In my MRI report from 6 years ago, it said I had encephalomalacia - pen point sized- in the pons (I had a severe flare in 2007 via large lesion in brainstem). Would dead tissue that size, in that area, cause disability/dysfunction? If so, what would be affected?
This is difficult to answer for a couple reasons...
- The “clinical-radiographic paradox”: burden of disease seen on MRI does not always predict neurological disability. Individuals with a very large burden of disease on MRI can have a fairly normal neurological exam; however, I’ve seen individuals with very little evidence of disease on the MRI with significant neurological disability. The reason for this is typically due to where the lesions are found (ie, if they happen to involve critical areas that subserve vision, strength, and/or coordination, then it is more devastating to the patient from a functional standpoint). Also, keep in mind that conventional MRI scanners do not pick up all disease activity. Much of the disease burden is known to occur in the cortical grey matter of the brain, yet only high field MRI (used in research settings) have found these hard to see lesions. Therefore, there are other areas that may be involved that you simply cannot see on standard MRI scans.
- MS plaque “topography”: the areas of nervous system involvement may suggest a proclivity for future neurological disability. Individuals with brain stem, cerebellum, and/or spinal cord disease tend to have greater odds of disability in the future compared with patients without these areas of involvement. However, this isn’t 100% predictive.
The bottom line is that MRI isn’t a perfect biomarker of MS—nothing is. However, the MRI is very important in confirming the diagnosis but also plays a critical role in evaluating the effectiveness of MS disease modifying therapies in the individual patient.
A. Scott Nielsen MD MMSc
Neurologist and MS Specialist at Kaiser Permanente