Objective: To find a correlation between  off-related pain, and dopaminergic dysregulation syndrome (DDS );  to investigate in a subgroup of patients the neural underpinnings of the DDS, and then  to  present  our suggested pharmacological and non-pharmacological  interventions on symptoms correlated with DDS, according to each clinical picture.

Background: The DDS is a condition when the PD patient intakes an amount of dopaminergic drugs more than he effectively  needs.  Our hypothesis is that  off-related pain may represent  an internal cue to increase the demand of therapy within a behavioral addiction LD-related.

Method: In 80 PD patients we analyzed over the  clinical variables and  Levodopa  equivalent day dosage (LEDD), King Pain Scale score, the PD Impulsive-Compulsive Disorders Questionnaire (QUIP) score. In a subgroup (PET group) of 10 PD patients, we compared DDS with and without pain, by means 18-FDG-PET (positron emission tomography).In a subgroup (NIRS/VR group) of 10 PD patients,  5 patients with DDS and pain were compared with 5 PD patients without DDS as control group, by means of Cerebral Near Infrared Spectroscopy (NIRS), during an immersion in a dedicated virtual game room (www.neurovr.com). At the end, we present our personal clinical cases following our proposed exploratory guidelines such as pharmacological interventions or non-pharmacological interventions (such as repetitive Transcranial Magnetic Stimulation, rtms) aiming to inhibit the compulsive behavior.

Results: A positive DDS UPDRS item score  correlates significantly   with  fluctuation-related King pain score ( p< 0.001). In our sample, the LEDD is higher in the group with chronic pain compared with the group without (p<0.042). DDS-PD patients showed a  major hypometabolism of bilateral parieto-temporo-occipital cortex than PD (p=0.001).Futhermore, DDS-PD patients showed an hypermetabolism of bilateral mesial orbitofrontal cortex during off-phase (p=0.001) that disappear during on-phase.

Conclusion: Patients with DDS  present a positive correlation with motor fluctuation-related pain. Neurocircuitries related to impulsivity and reward are altered by over dopaminergic stimulation in PD, and pain may represent a signal of dopaminergic addictionThese finding may encourage new therapeutical strategies aimed to reduce pain in PD,  by abolishing extradoses of LD, ameliorate global motor response and reduce severity and frequency of off-phase and/or treating directly impulsivity.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/impulse-control-and-pain-a-link-in-parkinsons-disease/