Watershed (borderzone) infarcts
The patient is an 8 month old girl, a known case of sickle cell anaemia who presented with sickle cell crisis, loss of consciousness and severe shortness of breath. Patient started to develop tonic clonic convulsion which were focally localised mainly to the right arm with associated up-rolling of eyes. CT of the brain was unremarkable.
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There are multiple bilateral near symmetrical foci of restricted diffusion (appearing hyperintense on DWI with corresponding ADC images showing dark signal) seen in both cerebral hemispheres seen involving the deep white matter and sub-cortical white matter. There is no perilesional edema.
No large territorial infarctions.
No gyral swelling or sulcal effacement.
Case courtesy Dr. Ahmed Ajamy Elsayed
Watershed infarctions typically occur at the junctional zones or border zone of the arterial territories due to reduced cerebral perfusion of variable etiologies.
- external or Cortical water shed infarcts: these are the more common ( and widely published ) variety of water shed infarction. These are seen at the junction of the major arterial territories, most commonly between the anterior cerebral artery (ACA) - middle cerebral artery (MCA) and middle cerebral artery (MCA) – posterior cerebral artery (PCA). These are seen as larger confluent white matter hyper-intensities on T2 weighted MR images and are usually wedge shaped or oval in shape
- internal watershed infarcts: these are relatively smaller foci of restricted diffusion seen symmetrically in both cerebral hemispheres, in the deep white matter, sub-cortical white matter and in the basal ganglia region in particular in the zone of the lenticulostriate perforator circulation
- Mangla R, Kolar B, Almast J et-al. Border zone infarcts: pathophysiologic and imaging characteristics. Radiographics. 2011;31 (5): 1201-14. Radiographics (full text) - doi:10.1148/rg.315105014 - Pubmed citation
- Bladin CF, Chambers BR. Clinical features, pathogenesis, and computed tomographic characteristics of internal watershed infarction. Stroke. 1993;24 (12): 1925-32. Stroke (abstract) - doi:10.1161/01.STR.24.12.1925 - Pubmed citation
- Momjian-Mayor I, Baron JC. The pathophysiology of watershed infarction in internal carotid artery disease: review of cerebral perfusion studies. Stroke. 2005;36 (3): 567-77. Stroke (full text) - doi:10.1161/01.STR.0000155727.82242.e1 - Pubmed citation