How Is Multiple Sclerosis Diagnosed?

Multiple sclerosis (MS) is a condition of the central nervous system—which includes the brain and spinal cord. It develops when your immune system attacks the protective myelin sheath around your nerves. MS affects the whole nervous system, so symptoms can be unpredictable and varied. Although most cases of MS are mild, you can experience reduced vision, movement, memory, and more.

Usually, this condition can develop in people aged 20–40. The most common type of MS is relapsing-remitting MS (RRMS): Your symptoms can flare up during a relapse period, which is then followed by a remission period—when there are reduced or no symptoms.

There’s no single test that diagnoses MS. But your healthcare provider, like your primary care provider or neurologist (who specializes in nerve conditions), can usually diagnose MS from your symptoms. They’ll start by asking about your medical history and test your brain-related functions, like your motor skills and eyesight. Then, they will use brain imaging, blood tests, and other procedures to confirm a diagnosis.

How long the diagnosis takes will depend on the number of tests you’ll need. Here’s what you can expect during the process.

Medical History

Discussing your symptoms and medical history with a healthcare provider is the first step toward an MS diagnosis. Common symptoms include: 

• Seeing double (double vision), eye pain, vision loss, or swelling of the optic nerve (which connects your brain to your eye)
• Having imbalance when walking or vertigo (the feeling that you and your direct environment are spinning)
• Weakness, shaking, or fatigue
• Numbness, feeling “pins and needles,” or abnormal burning and tingling in the skin
• Constipation, diarrhea, or incontinence (trouble holding your urine)
• Memory issues or trouble concentrating
• Depression or anxiety
• Difficulty speaking or swallowing

You don’t have to experience all types of symptoms at once to have MS. You may not experience symptoms at all if you’re in remission. 

Although what causes MS is not known, experts suspect the disease may be a result of hereditary risk, environmental factors, and factors within your immune system. When discussing your medical history, your provider will also ask about your family history, living environment, other health conditions, and the places you’ve traveled. It’s important to share as much of your personal history as you can.

Physical and Neurological Exam

After learning about your medical history, your healthcare provider will perform a neurological exam to test how well your brain and spinal cord are working. They may use different tools to examine the following:

• Vision: This may involve a flashlight or other eye tool to check for uncontrolled movements, double vision, and pain in your eyes. 
• Hearing: This can include using a tuning fork to test whether you have a loss of hearing.
• Muscles and nerves: Your provider may use a reflex hammer to check your muscle response and body coordination. They can check your ability to swallow or if you have signs of shaking, weakness, muscle spasms, and overactive reflexes. 
• Kidneys and urinary tract: Lab tests based on your blood and urine samples can check your kidney function. Your provider might also use ultrasound or a catheter (a thin tube inserted into the urethra) to determine if you have urinary retention (leftover urine in your bladder after peeing).
• Genitals: If you have a penis, your provider may teach you how to do a nocturnal penile tumescence stamp test, which can determine whether you have erectile dysfunction.
• Mental health: Your provider can ask about your recent mood and behaviors to determine if you have depression or anxiety.

Types of MS

Depending on how often you experience symptoms, a healthcare provider can determine what type of MS you have. There are four main types:

• Clinically isolated syndrome (CIS): This is the first MS attack—when you have never had any previous symptoms of MS and you don’t have a fever or infection. Symptoms can happen suddenly, flaring for at least 24 hours, and can last a few days or weeks. 
• Relapsing-remitting MS (RRMS): This is the most common type of MS. During a relapse, your symptoms can flare up within 24–48 hours and develop over several days to weeks. You can usually recover from symptoms after several weeks or months, with or without medication. Afterward, you enter remission—a period of little to no symptoms.
• Secondary progressive MS (SPMS): This type happens after a case of relapsing-remitting MS has worsened, usually about one to two decades since you first developed MS. You can have more frequent or different types of symptoms that relapse at the same time.
• Primary progressive MS (PPMS): This is characterized by a gradual worsening of symptoms over time since the start of developing MS. There are fewer relapse and remission periods with this type. 

Additional Tests to Confirm an MS Diagnosis

Your healthcare provider or neurologist may refer you to other specialists. The following tests can help confirm your diagnosis and exclude other conditions with similar symptoms.

MRI

A magnetic resonance imaging (MRI) test is a non-invasive procedure that uses radio waves and a magnetic field to capture images of the body. This method does not use radiation. A radiologist can take an MRI of your brain and spinal cord to determine the severity, shape, and location of any nerve damage. They can use MRIs to determine whether you have MS or another condition, as well as to track your condition long term, such as by detecting new areas of nerve damage.  

Cerebrospinal Fluid Analysis

Your brain and spinal cord tissues have a protective layer of cerebrospinal fluid (CSF). Using a CSF analysis, a healthcare provider can remove a small amount of CSF and examine it for signs of neurological diseases. 

CSF analysis is especially useful for diagnosing early stages or rare forms of MS. It can also help rule out other nervous system conditions and viral infections. 

The procedure to collect CSF is a spinal tap (also called a lumbar puncture). You’ll get a local anesthetic injection in your back to numb any pain. A healthcare provider will then use a special needle to take some fluid (about 3 teaspoons) from your spinal sac.

Blood Tests

A healthcare provider can use blood tests to rule out other conditions that may cause similar symptoms. These blood tests may measure:

• Cholesterol
• Thyroid-stimulating hormone (TSH)
• Electrolytes
• Vitamins D and B12
• Blood cell counts

Your healthcare provider can use these measurements to analyze your liver and kidney function, inflammation, and immune system activity. 

Brain Signal Tests

A neurologist can use an evoked response test (also called evoked potentials) to monitor your brain signals as you hear, touch, and see. Your doctor will apply a special paste to your scalp and attach electrodes that are connected to a machine. This test can help determine if you have MS. In people with MS, signals sent through the nerve cells travel at a slower speed.

Screening for Related Conditions

MS symptoms vary widely, so it’s essential to rule out similar diseases, such as lupus, neuromyelitis optica (NMO) spectrum disorders, acute disseminated encephalomyelitis (ADEM), and Sjögren’s syndrome—all of which can affect your central nervous system. Your provider may also order tests for specific conditions, including:

• Optical coherence tomography (a non-invasive imaging test for your retina) or other eye examination
• Urodynamic testing (study of your bladder and urethra function)
• Tests for specific infections such as Lyme disease, syphilis, or human immunodeficiency virus (HIV)
• Cognitive testing
• Hearing tests
• X-ray imaging
• Biopsy (a procedure that removes cells or tissue from your body to check for damage or disease)
• Heart tests such as an echocardiogram

Your healthcare provider or neurologist will consider certain features of your disease to determine what additional tests, if any, are necessary. For example, they may consider your family history of neurological diseases other than MS and any experiences of headaches, weight loss, and fever. They’ll also get a detailed picture of the timing and seriousness of your symptoms.

A Quick Review

A timely diagnosis of multiple sclerosis can help you get the right treatment earlier. Be prepared to talk to a doctor or neurologist about your medical history—they may be able to determine whether you have MS based on your symptoms and a neurological exam. MRIs, blood tests, and cerebrospinal fluid analyses are also commonly used as diagnostic tools.