Pantothenate Kinase-Associated Neurodegeneration (PKAN)

Previously known as Hallervorden Spatz disease, pantothenate kinase-associated neurodegeneration (PKAN), or neurodegeneration with brain iron accumulation 1 (NBIA1), is an autosomal recessive neurodegenerative disorder caused by a deficiency in the enzyme pantothenate kinase 2. This defect results in iron deposition in the globus pallidus and substantia nigra, producing dystonia, rigidity, choreoathetosis, dementia, and tremor. 

Due to iron accumulation, MR imaging classically shows bilateral low signal intensity at the globus pallidus and substantia nigra on T2WI. Central areas of high signal on T2WI (arrows) corresponding to edema and gliosis are found within the dark globus pallidi. This has been referred to as the "eye-of-the-tiger" sign.

Ref : AJNR and WWW.