The brain is divided into four major lobes based on their location in the human skull. These are the major regions of the cerebral cortex that serve as centers for processing sensory information.
Since all parts and structures of the body are under the direct or indirect control of the brain, any type of damage can lead to their disruption or severely affect the processes that control some of the brain’s vital functions.
A brain lesion is damage to any tissue or part of the human brain. The lesion can appear in the form of a wound, ulcer, abscess, or a tumor.
The lesions of the brain can occur either locally, in one particular brain area, or they can be scattered, affecting several different regions of the brain.
What Are the Types of Brain Lesions?
There are several types of brain lesions, depending on the area where they occur, or the triggers::
- Vascular brain lesions
- Genetic brain lesions
- Aging-related brain lesions
- Space-occupying brain lesions
- Tumors
Vascular Brain Lesions
Vascular brain lesions are a collection of malformed blood vessels that alter the blood flow of the brain structures. Very often, these brain lesions pressure the brain structures and cause inflammation of their tissue, seizures, changes in cognitive functions of the brain, vision impairment, etc.
Genetic Brain Lesions
Some hereditary diseases can lead to genetic brain lesions. Such is the neurofibroma – a genetic disorder that results in tumors that form on nerve tissue.
These tumors can develop in any structure or area of the brain, and cause loss of hearing, learning impairment, heart and blood vessel (cardiovascular) problems, loss of vision, and severe pain.
Aging-related Brain Lesions
As we age, our body (including the brain) also ages and changes. More specifically, the brain shrinks, triggering the molecular and morphological changes of the neurons. In this way, the incidences of stroke, dementia, and lesions in the white matter of the brain increase.
Space-Occupying Brain Lesions
This type of brain lesion is usually caused by extensive damage to the brain structure due to malignancy. However, this mass brain lesion can also be the result of an abscess or hemorrhage, a benign or malignant neoplasm, an inflammatory or parasitic lesion, hematoma, or an arteriovenous malformation.
Tumors
A brain tumor is a collection of abnormal brain cells that spread rapidly within the skull. Since the skull is a rigid structure, the abnormal multiplication and growth of the brain cells create pressure on the brain structures.
Brain tumors can be either cancerous (malignant) or noncancerous (benign), and categorized as:
- Primary tumors
- Secondary tumors
Primary Brain Tumors
The primary brain tumors begin to develop and grow in the brain. They can develop from the brain cells or the membranes that surround the brain, i.e. the meninges, nerve cells, or from the glands.
Gliomas and meningiomas are the most common types of brain tumors. Unfortunately, the list of primary brain tumors does not end there. It continues with:
- Pituitary tumors (usually benign)
- Pineal gland tumors (benign or malignant)
- Ependymomas (usually benign)
- Craniopharyngiomas (they occur mostly in children and are benign)
- Primary central nervous system (CNS) lymphomas (malignant)
- Primary germ cell tumors of the brain (benign or malignant)
- Meningiomas (they originate in the meninges)
- Schwannomas (they originate in cells that produce the myelin sheet of the Schwann cells)
Secondary Brain Tumors
The secondary brain tumors are always malignant and first start to grow in some other parts of the body and eventually spread (metastasize) to the brain later.
In fact, a part of the tumorous cells breaks away from the primary tumor and spreads through the bloodstream to the brain as a secondary tumor.
These tumors are also labeled as metastatic brain tumors. Such are:
- Lung tumor
- Breast tumor
- Colon tumor
- Kidney tumor
- Melanoma tumor
Surgery combined with chemotherapy and immunotherapy are almost always the recommended treatment for individuals suffering from any form of secondary brain cancer. Most often, these treatments target the reduction of pain and the symptoms caused by the abnormal growth of the brain cells.
How and Why Do Brain Lesions Appear?
Brain lesions can result from an injury, a weak immune system, mutation of the neuron cells, or some medical condition or disease. They have a characteristic appearance which allows doctors to determine their cause.
The triggers that lead to an increased risk of getting brain lesions are various and numerous. They include:
- autoimmune disease
- aging
- family history
- trauma to the brain
- vascular conditions
- autoimmune disease
- decreased blood supply to brain tissue
- exposure to toxic chemicals or radiation
- poor diet
There are also some neurological diseases that can cause brain lesions:
- Brain aneurysm
- Brain AVM (arteriovenous malformation)
- Brain tumor
- Encephalitis
- Epilepsy
- Hydrocephalus
- Multiple sclerosis
- Stroke
- Lupus
What Are the Symptoms of Brain Lesions?
The symptoms of brain lesions generally depend on the type of the lesion, as well as the location, and the extent to which the lesion has grown. The general manifestations that a brain lesion has occurred in the brain include:
- headache
- altered gait and posture
- altered speech
- short-term memory loss
- nausea and vomiting
- dizziness
- fever
- neck pain and stiffness
- generalized weakness
- speech impairment
- loss of motor activity on one or both sides of the body
Symptoms of the Temporal Lobe Brain Lesions
The temporal lobe is strongly involved with the stability of our feelings. This is because one of the primary roles of the temporal lobe is the processing of emotions.
