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Updated: Feb 5, 2026
Comprehensive Autopsy Program for Individuals with Multiple Sclerosis
Published on: July 19, 2019
Brain and spinal cord MRI lesions in primary progressive vs. relapsing-remitting multiple sclerosis
Akram Dastagir1, Brian C Healy1,2, Alicia S Chua1
1Departments of Neurology and Brigham and Women's Hospital, Laboratory for Neuroimaging Research, Partners MS Center, Harvard Medical School, USA.
Background:
Primary progressive (PP) multiple sclerosis (MS) is considered a clinically distinct entity from the spectrum of relapsing-remitting (RR) forms of the disease.
Objective:
To compare the presence of brain and spinal cord lesions between PP and RR subjects.
Methods:
We studied people with PPMS [n = 40, 17 (42.5%) men, age 50.7 ± 7.7 years, disease duration 10.1 ± 7.4 years, Expanded Disability Status Scale (EDSS) score 4.6 ± 2.1] and RRMS [n = 40, 12 (30%) men, age 47.9 ± 4.2, disease duration 13.7 ± 5.9, EDSS 1.7 ± 1.3]. MRI of the brain and full spinal cord at 1.5T was analyzed to define patients having: 1. brain only, 2. spinal cord only, or 3. brain and spinal cord MS lesions.
Results:
Lesions in the brain only were less common in PP (n = 1, 2.5% of people) than RR (n = 10, 25%) (Fisher's exact p = 0.007). Lesions in the spinal cord only (PP: n = 6, 15%, RR: n = 3, 7.5%, p = 0.481) or brain plus spinal cord (PP: n = 33, 83%, RR: n = 27, 68%, p = 0.196) were similar between groups. PP had higher EDSS and timed 25-ft walk (Wilcoxon tests, both p < 0.001), higher age (t-test p = 0.049), lower disease duration (t-test, p = 0.02), and a similar sex ratio (Fisher's exact p = 0.352) vs. RR.
Conclusions:
We report a topographic difference in MRI lesion involvement between PPMS and RRMS. Lesions restricted to the brain are more common in RRMS. These findings provide support to the notion that PP may have features distinctive from the RR spectrum of the disease. Longitudinal comparisons and quantitative MRI analysis would be necessary to confirm and extend these results.
Insights
Brain-only lesions are less common in primary progressive multiple sclerosis (PPMS) than relapsing-remitting MS (RRMS). This finding supports PPMS as a distinct disease entity from the RRMS spectrum.
Area of Science:
- Neurology
- Neuroimmunology
- Radiology
Background:
- Multiple Sclerosis (MS) encompasses various clinical subtypes, including primary progressive MS (PPMS) and relapsing-remitting MS (RRMS).
- PPMS is often considered clinically distinct from the relapsing-remitting forms of MS.
- Understanding lesion distribution differences can elucidate disease mechanisms.
Purpose of the Study:
- To compare the location and presence of brain and spinal cord lesions between patients with PPMS and RRMS.
- To investigate potential differences in lesion topography that may support the distinct nature of PPMS.
Main Methods:
- A cohort of 40 patients with PPMS and 40 patients with RRMS were recruited.
- Brain and full spinal cord MRI scans were performed at 1.5T.
- Lesion distribution was categorized into three groups: brain only, spinal cord only, or both brain and spinal cord.
Main Results:
- Brain-only lesions were significantly less frequent in PPMS (2.5%) compared to RRMS (25%) (p=0.007).
- Lesions in the spinal cord only or in both the brain and spinal cord showed no significant difference between PPMS and RRMS groups.
- Patients with PPMS exhibited higher Expanded Disability Status Scale (EDSS) scores and poorer performance on the timed 25-foot walk compared to RRMS patients.
Conclusions:
- A distinct topographic pattern of MRI lesions exists between PPMS and RRMS.
- The higher prevalence of brain-only lesions in RRMS suggests potential differences in disease pathogenesis.
- These findings support the classification of PPMS as a separate entity within the multiple sclerosis spectrum, warranting further longitudinal and quantitative MRI studies.
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