A brain lesion is a general term for an area of brain tissue damaged by injury or disease, appearing as an abnormality on a scan. These areas of damage can range from a single, small spot to multiple, widespread areas. The term itself is not a diagnosis but a descriptive finding that prompts further medical investigation into its cause, which can range from temporary issues to permanent conditions.
Causes of Brain Lesions
Traumatic Injury
Direct injury to the head is a frequent source of brain lesions. A traumatic brain injury (TBI) from a fall, car accident, or blow to the head can cause localized damage to brain tissue. This damage can manifest as bruising, bleeding, or tearing of nerve fibers, creating a lesion visible on imaging scans. Concussions, even mild ones, are a form of TBI that can result in lesions, disrupting normal brain activity.
Vascular Events
Problems with the brain’s blood vessels are a common cause of lesions. A stroke, or cerebral infarction, occurs when the blood supply to a part of the brain is interrupted, leading to the death of brain cells and creating a distinct lesion. Another vascular issue is an aneurysm, a bulge in a blood vessel wall that can rupture and bleed into the brain. Arteriovenous malformations (AVMs), abnormal tangles of blood vessels, can also lead to lesions by disrupting blood flow or rupturing.
Infections and Autoimmune Conditions
Infections can lead to brain abscesses, which are localized collections of pus and inflamed tissue. These can result from infections in nearby areas, like the sinuses, or from systemic infections that travel to the brain. Autoimmune conditions, such as multiple sclerosis, are another cause. In multiple sclerosis, the body’s immune system mistakenly attacks the myelin sheath that protects nerve fibers, creating characteristic lesions.
Growths
Both noncancerous (benign) and cancerous (malignant) growths, or tumors, are classified as brain lesions. Primary brain tumors originate within the brain, while metastatic tumors are cancers that have spread to the brain from another part of the body. The presence of this abnormal tissue disrupts the structure and function of the surrounding brain areas.
Associated Symptoms
The effects of a brain lesion are dictated by its size and location. Because different brain regions control distinct functions, symptoms directly correlate to the part of the brain that is damaged. A small lesion in a highly functional area may produce more noticeable symptoms than a larger one in a less active region.
Symptoms are often grouped by the brain functions they affect. Motor symptoms may include muscle weakness, difficulty with balance and coordination, or trouble with fine motor skills. A lesion in the cerebellum, for example, can directly impact balance and coordinated movement.
Sensory changes also depend on the lesion’s placement. A lesion in the occipital lobe, which processes visual information, can cause vision changes or loss. Damage to the temporal lobe might result in hearing difficulties, while a lesion affecting the parietal lobe can cause numbness or tingling sensations.
Cognitive symptoms can include memory problems, confusion, and difficulty with concentration or speaking. Lesions in the frontal lobe are often associated with changes in personality, mood, and behavior. More generalized symptoms that can occur regardless of lesion location include headaches, nausea, and seizures.
Diagnostic Process
Identifying a brain lesion begins with a neurological examination. During this exam, a healthcare provider tests motor skills, sensory perception, balance, mental status, and reflexes. The results help to pinpoint which parts of the brain may be affected, guiding the next steps of the diagnostic process.
Neuroimaging is the primary method used to visualize and confirm a brain lesion. Magnetic Resonance Imaging (MRI) is often preferred because it produces highly detailed images of the brain’s soft tissues, showing the lesion’s size, shape, and location. Computed Tomography (CT) scans are another common technique, useful in emergencies to quickly detect bleeding or significant structural damage.
In some cases, imaging alone is not enough to determine the lesion’s exact nature, so a biopsy may be performed for a definitive diagnosis. This surgical procedure involves removing a small sample of the abnormal tissue. The tissue is then examined by a pathologist to identify the specific type of cells involved, which helps distinguish between different types of tumors or infections.
Treatment Approaches
The management strategy for a brain lesion depends on its underlying cause, size, location, and symptoms. Not all lesions require immediate intervention. A small, stable lesion that is not causing problems may be monitored with a “watchful waiting” approach, which involves regular imaging scans to check for any changes.
Medication is a common treatment tailored to the lesion’s specific cause. If the lesion is from an infection, antibiotics are prescribed. For autoimmune conditions like multiple sclerosis, medications that modify the immune system are used. Steroids are often administered to reduce swelling and inflammation around a lesion, which can help alleviate symptoms like headaches.
For lesions that can be safely accessed, surgical removal may be an option, particularly for brain tumors, abscesses, and some vascular malformations. The goal is to remove the abnormal tissue while preserving as much healthy brain function as possible. For cancerous lesions, surgery is often followed by radiation therapy or chemotherapy to target any remaining cancer cells.
Following treatment, rehabilitation therapies are frequently recommended to help individuals manage symptoms and regain function. These therapies can include physical, occupational, and speech therapy.