title: Spontaneous pain, pain threshold, and pain tolerance in Parkinson's disease.
abstract: The mechanisms underlying pain in Parkinson's disease (PD) are unclear. Although a few studies have reported that PD patients may have low pain threshold and tolerance, none could accurately assess whether there was a correlation between sensory thresholds and demographic/clinical features of PD patients. Thus, tactile threshold, pain threshold, and pain tolerance to electrical stimuli in the hands and feet were assessed in 106 parkinsonian patients (of whom 66 reported chronic pain) and 51 age- and sex-matched healthy subjects. Linear regression models determined relationships between psychophysical parameters and demographic/clinical features. Female gender, severity of disease, medical disease associated with painful symptoms, and dyskinesia were more frequently observed in PD patients experiencing pain, even though dyskinesia did not reach significance. Pain threshold and pain tolerance were significantly lower in PD patients than in control subjects, whereas the tactile threshold yielded comparable values in both groups. Multivariable linear regression analyses yielded significant inverse correlations of pain threshold and pain tolerance with motor symptom severity and Beck depression inventory. Pain threshold and pain tolerance did not differ between PD patients with and without pain. In the former group, there was no relationship between pain threshold and the intensity/type of pain, and number of painful body parts. These findings suggest that pain threshold and pain tolerance tend to decrease as PD progresses, which can predispose to pain development. Female gender, dyskinesia, medical conditions associated with painful symptoms, and postural abnormalities secondary to rigidity/bradikinesia may contribute to the appearance of spontaneous pain in predisposed subjects.
authors.affiliation: Neurology Unit, San Martino Hospital, Belluno, Italy.
authors.forename: Sandro
authors.initials: S
authors.lastname: Zambito Marsala
authors.forename: Michele
authors.initials: M
authors.lastname: Tinazzi
authors.forename: Roberta
authors.initials: R
authors.lastname: Vitaliani
authors.forename: Serena
authors.initials: S
authors.lastname: Recchia
authors.forename: Federico
authors.initials: F
authors.lastname: Fabris
authors.forename: Corrado
authors.initials: C
authors.lastname: Marchini
authors.forename: Antonio
authors.initials: A
authors.lastname: Fiaschi
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Moretto
authors.forename: Bruno
authors.initials: B
authors.lastname: Giometto
authors.forename: Antonella
authors.initials: A
authors.lastname: Macerollo
authors.forename: Giovanni
authors.initials: G
authors.lastname: Defazio
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000209:etiology* / Q000523:psychology*; D010147:Pain Measurement; D017288:Pain Threshold / Q000502:physiology*; D010300:Parkinson Disease / Q000150:complications*; D012684:Sensory Thresholds / Q000502:physiology; D012720:Severity of Illness Index