Beginner's Guide to MS: How is MS Diagnosed?

Patient Expert

You know that something is not right and your doctor has referred you to a specialist.  Your next step is to Consult with a Neurologist.

The Neurologist

A neurologist is a medical doctor or osteopath who has trained in the diagnosis and treatment of nervous system disorders, including diseases of the brain, spinal cord, nerves, and muscles. Neurologists use diagnostic tools such as:
§  CAT (computed axial tomography) scan
§  MRI/MRA (magnetic resonance imaging/magnetic resonance angiography)
§  Lumbar puncture (spinal tap)
§  EEG (electroencephalography)
§  EMG/NCV (electromyography/nerve conduction velocity)

The Initial Appointment

Prepare in advance for your first visit to the neurologist. Compile a summary (or chronology) of your illness (and other diagnoses) which should include:
§ When did symptoms begin? What symptoms did you have at the beginning?
§ What brought on the symptoms or made them worse?
§ What other symptoms have occurred? When did they occur?
§ What tests have been done? What were the results?
§ What medications have you taken? What were the results of the treatment?
§ List all current medications with dosage and supplements you are currently taking.

Symptoms to Consider § Changes in Vision
§ Vertigo
§ Weakness and/or numbness in arms/hands/legs/feet
§ Coordination problems in arms or legs
§ Balance problem
§ Trouble walking or falling
§ Speech problems
§ Memory loss/cognitive problems
§ Confusion/hallucinations
§ Decreased attention/concentration
§ Poor judgement/reasoning
§ Depression/anxiety
§ Fatigue (constant or intermittent)
§ Bladder or Bowel problems
§ Sexual dysfunction

The neurologist will want to discuss your current symptoms and history of symptoms, as well as other diseases you may have and those of your immediate and extended family members. Be as accurate and truthful as possible. After the interview, the doctor will conduct a neurological exam looking for clinical evidence of impairment of the central nervous system, which includes the brain, spinal cord and optic nerves.


Evidence of damage in at least two separate areas of the central nervous system (dissemination in space), AND, Evidence that the damage occurred at least one month apart (dissemination in time), AND, Elimination of all other possible diagnoses

The Revised McDonald Criteria (2010) includes the following:
§ At least two attacks with objective clinical evidence of at least two lesions;
§ At least two attacks with objective clinical evidence of one lesion plus dissemination in space shown on MRI, or positive CSF finding with two or more MRI lesions consistent with MS, or second clinical attack;
§ One attack with objective clinical evidence of at least two lesions plus dissemination in time on MRI, or second clinical attack;
§ One attack with objective clinical evidence of one lesion plus dissemination in space shown on MRI, or positive CSF finding with two or more MRI lesions consistent with MS, AND dissemination in time shown on MRI, or second clinical attack;
§ Insidious neurologic progression suggestive of MS plus one year of disease progression determined retrospectively or prospectively, AND two of the following: positive brain MRI result (nine T2 lesions or at least four T2 lesions with positive Visual Evoked Potential), positive spinal cord MRI result with two focal T2 lesions, and positive CSF findings.

For a brief explanation of how lesions develop, see Beginner's Guide to MS: What is Multiple Sclerosis?

Dissemination in time is shown by detection of gadolinium enhancement at least three months after the onset of the first clinical event or detection of a new T2 lesion appearing at any time compared with a reference scan done at least 30 days after the onset of the initial clinical event.** Dissemination in space** is shown by three of the following: one or more gadolinium-enhancing lesions or nine T2 hyperintense lesions; one or more infratentorial lesions; one or more juxtacortical lesions; or three or more periventricular lesions.

For a history of the criteria used in the diagnosis of multiple sclerosis from 1965 to the present, see Beginner’s Guide to MS: The History of Diagnostic Criteria.

TESTS USED TO DIAGNOSE MULTIPLE SCLEROSISComplete Neurological Exam—This exam evaluates the nerves of the head and neck; muscle strength and movement; balance, ambulation, and reflexes; and sensation, memory, speech, language, and other cognitive abilities.

Magnetic Resonance Imaging—MRIs can show inflammation, demyelination, and permanent damage, in persons with MS. They are one tool used to show dissemination in time and space, as required in the diagnostic criteria, and should be conducted with and without gadolinium contrast agent.

