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

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.

Epidemiology of Parkinson’s disease

The burden of Parkinson’s disease (PD) is likely to increase in the years to come as many countries, particularly those in Asia, face an ageing population. As such, it has been estimated that the number of individuals suffering PD in the world will double by the year 2030. There have been many descriptive epidemiological studies conducted to understand the prevalence and incidence of PD. In this article, the prevalence and incidence of PD in Asians will be reviewed. Analytical epidemiological studies have broadly focussed on demographic and environmental factors associated with PD. Amongst the environmental factors that will be reviewed are: occupational, lifestyle, dietary, and pharmacological factors. This article will also attempt to grade the strength of the association of these epidemiological factors with PD by weighing the evidence for each of these factors. Such an approach will provide a better understanding of the association of epidemiological factors with PD so as to further the understanding of the pathogenesis of PD and to develop better therapeutic interventions.