Brain iron accumulation on T2 MRI produces bilateral globus pallidus hyperintensity with surrounding hypointensity, so-called "Eye-of-the-tiger" sign. Abnormality highlighted.
Adapted from: https://commons.wikimedia.org/wiki/File:Pkan-basal-ganglia-MRI.J
Neurodegeneration with Brain Iron Accumulation
Neurodegneration with Brain Iron Accumulation (NBIA) is a spectrum of disorders that involve brain iron accumulation, which presents variably with symptoms of dystonia, parkinsonism, ataxia, spasticity, and neuropsychiatric abnormalities.
Brain iron accumulation on T2 MRI produces bilateral globus pallidus hyperintensity with surrounding hypointensity, so-called "Eye-of-the-tiger" sign.
This sign was originally considered to be pathognomic for Pantothenate kinase-2-associated neurodegeneration (PKAN) (aka Hallervorden-Spatz syndrome), which occurs from in mutation in pantothenate kinase 2 (PANK2), typically before the age of 6.
However, since then, this radiographic sign has been found in other patient populations, as well, such as those with late onset brain iron accumulation disorders (eg, neuroferritinopathy) and other atypical parkinsonism disorders (ie, multiple systems atrophy spectrum disorders).