title: Abnormal tactile temporal discrimination in psychogenic dystonia.
abstract: OBJECTIVE
  Neurophysiologic studies demonstrated that patients with primary torsion dystonia (PTD) and with psychogenic dystonia (Psy-D) share similar abnormalities in the motor system. In this study, we evaluated somatosensory function in Psy-D by testing temporal discrimination threshold (TDT), and compared the results with those obtained in patients with PTD.
  
  
  METHODS
  TDT of tactile stimuli was assessed in 10 patients with Psy-D, 10 patients with PTD, and 16 control subjects. The 2 groups of patients were matched for age, gender, disease duration, and distribution of dystonia. Tactile stimuli consisted of pairs of non-noxious electrical shocks delivered to the right or left hand at interstimulus interval increasing from 0 to 400 msec, in 10-msec steps. TDT was defined as the value at which subjects recognized the 2 stimuli as asynchronous.
  
  
  RESULTS
  TDT was higher in Psy-D and PTD compared to control subjects, for both the right and the left hand. In a subgroup of patients with unilateral dystonia (Psy-D = 4, PTD = 5), TDT did not differ between the affected and the unaffected side in both groups of patients. Disease duration was not correlated to the increased TDT value.
  
  
  CONCLUSIONS
  Our study suggests an impaired processing of somatosensory inputs in both Psy-D and PTD. These abnormalities might represent a neurophysiological trait predisposing to develop a dystonic posture triggered by psychiatric and psychological factors.
authors: Dipartimento di Neuroscienze, Scienze Psichiatriche ed Anestesiologiche, Università di Messina, AOU G. Martino, Via Consolare Valeria 1, 98125 Messina, Italy. fmorgante@gmail.com
authors: F
authors: F
authors: Morgante
authors: M
authors: M
authors: Tinazzi
authors: G
authors: G
authors: Squintani
authors: D
authors: D
authors: Martino
authors: G
authors: G
authors: Defazio
authors: L
authors: L
authors: Romito
authors: A
authors: A
authors: Albanese
authors: A
authors: A
authors: Di Matteo
authors: A
authors: A
authors: Quartarone
authors: P
authors: P
authors: Girlanda
authors: M
authors: M
authors: Fiorio
authors: A
authors: A
authors: Berardelli
mesh_terms: D000328:Adult; D004192:Discrimination, Psychological / Q000502:physiology*; D020821:Dystonic Disorders / Q000175:diagnosis / Q000503:physiopathology* / Q000523:psychology; D004558:Electric Stimulation / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012684:Sensory Thresholds / Q000502:physiology*; D013998:Time Perception / Q000502:physiology*; D014110:Touch / Q000502:physiology*; D055815:Young Adult