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Descriptive neuroradiology: beyond the hummingbird
  1. Inna Page1,
  2. Frank Gaillard1,2
  1. 1 Radiology Department, The Royal Melbourne Hospital, Melbourne, Victoria, Australia
  2. 2 Faculty of Medicine, Dentistry, and Health Sciences, The University of Melbourne, Melbourne, Victoria, Australia
  1. Correspondence to Frank Gaillard, Radiology Department, Royal Melbourne Hospital, Melbourne 3050, Australia; frank.gaillard{at}


Radiology signs have long been described in ways that communicate the imagery around us to enhance our cognitive perception. Here, we describe the use and limitations of 10 such signs in neuroradiology, divided into three groups. The first are signs that are reliable for a specific diagnosis, such as the Medusa head sign indicating a developmental venous anomaly, or a racing car sign in agenesis of corpus callosum. The second group of signs helps us to diagnose rare conditions, such as the onion skin sign in Balo’s concentric sclerosis. The third group is of unreliable signs that may lead clinicians astray. For example, the absence of a swallow-tail sign in Parkinson’s disease or the presence of a hummingbird sign and Mickey Mouse sign in progressive supranuclear palsy. The appropriate use of these signs in clinical practice is essential.

  • Neuroradiology
  • Parkinson’s disease
  • Creutzfeldt-Jakob disease
  • multisystem atrophy
  • supranuclear palsy

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  • Twitter Frank Gaillard @frankgaillard.

  • Contributors IP and FG contributed equally to this manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests Frank Gaillard is the Founder and Editor-in-Chief of

  • Patient consent for publication Not required.

  • Provenance and peer review Commissioned. Externally peer reviewed by Huw Morris, London, UK, and Frederik Barkhof, Amsterdam, The Netherlands.

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