The pimple sign of progressive supranuclear palsy syndrome

Hugo Botha, Jennifer L. Whitwell, Ajay Madhaven, Matthew L. Senjem, Val Lowe, Keith A. Josephs

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


Background: Some patients with progressive supranuclear palsy syndrome (PSPS) demonstrate a focal area of midbrain hypometabolism on FDG-PET scans which we call the 'pimple sign'. We assessed its association with midbrain atrophy, its reliability and its ability to differentiate PSPS from corticobasal syndrome (CBS) and multiple system atrophy (MSA). Methods: We identified 67 patients with PSPS, CBS or MSA who had volumetric MRI as well as FDG-PET imaging. Midbrain volume was measured and expressed as a percentage of total intracranial volume. Two independent, blinded specialists rated the 'pimple sign' on FDG-PET as 'absent', 'possible' or 'definite'. Midbrain volumes were compared across these groups and reliability assessed with the kappa statistic. Sensitivity and specificity were calculated using CBS and MSA patients as controls. Results: Midbrain volume was decreased in the 'definite' group compared to the 'absent' and 'possible' groups (p=0.0036). Inter-rater reliability for the pimple sign was high (κ=0.90). A 'definite pimple sign' had a high specificity (100%) but low sensitivity (29%) for PSPS, whilst the presence of a possible or definite sign had a sensitivity of 79%. Conclusion: The 'pimple sign' of PSPS is associated with midbrain atrophy, and may be helpful in differentiating PSPS from CBS and MSA.

Original languageEnglish (US)
Pages (from-to)180-185
Number of pages6
JournalParkinsonism and Related Disorders
Issue number2
StatePublished - Feb 2014


  • Midbrain atrophy
  • PSPS
  • Parkinsonism
  • Pimple sign

ASJC Scopus subject areas

  • Neurology
  • Geriatrics and Gerontology
  • Clinical Neurology


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