How is Multiple Sclerosis (MS) Diagnosed?
By themselves, there are no specific tests that can determine if a person has MS or is likely to have it in the future. Current diagnosis of definite MS involves both clinical (history and neurological exam) and paraclinical (MRI, Spinal Tap, Evoked potentials) evidence.
The diagnosis evolves from a discussion between the patient and the physician. A careful medical history is taken; symptoms and signs are assessed. Other ailments are ruled out. The diagnosis is highly dependent on the accuracy of the patient’s medical history and the physician's skill in eliciting and evaluating this information. The diagnosis is sometimes obvious and sometimes very difficult. Even in the hands of experts, the diagnosis is correct only 90 - 95 percent of the time.
The physician will ask about past surgeries, illnesses, allergies, any family neurological disorders including MS, geographic locations where you have lived, if adversely affected by heat, medications taken, history of substance abuse (alcohol, drugs, and tobacco).
During the neurological examination the physician will check for exaggerated reflexes such as Babinski's reflex, an upward movement of the big toe when the sole of the foot is stimulated. For patients with balance and gait difficulties, an eye examination is done to determine optic nerve damage.
The physician must be able to find neurological evidence of lesions or plaques in at least two distinct areas of the Central Nervous System white matter, evidence that the plaques have occurred at different points in time, and most importantly, that these plaques have no other reasonable explanation thus ruling out other illnesses that mimic MS.
For some patients no tests beyond medical history and neurologic exam are necessary to diagnose. However, most physicians will not rely entirely on this type of evaluation and will do at least one other test to confirm the diagnosis.
In this era, even a clear-cut diagnosis will usually be confirmed with an MRI of the brain, one of the major diagnostic tools currently used.
Major Diagnostic tools
MRI of the brain and spinal cord with contrast, FLAIR MRI (fluid-attenuated inversion recovery), evoked potentials, lumbar puncture (spinal tap) are the major diagnostic tools at this time.
MRI is the most sensitive non-invasive method available to detect areas of demyelination, (damaged myelin surrounding the nerves). MRI is safe and accurate providing the clearest evidence of white matter lesions in the CNS, and is also used to monitor the disease.
Flair MR with Echo-Planner technology significantly reduces the time necessary to complete the FLAIR sequence and the standard MRI, while giving a greater picture of lesions on the brain.
Evoked Potential Tests include VEP, BAEP'S, and SSEP'S. A painless procedure where electrodes are placed on the head and body. Response is recorded to determine where delays in nerve transmission occur.
- VEP (visual evoked potentials) an electrical response to repeated visual stimuli to detect optic neuritis.
- BAEP (brain stem auditory evoked potentials) detect abnormalities in patients with demylenating lesions in the brainstem which cause delays in the transmission of sounds.
- SSEP (somatosensory evoked potentials) delivers brief electrical stimulus to the wrist or ankle. Permits detection of disruptions in the pathways from the arms and legs to the brain at very specific positions of the CNS.
Spinal Fluid Analysis the brain, spinal cord are bathed in a fluid called cerebrospinal fluid (CSF). In some instances, the patient undergoes a lumbar puncture (spinal tap). This is done to make certain that some other disease is not masquerading as MS. The oligoclonal bands and the IgG index are abnormal in about 90% of MS patients.
(Last reviewed 7/2009)