Lesions in multiple sclerosis (MS) are the result of damage to the cells of the central nervous system, which is made up of the brain and spinal cord. “Sclerosis” refers to the characteristic scar tissue that forms in lesions in the brains of people who have MS. MS lesions are also known as scleroses or plaques. This scar tissue is a result of damage to myelin (a fatty tissue that insulates nerve fibers) and the inflammatory processes characteristic of MS.
Lesions in people with MS usually appear in the brain stem, cerebellum, spinal cord, and cranial nerves (including the optic nerve, trigeminal nerve, and facial nerve). Lesions can appear in one specific area of the brain, in multiple areas, or in large swathes of the central nervous system.
Brain lesions can have many different causes. Age, a family history of brain lesions, trauma, and viral or bacterial infections are just a few things that can cause brain lesions. Autoimmune diseases, such as lupus and MS, are another. In the case of MS, brain lesions are the result of inflammation and damage caused by a misfiring immune response and the formation of scar tissue.
Symptoms of MS vary from person to person and are largely dependent on where MS lesions develop in the central nervous system. The severity, size, and location of lesions all influence what functions of the central nervous system are impacted.
The frontal lobes are the largest of the brain’s lobes. They are located immediately behind the forehead. The frontal lobes comprise the motor area, which is responsible for voluntary movement. The frontal lobes also control memory, intelligence, reasoning, concentration, and aspects of our personality. Lesions on the frontal lobe can cause symptoms including speech impairment, loss of motor function on one or both sides of the body, and changes in mood or behavior.
The parietal lobes are located at the center of the brain. This is where sensory information is processed. Our parietal lobes allow us to feel temperature, taste, touch, and movement. The parietal lobes are also responsible for our ability to read and do math. Lesions in the parietal lobes may cause symptoms such as forgetting words for common objects and loss of sensations such as heat, cold, and pain. The parietal lobe also carries a portion of the nerve fibers originating from the eyes, so lesions in this area can affect the lower part of the visual field.
The occipital lobes are located at the back of the brain. Their job is to process images from the eyes and link that information with images stored in memory. Essentially, our occipital lobes enable us to identify what we’re seeing. Symptoms of lesions in the occipital lobes may present as changes to vision. Optic neuritis, which can include blurry vision and pain with eye movement, is a common early symptom of MS.
The temporal lobes are located in the center of the brain. Specifically they’re in front of the occipital lobes and beneath the parietal and frontal lobes. Temporal lobes play a large role in our senses of hearing, touch, and smell. The temporal lobes also play a role in forming and storing memories. Lesions in the temporal lobes can result in cognitive symptoms, including forgetfulness, moodiness, and difficulty focusing. Sensory symptoms, such as loss of taste, smell, and hearing, can be symptomatic of lesions in this part of the brain — as can changes in behavior, mood, and emotions. The temporal lobes also carry optic nerve fibers, and lesions in this area can cause problems with the upper field of vision.
Brain lesions do not always cause noticeable symptoms, especially in the case of clinically isolated syndrome (CIS) and early phases of different types of MS. Brain lesions that do not cause symptoms are known as “silent” lesions. If lesions worsen with time, symptoms become more noticeable.
In some instances, lesions or symptoms of lesions are detected during an exam, scan, or routine monitoring for an unrelated condition. Brain lesions appear as darker or lighter spots on a magnetic resonance imaging (MRI) scan. Other times a person's neurologic symptoms bring them to the doctor’s office.
Sometimes, these symptoms lead to a diagnosis of MS or clinically isolated syndrome. The findings from an MRI scan are vital diagnostic indicators. The type, size, and distribution of brain lesions in MS are also an important part of the McDonald diagnostic criteria. This is the set of criteria most frequently used to diagnose MS and monitor MS disease progression.
Diagnosing lesions in the brain may involve a neurologist taking a complete medical history, conducting a physical examination, and performing a detailed neurological exam. The doctor may use vibration or hot or cold objects to assess the ability to detect sensations. The doctor may pinch a person’s cheek or other part of the body to check pain responses. These stimulus response tests may also help pinpoint the possible location of the lesion or lesions.
Computed tomography (CT) is a type of imaging technology that uses radiation to take images of brain tissue. A solution may be injected into a person’s vein to help highlight brain structures. CT scans can be used to diagnose brain lesions.
Magnetic resonance imaging is a noninvasive diagnostic tool that uses magnetic fields and computer technology to produce three-dimensional images of the brain. MRI shows greater detail in brain tissue, the cerebellum, and brain stem than a CT scan. MRI conducted with a contrast fluid called gadolinium can show whether or not the lesions are active (recent) and whether there is evidence of preexisting inflammation or lesions. If lesions do not appear brighter on a high-contrast MRI, they’re likely older than three months.
If you or your health care provider suspect your symptoms may be related to brain lesions, prompt attention is your best bet. A timely, thorough evaluation by a neurologist with specialized training is very important to identify the underlying cause of the lesions and recommend the most appropriate treatment plan.
There are more than 15 disease modifying therapies (DMTs) approved by the U.S. Food and Drug Administration (FDA) to treat relapsing MS or progressive MS. Different treatments for MS have varying mechanisms of action. The different mechanisms of DMTs include:
Multiple sclerosis is a chronic illness with no known cure. Regular monitoring and follow-up care are important parts of tracking and managing disease progression. Brain lesions can be caused or worsened by things other than MS, such as aging or stroke.
Maintaining a generally healthy lifestyle, including diet and exercise, can also go a long way toward keeping your brain functioning smoothly, whether or not you have MS. There are several things you can do to help keep your brain healthy when you have multiple sclerosis.
Here are some ways to limit your risk for new or worsening brain lesions:
When you join MyMSTeam, you gain a support group of more than 160,000 other people who are living with multiple sclerosis. Brain lesions are a frequent topic of conversation among MyMSTeam members.
Do you have questions about brain lesions and MS? Comment below or start a new conversation on MyMSTeam.