A lesion is basically any area of the body that has suffered damage due to trauma or disease. The damaged area in any tissue of the body is called a lesion. Lesion is a broader term generally used for an ulcer, wound, abscess or tumor. This term may be used specifically for the damaged area in a particular organ; such as cardiac lesions, brain lesions, lesions in lungs and liver, etc.

Our main focus in this article will be on the different
brain lesions, their types, causes, symptoms, and complications. We will also
compare brain lesions with lesions occurring in other parts of the body.

Brain Lesions

Brain lesions are the areas of damage inside the brain. Brain is the most important organ in the body. It is involved in the processes of judgment, thinking, learning and memory. All the movements are performed with the aid of the brain.

Many crucial body functions necessary for the maintenance of life are under the control of the brain.  There is not a single process in the body that is not controlled by the brain; either directly or indirectly. Brain lesions can affect all these processes.

Brain is a complex organ having different regions. The regions in the brain overlap with one another. Each region is responsible for controlling the specific function of the body. Lesions in the brain may be localized occurring in a particular region or they may be diffused, affecting different regions of the brain.

As two types of cells are present in the brain;
neurons and the supporting cells called glial cells. Brain lesions can involve
either neurons or glial cells or both.

Types of Brain lesions

Brain lesions are of several types. The type of brain
lesion depends on the type of injury occurring to the brain.

Vascular lesions

These occur due to disturbances in the blood supply to the brain. They may occur due to stroke or cerebral artery aneurysm.

Genetic lesions

They are associated with the genetic makeup of the person. Hereditary diseases cause genetic lesions such as neurofibromas.

Aging lesions

These occur as a result of the aging process. The normal aging process of the body causes loss of brain cells. These lesions present with the symptoms of loss of memory, poor judgment and loss of sight as a person ages.

Abscesses

These are the brain lesions that occur in infectious
diseases. They include the localized areas of the brain containing pus and
inflamed tissue.

Plaques

These are the abnormal deposits in the brain that act
as space-occupying lesions. They can cause the death of brain cells. They also
compress the neighboring tissue severely affecting the normal functioning of the
brain. 

Tumors

Tumors also act as brain lesions. They may be benign
or malignant. Brain tumors may also be metastatic spreading to the brain from
other organs of the body.

Causes of Brain Lesions

Brain lesions can occur due to trauma or a disease
process. They may occur spontaneously or develop over a period of time. A brief
detail of different conditions that can cause brain lesions is given below:

Trauma

The most common cause of brain lesions is trauma to the brain. Injury to the brain can occur either due to fall from height or blowing off some hard object on the head of a person. Trauma to the head can cause bleeding in the brain or swelling of the brain tissue. Bleeding and swelling can cause the death of brain cells forming brain lesions.

Infections

Brain infection by different microbes can cause meningitis or encephalitis. These infections can cause inflammation within the brain tissue leading to brain lesions. Some microbes can cause calcified deposits in the brain.

These calcified deposits act as space-occupying lesions, compressing other areas of the brain.

Autoimmune disease

Autoimmune diseases can cause damage to the brain cells or form space-occupying lesions in the brain. These diseases include amyloidosis, sarcoidosis, and rheumatoid arthritis.

Stroke

Stroke, also called brain infraction, is a condition in which blood supply to the entire brain or part of the brain is stopped. If the blood supply is not established within a few seconds, it can cause irreversible brain damage and cell death.  Depending on the area of brain deprived of blood supply, it can cause brain lesions or complete loss of brain functions.

Bleeding

It can occur either due to brain trauma or cerebral
artery aneurysm.

Specific disease

Certain diseases can cause lesions in the specified
areas of brain. For example; in Parkinson’s disease, lesions occur in
substantia nigra, a part of the midbrain. 

Symptoms of Brain Lesions

Symptoms of brain lesions depend on the part of the brain affected the most. Not all brain lesions show symptoms. Many cases have been reported in which brain lesions spread to larger areas of the brain without causing any disease signs or symptoms.

On the other hand, some lesion affecting only a small region of the brain show severe symptoms as in Parkinson’s disease.

