title: A reappraisal of the ten steps test for identifying atypical parkinsonism.
abstract: BACKGROUND
  Gait abnormalities are prominent in atypical parkinsonian disorders and clinical signs such abnormal tandem walk have been suggested as a red flag for differential diagnosis. The objective is to determine the sensibility and specificity of the ten-steps test to discriminate atypical parkinsonisms from Parkinson's disease.
  
  
  METHODS
  A sample of subjects with a parkinsonian disorder was evaluated. The ten-steps test was applied to all subjects. A Bayesian analysis model was used to calculate sensibility and specificity.
  
  
  RESULTS
  A total of 32 subjects with atypical parkinsonism and 54 subjects with Parkinson's disease were included. Abnormal tandem gait had a sensitivity of 90.6% and specificity of 66.6% to differentiate between groups. When adjusted to the actual atypical parkinsonism prevalence the positive predictive value fall from 61.7% to 13.8%.
  
  
  CONCLUSIONS
  The ten-steps test provides additional information for the differential diagnosis in parkinsonian disorders but can only be regarded as a red flag.
authors.affiliation: Department of Neurology, Instituto Nacional de Neurología y Neurocirugía, México, Mexico; Movement Disorders Clinic, Instituto Nacional de Neurología y Neurocirugía, México, Mexico. Electronic address: moralhu@gmail.com.
authors.forename: Hugo
authors.initials: H
authors.lastname: Morales-Briceño
authors.affiliation: Clinical Neurodegenerative Disease Research Unit, Instituto Nacional de Neurología y Neurocirugía, México, Mexico; Movement Disorders Clinic, Instituto Nacional de Neurología y Neurocirugía, México, Mexico.
authors.forename: Mayela
authors.initials: M
authors.lastname: Rodríguez-Violante
authors.affiliation: Movement Disorders Clinic, Instituto Nacional de Neurología y Neurocirugía, México, Mexico.
authors.forename: Daniel
authors.initials: D
authors.lastname: Martinez-Ramirez
authors.affiliation: Clinical Neurodegenerative Disease Research Unit, Instituto Nacional de Neurología y Neurocirugía, México, Mexico; Movement Disorders Clinic, Instituto Nacional de Neurología y Neurocirugía, México, Mexico.
authors.forename: Amin
authors.initials: A
authors.lastname: Cervantes-Arriaga
mesh_terms: D000368:Aged; D001499:Bayes Theorem; D016022:Case-Control Studies; D003937:Diagnosis, Differential; D005260:Female; D005684:Gait; D020233:Gait Disorders, Neurologic / Q000175:diagnosis* / Q000209:etiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000150:complications / Q000175:diagnosis*; D020734:Parkinsonian Disorders / Q000150:complications / Q000175:diagnosis; D012680:Sensitivity and Specificity
keywords: Atypical parkinsonism; Gait disorders; Parkinson's disease