title: Olfactory function in atypical parkinsonian syndromes.
abstract: BACKGROUND
  Olfaction is markedly impaired in patients with idiopathic Parkinson's disease (IPD). This deficit contrasts with reports of preserved or only mildly reduced olfaction in patients with atypical parkinsonism. However, the sensitivity and specificity of olfactory function testing in the differential diagnosis of parkinsonian syndromes has not been studied. In addition, olfactory function in patients with corticobasal degeneration (CBD) is unknown.
  
  
  METHODS
  Using the University of Pennsylvania Smell Identification Test (UPSIT) with a test score ranging from 0 to 40 we studied olfactory function in patients with IPD as well as other parkinsonian syndromes including CBD and progressive supranuclear palsy (PSP).
  
  
  RESULTS
  UPSIT scores in 118 patients with IPD, 29 with MSA, 15 with PSP, and 7 patients with CBD, as well as in 123 healthy control subjects revealed a marked impairment in the IPD group in contrast to mild impairment in MSA patients and normal olfaction in PSP and CBD patients. An UPSIT score of 25/40 was associated with a sensitivity of 77% and a specificity of 85% in differentiating IPD from atypical parkinsonism.
  
  
  CONCLUSIONS
  These results indicate that olfactory function is differentially impaired or preserved in distinct parkinsonian syndromes and that it might also have some value as a diagnostic pointer. Thus, preserved or mildly impaired olfactory function in a parkinsonian patient is more likely to be related to atypical parkinsonism such as MSA, PSP or CBD, whereas markedly reduced olfaction is more suggestive of IPD.
authors.affiliation: University Department of Clinical Neurology, Institute of Neurology, Queen Square, London, England.
authors.forename: G K
authors.initials: GK
authors.lastname: Wenning
authors.forename: B
authors.initials: B
authors.lastname: Shephard
authors.forename: C
authors.initials: C
authors.lastname: Hawkes
authors.forename: A
authors.initials: A
authors.lastname: Petruckevitch
authors.forename: A
authors.initials: A
authors.lastname: Lees
authors.forename: N
authors.initials: N
authors.lastname: Quinn
mesh_terms: D000328:Adult; D000368:Aged; D001479:Basal Ganglia / Q000503:physiopathology; D001480:Basal Ganglia Diseases / Q000175:diagnosis / Q000503:physiopathology; D002540:Cerebral Cortex / Q000503:physiopathology; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009410:Nerve Degeneration / Q000502:physiology; D000857:Olfaction Disorders / Q000175:diagnosis / Q000503:physiopathology*; D009830:Olfactory Bulb / Q000503:physiopathology; D009833:Olfactory Pathways / Q000503:physiopathology; D009849:Olivopontocerebellar Atrophies / Q000175:diagnosis / Q000503:physiopathology; D010302:Parkinson Disease, Secondary / Q000175:diagnosis / Q000503:physiopathology*; D012684:Sensory Thresholds / Q000502:physiology; D013494:Supranuclear Palsy, Progressive / Q000175:diagnosis / Q000503:physiopathology