Eye Tiger Sign

A sign seen on T2-weighted MRI, in which there is a very low signal intensity in the globus pallidus due to an excess accumulation of iron, surrounding a central region of high signal intensity attributed to gliosis, increased water content and neuronal loss with disintegration, vacuolization and cavitation of the neuropil. First described in Hallervorden-Spatz syndrome, the sign has also been reported in other extrapyramidal parkinsonian disorders: cortical-basal ganglionic degeneration, early-onset levodopa-responsive parkinsonism and Steele-Richardson-Olszewski syndrome (progressive supranuclear palsy)
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