Related Experiment Video
Updated: Oct 5, 2026
Brain Infarct Segmentation and Registration on MRI or CT for Lesion-symptom Mapping
Published on: September 25, 2019
Ipsilateral blooming of microbleeds after Hyperintense Acute Reperfusion Marker sign in an ischemic Stroke patient, a
Luigi Francesco Saccaro1, Imen Bekri2, Maxime De Malherbe3
1Versailles Hospital, Neurology and Stroke Care Unit, Le Chesnay, France. luigisaccaro@gmail.com.
Background:
Hyperintense Acute Reperfusion Marker (HARM) is a hyperintense subarachnoid signal on FLAIR MRI sequence caused by gadolinium contrast leakage into the subpial space. While, on FLAIR, HARM may mimic subarachnoid hemorrhage, it is differentiated from it on computed tomography (CT) and SWAN MRI sequences. Cerebral microbleeds are black, rounded spots on SWAN caused by blood-products deposition following red blood cell leakage from small cerebral vessels brain. Both microbleeds and HARM carry important prognostic implication as they are associated with blood-brain barrier disruption and an increased risk of intracerebral hemorrhage.
Case Presentation:
A 79-year-old man presented with aphasia and right hemiparesis due to ischemic stroke with left middle cerebral artery occlusion. Admission NIHSS score was 7, and he was successfully treated by intravenous thrombolysis and mechanical thrombectomy. On day 1, his clinical condition worsened, and he had an urgent gadolinium-enhanced MRI. There was no evidence of early recurrence, nor of hemorrhage on SWAN or on FLAIR. Left middle cerebral artery was permeable. The patient was anticoagulated for newly diagnosed atrial fibrillation, and a second MRI following a generalized tonic-clonic seizure showed multiple left hemispheric diffusion-weighted imaging (DWI) hyperintense spots and a left hemispheric sub-arachnoid hyperintensity on FLAIR, compatible with a subarachnoid hemorrhage. This diagnosis was excluded by SWAN MRI sequence and a normal cerebral CT the same day. The diagnosis of HARM was retained. At day 9, patient's condition improved, and a control MRI did not show evidence of HARM. However, numerous microbleeds were detected in the left hemisphere only (ipsilateral with HARM and stroke).
Conclusions:
This case highlights first of all the importance of differentiating HARM and subarachnoid hemorrhage, especially in an anticoagulated patient with clinical aggravation. Secondly, it is crucial to identify microbleeds and understand their pathophysiology, as they are associated with higher risk of hemorrhage and stroke recurrence in ischemic stroke patients. Finally, the mono-hemispheric appearance of microbleeds in this case suggests for the first time that, in some acute ischemic stroke patients, a relationship between HARM and cerebral microbleeds may exist.
Insights
Hyperintense Acute Reperfusion Marker (HARM) can mimic subarachnoid hemorrhage on MRI. This case suggests a potential link between HARM and cerebral microbleeds in acute ischemic stroke patients, highlighting their prognostic importance.
Area of Science:
- Neurology
- Radiology
- Neuroimaging
Background:
- Hyperintense Acute Reperfusion Marker (HARM) is a FLAIR MRI signal from gadolinium leakage, mimicking subarachnoid hemorrhage.
- Cerebral microbleeds are SWAN MRI findings indicating small vessel damage and blood-product deposition.
- Both HARM and microbleeds signify blood-brain barrier disruption and increased hemorrhage risk.
Observation:
- A 79-year-old male with ischemic stroke treated with thrombolysis and thrombectomy developed worsening symptoms.
- Initial MRI showed no hemorrhage; however, a subsequent MRI revealed findings suggestive of subarachnoid hemorrhage, later identified as HARM.
- A follow-up MRI demonstrated numerous left-hemispheric microbleeds ipsilateral to the HARM and stroke.
Findings:
- HARM was distinguished from subarachnoid hemorrhage using CT and SWAN MRI sequences.
- The patient, anticoagulated for atrial fibrillation, experienced a seizure and subsequent HARM diagnosis.
- Microbleeds were exclusively observed in the left hemisphere, correlating with the location of HARM and the initial ischemic stroke.
Implications:
- Accurate differentiation of HARM from subarachnoid hemorrhage is critical, especially in anticoagulated patients with clinical decline.
- Identifying microbleeds is essential due to their association with increased hemorrhage risk and stroke recurrence.
- The unilateral distribution of microbleeds suggests a potential relationship between HARM and cerebral microbleeds in acute ischemic stroke.
Related Concept Videos
01:15Ischemic Stroke l: Introduction
01:15Ischemic Stroke ll: Pathophysiology
01:26Transient Ischemic Attack l: Introduction