Abnormal processing of the nociceptive input in Parkinson's disease: A study with CO2 laser evoked potentials

Michele Tinazzi, Claudia Del Vesco, Giovanni Defazio, Emiliana Fincati, Nicola Smania, Giuseppe Moretto, Antonio Fiaschi, Domenica Le Pera, Massimiliano Valeriani

Research output: Contribution to journalArticlepeer-review


Since a number of patients with Parkinson's Disease (PD) complain of painful sensations, we studied whether the central processing of nociceptive inputs is abnormal in PD. To test this hypothesis, we recorded scalp CO2 laser evoked potentials (LEPs) to hand skin stimulation in 18 pain-free PD patients with unilateral bradykinetic-rigid syndrome (hemiparkinson) during the off state and in 18 healthy subjects. This technique allows us to explore non-invasively the functional status of some cerebral structures involved in nociceptive input processing. In both PD patients and control subjects, CO2 laser stimulation gave rise to a main negative N2 potential followed by a positive P2 response at vertex peaking at a latency of about 200 and 300 ms, respectively. These potentials are thought to originate from several brain structures devoted to nociceptive input processing, including the cingulate gyrus and insula. PD patients and normal subjects showed comparable N2 and P2 latencies, whereas the N2/P2 peak-to-peak amplitude was significantly lower in PD patients (regardless of the clinically affected body side) than in controls. LEPs were even recorded after acute L-dopa administration in 7 additional PD patients. L-dopa administration yielded no significant change in N2/P2 amplitude as compared to the off state. These results suggest an abnormal nociceptive input processing in pain-free PD patients which appears to be independent of clinical expression of parkinsonian motor signs and is not affected by dopaminergic stimulation.

Original languageEnglish
Pages (from-to)117-124
Number of pages8
Issue number1-2
Publication statusPublished - May 2008


  • CO laser evoked potentials
  • Nociception
  • Pain
  • Parkinson's disease
  • Somatosensory system

ASJC Scopus subject areas

  • Clinical Neurology
  • Psychiatry and Mental health
  • Neurology
  • Neuroscience(all)
  • Pharmacology
  • Clinical Psychology


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