Nonmotor fluctuations in Parkinson's disease: Clinical spectrum and classification

The majority of patients with Parkinson's disease (PD) on levodopa (LD) treatment usually experience motor fluctuations (MFs) within several years of initiation of treatment. Besides the classic MFs, many nonmotor fluctuations (NMFs) may occur in PD. NMFs appear both in the “on” state and “off” state. However, the clinical spectrum and the frequency of these symptoms are not well recognized. NMFs are usually mild and less disabling than MFs but sometimes can lead to unnecessary tests and therapies. NMFs occurring in association with the “on” state are better known and therefore more frequently diagnosed than those occurring in the “off” state. NMFs can be classified into three groups: autonomic, cognitive/psychiatric, and sensory. They include gastrointestinal and urinary symptoms, drenching sweats, temperature and blood-pressure changes, depression, anxiety, hallucinations, hypomania, moaning/screaming, confusion, cognitive dysfunction, sexual deviations and dopamine dysregulation syndrome (DDS), pain, akathisia, internal tremor, numbness/parasthesia, and dyspnea. Conclusion: Recognition of NMFs may prevent unnecessary diagnostic tests and may lead to treatment modifications aimed to minimize their occurrence.