypertension give similar changes on MRI in a chronic course, can be combined and are characteristic of people after the 50th birthday.

Diseases accompanied by demyelination and a diffuse dystrophic process often require careful differential diagnosis, taking into account symptoms and medical history. Thus, sarcoidosis can simulate a variety of pathologies, including multiple sclerosis, and requires contrast-enhanced MRI, which shows characteristic focal changes in the basal ganglia and meninges.

In Lyme borreliosis, the most important facts are a tick bite shortly before the onset of neurological symptoms and a skin rash. Focal changes in the brain are similar to those in multiple sclerosis, measure no more than 3 mm and are combined with changes in the spinal cord.

What brain diseases can MRI detect?

Changes in white matter on MRI in various pathologies

MRI of the brain is performed to diagnose:

• tumors. MRI is one of the highly informative methods in identifying oncological processes in the brain; it allows one to establish the relationship of the tumor with surrounding tissues;
• metastatic lesions (tumor screenings). For many malignant neoplasms, the brain is the target organ.
• lesions that appeared against the background of various angiopathy, hypertension, atherosclerosis, migraine, hyperhomocysteinemia;
• inflammatory processes, including those of an autoimmune nature: multiple sclerosis, sarcoidosis, etc.;
• infections: HIV, tuberculosis, herpes, neurosyphilis, mycoplasmosis, etc.;
• post-traumatic changes after receiving a direct blow to the head or to identify lesions after radiation therapy, which is also considered by radioradiologists as an altering factor;
• various metabolic disorders, toxic damage;
• heart attacks and strokes, foci of ischemia, dyscirculatory encephalopathy (impaired blood microcirculation is manifested by hypoxic/dystrophic changes in the brain);
• vascular malformations;
• anomalies and developmental defects.

What diseases cause lesions in the brain on MRI?

The principle of constructing an image during MRI of the brain is based on combining many slices, ranging in size from 1 mm, into a single whole, but the doctor can evaluate each layer separately

An example of damage to gray matter with the formation of foci is heterotopia and its most common variant is subependymal, which is associated with epilepsy and developmental delay. In the diagnosis of this pathology, magnetic resonance imaging of the brain is the predominant study. Epileptic seizures may appear in adulthood, which requires exclusion of a tumor. Changes in the gray matter are found in schizophrenia (loss of tissue density in the superior frontal lobule, left superior temporal gyrus), bipolar disorder, etc. Foci in the brain of a patient suffering from mental disorders are often found, but the main criterion for diagnosis is symptoms.

Differentiation of white matter pathologies includes a whole spectrum of diseases, but MRI of the brain also shows areas that do not always indicate disease and are a normal variant in older people. The latter are included in the concept of “benign aging of the brain.” Destructive zones can occur against the background of hypoxia and ischemia. On MRI, changes in the white matter of the brain associated with focal lesions are found in:

An MRI image shows changes in the white matter of the brain: green arrows indicate multiple demyelinated lesions in multiple sclerosis

• Multiple sclerosis. MS is an inflammatory (autoimmune) disease that causes spots in the white matter of the brain. The pathogenesis is not known for certain. Similar areas are found in herpesvirus infection, leukoencephalopathy, intoxication, therefore, before making a diagnosis, tomogram data is always assessed after analyzing the clinical situation and testing the cerebrospinal fluid. An MRI of the spinal cord is often required.

MRI: acute disseminated encephalomyelitis

• Acute disseminated encephalomyelitis. Multifocal lesions appear on tomograms 1.5-2 weeks after contact with the pathogen or vaccination. Other structures of the nervous system may also be involved in the process. Better visualization of lesions is provided by contrast. The size of the demyelinated areas is larger than in multiple sclerosis, and the disease is more often diagnosed at a young age.

MRI: Neuroborreliosis (tick-borne encephalitis)

• Lyme disease. Magnetic resonance scanning shows pinpoint lesions, a similar picture can be observed in autoimmune diseases. But for this nosology, a specific rash on the skin and a malaise resembling a cold and arthralgia are also typical. Tomograms show a hyperintense signal from the spinal cord and accumulation of paramagnetic in the region of the root zone of the VII pair of cranial nerves.

Sarcoidosis on MRI: yellow arrows indicate lesions of the membranes, cranial nerves, similar changes are present in the trunk

• Sarcoidosis of the brain. The diagnosis is difficult to establish only with magnetic scanning; sometimes final verification occurs after a biopsy. The picture on the tomograms resembles the changes characteristic of multiple sclerosis.

Negative dynamics on tomograms performed at monthly intervals for leukoencephalopathy

• Progressive multifocal leukoencephalopathy. The pathogenetic factor is infection with the Cunningham virus, which affects people with immunosuppression (severe dysfunction of the immune system). There is damage to the arcuate fibers of the white matter, with contrast there is no accumulation effect. Pathological foci are often localized on one side, sometimes symmetrical changes are visible.

Manifestations of focal changes in brain matter

The brain is supplied with blood from two vascular basins - the carotid and vertebral arteries, which already have anastomoses in the cranial cavity and form the Circle of Willis. The possibility of blood flow from one half of the brain to the other is considered the most important physiological mechanism that allows one to compensate for vascular disorders, so the clinical picture of diffuse small-focal changes does not appear immediately and not in everyone.

At the same time, the brain is very sensitive to hypoxia, so long-term hypertension with damage to the arterial network, atherosclerosis, which impedes blood flow, inflammatory changes in blood vessels and even osteochondrosis can lead to irreversible consequences and cell death.

Since focal changes in brain tissue occur due to a variety of reasons, the symptoms may be different. Dyscirculatory and senile changes have similar features, but it is worth remembering that lesions in relatively healthy people are unlikely to have any manifestations.

