ClinicSpeak: not diagnosing multiple sclerosis

Can I have MS with a normal MRI? #ClinicSpeak #MSBlog #MSResearch

"I have recently had an email query from someone with multiple neurological symptoms. Each set of symptoms are compatible with a lesion in the neuraxis (brain and spinal cord), but the MRI has been reported as normal. The question is can you have MS with a normal MRI? The answer is yes, but this is uncommon."

"Please note that to make a clinical diagnosis of MS, like other diseases, there needs to be a clinical features that are matched with a pathological (abnormal) process; the so called clinicopathological correlate. Please note that many psychiatric diagnoses are not based on this principle, which is why there remains such a large divide between psychiatrists and neurologists in the way they diagnose diseases."

"In relation to making a diagnosis of MS, having symptoms of involvement of the nervous system is not enough; the symptoms have to be linked with objective signs and a pathological process compatible with MS. What do I mean by this? According to the McDonald criteria for diagnosing MS an attack has to be objectively documented; in other words the neurological examination needs to be abnormal and show objective signs of involvement of multiple neurological pathways; this is particularly relevant if the MRI is normal. This is why some sensory symptoms, particularly if they are intermittent, frequently don't fulfill the definition of a clinical attack or relapse."

"For a diagnosis of MS there has to be dissemination in time and space; in other words clinical attacks or MRI lesions have to develop at different times. The current criteria imply at least one month apart is sufficient for dissemination in time. The exception to the latter is the finding of old and new (Gd-enhancing) lesions on the same scan; the assumption is that these lesions developed months apart. The latter, however, clearly does not apply to someone with a normal MRI. What about dissemination in space? The MRI is usually very helpful here, but if  the MRI is normal the neurologist has to rely on the clinical examination, and possibly abnormal evoked potentials, to document involvement of the central nervous system in two distinct sites."

"Another essential part of the MS diagnostic criteria is to exclude other diagnoses. This is probably the main reason for doing the MRI scan. We all know that in MS the lesions can be microscopic hence the initial brain MRI can be normal. If the brain MRI is normal scanning the spinal cord may help and show the telltale lesions needed to support the diagnosis. Finally, I would not make a diagnosis of MS in anyone with a normal brain and spinal cord MRI without paraclinical and laboratory support; i.e. I would want to see abnormal evoked potentials, or central motor conduction times, compatible with demyelination in a particular pathway and I would want an abnormal spinal fluid analysis (positive oligoclonal bands or OCBs). In addition to this several other tests may be necessary to exclude other diagnoses or MS mimics."

"Getting the diagnosis of MS right is very important for several reasons. Having MS can be stigmatizing in that it may affect your future prospects; for example getting a job and obtaining insurance cover. As relapsing MS is now a treatable disease we need to be confident about the diagnosis; some of the treatments for relapsing MS can have life-threatening complications and it would be a tragedy to expose someone to these complications who did not have MS. Based on the literature the MS misdiagnosis rate is in the order of 2-5%; in other words 1-in-20 to 1-in-50 people diagnosed as having MS, don't have MS."

"My moto is if in doubt don't diagnose MS. I would prefer to wait and see than get the diagnosis wrong. If you have MS it will almost certainly manifest itself in the future. Professor Tom Bothwell, who was one of the most influential mentors, would frequently say: 'Time is often the best diagnostician'."

"I hope the message is clear, making the diagnosis or MS, or not, is complicated and requires skill. This may explain why it takes approximately 15 years of training to become a neurologist and why we sometimes get it wrong."

"The following slideshow is a presentation I posted last December. The presentation highlights some of the problems with defining a disease, the diagnostic pitfalls that occur when you try and make a diagnosis of MS and the impact biomarkers have on this process."

Defining a disease from Gavin Giovannoni

"For those new to this blog, you may find the following posts on this issue of misdiagnosis of MS helpful."
  1. Multiple Sclerosis Research: Research: Misdiagnosis in MS, 13 May 2012
  2. Multiple Sclerosis Research: Misdiagnosis. Doctors Not in ..., 13 May 2012
  3. Multiple Sclerosis Research: Clinic speak: should I start ..., 29 Jul 2013
  4. Multiple Sclerosis Research: Research: Misdiagnosis in MS, 13 May 2012

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