title: Heterogeneity of Monosymptomatic Resting Tremor in a Prospective Study: Clinical Features, Electrophysiological Test, and Dopamine Transporter Positron Emission Tomography.
abstract: BACKGROUND
  The relationship between monosymptomatic resting tremor (mRT) and Parkinson's disease (PD) remains controversial. In this study, we aimed to assess the function of presynaptic dopaminergic neurons in patients with mRT by dopamine transporter positron emission tomography (DAT-PET) and to evaluate the utility of clinical features or electrophysiological studies in differential diagnosis.
  
  
  METHODS
  Thirty-three consecutive patients with mRT were enrolled prospectively. The Unified Parkinson's Disease Rating Scale and electromyography were tested before DAT-PET. Striatal asymmetry index (SAI) was calculated, and a normal DAT-PET was defined as a SAI of <15%. Scans without evidence of dopaminergic deficits (SWEDDs) were diagnosed in patients with a subsequent normal DAT-PET and structural magnetic resonance imaging.
  
  
  RESULTS
  Twenty-eight mRT patients with a significant reduction in uptake of DAT binding in the striatum were diagnosed with PD, while the remained 5 with a normal DAT-PET scan were SWEDDs. As for UPRDS, the dressing and hygiene score, walking in motor experiences of daily living (Part II) and motor examination (Part III) were significant different between two groups (P < 0.05 and P < 0.01, respectively). Bilateral tremor was more frequent in the SWEDDs group (P < 0.05). The frequency of resting tremor and the amplitude of postural tremor tend to be higher in the SWEDDs group (P = 0.08 and P = 0.05, respectively).
  
  
  CONCLUSIONS
  mRT is heterogeneous in presynaptic nigrostriatal dopaminergic degeneration, which can be determined by DAT-PET brain imaging. Clinical and electrophysiological features may provide clues to distinguish PD from SWEDDs.
authors.forename: Hua-Guang
authors.initials: HG
authors.lastname: Zheng
authors.forename: Rong
authors.initials: R
authors.lastname: Zhang
authors.forename: Xin
authors.initials: X
authors.lastname: Li
authors.forename: Fang-Fei
authors.initials: FF
authors.lastname: Li
authors.forename: Ya-Chen
authors.initials: YC
authors.lastname: Wang
authors.forename: Xue-Mei
authors.initials: XM
authors.lastname: Wang
authors.forename: Ling-Long
authors.initials: LL
authors.lastname: Lu
authors.affiliation: China National Clinical Research Center for Neurological Diseases; Center of Neurodegenerative Disease, Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing 100050; Parkinson's Disease Center, Beijing Institute for Brain Disorders, Capital Medical University, Beijing 100069, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Feng
mesh_terms: D000328:Adult; D000368:Aged; D050483:Dopamine Plasma Membrane Transport Proteins; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000175:diagnosis; D049268:Positron-Emission Tomography / Q000379:methods*; D011446:Prospective Studies; D014202:Tremor / Q000175:diagnosis*
chemical_list: D050483:Dopamine Plasma Membrane Transport Proteins