Often changes in brain tissue do not manifest themselves at all, and in elderly patients they are even regarded as an age-related norm, therefore, with any MRI conclusion, its result should be interpreted by an experienced neurologist in accordance with the symptoms and age of the patient.

If the report indicates focal changes, but there are no signs of trouble, then there is no need to treat them, but you will still have to see a doctor and periodically monitor the MRI picture in the brain.

Often, patients with focal changes complain of persistent headaches, which are also not necessarily associated with the identified changes. You should always rule out other causes before you start “fighting” an MRI picture.

In cases where the patient has already been diagnosed with arterial hypertension, cerebral or neck atherosclerosis, diabetes, or a combination of these, it is very likely that an MRI will show corresponding focal changes. Symptoms may include:

• Emotional disorders - irritability, mood swings, tendency to apathy and depression;
• Insomnia at night, drowsiness during the day, circadian rhythm disturbances;
• Decreased mental performance, memory, attention, intelligence;
• Frequent headaches, dizziness;
• Disorders of the motor sphere (paresis, paralysis) and sensitivity.

Initial signs of dyscirculatory and hypoxic changes do not always cause concern in patients. Weakness, fatigue, bad mood and headaches are often associated with stress, overwork at work and even bad weather.

As diffuse changes in the brain progress, behavioral inappropriate reactions become more pronounced, the psyche changes, and communication with loved ones suffers. In severe cases of vascular dementia, self-care and independent existence become impossible, the functioning of the pelvic organs is disrupted, and paresis of certain muscle groups is possible.

Cognitive impairment almost always accompanies age-related degenerative processes with brain dystrophy. Severe dementia of vascular origin with multiple deep foci of rarefaction of nervous tissue and atrophy of the cortex is accompanied by memory impairment, decreased mental activity, disorientation in time and space, and the inability to solve not only intellectual, but also simple everyday problems. The patient ceases to recognize loved ones, loses the ability to produce articulate and meaningful speech, becomes depressed, but can be aggressive.

Against the background of cognitive and emotional disorders, the pathology of the motor sphere progresses: gait becomes unstable, trembling of the limbs appears, swallowing is impaired, paresis increases up to paralysis.

Focal changes of a post-ischemic nature are usually associated with strokes suffered in the past, so symptoms include paresis and paralysis, disorders of vision, speech, fine motor skills, and intelligence.

In some sources, focal changes are divided into post-ischemic, dyscirculatory and dystrophic. You need to understand that this division is very arbitrary and does not always reflect the symptoms and prognosis for the patient. In many cases, dystrophic age-related changes accompany dyscirculatory changes due to hypertension or atherosclerosis, and post-ischemic foci may well arise from existing disseminated vascular origin. The emergence of new areas of neuronal destruction will aggravate the manifestations of existing pathology.

What to do if MRI shows signs of focal lesions?

The question of what to do in the presence of focal changes in the brain substance on MRI is most troubling to those people who do not have any significant neurological symptoms at all. This is understandable: for hypertension or atherosclerosis, treatment has most likely already been prescribed, but if there are no symptoms, then what and how to treat?

The foci of changes themselves are not treated; doctors’ tactics are aimed at the main cause of the pathology - high blood pressure, atherosclerotic changes, metabolic disorders, infection, tumor, etc.

For age-related dystrophic and dyscirculatory changes, experts recommend taking medications prescribed by a neurologist or therapist (hypotensives, statins, antiplatelet agents, antidepressants, nootropics, etc.), as well as lifestyle changes:

1. Adequate rest and night's sleep;
2. A balanced diet with a limit on sweets, fatty, salty, spicy foods, coffee;
3. Elimination of bad habits;
4. Physical activity, walks, feasible sports activities.

It is important to understand that existing focal changes will not disappear anywhere, however, through lifestyle, monitoring blood levels and pressure, you can significantly reduce the risk of ischemia and necrosis, progression of dystrophic and atrophic processes, while prolonging active life and performance for years.

Dystrophic changes in the brain on MRI

Cerebral angiography

When the blood supply is disrupted, oxygen and trophic starvation of cells (ischemia) develops. This leads to degenerative processes and is accompanied by dysfunction. The severity of the latter is variable, depending on whether blood is completely blocked or a partial influx remains. Dystrophic changes can be local or diffuse. Total brain damage is recorded in meningitis, encephalitis, focal changes are typical for cysts, small ischemic processes, and the formation of post-traumatic scars.

Clinical manifestations may include:

• headache;
• high blood pressure;
• the appearance of paresthesia (a feeling of numbness or tingling in the limbs), loss of sensitivity;
• deterioration of vision (up to blindness, which indicates damage to the optic nerve), memory, decreased intellectual abilities;
• insomnia;
• hyperkinesis (uncontrolled muscle contractions) and convulsions.

As the pathology progresses, paresis and paralysis are expected, so it is important to do an MRI of the brain vessels at the first symptoms of trouble. Single lesions can be detected in young men and women and do not always indicate pathology. The doctor’s tactics are dynamic observation and repeated magnetic scanning after 3-6 months, which will allow not to miss the development of any serious disease, for example, multiple sclerosis. Over the age of 60-65 years, lesions are found in almost all patients, which is explained by natural aging. These changes are irreversible, but the progression of the process can be slowed down with adequate treatment.

Provoking factors include:

• chronic alcohol and nicotine intoxication;
• stressful situations;
• irrational work and rest regime;
• obesity;
• low physical activity;
• persistent increase in blood pressure;
• diabetes;
• hypercholesterolemia.

The type of dystrophic disorders in the gray and white matter of the brain on MRI will depend on the nature of the pathological process.