title: Facilitated temporal summation of pain at spinal level in Parkinson's disease.
abstract: BACKGROUND
  Pain is one of the major nonmotor symptoms of Parkinson's disease. We hypothesized that Parkinson's disease patients could show an early diffuse abnormal processing of the nociceptive inputs also in the absence of clinical pain syndrome and that this could represent the physiopathological substrate to explain the high incidence of diffuse pain symptoms.
  
  
  METHODS
  We used the temporal summation threshold of the nociceptive withdrawal reflex and the related pain sensation to evaluate the facilitation in pain processing at spinal level. Fifteen (7 Women; 8 Men; mean age 63.0 ± 9.1) Parkinson's disease patients without clinical pain and 12 (6 Women, 6 Men; mean age 61.2 ± 4.2) healthy subjects were recruited. Parkinson's disease group has been subdivided into two subgroups, 7 early-stage Parkinson's disease patients with unilateral signs (Hoehn and Yahr stage 1) and 8 patients in a more advanced stage of the disease showing bilateral parkinsonian signs (Hoehn and Yahr stages 2 and 2.5), both "on" and "off" treatments with levodopa.
  
  
  RESULTS
  A significant facilitation in temporal summation of pain (reduced temporal summation threshold and increased painful sensation) was found in Parkinson's disease patients when compared with controls. This facilitation is more evident in Parkinson's disease with bilateral signs and on the side more affected in Parkinson's disease with unilateral signs. Levodopa administration failed to significantly modify the neurophysiological abnormalities; however, a slight improvement has been detected.
  
  
  CONCLUSIONS
  The increased gain in pain processing at spinal level in Parkinson's disease patients could be a consequence of the degenerative phenomena involving supraspinal projections implicated in the modulation of pain processing and could make Parkinson's disease patients more predisposed to develop a pain condition.
authors.affiliation: Department of Neurology, IRCCS C. Mondino Institute of Neurology Foundation, University of Pavia, Pavia, Italy. armando.perrotta@mondino.it
authors.forename: Armando
authors.initials: A
authors.lastname: Perrotta
authors.forename: Giorgio
authors.initials: G
authors.lastname: Sandrini
authors.forename: Mariano
authors.initials: M
authors.lastname: Serrao
authors.forename: Simona
authors.initials: S
authors.lastname: Buscone
authors.forename: Cristina
authors.initials: C
authors.lastname: Tassorelli
authors.forename: Michele
authors.initials: M
authors.lastname: Tinazzi
authors.forename: Roberta
authors.initials: R
authors.lastname: Zangaglia
authors.forename: Claudio
authors.initials: C
authors.lastname: Pacchetti
authors.forename: Michelangelo
authors.initials: M
authors.lastname: Bartolo
authors.forename: Francesco
authors.initials: F
authors.lastname: Pierelli
authors.forename: Emilia
authors.initials: E
authors.lastname: Martignoni
mesh_terms: D000328:Adult; D000368:Aged; D000978:Antiparkinson Agents / Q000627:therapeutic use; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D007980:Levodopa / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000188:drug therapy / Q000209:etiology* / Q000473:pathology*; D010147:Pain Measurement; D017288:Pain Threshold / Q000187:drug effects / Q000502:physiology*; D010300:Parkinson Disease / Q000150:complications* / Q000188:drug therapy; D010812:Physical Stimulation; D011601:Psychophysics / Q000379:methods; D012018:Reflex / Q000502:physiology; D012720:Severity of Illness Index; D013116:Spinal Cord / Q000503:physiopathology*
chemical_list: D000978:Antiparkinson Agents; D007980:Levodopa