Teaching NeuroImages: Wishbone pattern of iron accumulation: A characteristic imaging sign in GM1 gangliosidosis

An 8-year-old girl, with no relevant developmental or family history, presented with progressive orolingual and limb dystonia since 3 years of age. MRI brain showed bilateral posterior putamen volume loss and hyperintensity. Susceptibility-weighted images showed globus pallidus blooming in characteristic wishbone pattern with medial and lateral parts forming the forked ends (figure). MRI spine showed features of dysostosis with platyspondyly and vertebral beaking. β-Galactosidase assay was low and genetic workup revealed compound heterozygous pathogenic mutation in GLB1 gene. Combination of putaminal finding and wishbone pattern of iron deposition is highly diagnostic of late onset/type 3 GM1 gangliosidosis1,2 and helps differentiate from neurodegeneration with brain iron accumulation.