title: Protocol of a prospective study on the diagnostic value of transcranial duplex scanning of the substantia nigra in patients with parkinsonian symptoms.
abstract: BACKGROUND
  Parkinson's disease (PD) is the second most common neurodegenerative disorder. As there is no definitive diagnostic test, its diagnosis is based on clinical criteria. Recently transcranial duplex scanning (TCD) of the substantia nigra in the brainstem has been proposed as an instrument to diagnose PD. We and others have found that TCD scanning of substantia nigra duplex is a relatively accurate diagnostic instrument in patients with parkinsonian symptoms. However, all studies on TCD so far have involved well-defined, later-stage PD patients, which will obviously lead to an overestimate of the diagnostic accuracy of TCD. We have therefore set out to conduct a prospective study testing the diagnostic accuracy of TCD in patients with a parkinsonism of unclear origin.
  
  
  METHODS
  We will enroll 250 consecutive patients, who are referred to neurology outpatient clinics of two teaching hospitals, for analysis of clinically unclear parkinsonism. Patients, whose parkinsonism is clearly diagnosable at the first visit, will be excluded from the study. All patients will undergo a TCD of the substantia nigra. As a surrogate gold standard we will use the consensus clinical diagnosis reached by two independent, blinded, movement disorder specialist neurologists after 2 years follow-up. At the time of TCD, patients will also undergo a SPECT scan of the brain.
  
  
  CONCLUSIONS
  As this prospective trial enroll only patients with an early-stage parkinsonism, it will yield data on the diagnostic accuracy of TCD that is relevant to daily clinical practice: The neurologist needs a diagnostic tool that provides additional information in patients with a clinically indefinable parkinsonian syndrome. The above described observational longitudinal study was designed to explicitly study this aspect in the diagnostic process.
authors.affiliation: Department of Neurology, University Hospital Maastricht, P,O, Box 5800, 6202 AZ Maastricht, The Netherlands. a.vlaar@neurologie.azm.nl
authors.forename: Annemarie M M
authors.initials: AM
authors.lastname: Vlaar
authors.forename: Angela E P
authors.initials: AE
authors.lastname: Bouwmans
authors.forename: Marinus J P G
authors.initials: MJ
authors.lastname: van Kroonenburgh
authors.forename: Werner H
authors.initials: WH
authors.lastname: Mess
authors.forename: Selma C
authors.initials: SC
authors.lastname: Tromp
authors.forename: Piet G W M
authors.initials: PG
authors.lastname: Wuisman
authors.forename: Alfons G H
authors.initials: AG
authors.lastname: Kessels
authors.forename: Ania
authors.initials: A
authors.lastname: Winogrodzka
authors.forename: Wim E J
authors.initials: WE
authors.lastname: Weber
mesh_terms: D002985:Clinical Protocols; D002986:Clinical Trials as Topic / Q000379:methods; D006801:Humans; D008137:Longitudinal Studies; D020734:Parkinsonian Disorders / Q000175:diagnosis / Q000000981:diagnostic imaging*; D011446:Prospective Studies; D013378:Substantia Nigra / Q000000981:diagnostic imaging*; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods*