title: A cross-sectional study contrasting olfactory function in autonomic disorders.
abstract: OBJECTIVE
  To compare odor identification function in patients with peripheral or central autonomic neurodegeneration and in patients with intact autonomic neurons but undetectable norepinephrine.
  
  
  METHODS
  Olfactory function was evaluated with the University of Pennsylvania Smell Identification Test (UPSIT) in 12 patients with pure autonomic failure, 10 patients with multiple system atrophy, and 4 patients with dopamine β-hydroxylase deficiency. Blood pressure and catecholamine data were also compared.
  
  
  RESULTS
  Odor identification was significantly impaired in patients with pure autonomic failure relative to patients with multiple system atrophy or dopamine β-hydroxylase deficiency. Out of 40 odors, the patients correctly identified mean (95% confidence interval) 19.2 (14.1 to 24.2), 34.4 (32.2 to 36.6), and 31.7 (29.4 to 34.1) (p < 0.001). The difference between patients with pure autonomic failure and those with multiple system atrophy or dopamine β-hydroxylase deficiency persisted after adjustment for age (p = 0.001). Patients with pure autonomic failure also had a greater orthostatic fall in blood pressure and lower plasma norepinephrine levels than patients with multiple system atrophy.
  
  
  CONCLUSIONS
  Olfactory function was relatively intact in patients with dopamine β-hydroxylase deficiency, who have intact noradrenergic neurons but lack norepinephrine. Odor identification was impaired in pure autonomic failure but not in multiple system atrophy, suggesting that 1) peripheral noradrenergic innervation is important for olfactory identification but norepinephrine is not essential and 2) UPSIT may be useful in the differential diagnosis between these disorders.
authors.affiliation: Autonomic Dysfunction Center, AA3228 Medical Center North, Vanderbilt University, Nashville, TN 37232-2195, USA. emily.garland@vanderbilt.edu
authors.forename: E M
authors.initials: EM
authors.lastname: Garland
authors.forename: S R
authors.initials: SR
authors.lastname: Raj
authors.forename: A C
authors.initials: AC
authors.lastname: Peltier
authors.forename: D
authors.initials: D
authors.lastname: Robertson
authors.forename: I
authors.initials: I
authors.lastname: Biaggioni
mesh_terms: D000368:Aged; D001342:Autonomic Nervous System Diseases / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology*; D003430:Cross-Sectional Studies; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019578:Multiple System Atrophy / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology; D009460:Neurologic Examination / Q000379:methods; D000857:Olfaction Disorders / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology*; D010808:Physical Examination / Q000379:methods; D011237:Predictive Value of Tests; D054970:Pure Autonomic Failure / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology; D012903:Smell / Q000235:genetics / Q000502:physiology*