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.
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.