On a brain MRI, the 'eye of the tiger' sign is seen in the globus pallidus on T2-weighted imaging. Which metabolic disorder is this pathognomonic of?

• A Wilson's disease
• B Leigh syndrome
• C Huntington disease
• D Pantothenate kinase-associated neurodegeneration (PKAN) — formerly Hallervorden-Spatz disease ✓

Explanation

The 'eye of the tiger' sign on T2-weighted MRI describes bilateral symmetric hypointensity (iron deposition) in the globus pallidus with a central T2 hyperintense spot (gliosis and oedema), creating the appearance of a tiger's eye. This is pathognomonic of pantothenate kinase-associated neurodegeneration (PKAN), the most common form of neurodegeneration with brain iron accumulation (NBIA). Wilson's disease shows T2 changes in the putamen and thalami. Leigh syndrome shows bilateral basal ganglia and brainstem signal changes. Huntington disease shows caudate atrophy.

Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.