Diagnosing Multiple Sclerosis and Evaluating Disease Activity

Diagnosing and evaluating MS disease activity is most reliably done by neurologists through a neurological history and examination. Tests that can indicate MS and rule out “MS mimickers” (other diseases that resemble MS but have other causes) are also performed.

Lesions (areas of inflammation and myelin damage in the brain and/or spine) may be viewed on a magnetic resonance imaging (MRI) scan. The MRI uses a computer, radiofrequency stimulator, and a large electromagnet to provide a picture of the brain and/or spine. While the picture looks a bit like an x-ray, please note that unlike an x-ray, the MRI does not expose the patient to any radiation.

For those with multiple sclerosis (MS), the MRI is used to evaluate the size and location of lesions. Inflammation can be better evaluated with gadolinium (or contrast) enhancement – a type of dye given to the patient via injection prior to the procedure.

An MRI image enables doctors to view lesions (areas of inflammation) and plaques (areas of scarring) as well as other changes in the CNS.

The MRI, particularly with gadolinium enhancement, allows doctors to measure disease activity within the central nervous system (brain, optic nerves, and spinal cord). Test results can help determine the effectiveness of a disease-modifying therapy (DMT), or to get an “inside view” of a patient’s disease status.

Another tool that is sometimes used in the diagnosis of MS is a lumbar puncture (also known as a spinal tap). This is a procedure where a very thin needle is inserted at the base of the spine and a small amount of cerebrospinal fluid (CSF) is collected. CSF is the liquid that surrounds the brain and spinal cord. By collecting a small amount of this fluid, laboratory testing may be performed to evaluate cellular and chemical abnormalities. Since the introduction of the MRI, CSF analysis is used less often, but it may be helpful in supporting an MS diagnosis if the MRI results are inconclusive.

Evoked potential (EP) tests may also be used to help diagnose MS, if further support is needed. These measure the speed of the brain’s response to visual, auditory (sound), or sensory (feeling) stimuli, using electrodes taped to the patient’s head. Delayed responses can indicate possible damage to the nerve pathways.

Biomarkers are measurable indicators of a health condition or worsening of that condition. With MS, these may be certain details viewed on imaging (MRI) or substances found in the blood or cerebrospinal fluid (CSF). Properly understood and utilized, they can provide laboratory scientists with critical guidance in developing new medications, help clinicians develop highly individualized treatment plans, and enable people with MS to make key decisions about their care in conjunction with their physician.

The study of biomarkers in MS is advancing quickly. One such measure is serum neurofilament light chain (sNfL), a protein that structurally supports the nerves of the central nervous system (CNS). When damage to these nerves occurs, these proteins break away from the nerves and enter the blood, also referred to as “serum.” The amount of serum NfL, or “sNfL” found in one’s blood, indicates how much damage is currently occurring, allowing the neurologist to monitor disease activity. Repeated testing over time allows the MS specialist to determine the effectiveness of one’s treatment regimen and if a change is indicated.

Measuring sNfL is proving to be an important biomarker for MS, and in December 2023, the Consortium of Multiple Sclerosis Centers (CMSC) published CMSC Best Practices for the Use of Serum Neurofilament in MS Management. As the guide is written for healthcare professionals, advocates for the MS community developed an accompanying guide for members of the MS community.