Pain perception in Parkinson’s disease: A systematic review and meta-analysis of experimental studies

While hyperalgesia (increased pain sensitivity) has been suggested to contribute to the increased prevalence of clinical pain in Parkinson’s disease (PD), experimental research is equivocal and mechanisms are poorly understood. We conducted a meta-analysis of studies comparing PD patients to healthy controls (HCs) in their response to experimental pain stimuli. Articles were acquired through systematic searches of major databases from inception until 10/2016. Twenty-six studies met inclusion criteria, comprising 1292 participants (PD = 739, HCs = 553). Random effects meta-analysis of standardized mean differences (SMD) revealed lower pain threshold (indicating hyperalgesia) in PD patients during unmedicated OFF states (SMD = 0.51) which was attenuated during dopamine-medicated ON states (SMD = 0.23), but unaffected by age, PD duration or PD severity. Analysis of 6 studies employing suprathreshold stimulation paradigms indicated greater pain in PD patients, just failing to reach significance (SMD = 0.30, p= = 0.06). These findings (a) support the existence of hyperalgesia in PD, which could contribute to the onset/intensity of clinical pain, and (b) implicate dopamine deficiency as a potential underlying mechanism, which may present opportunities for the development of novel analgesic strategies

Transcranial magnetic stimulation, synaptic plasticity and network oscillations

Transcranial magnetic stimulation (TMS) has quickly progressed from a technical curiosity to a bona-fide tool for neurological research. The impetus has been due to the promising results obtained when using TMS to uncover neural processes in normal human subjects, as well as in the treatment of intractable neurological conditions, such as stroke, chronic depression and epilepsy. The basic principle of TMS is that most neuronal axons that fall within the volume of magnetic stimulation become electrically excited, trigger action potentials and release neurotransmitter into the postsynaptic neurons. What happens afterwards remains elusive, especially in the case of repeated stimulation. Here we discuss the likelihood that certain TMS protocols produce long-term changes in cortical synapses akin to long-term potentiation and long-term depression of synaptic transmission. Beyond the synaptic effects, TMS might have consequences on other neuronal processes, such as genetic and protein regulation, and circuit-level patterns, such as network oscillations. Furthermore, TMS might have non-neuronal effects, such as changes in blood flow, which are still poorly understood

Pain in the neurodegenerating brain: insights into pharmacotherapy for Alzheimer disease and Parkinson disease

This is the final version. Available on open access from Lippincott, Williams & Wilkins via the DOI in this recordNational Institute for Health Research (NIHR)European Union Horizon 202

Effets moteurs de l'application de la stimulation magnétique transcranienne répétitive (rTMS) au cortex sain à la phase aigüe de l'accident vasculaire cérébral (AVC) (étude prospective randomisée en simple aveugle)

TOULOUSE3-BU Santé-Centrale (315552105) / SudocSudocFranceF

Effet de la levodopa sur la perception douloureuse dans la maladie de Parkinson

La douleur constitue une plainte fréquemment rencontrée dans la maladie de Parkinson. Cette douleur pourrait résulter d'une altération de la perception douloureuse secondaire au déficit dopaminergique central. La perception de la douleur chez les malades Parkinsoniens a fait l'objet de très peu d'études et les résultats sont hétérogènes. Dans cette étude randomisée, menée en ouvert 13 patients parkinsoniens et 10 volontaires sains ont été inclus. Le seuil nociceptif était évalué dans deux conditions différentes (avec ou sans L-dopa). Le seuil nociceptif était évalué grâce à deux modalités différentes de stimulation douloureuse : une stimulation thermique (au froid) et une stimulation électrique (estimation verbale et mesure du réflexe R III). Nous montrons que la L-dopa améliore significativement le seuil douloureux chez les patients parkinsoniens quelque soit la modalité testée. De plus les patients parkinsoniens présentent un seuil douloureux plus bas que les volontaires sains. En conclusion, nous confirmons une altération de la perception douloureuse chez les patients parkinsoniens. D'autre part la L-dopa semble normaliser la perception douloureuse chez ces mêmes patients parkinsoniens. Ce travail pilote nécessite d'être validé par un travail contre placebo en double aveugle.TOULOUSE3-BU Santé-Centrale (315552105) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF