The “eye-of-the-tiger” sign refers to a specific pattern of hyperintensity within a hypointense globus pallidus that is seen on T2-weighted magnetic resonance (MR) imaging. The central hyperintensity is possibly due to tissue necrosis and edema, and the surrounding hypointensity, due to iron deposition. This appearance has been considered to be pathognomonic of Hallervorden-Spatz syndrome.1 The proposed new nomenclature suggests that the group of disorders with high iron in the basal ganglia be called neurodegeneration with brain iron accumulation (NBIA).2 The most prevalent form of NBIA is due to mutations in the pantothenate kinase 2 (PANK2) gene (chromosomal locus 20p13-p12.3) and is called pantothenate kinase–associated neurodegeneration (PKAN). Within this group the recognized forms include an early-onset, rapidly progressive, extrapyramidal syndrome often associated with pigmentary retinopathy; a later-onset syndrome with prominent behavioral difficulties and slower progression (atypical PKAN); and HARP (hypoprebetalipoproteinemia, acanthocytosis, retinitis pigmentosa, and pallidal degeneration). Neuroferritinopathy and aceruloplasminemia are 2 disorders without the PANK2 mutation that are part of the NBIA spectrum. We herein describe 2 patients with a clinical picture of atypical PKAN who had the eye-of-the tiger sign on MR imaging but lacked the PANK2 mutation.
Kumar N, Boes CJ, Babovic-Vuksanovic D, Boeve BF. The “Eye-of-the-Tiger” Sign Is Not Pathognomonic of the PANK2 Mutation. Arch Neurol. 2006;63(2):292. doi:10.1001/archneur.63.2.292