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HOW CAN YOU HAVE MS AND HAVE A NEGATIVE MRI?
This is a question asked over and over. The answer "Yes!." A person certainly can have a "negative" MRI and still have a definite diagnosis of MS. It can occur in a few different ways, each of them dealing with a different meaning of the word "Negative." For the purposes of this discussion I am only speaking of the patient that does indeed have MS.
THE LESIONS CAN BE INVISIBLE ON THE MRI
It's important to realize that we are not saying that someone can have MS with "no lesions." That is a contradiction in terms. The words Multiple Sclerosis mean "multiple scars." A scar is a lesion. Someone who is presenting with symptoms of MS, whether they are paresthesias, weakness, vertigo, optic neuritis, bladder problems or whatever, has lesions in their central nervous system. Period. That's what causes the symptoms, the damaged nerves, the lesions. One must not assume that lesions are only things seen on MRI. Instead it is the areas of brain or spine tissue already lesioned that show up on MRI.
What shows on the conventional MRI is not the whole story of the damage and the disease activity in MS. We are going to be hearing more about the different kinds of nerve damage that can occur that is outside the usual discussion of MRI lesions.
Few medical articles talk about this directly, but most of them acknowledge indirectly that not all lesions, and possibly not even the majority of lesions, are yet visible on the MRI. Autopsy examination can show lesions that the MRIs didn't show when the patient was alive. Also, the areas damaged by MS don't show up as measurable lesions from the first minute of damage. At some point in their development, they are invisible. Some areas that would have been visible some time ago, no longer show up, but may not be perfectly healed and be still causing symptoms.
Lower Power MRI Machines Miss Lesions
Furthermore, we can't ignore the data from the repeated transition between generations of MRI machines. The power of an MRI machine is measured by its magnet strength, using the unit of measure, the Tesla. Its symbol is the letter "T" like "HP" indicates Horsepower. The old studies show that the 1T machines revealed a greater number of lesions than the machines with <1T power. The current MRI Guidelines specify that for the purposes of diagnosis the minimum power of the MRI machine must be 1T. When the 1.5T machines came out it was clear that they were superior to the lower MRIs at picking up lesions. The new generation of machine now in fairly common use in some parts of the country is a 3T in power. Back to back studies against the 1.5T machine show that the higher power 3T machine will pick up about 25% more lesions. And, yes, the newest high-intensity MRI, like the 7T, are picking up yet more than the 3T (data from autopsy MRIs). The 7T is not in common clinical use, but is being studied. We can only surmise that we are still missing a certain percentage of MRI lesions.
The spinal cord is especially hard to get clear images on. This is due to movement from breathing, pulsations of the heart and aorta, and the density of the spinal column and the body. It is also affected by the fact that the spinal cord is surrounded by fluid, CSF. The higher intensity MRIs pick up a much greater number of lesions.
I had back to back spine MRIs on a 1.5T machine and a 3T machine. The 1.5T picked up zero lesions. The 3T picked up six (6 !!) and clinched my diagnosis.
The Wrong Technique May Miss the Lesions That Are Present
Not Using Contrast - New, actively demyelinating lesions are only shown when the MRI is done with Gadolinium contrast. If the only lesions large enough to be seen are new and if contrast is not used, those lesions will be missed. Gadolinium is required for diagnostic MRIs by the current MS Protocol for MRIs. However, in countries where medical resources are scarce or where equipment is carefully rationed, the use of contrast may be denied until lesions are seen. Insurance may not allow the use of contrast until lesions are identified. Not using contrast may miss an entire category of lesion.
Wrong Imaging Techniques - The Consortium of Multiple Sclerosis Centers issued recommendations some years ago on the techniques that should be used in looking for MS lesions. From what we have seen on the forum, not all doctors who suspect MS are requesting this "MS Protocol" which includes 3mm slices, no skipping of areas (which is often done on other routine MRI studies) and the use of certain techniques, called "sequences," to visualize lesions. MRIs done outside large specialty centers may not use these techniques. Thicker image "slices" may miss lesions. Skipping areas of the brain may also miss lesions.
Is There Evidence That People With Negative MRI's Do Develop Clearcut MS?
Yes. Several studies have looked at people presenting with a highly suggestive, but incomplete picture of MS, called a Clinically Isolated Syndrome or a "Monosymptomatic" attack. They have performed MRIs of the brain and then followed these people for a length of time, usually some years, to see if they will develop full-blown MS. It is true that the vast majority with a positive MRI will show MS. But what about those who have a negative MRI when they entered the study? (remember they had a single neurologic attack highly suggestive of MS) The studies show that between 2% and 10% will convert to Definite MS status during the followup. The percentage difference has to do with the selection process for the patients. This is very good proof that a negative MRI does not definitively rule out MS in the diagnostic process.
These numbers are in agreement with the statement by the National MS Society that 5% of people with MS have normal MRIs. This statement is rather vague. It does not indicate whther this means that "at some point in their disease" 1 in 20 will have a negative MRI, or if 5% will have one at the time of diagnosis. Since, during the course of MS, one tends to acquire more lesions and loss of brain tissue, it is more likely the the 5% will occur at the beginning. I would not take bets on my life with the odds of 1 in 20.
Are Lesions the Only Abnormality That Can Indicate MS?
