Diagnosis:

Multiple sclerosis is characterized by recurring neurologic episodes that are due to multiple lesions (injured areas) in different locations in the central nervous system.

Most patients first seek medical help after an initial inflammatory event (known as a clinically isolated syndrome) originating from demyelination in the eye, the spinal cord, or the brain. About 30% of these individuals will develop progressive MS within the year. At this time, however, experts cannot predict who among these patients are at highest risk for rapid progression.

The McDonald Criteria. No single test can accurately diagnose MS, and a number of other conditions may mimic its symptoms. Some doctors use a set of factors, called the McDonald criteria, for diagnosing multiple sclerosis in early stages. The criteria include the presence of specific symptoms, spinal fluid evaluation, and magnetic resonance imaging techniques for detecting lesions within the central nervous system and tracking them over time. The criteria show high reliability in identifying MS in patients with a variety of disease stages or states, including having only one episode, a typical relapsing-remitting course, or a slow insidious progression without clear attacks or remissions. Depending on the MRI and other findings, the patient is then categorized as having MS, possible MS, or no MS.

Ruling out Other Disorders

The symptoms of MS are similar to a number of other diseases that must be ruled out. These conditions include stroke, alcoholism, emotional disorders, Lyme disease, chronic fatigue syndrome, fibromyalgia, AIDS, cervical spondylosis, certain neurologic degenerative illnesses, transverse myelitis, and certain other autoimmune disorders (hypothyroidism, scleroderma, Sjögren syndrome, vasculitis and systemic lupus erythematosus).

Expanded Disability Status Scale

Doctors and investigators generally use a test called the Expanded Disability Status Scale (EDSS) to rate the severity of symptoms. It is also used after a diagnosis to gauge the status of the disease, and score the effectiveness of treatments. The scale ranges from 0 to 10, with higher scores indicating more severe symptoms. These are subjective ratings that require doctor observation skills.

Objections to the use of the EDSS are that it assesses only limp and walking problems and does not assess other important complications, including fatigue, sexual function, and mental function.

Laboratory Tests

No reliable single laboratory procedure or test can establish the diagnosis of multiple sclerosis. Several are necessary before a diagnosis can be made.

Analysis of Cerebrospinal Fluid (CFS). Obtaining a sample of spinal fluid requires a lumbar puncture, or spinal tap. Testing spinal fluid is becoming increasingly important for detecting abnormal proteins, tiny fragments of myelin, or specific white blood cells that can help in making a diagnosis. For example, high levels of the immunoglobulin IgG is useful for making a diagnosis and may be a marker for disease progression. (Immunoglobulins are protein chains that are part of the immune system.)

A lumbar puncture, or spinal tap, is a procedure to collect cerebrospinal fluid to check for the presence of disease or injury. A spinal needle is inserted, usually between the 3rd and 4th lumbar vertebrae in the lower spine. Once the needle is properly positioned in the subarachnoid space (the space between the spinal cord and its covering, the meninges), pressures can be measured and fluid can be collected for testing.

Evoked Potential (EP) Test. This is a simple and painless electrical test of nerve function that assesses how long it takes nerve impulses from the eye, ear, or skin to reach the brain.

Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) scans are important diagnostic tools in MS and are used for diagnosing multiple sclerosis, tracking changes over time, and helping to determine treatment effectiveness.

Making a Diagnosis and Tracking the Disease. Magnetic resonance imaging (MRI) scans can detect bright patches that indicate injured tissue (lesions) caused by MS. Such lesions may also indicate other conditions, such as infections, migraines, or clots. Importantly, a very sensitive MRI technique using enhancement by a contrast material called gadolinium can indicate recent activity by showing if the blood-brain barrier has been broken down (the first step in the development of MS lesions). Detecting lesions and treating MS early in the disease process may help reduce progression. Many experts therefore now advocate performing a brain MRI as soon as symptoms appear.

Once diagnosed, periodic follow-up MRIs can be used to track the disease and effectiveness of treatments in two ways:

• By distinguishing new lesions from old ones
• Revealing increasing or decreasing numbers of lesions within the central nervous system over time

Unfortunately, neither the rate nor the number of new or growing lesions necessarily predicts whether symptoms will worsen or if the patient will develop secondary progressive MS.

Measuring Atrophy in Brain and Spinal Cord. As myelin, axons, oligodendrocytes, and neurons are destroyed, the brain begins to shrink. Processing MRI images to determine brain volume may be a useful way to monitor progression and treatment effects. MRI can also detect shrinkage in the spinal cord, which is proving to be a very strong marker of disease progression. A variation of MRI, magnetic resonance spectroscopy (MRS), provides information on the biochemistry of the brain, and may be particularly helpful in detecting this destructive aspect of MS.

Detecting "Black Holes." Severe disease progression can be gauged by the presence of so-called "black holes.” These are lesions in the brain that emit very low signals on an MRI scan. Some evidence suggests that they may represent iron deposits in the brain.