Dopaminergic and non-dopaminergic pharmacological hypotheses for gait disorders in Parkinson's disease.
Gait disorders form one component of the axial disorders observed in Parkinson's disease (PD). Indeed, short steps with a forward-leaning stance are diagnostic criteria for PD in the early stages of the condition. Gait disorders also represent a major source of therapeutic failure in the advanced stages of PD (with the appearance of freezing of gait and falls) because they do not respond optimally to the two hand late-stage therapeutics--levodopa and electrical subthalamic nucleus (STN) stimulation. The late onset of doparesistance in these disorders may be linked to propagation of neurodegeneration to structures directly involved in gait control and to non-dopaminergic neurotransmitter systems. The coeruleus locus (a source of noradrenaline) is rapidly and severely affected, leading to a major motor impact. The pedunculopontine nucleus (PPN) and lateral pontine tegmentum (rich in acetylcholine) are both involved in gait. Degenerative damage to the serotoninergic raphe nuclei appears to be less severe, although serotonin-dopamine interactions are numerous and complex. Lastly, dopaminergic depletion leads to glutamatergic hyperactivity of the efferent pathways from the the STN to the PPN. However, the relationships between the various parkinsonian symptoms (and particularly gait disorders) and these pharmacological targets have yet to be fully elucidated. The goal of this review is to develop the various pathophysiological hypotheses published to date, in order to underpin and justify ongoing fundamental research and clinical trials in this disease area.
Devos
David
D
Department of Neurology and Movement Disorders, EA2683, IMPRT, IFR 114, Faculty of Medicine Lille 2, University of Lille Nord de France, Lille University Hospital, Lille, France. d-devos@chru-lille.fr
Defebvre
L
L
Bordet
R
R
D000978:Antiparkinson Agents / Q000009:adverse effects / Q000494:pharmacology / Q000627:therapeutic use; D002986:Clinical Trials as Topic; D004298:Dopamine / Q000378:metabolism*; D020233:Gait Disorders, Neurologic / Q000188:drug therapy / Q000209:etiology* / Q000378:metabolism / Q000503:physiopathology; D006801:Humans; D009638:Norepinephrine / Q000378:metabolism; D010300:Parkinson Disease / Q000150:complications* / Q000188:drug therapy / Q000378:metabolism / Q000503:physiopathology; D045042:Pedunculopontine Tegmental Nucleus / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology; D020531:Subthalamic Nucleus / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology; D016896:Treatment Outcome
D000978:Antiparkinson Agents; D004298:Dopamine; D009638:Norepinephrine