Diagnosing of Multiple Sclerosis (MS)
While there is an accepted protocol for diagnosing of multiple sclerosis there is no single test at this point in time that is perfect every time. Diagnosing MS can be difficult, a neurologist will perform several tests and evaluate the results. As many as 10% of people today are still misdiagnosed with the disease.
A neurologist will perform a standard neurological examination to assist in evaluating movement and coordination functions, vision impairments, balance, speech function, muscle strength and other symptomatic criteria.
A blood test may be ordered. The blood test cannot positively diagnose multiple sclerosis the results are valuable however towards ruling out numerous other diseases where some symptoms mimic many of those found in MS.
Family Medical History
The family medical history will be discussed and it is important to be completely open about this aspect of diagnosing MS. While MS is not considered hereditary there are cases of MS where parents and their children do have the disease. The family medical history discussion can also help rule out other conditions that seem to mimic some multiple sclerosis symptoms.
Evoked Potentials Study (EPT)
Evoked potential (EP) studies are electrical activity tests that assist in determining a person’s nerve pathways are properly functioning. Signals are sent through the nervous system, visual, auditory (sound) and lastly hands and/or feet. The speed by which signals inputs are stimulated and the received is monitored along neurological pathways. Where damage has occurred due to demyelination the signals slow down. Evoked potentials tests help to differentiate whether symptoms are neurological or not. Evoked potentials help identify if a demyelinating event appears to have occurred and can locate deficits that the neurological examination did not.
Three types of evoked potential testing have been used in the past to help confirm a diagnosis of MS:
Evoked potentials studies involve three major tests that measure response to visual, auditory, and electrical stimuli.
- Visual evoked response (VER) test. This test can diagnose problems with the optic nerves that affect sight. Electrodes are placed on your scalp and the electrical signals are recorded as you watch a checkerboard pattern flash for several minutes on a screen.
- Brainstem auditory evoked response (BAER) test. This test can diagnose hearing ability and can point to possible brain stem tumors or multiple sclerosis. Electrodes are placed on your scalp and earlobes and auditory stimuli, such as clicking noises and tones, are delivered to one ear.
- Somatosensory evoked response (SSER) test. This test can detect problems with the spinal cord as well as numbness and weakness of the extremities. For this test, electrodes are attached to your wrist, the back of your knee, or other locations. A mild electrical stimulus is applied through the electrodes. Electrodes on your scalp then determine the amount of time it takes for the current to travel along the nerves to the brain.
Presently only the VEP testing is used in diagnosing multiple sclerosis as it has shown to be useful. VEP can display damage along the optic nerves which is quite common in multiple sclerosis however other disorders or conditions can also result in this.
The current diagnostic criteria for MS consider only VEP findings because this particular EP study has been shown to be the most useful.
The VEP is used to identify impaired transmission along the optic nerve pathways, which is a fairly common early finding in MS, even in someone who has never been aware of any visual symptoms. Information that evoked potentials tests provide needs to be considered along with other laboratory and clinical information before a diagnosis of MS can be made.Read More : Detailed Evoked Potentials Information
Cerebrospinal fluid (CSF), is a clear, colorless liquid that fills and surrounds the brain and spinal cord it provides a mechanical barrier against shock. The cerebrospinal fluid supports the brain and provides lubrication between surrounding bones and the brain and spinal cord.
A lumbar puncture also known as a “spinal tap” reveals a large number of immunoglobulins (antibodies), as well as oligoclonal bands (the pattern of immunoglobulins on a more specific test) or certain proteins that are the breakdown products of myelin, is suggestive of MS. These findings indicate an abnormal autoimmune response within the brain and spinal cord, meaning that the body is attacking itself.
Over 90% of people with MS have oligoclonal bands in their CSF. While increased immunoglobulin in the CSF and oligoclonal bands are seen in many other brain and spinal cord conditions, their presence is often useful in helping to establish a diagnosis of MS.
However, a “negative” spinal tap does not rule out MS or other diseases; some 5% to 10% of people with MS never show CSF abnormalities. And, an abnormal autoimmune response in CSF is found in a number of other diseases, so the test is not specific for MS. Therefore, a spinal tap by itself cannot confirm or rule out a diagnosis of MS. It must be part of the total picture that takes into account other diagnostic procedures such as evoked potentials and magnetic resonance imaging (MRI).
