Disease Activity in Multiple Sclerosis

Clinical Markers of Disease Activity

Clinical assessments alone substantially underestimate true disease activity, as most inflammatory activity occurs asymptomatically, with early relapsing-remitting and secondary progressive MS demonstrating the highest rates of asymptomatic disease activity 3, 4

Gadolinium-DTPA enhancement is the gold standard for detecting active inflammation, indicating blood-brain barrier breakdown and acute inflammatory activity 3, 5
Approximately 80% of new lesions show gadolinium enhancement in relapsing-remitting and secondary progressive MS 4, 6
New and enlarging T2 hyperintense lesions represent active disease and can provide sufficient information about subclinical activity when contrast is not used 1, 8
Chronic T1 hypointense lesions persisting longer than 6 months indicate focal neurodegeneration and irreversible tissue damage, representing a marker beyond acute inflammation 1

Disease activity varies dramatically between patients and within individual patients over time, with serial data from untreated patients over 6 months showing a range of active lesions: 1 to 207 in relapsing-remitting patients 2
Serial MRI monitoring is essential to capture the dynamic nature of MS activity, as single timepoint assessments cannot capture this variability 3

Brain atrophy can be present even in early MS stages and correlates with long-term cognitive impairment and disability progression 2

Brain MRI should be performed using the same MRI system and identical imaging protocol as baseline, with contrast-enhanced T1-weighted sequences to detect acute inflammation and T2-weighted sequences to identify new/enlarging lesions 1, 2, 8
Clinical assessments measuring disability and recording relapses must always be performed in parallel with MRI, as imaging alone provides incomplete assessment 3, 4