Eye of Tiger Sign: Clinical Phenotypes

Abstract

The Eye-of-the-Tiger sign is a radiological sign that refers to abnormal low signal intensity in the globus pallidus with a central longitudinal zone of high signal as seen on T2-weighted MRI images. The sign is considered the distinctive radiologic feature of Neurodegeneration with Brain Iron Accumulation (NBIA) type 1, also known as Pantothenate Kinase Associated Neurodegeneration (PKAN). NBIA is a group of inherited neurologic disorders, in which iron accumulates in the basal ganglia resulting in progressive extrapyramidal symptoms. Clinical features and severity may vary with the age of onset and the nature of the underlying mutation. PKAN can present as early onset and late onset forms. We report a few case studies with varying clinical phenotypes and showing imaging features of eye of tiger. Two patients did not develop the characteristic features of PKAN even after five years of follow-up.