Diagnosis

History
The symptoms of multiple sclerosis vary significantly from person-to-person but usually begin in the second or third decade of life.

Symptoms often develop with decreased sensation and visual difficulties.  This may occur in isolated areas initially and then spontaneously improve over days or weeks.  These types of symptoms often recur, which causes the individual to seek an evaluation by a physician.

Other symptoms that can initially be seen in multiple sclerosis include:

• Weakness
• Vision problems (blurred vision, decreased ability to focus, pain in the eye with movement)
• Double vision
• Balance problems
• Cognitive problems (memory, attention, concentration)
• Fatigue
• Bladder problems
• Bowel problems
• Speech problems

The most important component of the history in the diagnosis of multiple sclerosis is the separation of symptoms by time with a different location of the central nervous system being affected.  This is often referred to as a separation in time and space. For example, one could initially experience decreased vision in one eye and then have weakness or numbness in an arm or leg.  This demonstrates that the disease process is affecting different parts of the central nervous system and that it is an ongoing, or recurrent, process.

Physical Exam
The physical exam focuses on the neurological examination and includes tests of strength, sensation, vision, reflexes, and walking.  In early multiple sclerosis, an area of slight numbness or visual difficulty may be the only symptom present or it may have a more aggressive presentation with more significant symptoms such as weakness or walking difficulty.  During a physical examination, the physician may identify findings that suggest involvement of the brain and spinal cord.

Diagnostic Tests
• Laboratory Studies
There is no blood test that can be used to diagnose multiple sclerosis.  However, there are blood tests that are frequently done to rule out diseases that can mimic multiple sclerosis.  Test that are often ordered to rule out other diseases include vitamin B12, folate, erythrocyte sedentary rate (ESR), anti-nuclear antibody (ANA), rapid plasma regain (RPR), and thyroid tests.  If an individual has been in an area with Lyme disease or has recently been bitten by a tick, then Lyme disease testing may be indicated.  

• Cerebrospinal Fluid (CSF)
Cerebrospinal fluid (CSF) may be used to assist in the diagnosis of multiple sclerosis.  CSF is obtained through a lumbar puncture (also known as a spinal tap) with a needle through the lower back. There are no tests or findings of the CSF that are absolutely diagnostic for multiple sclerosis.  However, the amount and type of antibody in the CSF may assist in the diagnosis.  Specifically, antibodies in the CSF that are not in the blood (oligoclonal bands) or increased amounts of antibodies in the CSF (measured with the IgG index or IgG synthesis rate) are indicative of multiple sclerosis.

• Magnetic Resonance Imaging (MRI)
Magnetic resonance imaging (MRI) is the test of choice in assisting in the diagnosis of multiple sclerosis.  Alone, the results of the MRI do not diagnose or exclude multiple sclerosis.  MRI can be performed with an intravenous material called gadolinium, which can show areas of inflammation in multiple sclerosis.  MRI is typically done of the brain, but, for some people it may also be important to obtain MRI of the spine.

• Evoked Potentials 
MRI is an excellent tool for showing the structure of the central nervous system.  However, it does not provide any measurement of the function of the nervous system.  Evoked potentials are tests that do measure function.   With evoked potentials, an electrical stimulus is applied outside the body and then recorded at another location as it travels through the nervous system.  When demyelination occurs, the speed of the electrical transmission may be reduced or blocked.   Evoked potentials can be used to test vision, hearing, or sensation.  Visual evoked potentials (VEPs) can be used during the diagnostic evaluation of multiple sclerosis.  During this test, blinking lights or a flashing checkerboard are presented to the patient while electrodes on the scalp record electrical activity in the brain.  A delay in normal transmission time is suggestive of optic nerve injury which may be seen in multiple sclerosis.

• Summary of Diagnostic Tests
The above components of history, physical exam, and laboratory tests are combined to determine the probability of a diagnosis of multiple sclerosis.  However, a diagnosis cannot be made unless all other potential conditions that may mimic multiple sclerosis are ruled out and a re-occurrence of symptoms or MRI lesions occurs which is separated by time and space.

Making an MS Diagnosis
Prior to 2001, the Poser Criteria were used for determining the diagnostic categories for multiple sclerosis.  Individuals who were thought to have MS were divided into Definite MS, Probable MS, and Possible MS.  This criteria were based on clinical signs and symptoms and did not incorporate MRI findings.

In 2001, the International Panel on the Diagnosis of Multiple Sclerosis revised the Poser criteria to take advantage of the usefulness the MRI, cerebral spinal fluid, evoked potentials, and spinal cord lesions.  This new criteria is referred to as the McDonald Criteria after the chair of the Panel, Dr. W.I. McDonald.  The Panel wanted to clarify and simplify the diagnostic criteria so that it could be used by all practicing physicians.  Previously used terms were eliminated and replaced with three possibilities--these include "MS", "possible MS", or "not MS."

In 2005, the International Panel on the Diagnosis of Multiple Sclerosis further revised the McDonald criteria.  The 2005 revisions to the McDonald Criteria were based on research since 2001.  The aim of the revisions was to simplify and speed the diagnosis of multiple sclerosis so that appropriate treatments could be started earlier. One of the advantages of the McDonald Criteria is that, through the use of MRIs, they greatly assist in the early diagnosis of multiple sclerosis. 

 Possible Future Diagnostic Tests

• Specialized MRI Techniques
MRI techniques are currently being developed that will increase our ability to detect MS lesions.  In addition, these techniques may allow us to visualize and monitor more subtle inflammatory and degenerative changes in the central nervous system.

• Optical Coherence Tomography (OCT)
An ophthalmological test known as optical coherence tomography, or OCT, has undergone recent investigation in MS.  Several studies indicate that this simple, non-invasive test, which measures the thickness of the nerve fibers in the back of the eye, may be very helpful for monitoring MS-related nerve fiber loss (degeneration).  In the future, this test could be used in clinical trials to determine the effectiveness of experimental medications or in clinical practice to assist in diagnosing and monitoring MS.