Friday, February 20, 2009

Subacute Stroke: Loss of Sensation

This 65 year old right-handed man had a history of previous stroke, associated with a very mild left hemiparesis, and atrial fibrillation. He suddenly experienced tingling in the left hand and arm, and on examination had a syndrome of left neglect: he failed to explore the left half of space, and extinguished both left tactile and left visual stimuli when presented on both sides simultaneously. MR images were obtained approximately 15 hours after onset of new symptoms.


Image findings:

Right frontal encephalomalacia
The frontal pole is largely replaced with the high signal of cerebrospinal fluid left after liquifaction necrosis in this old infarct. It corresponded clinically to a remote ictus, or suddent event many years ago, and anatomically was limited to the superior frontal gyrus.
 

Right parietal infarction with hyperperfusion
There is a subtle, early MR abnormality in the right posterior parietal, with corresponding marked hyperperfusion, so-called luxury hyperperfusion, seen on SPECT images. See below slices 15 and 16.
 



Crossed cerebellar diaschesis
The left cerebellum, because of its dense connection to the right frontal lobe, demonstrates reduced function, while remaining structurally intact. This phenomenon is seen with several types of frontal pathology, including neoplasia, infarction, and contusion. See below slice 4.