How to diagnose multiple sclerosis?
Diagnosing multiple sclerosis at the first visit to your physician is really challenging. Your physician will evaluate you, review your family and past medical history as well as your symptoms. A young women with optic neuritis (complaining of painful eye movements and diminished vision) should be throughly searched and followed up for MS. There are several tests to diagnose multiple sclerosis and rule out other conditions that may have similar signs and symptoms.
It is done to rule out some other infectious or inflammatory diseases that share the symptoms similar to multiple sclerosis.
Spinal tap (lumbar puncture)
In this procedure, a needle is inserted into your lower back to remove a small amount of spinal fluid for laboratory analysis. It is indicated if the diagnosis is uncertain and neurological presentation and neuroimaging raises the suspicion of CNS infections. Up to 5% patients with multiple sclerosis have normal CSF (cerebrospinal fluid or lumber puncture) finding. But the most common findings in CSF are:
Normal or slightly elevated protein
Oligoclonal bands in CSF (increased IgG level in CSF but not in serum)
Magnetic resonance imaging (MRI)
An MRI scan is the most useful test for confirming the diagnosis of multiple sclerosis. It uses powerful magnets and radio waves to produce detailed images of your brain, spinal cord and other areas of your body. An MRI reveal lesions (also known as plaques), which may appear due to myelin loss in your brain and spinal cord. You can't diagnose MS only on the basis of plaques as these types of lesions can also be caused by other conditions, such as lupus, sarcoidosis, Lyme disease, migraine, diabetes etc. In fact there are some common sites of demyelination in MS that help us to prefer this diagnosis over others.
Areas of demyelination (white areas) on an MRI scan (also called Dawson's fingers)
Usually some dye are injected into the blood vessels of the patients that may help highlight "active" lesions. Lesions that enhance with gadolinium reflect active disease. These enhancements correspond to breakdown of the blood brain barrier. If there is combination of enhancing and non-enhancing lesions, it reflects the chronic nature of the multiple sclerosis. Typical lesions appear as T2 hyperintense lesions in the periventricular white matter of the brain and spinal cord. A hypointense T1 lesion reflect axonal damage.
Evoked potential test
This test was popular before the MRI facility was available. This test measures electrical signals sent by the brain in response to a visual or auditory stimuli. If there is demyelination, there should be a delay in the response of the brain. This delay is detected in evoked potential. It can detect damage in your optic nerves, brain or spinal cord.