If your neurologist suspects MS, she'll probably schedule a battery of tests that may help confirm her suspicions. While this may sound pretty straightforward, getting a firm diagnosis can be a frustrating process for some. One reason is that MS can mimic other diseases and they must first be excluded. This is called a differential diagnosis — a list of diseases that are similar to MS that must be ruled out by your doctor.

Since there are many potential symptoms associated with MS, there are a large number of conditions that are clinically similar. A few of the diseases that have similar symptoms to MS include:

• Lyme disease. An infection caused by bacteria that is carried by deer ticks. Lyme disease can cause symptoms similar to MS, including fatigue, muscle weakness, and sensory symptoms such as pins and needles sensations.

• Vitamin B12 deficiency. A deficiency of vitamin B12 in the body can cause multiple neurological symptoms including numbness and tingling in the hands and feet, fatigue, and muscle weakness.

• Acute disseminated encephalomyelitis (ADEM). A demyelinating neurological disease characterized by inflammation of the brain and spinal cord. ADEM is characterized as an autoimmune disease.

• Sarcoidosis. A disease that causes inflammation in the tissues of multiple organs, including the brain and spinal cord.

• Sjögren's syndrome. An autoimmune disease in which the immune system of the body attacks its own moisture-producing glands. CNS symptoms may include fatigue, weakness, and walking difficulty.

• Lupus. An autoimmune disease that can cause inflammation and damage to almost any part of the body, including the heart, lungs, kidneys, blood vessels, or brain. As with MS, symptoms may come and go.

In addition to this list, there are other diseases that mimic MS; in fact, as many as 10 percent of people diagnosed with the disease actually have another condition, including strokes, tumors, and the diseases and disorders mentioned above. Once your neurologist has ruled them out — performed the necessary tests to exclude them from the list — she may conduct procedures that often help in pinpointing MS. These include obtaining a thorough medical history from the patient, imaging techniques, lumbar punctures, evoked potentials (a test that measures the time it takes for nerves to respond to stimulation), and laboratory examination of blood samples.