15 February 2011
Perrotta A, Sandrini G,
Serrao M, Buscone S, Tassorelli C, Tinazzi M, Zangaglia R, Pacchetti C, Bartolo
M, Pierelli F, Martignoni E
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.
Materials and 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.
