Teaching Neuro Images : Marked reduced apparent diffusion coefficient in acute multiple sclerosis lesion

Abstract

A 24-year-old woman presented with sudden right-sided weakness and aphasia. Brain MRI was performed 5 hours after symptoms onset. On diffusion-weighted imaging (DWI), the lesion showed a marked increase in signal intensity and an approximatively 70% mean apparent diffusion coefficient (ADC) decline as compared with the contralateral hemispheric white matter ( figure). The patient met diagnostic criteria for multiple sclerosis and other etiologies were excluded.ADC decline in acute multiple sclerosis lesions, suggesting a diagnosis of ischemic stroke, has been previously reported.1,2 However, the decline in ADC values (22% to 40% decrease) was not as pronounced as our observation. Thus this fourth case of reduced ADC in acute demyelinating lesion indicates that the ADC drop may be important and close to that observed in the core of an acute brain infarction.

Lesions masquerading as acute stroke

“…MS is an inflammatory demyelinating disorder of the central nervous system (53–58). The initial symptoms can in some patients present as an acute pseudostroke with sudden onset of, eg, aphasia, deafness, or hemiplegia, thus mimicking an acute stroke (54–56). Most of these cases can be distinguished from ischemic stroke without difficulty by a careful evaluation of the patient's history, actual clinical findings, and findings on MRI.…”

Reduced Diffusion in a Subset of Acute MS Lesions: A Serial Multiparametric MRI Study

“…7,11 Several recent case studies have reported a reduced ADC in acute demyelinating lesions and have emphasized their strokelike ADC appearance. [12][13][14][15] The temporal evolution of the ADC signal intensity has been well characterized in acute ischemic stroke showing typical phases of an initial reduction, followed by a pseudonormalization and an ADC elevation in the subacute-to-chronic phases. 9,16 In this study, we report the development of multiparametric MRI signal-intensity characteristics in hyperacute lesions of patients with MS with the main focus on the time course of the ADC signal intensity.…”

“…[12][13][14][15]19 In contrast to MS, the evolution of the ADC has been analyzed in numerous studies in hyperacute ischemic stroke. 9,16 It may be for this reason that an ischemic mechanism has been suggested as involved in the ADC reduction.…”

Diffusion-weighted imaging in acute demyelinating myelopathy

“…Second, the spinal cord has a relatively fixed position ensured by ligament connections, and it is thus particularly susceptible to micro-traumatic injury precipitating inflammation processes. Therefore, although small in diameter, spinal lesions can share the diffusion signal of MS larger/pseudotumoural/stroke-like lesions (DWI+/ADC−) due to the pronounced inflammatory process taking place [8,11,13,31,32]. Another factor that may contribute to the high prevalence of DWI+/ADC− pattern in our cohort could be related to the fact that the examination was conducted in the very early phase of the inflammatory process [11].…”