How is MS diagnosed?
Diagnosing MS isn't always easy and, in some cases, may take a long time. The first symptoms may be vague, and many of the symptoms can be caused by conditions other than MS. An accurate diagnosis is critical in creating an effective care plan.
An important feature of RRMS is “dissemination (or separation) in space and time,” meaning there must be evidence of two or more lesions that developed at different locations in the central nervous system at different time points. A patient must have experienced at least one clinical attack for a definitive diagnosis to be made.
According to the most recent guidelines (called the McDonald Criteria), the requirement for separation in time can be replaced by the finding of “oligoclonal bands” via a spinal tap test (see below).
In contrast, progressive MS is characterized by a gradual neurological decline, with or without superimposed clinical relapses, along with the presence of typical MS lesions in the brain and/or spinal cord, as revealed on MRI scans. Alternative diagnoses must be ruled out. The doctor will examine you, ask you questions about your symptoms and do some tests. Tests may help confirm or rule out the diagnosis when your history and exam don’t provide enough information.
Some of the tests used in MS diagnosis:
MRI (magnetic resonance imaging) is a common procedure that uses a magnetic field and radio waves to create detailed images of the brain and spinal cord. MRI is often used to confirm the diagnosis of MS, because the patches of damage (lesions) in the brain and spinal cord caused by MS attacks can be visualized using this technique. Even when inflammation subsides, a permanent scar is often left behind. MRI scans of the brain and different segments of the spinal cord are usually ordered individually. Scans may be done before and after administering a dye, called gadolinium, in order to highlight areas of active inflammation.
Blood tests check for vitamin deficiencies, infections and markers of alternative autoimmune diseases and inflammatory diseases of the CNS that cause symptoms that overlap with MS.
Lumbar puncture (spinal tap) can check spinal fluid for specific markers associated with MS. One important spinal fluid marker is called “oligoclonal bands,” which are inflammatory proteins present in the majority of individuals with MS.
Evoked potential tests measure the speed at which the brain tracks electrical signals in response to light, sound or touch stimuli. There are three types: visual evoked potentials measure signals triggered by watching an alternating checkerboard pattern; brainstem auditory evoked potentials measure signals triggered by a series of clicks in each ear; and sensory evoked potentials measures signals triggered by short electrical pulses on the arms or legs.
Optical coherence tomography (OCT) is an instrument that allows doctors to examine the retina (the lining at the back of the eye), which is often thinned in people with MS.
Tests used to diagnose health problems associated with MS:
Urinary tests, such as a bladder ultrasound, may be needed to help determine the cause of bladder control difficulties in a person who has MS, and to aid with symptomatic management.
Neuropsychological tests may be necessary to diagnose thinking or emotional problems, which may be present without the person being aware of them. Typically, these tests follow a question-and-answer format.
Blood tests may be ordered to help gauge the likelihood of side effects from a potential disease-modifying drug, or a drug used to alleviate symptoms. Such tests may include blood cell counts, liver function tests and tests to determine immunity against (and susceptibility to) certain viral infections. For example, a blood test for exposure to the JC virus can help you and your doctor gauge the risk for getting a rare but serious brain infection called PML (progressive multifocal leukoencephalopathy) that’s more common in patients taking specific disease-modifying therapies. In addition, your blood may be taken to measure your serum vitamin D level, since there is some evidence that low vitamin D levels are associated with increased MS disease activity.