Apomorphine Effect on Nociceptive Perception in Parkinson's: a Clinical and Imaging Study
Condition: Parkinson's Disease
MeSH terms: Parkinson Disease
Study type: Interventional

Summary: 
      Patients suffering from Parkinson's disease (PD) frequently experienced painful sensations.
      We suppose that painful symptoms could be related to the neurotransmitter deficit of PD. So,
      we would like to evaluate the involvement of dopaminergic system in nociceptive processing in
      PD patients. The objectives of this study is to assess and to compare the effect of a
      dopamine agonist administration on the nociceptive threshold and on the cerebral activity
      using positrons emission tomography (PET scan) in two groups of PD patients (in 16 painful PD
      patients and in 16 pain free PD patients). We hypothesise that dopamine agonist could
      normalise nociceptive threshold and cerebral activity which were both abnormal in PD
      patients. Moreover, we think that painful PD patients could be more improved by dopamine
      agonist than pain free PD patients.
    

Detailed description: 
      Patients suffering from Parkinson's disease (PD) frequently experienced painful sensations.
      Painful complaints with various description (muscle cramps, painful dystonia, aching,
      numbness, tingling, burning, vibrating, lancinating) are described and can or cannot be
      related to motor symptoms. Physiopathology of pain in PD is discussed. It has been suggested
      that the occurrence of painful symptoms could be in part due to central modification of
      nociception and basal ganglia damage and the dopaminergic deficit would be expected to
      eliminate the inhibitory influence on thalamic nociceptive activity. Recently, data have
      shown that PD patient had a lower nociceptive threshold than healthy volunteers. Our team has
      reported that levodopa administration normalised this nociceptive threshold and decreased
      cerebral activity measured with positrons emission tomography (PET- H215O during experimental
      nociceptive stimulation) in several nociceptive cortical areas which were overactive in PD.
      These findings suggest that central dopamine system plays an important part in the control of
      the nociceptive pathways in PD. Nevertheless, in the central nervous system, levodopa could
      be converted in dopamine but also in noradrenaline modulating noradrenergic system. In order
      to confirm the involvement of dopaminergic system in nociceptive processing in PD, we would
      like to assess a specific drug of dopamine system (a dopamine agonist, apomorphine) in PD
      patients.

      The primary objective of this study is to assess the effect of dopamine agonist acute
      administration versus placebo on the nociceptive subjective threshold in two groups of PD
      patients (painful PD patients, n =16 and pain free PD patients, n = 16). This is a controlled
      cross over, double blind, randomised study.

      The secondary objectives are to assess and to compare the apomorphine effect on the objective
      nociceptive threshold (nociceptive flexion reflex) and on the activation of cerebral areas
      using functional imaging (TEP- H215O) during experimental nociceptive stimulation in the two
      groups of PD patients.
    

Intervention name(s): apomorphine; placebo
Intervention type(s): Drug; Drug
Intervention description(s): Acute apomorphine subcutaneous 3 mg; placebo subcutaneous
Intervention MeSH terms: Apomorphine
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Participant, Investigator)
Primary purpose: Basic Science
Keywords: Parkinson's disease; Pain; Nociceptive threshold; Functional imaging; Cerebral activity; Dopamine agonist.