title: Temporal discrimination in patients with dystonia and tremor and patients with essential tremor.
abstract: OBJECTIVE
  To investigate whether psychophysical techniques assessing temporal discrimination could help in differentiating patients who have tremor associated with dystonia or essential tremor.
  
  
  METHODS
  We tested somatosensory temporal discrimination thresholds (TDT) and temporal discrimination movement thresholds (TDMT) in 39 patients who had tremor associated with dystonia or essential tremor presenting with upper-limb tremor of comparable severity and compared their findings with those from a group of 25 sex- and age-matched healthy control subjects.
  
  
  RESULTS
  TDT was higher in patients who had tremor associated with dystonia than in those with essential tremor and healthy controls (110.6 ± 31.3 vs 63.1 ± 15.2 vs 62.4 ± 9.2; p < 0.001). Conversely, TDMT was higher in patients with essential tremor than in those with tremor associated with dystonia and healthy controls (113.7 ± 14.7 vs 103.4 ± 11.3 vs 100.4 ± 4.2; p < 0.001). Combining the 2 tests in a pattern for essential tremor (abnormal TDMT/normal TDT) and tremor associated with dystonia (normal TDMT/abnormal TDT) yielded a positive predictive value (PPV) of 86.7% and a negative predictive value (NPV) of 70.8% for diagnosing essential tremor and a PPV of 100.0% and NPV of 74.1% for diagnosing tremor associated with dystonia.
  
  
  CONCLUSIONS
  TDT and TDMT testing should prove a useful tool for differentiating tremor associated with dystonia and essential tremor. Our findings imply that the pathophysiologic mechanisms underlying tremor associated with dystonia differ from those for essential tremor.
authors.affiliation: Department of Neurological, Psychological, Morphological and Motor Sciences, University of Verona, Verona, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Tinazzi
authors.forename: Alfonso
authors.initials: A
authors.lastname: Fasano
authors.forename: Alessandro
authors.initials: A
authors.lastname: Di Matteo
authors.forename: Antonella
authors.initials: A
authors.lastname: Conte
authors.forename: Francesco
authors.initials: F
authors.lastname: Bove
authors.forename: Tommaso
authors.initials: T
authors.lastname: Bovi
authors.forename: Alessia
authors.initials: A
authors.lastname: Peretti
authors.forename: Giovanni
authors.initials: G
authors.lastname: Defazio
authors.forename: Mirta
authors.initials: M
authors.lastname: Fiorio
authors.forename: Alfredo
authors.initials: A
authors.lastname: Berardelli
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D003937:Diagnosis, Differential; D004192:Discrimination, Psychological; D004421:Dystonia / Q000150:complications / Q000175:diagnosis / Q000523:psychology*; D020329:Essential Tremor / Q000175:diagnosis / Q000523:psychology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009039:Motion Perception; D009068:Movement; D011237:Predictive Value of Tests; D012684:Sensory Thresholds; D013998:Time Perception; D014202:Tremor / Q000150:complications / Q000175:diagnosis / Q000523:psychology*