Evoked Potential Tests—These tests record the nervous system's electrical response to the stimulation of specific sensory pathways (e.g., visual, auditory, general sensory). A slowed response time can sometimes provide evidence of scarring along nerve pathways that does not show up during the neurological exam. For a more detailed discussion of Evoked Potential Tests and their role in diagnosis MS in addition to other diseases, see Clinical Utility of Evoked Potentials.

Cerebrospinal Fluid Analysis—Obtained by lumbar puncture (i.e., spinal tap), cerebrospinal fluid (CSF) is analyzed to detect the levels of certain immune system proteins and the presence of oligoclonal IgG bands (not found in blood serum) or elevated IgG antibodies. These bands indicate an immune response within the CNS and are found in the CSF of about 90-95% of people with MS. But because they are present in other diseases as well, oligoclonal bands cannot be relied upon as positive proof of MS.

Blood Tests—While there is no definitive blood test for MS, blood tests can rule out other conditions that cause symptoms similar to those of MS, including Lyme disease, a group of diseases known as collagen-vascular diseases, certain rare hereditary disorders, AIDS, and vitamin B12 deficiency.


The term clinically isolated syndrome (CIS) has been used to describe a first neurologic episode that lasts at least 24 hours, and is caused by inflammation/demyelination in one or more sites in the central nervous system (CNS). The episode can be monofocal or multifocal:

  • Monofocal episode—The person experiences a single neurologic sign or symptom—for example, an attack of optic neuritis—that’s caused by a single lesion.
  • Multifocal episode—The person experiences more than one sign or symptom—for example, an attack of optic neuritis accompanied by weakness on one side—caused by lesions in more than one place.

What is the risk for a person with CIS to develop MS? Individuals who experience CIS may or may not go on to develop multiple sclerosis. The challenge for the physician is to determine the likelihood that a person experiencing this type of demyelinating event is going to experience a second demyelinating event in the future, thereby meeting the criteria for a definite diagnosis of MS.

  • High Risk—When CIS is accompanied by MRI-detected brain lesions that are similar to those seen in MS, the person has a high risk of a second neurologic event, and therefore a diagnosis of clinically definite MS, within several years.
  • Lower Risk—When CIS is not accompanied by MRI-detected lesions, the person has a lower risk of developing MS over the same time period.

In 85% of young adults with MS, onset of disease began with a subacute CIS of the optic nerves, brainstem, or spinal cord. Only 30-70% of patients with CIS develop MS. When clinically silent brain lesions are seen on MRI, the likelihood of developing MS is high. MS can be diagnosed within 3 months of CIS presentation with certain MRI and CSF criteria. Disability from MS is less likely in patients with CIS of optic neuritis or sensory symptoms only, few or no MRI lesions, a long period to the first relapse, and no disability after the first 5 years.

RADIOGRAPHICALLY ISOLATED SYNDROME (RIS)The term radiographically isolated syndrome (RIS) is used when lesions that resemble MS are detected on MRI scan in a patient without clinically symptoms of MS. A 2008 study that followed asymptomatic patients who were found to have anomalies highly suggestive of MS on MRI scans performed for other diagnostic reasons showed that about one-third of these patients progressed to clinically isolated syndrome (CIS) or definite MS over a time frame of 5 years. Follow-up is recommended in patients with RIS. RULING OUT OTHER CONDITIONS

Other conditions that can damage myelin in the CNS include viral infections, side effects from high exposure to certain toxic materials, severe vitamin B12 deficiency, autoimmune conditions that lead to inflammation of blood vessels (the "collagen-vascular diseases"), and some rare hereditary disorders. Demyelination of the peripheral nervous system (the nerves outside the brain and spinal cord) occurs in Guillain-Barré Syndrome. Since some demyelinating conditions are self-limiting, while others may be progressive, careful and sometimes repetitive examinations may be needed to establish an accurate diagnosis.

SOURCES: Neurology Center of Fairfax - Forms for New Patients with Multiple Sclerosis.

National Multiple Sclerosis Society - Diagnosing Multiple Sclerosis.

Miller D, Barkhof F, et al. Clinically isolated syndromes suggestive of multiple sclerosis, part I: natural history, pathogenesis, diagnosis, and prognosisLancet Neurology.  2005 May; 4(5):281-8.