General symptoms seen with all non-specific brain
lesions include:

• Headache
• Nausea and vomiting
• Dizziness
• Fever
• Neck pain and stiffness
• Generalized weakness
• Altered gait and posture
• Altered speech
• Short-term memory loss

Specific brain lesions cause specific symptoms such as
dyskinesias and altered movements in Parkinson’s disease and dementia (memory
loss) in Alzheimer’s disease.

Complications of Brain Lesions

Brain lesions, if left untreated, can cause severe complications. They can expand to the other areas of the brain causing complete loss of brain functioning.

Loss of brain functioning decreases the quality of life causing paralysis, speech and hearing abnormalities. Involvement of the brain stem can interfere with the process of respiration and cardiac control leading to the death of the person. Bleeding lesions inside the brain can cause severe blood loss.

This can also cause circulatory shock and sudden death. Brain tumors can spread to other areas of the brain. If left untreated, brain tumors are the most lethal brain lesions having a much higher mortality rate.

Lesions in other organs of the body:

As said earlier, lesion is any area of damage or
injury in the body. However, in medical science, the term lesion is most
commonly used to describe any type of injury to the brain tissue. For other
organs of the body, the term lesion is used only for a specific illness or
disease.

Skin Lesion

Area of skin having abnormal appearance. They may be
primary lesions present at birth or acquired later in life. Secondary skin
lesions develop by modification of primary lesion.

Liver Lesions

These are the group of abnormal cells in the liver.
The term liver lesion is specifically associated with some tumors of the liver.
They may be benign tumors or malignant tumors of the liver.

Lung Lesion

Pulmonary nodules or cancerous cells in the lung are
sometimes called lesions in the lungs.

Cardiac Lesions

The term cardiac lesion is specific to the calcified
or fibroid deposits in the heart which can cause obstructive anomalies of the
heart.

Diagnosis of Lesions

The diagnosis of lesions depends on their location. Diagnosis always begins with the history and examination. History of progression of the lesion can give a clue about the type of the lesion and the underlying cause.

Some lesions such as skin lesions can be diagnosed
upon proper examination.

For the diagnosis of lesions occurring in deeper
tissue areas, such as brain lesions, cardiac lesions, etc. radiological methods
are used. These include MRI or CT Scans. The cardiac lesions can be diagnosed
by echocardiography. Ultrasonography can give a clue about the lesions in the liver.

Prevention

Medical specialists are of the opinion that brain
lesions and other lesions occurring in the body can not be predicted or
prevented. However, a person can follow some general guidelines that can help
prevent a number of diseases including brain lesions. These include:

• Quit Smoking (can prevent cancerous
  lesions)
• Keep blood pressure under control(can
  prevent aneurysm)
• Control cholesterol levels in blood
  (can prevent stroke)
• Using helmet while driving a bike,
  or playing some sports such as baseball, cricket, etc. (can reduce the chances
  of trauma to head)
• Avoid unnecessary exposure to
  radiations (this will prevent cancer)

Conclusion/Summary

Lesions are the areas of injury or damage in different
tissues of the body. The term lesion is most commonly used to describe the
damage to the brain tissue. Brain lesions may be

• Vascular
• Genetic
• Aging-related
• Space occupying lesions
• tumors
• Plaques.

Different conditions that can cause brain lesions
include:

• Trauma or injury to brain
• Decreased blood supply to brain
  tissue
• Infectious diseases such as
  meningitis
• Auto-immune disorders
• Certain diseases of the brain such
  as Parkinson’s disease

Symptoms of brain lesion vary depending upon the area
of the brain most severely affected. The general symptoms are nausea, headache,
and loss of concentration.

There is no specific way to predict or prevent brain
lesions. However, following a general guideline can help a person prevent the
underlying diseases that lead to brain lesions.

Once diagnosed, the brain lesions must be treated
immediately. Otherwise, they can cause severe complications and can even lead
to the death of the person.

References

Brain Lesions (Lesions on the Brain) Benjamin Wedro, MD, FACEP, FAEEM
https://www.medicinenet.com/brain_lesions_lesions_on_the_brain/article.htm#brain_lesions_facts
Lesion, Wikipeida Web Page
https://en.wikipedia.org/wiki/Lesion