A diagnosis of multiple sclerosis (MS) is usually made by your primary care provider or specialist in conditions of the brain and nervous system (neurologist). To diagnose MS, your health care team must rule out other possible causes of your symptoms. Doctors use a variety of strategies to do this, including taking a thorough medical history and conducting a neurologic exam and screening tests. They may order cerebrospinal fluid analysis and magnetic resonance imaging (MRI) scans of the brain and spine to check for MS-related changes in tissue. They may also order nerve function studies, such as evoked potential tests that measure the speed at which messages move from one area of the body to another.
Symptoms of MS come in the form of attacks that last for days, weeks or months. These are called relapses or exacerbations, and they are followed by periods of disease inactivity, known as remissions. The location and severity of an attack may vary, and they can be triggered by things such as fever, hot baths, sun exposure or stress. Symptoms can affect many parts of the body, and they can range from difficulty walking or speaking to severe fatigue.
There are different types of MS, but about 85% of people with the condition are diagnosed with relapsing-remitting MS. This is the most common form of the disease, and it involves episodes of new or worsening symptoms that are followed by remissions. In relapsing-remitting disease, the progression of disability is slower than in other forms of MS.
Your neurologist may also suspect a diagnosis of MS if you have had a single episode with certain characteristics, called the McDonald criteria. The neurologist will take a detailed medical history and do a neurologic exam to determine your symptoms and how they have changed over time. They will also examine for other disorders that can cause similar symptoms, such as trigeminal neuralgia, a chronic pain condition that causes sudden, burning or shock-like facial pain.
An MRI scan can detect demyelinating lesions that damage the sheath that protects nerve fibers. When these lesions occur, signals do not travel properly, and your neurologist will consider this evidence of MS. A neurologist will also look for two areas of decreased function in the central nervous system at different times to make a diagnosis of relapsing-remittingMS.
Blood tests and spinal fluid analysis may also be done to check for antibodies that are typical of MS. These are called oligoclonal bands and help confirm the diagnosis. Your neurologist will also do a lumbar puncture or spinal tap to obtain a sample of your cerebrospinal fluid, and they will perform an MRI to analyze the fluid for MS-related changes in tissue. This test will also rule out other diseases that can mimic the symptoms of MS.
