Unlike many other diseases, there is no straightforward ‘positive or negative’ test for MS and none of the range of tests available to help doctors with their diagnosis is 100 percent conclusive on its own.

This means that ultimately a doctor will diagnose MS by a combination of observing a person’s symptoms, and ruling out other possibilities. This is called a ‘clinical diagnosis’.

Problems with diagnosis

Unfortunately for a significant minority of people (10–15 percent) a definite diagnosis is still not possible even after all the available tests have been carried out. However, it is possible to rule out other very serious causes of MS type symptoms, and over time with periodic examinations and the monitoring of changes in a person’s condition, diagnosis is possible in the vast majority of cases.

New MS Diagnostic Criteria

MSIF’s International Medical and Scientific Board have drawn up new MS diagnostic criteria to help medical professionals distinguish between MS and other conditions that may present similar symptoms. The new criteria allow the results of MRI scanning to included so that it may be possible to diagnose MS when someone has had only one episode of symptoms. When the new criteria are used, a person may be classified as having MS, possible MS or not MS.

Diagnostic Criteria for Multiple Sclerosis:
2005 Revisions to the “McDonald Criteria” (79 kb)

Clinical diagnosis

Early MS may present itself as a history of vague symptoms, which may occur sporadically over a prolonged period of time and could often also be attributed to a number of other medical conditions. Invisible or subjective symptoms are often difficult to communicate to doctors and health professionals and sadly it has not been uncommon for people with MS to be treated unsympathetically in the very early stages of diagnosis.

Even when a person shows a ‘classic’ pattern of MS type symptoms, the symptoms must conform to agreed criteria before a doctor or neurologist can diagnose clinically ‘definite’ MS. These criteria are that:

‘Two different areas of the central nervous system are affected, and that these effects have been experienced on at least two separate occasions of at least one month apart and that the person is within the normal age range for the onset of MS’

So although it is possible to be diagnosed as having ‘definite’ MS on your first visit to a neurologist, it is also quite likely that the diagnosis will be uncertain, and that the person will be referred for further tests.