title: Single photon emission computed tomography striatal asymmetry index may predict dopaminergic responsiveness in Parkinson disease.
abstract: OBJECTIVE
  Parkinson disease (PD) is a neurodegenerative disorder, characterized by the excellent response to l-dopa and by asymmetry of neurological signs. The aim of the present study is to investigate a possible relationship between responsiveness to l-dopa in patients with PD and asymmetry detected by single photon emission computed tomography (SPECT) with [I]FP-CIT (DaTSCAN).
  
  
  METHODS
  We performed a retrospective study in 20 patients with PD never previously exposed to l-dopa, who had undergone (1) a short-term l-dopa test with l-dopa/carbidopa 250/25 mg to quantify dopaminergic responsiveness, and (2) a SPECT with DaTSCAN to assess the degree of nigrostriatal neuronal degeneration. We estimated the magnitude and the duration of the response to l-dopa test as well as the striatal asymmetry index (SAI) detected by SPECT with DaTSCAN.
  
  
  RESULTS
  At l-dopa short-term test, most patients showed at least a mild response to the drug, and only 3 patients presented no response. Overall, the Unified Parkinson's Disease Rating Scale-Motor Examination section score at baseline was 24.9 ± 8.2, and that at peak was 21.2 ± 8 with a magnitude of the response scoring 16 ± 13.9%; the duration was 254 ± 91.2 minutes. The caudate and putamen uptakes of DaTSCAN were lower contralaterally to the most affected side. A significant positive correlation between the SAI and the magnitude of the response to l-dopa was found (r = 0.64, P = 0.002). Linear regression model provided an increase of 0.76 units of magnitude of l-dopa response every SAI unit.
  
  
  CONCLUSIONS
  Asymmetry resulted positively related to the magnitude of the response to l-dopa short-term test and may be usefully used to predict dopaminergic responsiveness in patients with PD.
authors.affiliation: Department of Neurosciences, University of Catania, Catania, Italy.
authors.forename: Donatella
authors.initials: D
authors.lastname: Contrafatto
authors.forename: Giovanni
authors.initials: G
authors.lastname: Mostile
authors.forename: Alessandra
authors.initials: A
authors.lastname: Nicoletti
authors.forename: Loredana
authors.initials: L
authors.lastname: Raciti
authors.forename: Antonina
authors.initials: A
authors.lastname: Luca
authors.forename: Valeria
authors.initials: V
authors.lastname: Dibilio
authors.forename: Salvatore
authors.initials: S
authors.lastname: Lanzafame
authors.forename: Angela
authors.initials: A
authors.lastname: Distefano
authors.forename: Filippo
authors.initials: F
authors.lastname: Drago
authors.forename: Mario
authors.initials: M
authors.lastname: Zappia
mesh_terms: D000368:Aged; D000978:Antiparkinson Agents / Q000627:therapeutic use; D003342:Corpus Striatum / Q000000981:diagnostic imaging*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007457:Iodine Radioisotopes; D007980:Levodopa / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000473:pathology* / Q000503:physiopathology; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D014326:Tropanes
chemical_list: D000978:Antiparkinson Agents; D007457:Iodine Radioisotopes; D014326:Tropanes; C087552:2-carbomethoxy-8-(3-fluoropropyl)-3-(4-iodophenyl)tropane; D007980:Levodopa