Nervous System Functioning
Testing of reflexes, balance, coordination, and vision— as well as checking for areas of numbness
Tests may include the following:
Evoked potentials (EP) to measure how quickly nerve impulses travel along the nerve fibres in various parts of the central nervous system.
Computer-assisted tomography (CT) to scan the central nervous system using an x-ray technique which can detect areas of demyelination.
Magnetic resonance imaging (MRI) to scan the central nervous system, without the use of x-rays. More sensitive than the CT scan, MRI can detect areas of demyelination that may not be seen by the CT scanner.
Lumbar puncture or spinal tap to draw out cerebrospinal fluid. The fluid is examined for increased levels of gamma globulin and oligoclonal banding. The results may not definitively pinpoint MS, but they may help confirm the diagnosis.
Two Basic Signs are Required to Confirm MS
- Signs of disease in different parts of the nervous system
- Signs of at least two separate relapses (also called flare-ups or exacerbations) of the disease
Diagnosis: The Basic Facts
MS is a disease of the central nervous system. The central nervous system consists of the brain, spinal cord, and the optic nerves. Surrounding and protecting the nerve fibers (or axons) of the central nervous system is a fatty tissue called myelin, which helps nerve fibers conduct electrical impulses.
In MS, myelin is lost in multiple areas, leaving scar tissue called sclerosis.
These damaged areas are also known as plaques or lesions. Sometimes the underlying nerve fiber (or axon) is also damaged or broken.
When myelin or the nerve fiber is destroyed or damaged, the ability of the nerves to conduct electrical impulses to and from the brain is disrupted, and this produces the various symptoms of MS.
MS is not contagious. No one can catch MS from another person.
There are no laboratory tests, symptoms, or physical findings that can, by themselves, determine if a person has multiple sclerosis. Furthermore, there are many symptoms of MS that can also be caused by other diseases. Therefore, the MS diagnosis can only be made by carefully ruling out all other possibilities.
The long-established criteria for diagnosing MS are:
There must be objective evidence of two attacks (i.e. two episodes of demyelination in the central nervous system). An attack, also known as an exacerbation, flare, or relapse, is defined clinically as the sudden appearance or worsening of an MS symptom or symptoms, which lasts at least 24 hours. The objective evidence comes from findings on the neurologic exam and additional tests.
The two attacks must be separated in time (by at least one month) and space (indicated by evidence of inflammation and/or damage in different areas of the central nervous system).
There must be no other explanation for these attacks or the symptoms the person is experiencing.
Over the last twenty years, tests such as magnetic resonance imaging, examination of cerebrospinal fluid, and evoked response testing have played an increasingly important role in the diagnostic process. In 2001, the International Panel on the Diagnosis of Multiple Sclerosis, chaired by W.I. McDonald, FRCP (Royal College of Physicians, London), issued a revised set of diagnostic criteria ( Annals of Neurology 2001; 50:121-127). In addition to the traditional requirements, the revision provided specific guidelines for using findings on MRI, cerebrospinal fluid analysis, and visual evoked potentials to provide evidence of the second attack in those individuals who have had a single demyelinating episode (called clinically isolated syndrome) and thereby confirm the diagnosis more quickly. These guidelines also facilitated the diagnostic process in those patients who have had steady progression of disability without distinct attacks.
Since 2001, the McDonald Criteria for Diagnosis of MS have been used worldwide. The International Panel, chaired by Chris Polman, MD, reconvened in March 2005 to consider extensive data that had been collected since 2001 and to recommend appropriate revisions to the criteria. These revisions, termed the 2005 Revisions to the McDonald Diagnostic Criteria for MS. These revisions will help to enhance the speed and accuracy of an MS diagnosis.