Differentiation of a symptomatic cerebral microbleed from silent microbleeds

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Dear editor,

Cerebral microbleeds (CMBs) on gradient-echo image have generally been considered to be silent, but there have been a few case reports about acutely developing CMBs that can be expected to cause focal symptoms [1-3]. It is not known how to differentiate an acute symptomatic CMB from underlying CMBs.

A 51-year-old man with known hypertension, diabetes, and hyperlipidemia presented with sudden onset of dysarthria and left hemiparesis. His initial National Institutes of Health stroke scale score was 3. An urgent brain computed tomography showed no focal abnormalities, and magnetic resonance imaging (MRI) performed on the same day revealed a CMB on the right mid-pons with hyperintense rim on diffusion-weighted image (DWI) (Fig. 1a,b). His symptoms that were likely caused by the CMB continued for over 24 h and resolved completely within seven-days. The follow-up MRI performed two-years later showed that the hyperintense rim disappeared on DWI (Fig. 1c,d).

Figure 1.

(a and b) Brain MRIs performed on the day of onset show a cerebral microbleed (CMB) within the relevant area (4 mm) on gradient-echo image and hyperintense rim (arrow in b) around the lesion on diffusion-weighted image (DWI). (c and d) Follow-up brain MRIs two-years after onset show a new tiny CMB (arrow in c) in addition to underlying two CMBs and the size of small foci suggesting previous symptomatic CMB is slightly decreased on gradient-echo image, and the hyperintense rim disappeared (arrow in d) on DWI.

In our patient, a CMB with a hyperintense rim on DWI was found in a location typical for the clinical syndrome. The hyperintense rim on DWI is suggested to be the perihematomal edema frequently seen in acute intracerebral haemorrhage [4]. DWI changes may be normalized with time due to a progressive resolution of perihematomal edema. We suggest that a combination of DWI and gradient-echo image can help diagnosing acute symptomatic CMBs.

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