Magnetic Resonance Imaging Scan (MRI)
MRI is a diagnostic procedure that uses a combination of a large magnet, radio frequencies, and a computer to produce detailed images of organs and structures within the body. MRI does not use ionizing radiation, as do X-rays and computed tomography (CT scans).
Magnetic resonance imaging (MRI) is the diagnostic tool that currently offers the most sensitive non-invasive way of imaging the brain, spinal cord, or other areas of the body. It is the preferred imaging method to help establish a diagnosis of MS and to monitor the course of the disease. MRI has made it possible to visualize and understand much more about the underlying pathology of the disease.
How it works
Unlike a computed tomography (CT) scan or conventional X-ray, MRI does not use radiation. Instead, MRI uses magnetic fields and radio waves to measure the relative water content in tissues — both normal tissue and abnormal — in the body.
MRI works in the following way:
- A very strong magnetic field causes a small percentage of the hydrogen protons in water molecules to line up in the direction of the magnetic field. The percentage lined up is small but large enough to give a strong signal for imaging.
- Once the hydrogen protons have been lined up, radio waves and some additional but weaker magnetic fields are used to knock them out of line.
- When the radio waves are stopped, the protons relax back into line. As they relax, the protons release resonance signals that are transmitted to a computer.
- The various types of MRI scans that are used — most commonly the T1-weighted scan and the T2-weighted scan — measure this relaxation time in different ways. Computer programs translate these data into cross-sectional pictures of the water in human tissue.
Because the layer of myelin that protects nerve cell fibers is fatty, it repels water. In the areas where the myelin has been damaged by MS, the fat is stripped away. With the fat gone, the area holds more water and shows up on an MRI scan as either a bright white spot or a darkened area depending on the type of scan that is used.
MRI in Diagnosis of MS
Because MRI is particularly useful in detecting central nervous system demyelination, it is a powerful tool in helping to establish the diagnosis of MS. However, approximately 5 percent of people with clinically-definite MS do not initially show lesions on MRI at the time of diagnosis. If repeat MRIs continue to show no lesions, the diagnosis of MS should be questioned.
Since many lesions seen on MRI may be in so-called “silent” areas of the brain that don’t produce symptoms, it is not always possible to make a specific correlation between what is seen on the MRI scan and the person’s clinical signs and symptoms.
In addition, with advancing age (probably over age 50), there are often small areas seen on MRI in healthy people that resemble MS but are actually related to the aging process.Read More : Detailed MRI Information
Criteria for a Diagnosis of Multiple Sclerosis:
In order to make a diagnosis of MS, the physician must:
- Find evidence of damage in at least two separate areas of the central nervous system (CNS), which includes the brain, spinal cord and optic nerves AND
- Find evidence that the damage occurred at least one month apart AND
- Rule out all other possible diagnoses
The Revised McDonald Criteria, published In 2010 by the International Panel on the Diagnosis of Multiple Sclerosis, include specific guidelines for using MRI, visual evoked potentials (VEP) and cerebrospinal fluid analysis to speed the diagnostic process. These tests can be used to look for a second area of damage in a person who has experienced only one attack (also called a relapse or an exacerbation) of MS-like symptoms — referred to as clinically-isolated syndrome (CIS). A person with CIS may or may not go on to develop MS.
Depending on the region one lives in on the planet diagnostic criteria may vary.Read More : Detailed McDonald Criteria Information
There are several new areas of research seeking to locate more definitive ways of diagnosing multiple sclerosis. Research into locating biomarkers of MS in a person’s blood and optical coherence tomography (OCT) are both currently being studied in both diagnosis MS and attempting to project disease progression pathology.
Multiple sclerosis can be difficult and complex to positively diagnose. Many symptoms may mimic many other diseases such as Lyme disease. A neurologist will try and rule out other diseases by a variety of tests, discussion, and examination. Supporting evidence from procedures such as evoked potentials, MRI, and lumbar puncture may or may not result in a probable diagnosis of multiple sclerosis along with evaluating of common disease presenting symptoms.
The neurologist if uncertain may order a test to be repeated. The majority of patients diagnosed with MS have clear characteristics across the criteria to confirm multiple sclerosis. However, it is estimated that some 10% of patients go underdiagnosed or misdiagnosed due to the complexity in knowing for certain a person has multiple sclerosis.