Diagnosing Multiple Sclerosis
Arriving at a correct diagnosis of multiple sclerosis (MS) is often a complex process. NYU Langone doctors are experts at diagnosing the disease and in identifying the exact type.
In people with MS, the protective coating of nerves surrounding the central nervous system, which is made up of the brain and spinal cord, is damaged by the body’s own immune system. This damage leads to scarring in the form of lesions—also called sclerosis—that affect the nerve signals sent between the brain and spinal cord.
Weakness and sensory disturbances are some of the most common initial symptoms of MS. It’s easy to initially ignore numbness or weakness, especially because these symptoms may go away without treatment.
It is also common for people and doctors to misattribute the initial symptoms of MS to something more benign, such as a pinched nerve or muscle strain. Sometimes a person may have the symptoms of MS for many years before he or she seeks medical attention and receives a correct diagnosis.
Medical History and Neurological Exam
Your doctor takes a detailed medical history and asks about your symptoms before performing a neurological examination. During this exam, your doctor evaluates your movement, coordination, and balance as well as your vision and sensation.
A neurological exam helps your doctor determine if there is impairment in the central nervous system. It also helps to rule out other neurological diseases that may affect the peripheral nerves or muscles.
If a person has had two separate neurological attacks—for example, blurry vision followed by numbness a few years later—and imaging scans reveal two or more lesions, no further testing is required to make a diagnosis. However, the neurological history is not always clear and often doctors need to perform additional testing to make a definitive diagnosis.
When a person shows neurological symptoms that are suggestive of MS, a doctor may order an MRI scan, in which magnetic waves and computers create images of the body’s tissues and structures. This allows doctors to see inside the brain and spinal cord and to identify areas of scarring caused by MS.
Doctors may also give you an intravenous (IV) dye before the scan. The dye highlights any abnormalities and can help your doctor to identify lesions that indicate MS is in an active phase.
MRI scans are performed at NYU Langone. If an MRI reveals lesions typical of MS, your doctor does not need to order additional tests to make a diagnosis.
If an MRI scan does not indicate a definitive diagnosis, doctors may perform a lumbar puncture, or spinal tap, to look for markers of inflammation in the central nervous system.
After injecting a local anesthetic, the doctor inserts a thin needle into the lower back and removes a sample of cerebrospinal fluid. This fluid surrounds and cushions the brain and spinal cord and helps distribute important nutrients within the central nervous system.
The procedure takes about 30 minutes from start to finish, and you can go home two hours after the procedure.
Certain substances in the cerebrospinal fluid can help your doctor to determine if your immune system is overactive, meaning that the body is mistakenly attacking its own tissues. Elevated levels of immunoglobulin—a protein produced by blood cells—in the spinal fluid suggest inflammation.
Additionally, many people with MS are found to have oligoclonal bands of immunoglobulin that are produced in the central nervous system. These proteins are also associated with inflammation and are not usually detected in people who do not have MS.
Doctors send the cerebrospinal fluid sample to a laboratory, where it is analyzed for these substances that indicate an abnormal autoimmune response, which may indicate multiple sclerosis. This autoimmune response can indicate diseases other than MS as well. In addition, about 5 percent to 10 percent of people with MS are never found to have substances in the cerebrospinal fluid that would indicate an abnormal autoimmune response.
A spinal tap also helps the doctor to rule out other conditions that may cause central nervous system dysfunction, such as an infection. The most common side effects of a lumbar puncture include mild pain at the injection site and headaches.
By itself, a spinal tap cannot confirm or rule out a diagnosis of MS. It is used as a piece of the diagnostic puzzle, which takes into account a person’s symptoms and medical history as well as the results of a neurological exam and other diagnostic tests, such as MRI.
Evoked Potential Test
Evoked potential testing measures electrical activity in certain areas of the brain, such as responses to stimulation of specific nerve pathways. This test is performed in a doctor’s office and is often used to help make a diagnosis of MS. It can indicate problems along these nerve pathways.
In order to measure evoked potentials—or responses—specialists place electrodes on the scalp over the area of the brain being tested. The examiner then provides gentle electronic stimulation and records the person’s responses.
The test is painless and very sensitive. It can detect lesions—or damaged areas—in the brain or spinal cord and usually takes about two hours to complete. The results of evoked potential testing can help doctors to make a diagnosis of MS.
If you are diagnosed with MS, you can talk to one of the Multiple Sclerosis Comprehensive Care Center physicians and learn about available treatment and management options. You also can also meet with the other members of the team, including our nurses and nurse practitioners, who can help to address any questions you may have.
Our specialists can provide specific recommendations about how to manage any symptoms you are experiencing. They can also share important educational materials about how to understand your diagnosis and manage your treatment.
Many people find it beneficial to meet with one of the Multiple Sclerosis Comprehensive Care Center social workers or our on-site psychologists to discuss the emotional consequences of living with a chronic illness and the ways in which this affects your family and work.