SC15
Diffusion Restricted Lesions in Multiple Sclerosis
MRI is valuable in the diagnosis of MS. Demyelinating lesions are typically visualized on T1, T2 weighted and FLAIR sequences. Hyper intense DWI (Diffuse weighted images) lesions with corresponding hypo intensity on ADC (Apparent Diffusion Coefficient) reflect diffusion restriction due to regional cytotoxic edema. Cavitation or gliosis in the area of previous ischemia or demyelination results in elevation of ADC values (T2 shine through).
Objectives: Reporting a case of RRMS and coexistent acute ischemic lesions with an emphasis on neuroimaging findings and diagnostic clues
Methods:
We report a 43 y/o male with RRMS that presented with optic neuritis, dizziness and numbness. Brain MRI showed multiple white matter lesions and Dawson fingers consistent with the diagnosis of MS. Patient was readmitted 4 months later with difficulty walking and blurred vision. Repeat brain MRI showed new enhancing lesions, some with diffusion restriction. Patient’s symptoms improved with IV steroids. MRI, 3 weeks after treatment showed improvement of enhancing lesions with increased ADC levels. Patient’s clinical presentation, neuro imaging and responsiveness to steroids were consistent with RRMS. One month after his last relapse, the patient developed acute onset left sided hemiparesis. Repeat MRI revealed diffusion-restricted lesion in the right ACA territory. (MRI and more clinical information will be presented).
Results:
Recent studies have shown that MS patients tend to have increased risk of cerebrovascular events. Contrast enhancement is a neuroimaging biomarker that identifies active MS lesions. Rarely, active lesions may show diffusion restriction (pseudo strokes). The differentiation of infarcts and demyelinating lesions is critical since the management options differ significantly. Histologically, acute demyelinating MS plaques show vasogenic edema that accounts for the high ADC values. ADC sequence appears to play a key role in differentiating these two distinct histological variations.
Conclusions:
This case illustrates a patient with both acute demyelinating and ischemic lesions on MRI. The presence of diffusion restriction in patients with acute neurological symptoms, distribution of the lesion in a distinct vascular territory and appearance of diffusion-restricted lesions in the cortex, strongly suggests ischemia. Demyelinating lesions typically involve white matter and likely shows T2 shine through, although diffusion restriction can be seen and it can vary remarkably, mimicking an ischemic infarct. Perfusion MRI scans can offer superior demarcation in complicated MS patients with coexistent ischemic infarcts.