Some more severe cases of brain lesions in the temporal lobe can result in the following symptoms:
- Temporal lobe epilepsy
- Agnosia
- Broca’s aphasia
- Global aphasia
- Wernicke’s Aphasia (receptive aphasia)
- Primary progressive aphasia
- Logopenic primary progressive aphasia
Damage inflicted on the cerebral cortex in the temporal lobe area can lead to various medical conditions, such as memory loss, attention problems, impaired auditory perception, difficulty in understanding and producing language, etc.
Symptoms of the Parietal Lobe Brain Lesions
The parietal lobe is one of the most important centers for the integration of sensory impulses in the brain. It receives and processes sensory information from the body and skin, and coordinates the information received from all the other parts of the brain.
After injury to the parietal lobe, the following symptoms can occur:
- loss of sensations, like touch
- inability to identify things placed in the hand
- a change in behavior and emotions
- disruption in the sense of smell, taste, and hearing
- language and speech disorders
- problems with the field of vision
- forgetfulness and the inability to focus
- difficulties in reading, writing, and comprehension
- visual impairment
- motor skill problems
- difficulty in distinguishing left from right
- immediate memory impairment
- eye-movement problems
- problems with spatial orientation
- problems with eye-hand coordination
- difficulty with mathematics
- lack of awareness or neglecting some parts of the body
We’d be literally lost without a healthy and properly functional parietal lobe, as it governs our sense of orientation in space by allowing us to analyze and decide on the position and distance of our body in the space that surrounds us in relation to another person or object.
Symptoms of the Occipital Lobe Brain Lesions
The occipital lobe is mainly concerned with analyzing and interpreting visual information from sensory nerve signals sent by the eyes. It is responsible for receiving, selecting, organizing, processing, and integrating the visual signals received through the retina of the eye.
Since the occipital lobe is responsible for making sense of the things we see, any injury to it would mean loss of our ability to process visual information correctly.
Brain lesions to the occipital lobe mainly occur after a strong hit at the back of the head. These injuries can lead to some of the most severe health problems, including loss of vision or blindness.
But, the list of the medical conditions and health difficulties related to the occipital lobe is much longer, which proves the vital functions of the occipital lobe. It includes the following:
-
- defects in vision
- loss of vision
- difficulty locating objects in the environment
- difficulty identifying colors (visual agnosia)
- hallucinations
- Inability to see objects accurately
- inability to recognize words
- inability to recognize drawn objects or patterns
- inability to recognize the movement of an object (movement agnosia)
- difficulty in both reading and writing
The symptoms of a brain lesion in the occipital lobe range from strong headache, dizziness, weakness, and tingling sensation at the back of the skull, to photophobia and paralysis.
Symptoms of the Frontal Lobe Brain Lesions
The frontal lobe is the so-called ‘center of intelligence’ or a ‘control panel’ of our personality, because it regulates and controls all intellectual processes, movement, speech, as well as some aspects of our personality.
This is the area of the brain which controls our walking, running, ability to compare and distinguish one object from another, some personality traits (such as responsibility), etc. It controls and directs the muscles that move our feet, help us ride a bike, play tennis, etc.
In case of an injury or damage to the frontal lobe of the cerebral cortex, the following symptoms and medical conditions can appear:
- memory loss,
- impaired vision,
- difficulty in speaking,
- reduced motor skills,
- forgetfulness (dementia)
- absence of the sense of smell, usually limited to one nostril
- behavioral changes
Fun Facts
Did you know?
- The human brain suffers changes caused by stress and high levels of cortisol. Namely, chronic stress can lead to long-lasting changes in its function and structure.
- An injury to the left parietal lobe can affect our verbal memory, as well as the ability to memorize a string of digits.
- Damage to the right parietal lobe can result in the impairment of our self-care skills, such as maintaining personal hygiene and dressing.
- Even though the occipital lobe is well protected under the skull, an injury of the occipital lobe can lead to blindness, hallucinations, or illusions.
- Nutritional support can be of great help when it comes to temporal lobe problems. A high sugar load, for instance, can worsen the behavior of aggressive people. If aggressiveness is present without symptoms of depression, a higher-protein diet with simple carbohydrates could improve the condition.
- Temporal lobe damage can result in capgras delusion. With this disorder, the affected individual holds a belief that the people that are close to that person are not who they appear to be.
- Increased irritability, as well as changes in mood, are only some of the medical outcomes that can result from a change due to a brain lesion in the frontal lobe.
- A brain lesion in the primary motor cortex of the frontal lobe can lead to paralysis, i.e inability to perform fine motor movements (fingers, wrists, hands) or move the other parts of the body.
- If damage is inflicted to the Broca’s area of the frontal lobe, the individual will have difficulty in speaking.
- Arteriovenous malformations (AVMs), brain abscesses, cerebral infarction, and cerebral palsy also belong to the list of brain lesion types.