Clinically Suspected Atypical Pantothenate Kinase-Associated Neurodegeneration Without the Eye-of-the-Tiger Sign: A Case Report

Pantothenate kinase-associated neurodegeneration (PKAN) is the most common form of neurodegeneration with brain iron accumulation (NBIA), typically characterized by extrapyramidal symptoms and the classical eye-of-the-tiger sign on MRI. However, atypical forms may lack this hallmark feature, leading to diagnostic challenges. We report a 27-year-old male with a 12-year history of progressive tremors, gait disturbance, dysarthria, dysphagia, and behavioral changes. Neurological examination revealed extrapyramidal features, including dystonia and sialorrhea. MRI brain demonstrated bilateral T2 hypointensity in the globus pallidus with prominent blooming on susceptibility-weighted imaging (SWI), suggestive of iron deposition, without the classical eye-of-the-tiger sign. A diagnosis of clinically suspected atypical PKAN was made based on the characteristic clinical and radiological findings, and genetic confirmation by PANK2 mutation testing was advised. Atypical PKAN often presents later with slower progression and may lack characteristic MRI findings. This case highlights the diagnostic limitations of conventional MRI and emphasizes the importance of SWI in detecting basal ganglia iron deposition. PKAN should be considered in young patients with progressive extrapyramidal symptoms even in the absence of the eye-of-the-tiger sign. SWI can improve diagnostic accuracy and help reduce delays in diagnosis.