No. There is the situation that T-Lynn, here on the forum, had. She had years of symptoms, but no "lesions" on MRI. However, she obviously had a huge load of invisible lesions. Her first positive MRI finding was "brain atrophy." There had been so many "invisible lesions" that eventually large amounts of brain tissue was destroyed and it became obvious on MRI that her brain had actually shrunk. It is not routine to do the special computer calculations that show early brain atrophy, but in her case that would have alerted her doctors much earlier to the atrophy before it became painfully obvious.
In all fairness, a doctor cannot use invisible lesions to make a diagnosis. We can't ask them to. But, we can ask that if a person presents with a clinical picture highly suggestive of MS, that the door to the diagnosis not be immediately and permanently slammed shut with the statement (which we have all heard) "You do not possibly have MS and will not develop it" (Yes, doctors have said this to us)
THE LESIONS WERE NEVER IMAGED IN THE FIRST PLACE
In a large group of patients who present with clinical findings (history and physical) suggestive of MS, the only MRI that is ordered in of the brain. If the doctor fails to see lesions in the brain and then dismisses the patient as definitely not having MS, they are failing at their job. If the brain MRI is negative or equivocal, and the doctor should still suspect MS, an MRI of the spine should be done. This is the recommendation of the Consortium of MS Centers. Many clinics, though, do the spine routinely if MS is being considered. Yet over and over we have to tell people to make sure they get the spinal cord (cervical and thoracic) imaged. A large percentage of patients will have lesions in both places. If the diagnosis can't be made from the brain alone, sometimes the information from the spine will clinch it (as it did for me.) While only a small minority of patients will have lesions in the spinal cord only, they do exist. The lesions can't be seen if nobody looks for them.
THE LESIONS ARE MIS-IDENTIFIED
In this case the lesions are seen but somehow lost in the translation of the information to patient. Basically this is a False Negative MRI. It gets reported as "negative" to the patient. This can happen a couple of ways.
First, the radiologist may miss the lesion(s) entirely. (Bad! Bad, Radiologist!) This is the radiologist's malpractice. It won't be caught unless someone else re-examines the images. People in all professions make mistakes. Some are worse than others, unfortunately. If the treating doctor does not look at the films themself, then the error will stick. In my opinion, no neurologist who is capable of diagnosing MS would EVER just accept the radiology report as gospel. Yet , we hear time and again that our neurologist never looked at our films.
Or, the radiologist may see the lesion and mention it in the report, but accidentally neglect to mention it in the Summary or Impression. If the neuro of doctor only reads the Impression (this also seems to happen often), may erroneously report it to the patient as negative. Again, this is only a problem if the neuro doesn't look at his own images, and if someone (even the patient) doesn't read the entire report.
Second, the radiologist may see the lesion and interpret it as a normal finding. This is exactly one of the factors that delayed my diagnosis of MS for over two years. If the neurologist agrees that the lesion is not a lesion at all and is normal for the patient, the patient will be told the MRI is negative (and I was!) Sometimes this will be that the lesions are seen and attributed to something else, like age (even as young as 30! Not!), high blood pressure (even though the patient didn't ever have high BP!), migraines (yes, even without a history of migraines), smoking (an overcall, smoking is only a minor factor in causing lesions), obesity (??????????), etc. It my case the classic MS lesion was dubbed a UBO - "Unidentified Bright Object." I was told they "happen a lot at my age."
Alternatively, the radiologist may see the lesion and report it as suspicious for MS or for a demyelinating process, and mention it in the report, but the neurologist may look at the images and completely disagree with the report. The neuro then tells the patient that the MRI was negative. We actually have one report of a neurologist who dismissed the radiology report without even looking at the MRI images! The patient doesn't know until they look at their records, that there was a professional diagreement as to the significance of the lesions.The patient has a right to hear the different medical opinions which appear in the medical record.
THE POSITIVE MRI BECOMES NEGATIVE BY MISTAKE
Lastly, comes the occasional mistake made by someone dictating a report, like a patient summary. Occasionally a tired or distracted person (doctor) will mis-dictate a finding, stating something is "negative" when it was "positive." The consulting or subsequent doctor writes that down in the patient's database and it becomes Truth. Shame on the consulting doctor for not looking at the reports himself, but in this time-pressured world, such things happen.
HOW TO HELP MINIMIZE PROBLEMS
1) Get copies of all MRIs and the reports. Read all the reports. Check out anything you don't understand.
2) Request that your neurologist look at the images himself. If he/she won't, find a new one.
3) Find a neurologist who is as interested in your case as you are. If suspicion of MS remains after report of a negative MRI of brain and spine, make sure you are followed up at intervals.
4) Ask about whether the MRI will be done using an MS Protocol. If they don't know what you are talking about, get back to the ordering doctor and get it clarified. Ask about the use of contrast. Who has the discretion to use it? Is the decision the neurologist's or the radiologist's?
5) The spinal cord should be imaged on the highest MRI intensity available. 3T is definitely better than 1.5T. Any is better than none at all.
6) Get copies of your medical records and read them for mistakes, inconsistencies or things that do not match what you are told.
Finally, I do not mean to suggest that all people with a negative MRI have had things missed. I am merely describing the ways in which a patient who does have MS can erroneously believe they have a negative MRI. In reality, a negative MRI does lower the chances that a person will have MS, but it does not reduce that chance to zero.