[Non-motor fluctuations in Parkinson's disease]

Abstract

Nonmotor fluctuations (NMF) in Parkinson's disease are nonmotor symptoms that occur in coincidence with motor fluctuations or independently. Long under-assessed, NMF are now recognized as frequent and sometimes involving a greater degree of disability than motor fluctuations. They can be classified in three categories: dysautonomic, cognitive/psychiatric and sensory/pain. Recognition of these nonmotor fluctuations as part of Parkinson's disease has important implications. Some symptoms such as dyspnea, chest pain, or abdominal pains can mimic cardiac or gastrointestinal emergencies. The underlying pathogenic mechanisms of NMF are not well known. The dopaminergic system is probably involved via modulation of other systems (serotoninergic, adrenergic) since NMF usually respond to dopaminergic treatment. Subthalamic nucleus deep brain stimulation alleviates NMF-- particularly sensory, dysautonomic and cognitive fluctuations--while psychic fluctuations respond less consistently to this treatment. The development of new instruments that enable a comprehensive and precocious assessment of NMF is important for optimized management of advanced Parkinson's disease.