‘Hummingbird’ Sign in a Patient with Guam Parkinsonism-Dementia Complex

ABSTRACT

We present a case of a 71-year-old male Chamorro patient from Guam who presented with progressive supranuclear palsy (PSP)-Richardson’s syndrome. Considering his strong family history of parkinsonism and a PSP phenotype, he was clinically diagnosed with Guam parkinsonism-dementia complex (PDC). Magnetic resonance imaging (MRI) of the brain revealed prominent midbrain atrophy with preserved pontine volume, forming the ‘hummingbird’ sign, which has not been described before in Guam PDC. Molecular analysis of the chromosome 9 open reading frame 72 gene (C9orf72) showed only 6 GGGGCC repeats. We discuss the clinico-pathological similarities and differences between PSP and Guam PDC, and highlight the topography of neuropathological changes seen in Guam PDC to explain the appearance of the ‘hummingbird’ sign on MRI.