Multiple sclerosis is a chronic, progressive, autoimmune disease, in which the body’s own immune system mistakenly attacks its’ Central Nervous System (CNS). The Central Nervous system includes the brain and spinal cord, and is made up of nerves that send messages throughout the body.
For a person with MS, their immune system begins to initiate attacks targeting the protective covering that surrounds nerve fibers, called myelin. These attacks ultimately damage your myelin, disrupting normal nerve function and causing communication problems between your brain and the rest of your body.
Symptoms and signs of MS vary greatly, and the disease progresses at different rates among all individuals. Many of the symptoms are dependent upon the amount of nerve damage and which nerves have been affected. Some common symptoms include:
- Numbness or weakness in one or more limbs
- Partial vision loss
- Prolonged double vision
- Tingling or pain in parts of the body
- Electric shock sensations that occur with certain neck movements
- Tremors, lack of coordination
- Slurred speech
- Problems with bowel and bladder function
Many people suffering from MS experience periods where new symptoms develop over days or weeks. These relapses are usually followed by periods where the disease is in remission, which can last for months or even years. Some people instead experience a gradual onset and steady progression of symptoms without any relapses.
Doctors find it very challenging to define and diagnose MS, because the signs, symptoms, and manifestations of the disease are unique to every individual.
As many as 10 percent of people diagnosed with multiple sclerosis actually have a different condition with similar symptoms to MS. Conditions that mimic MS include inflammation in the blood vessels, multiple strokes, vitamin deficiency, and brain infection.
To properly diagnose MS, multiple tests and examinations must be completed by a neurologist who specializes in treating MS. Many physicians approach diagnosing MS as a three-step process:
- Identify cardinal clinical features- examine the patient for typical symptoms of MS, such as vision loss and weakness in the extremities
- Neurological exams- examine the patient’s mental status, vision, speech, motor strength, reflexes, and balance
- Perform investigations consistent with MS
The most significant investigation performed to accurately diagnose MS is the MRI scan of the brain, cervical, and thoracic spinal cord. This investigation creates a high-resolution image of the white tissue matter of the central nervous system, allowing surgeons to see if there are lesions on the brain.
To further investigate your condition, your neurologist may also recommend a spinal tap, and will likely perform blood tests to check your white blood cell and protein count. This information is useful in ruling out any mimicking conditions.
While all of these tests alone may suggest that a patient has MS, it is their combined information that ultimately leads a neurologist establishing the diagnosis of MS.
An international panel of MS experts recently revised the way that MS is diagnosed, and created a framework for neurologists to follow when attempting to diagnose. This framework is called The McDonald Criteria, and it allows for the diagnosis of MS if the MRI scan shows lesions forming over time on different dates, and if lesions are found on two or more parts of the central nervous system.
This criteria is significant because it allows neurologists to diagnose patients with MS at an earlier stage, therefore helping them start treatment sooner.
The Role of MRI in Diagnosing MS
Magnetic Resonance Imaging is considered one of the most useful and accurate tools when imaging for MS; revolutionizing the investigation, diagnosis, and even the treatment of this disease. Over the past 15 years, the strength and quality of MRI scanners has greatly improved.
Until this time, most imaging clinics used an MRI with a magnet strength of 1.5 Teslas (T). Due to advancements in technology, MRIs with an increased magnet strength of 3 Teslas are now being used more often in clinical settings.
Neurologists are using these 3T MRI machines to obtain highly detailed images of the brain and spinal cord. This information is helping them better study and understand the onset, symptoms, and progression of MS.
When a surgeon is initially ordering an MRI on a patient to establish the diagnosis of MS, they start by looking for white matter lesions on the brain. These lesions are usually ovoid in appearance, and they typically are found coming off the ventricles, occurring within the brain stem, or up against the cortical rim.
Often in an MRI, acute MS lesions may be seen to leak Gadolinium dye. This is the dye that is administered in the patient’s vein during the procedure to add visual contrast to the scan. The Gadolinium enhancement is seen as brightness on the scan, and indicates areas of inflammations where lesions are active; meaning they are either new, or getting bigger.
MRI is also particularly helpful with investigating MS in patients who have only had one demyelinating symptom attack, also known as clinically isolated syndrome (CIS). The number of lesions visible on an initial MRI of the brain or spinal cord can help the neurologist assess the person’s risk of experiencing a second attack in the future, cementing the diagnosis of definite MS.
For individuals who have only experienced a single demyelinating attack of MS, an MRI can also be used to determine if a second neurological event has occurred without noticeable symptoms. This helps neurologists confirm the diagnosis of MS as early as possible, and place patients on a treatment plan.
Different Types of Scans
There are different types of scans and radio frequency pulse sequences that neurologists will use when scanning for MS.
- T1-weighted brain MRI scan
- Provides information about current disease activity by highlighting areas of active inflammation.
- These areas of inflammation appear as active lesions.
- T1-weighted images also show dark areas that are thought to indicate areas of permanent nerve damage.
- T2-weighted images
- Supplies information about the total amount of lesion area, both old and new.
- Fluid Attenuated Inversion Recovery images are used to better identify brain lesions associate specifically with MS.
- Spinal cord imaging
- This can help identify pathology in the spinal cord and demonstrate that damage has occurred in different parts of the central nervous system and at different points in time.
After a diagnosis of MS has been clearly established, no additional MRI scans are necessary for diagnostic purposes. However, additional scans are essential for tracking the progress of the disease and making treatment decisions. A neurologist should consider the disease activity visible on an MRI, the person’s clinical symptoms, and their relapses when determining whether a treatment plan is effective or needs to be changed.
As 3T MRI continues to transition into clinical use, many people will benefit from the quality of the images that this machine can produce. Whether it is utilized to establish an early diagnosis, for the study of the progression of the disease, or for creating individualized treatment plans, MRI is a critical tool when dealing with MS.