title: Internal tremor in Parkinson's disease, multiple sclerosis, and essential tremor.
abstract: OBJECTIVE
  Internal tremor (IT) is a poorly recognized symptom that has been described in Parkinson's disease (PD). Described as a feeling of tremor in the extremities or trunk without actual movement, ITs are not debilitating but can be bothersome to patients. The origin of the sensation is unknown., and ITs may be prevalent in other diseases than PD. The present study sought to expand knowledge about IT by confirming their presence in PD, and determining their prevalence in Multiple Sclerosis (MS), and Essential Tremor (ET).
  
  
  METHODS
  A survey was developed in order to determine the prevalence of IT in PD, MS, and ET and to learn what associations with various disease characteristics were present. The survey was administered to 89 consecutive PD, 70 MS, and 11 ET patients.
  
  
  RESULTS
  ITs were found to be a prevalent symptom in all three disorders (32.6% of PD, 35.9% of MS, and 54.5% of ET subjects reported experiencing ITs). ITs were found to be associated both with the subjects' perceived levels of anxiety and the presence of visible tremors.
  
  
  CONCLUSIONS
  ITs appear to be a common symptom in all three disorders studied. These results need to be confirmed and compared to appropriate control populations.
authors: Butler Hospital/Alpert Medical School of Brown University, 345 Blackstone Blvd., Providence, RI 02906, USA.
authors: Graham D
authors: GD
authors: Cochrane
authors: Rhode Island Hospital, 2 Dudley Street Suite #555, Providence, RI 02905, USA.
authors: Syed
authors: S
authors: Rizvi
authors: Butler Hospital/Alpert Medical School of Brown University, 345 Blackstone Blvd., Providence, RI 02906, USA.
authors: Ana
authors: A
authors: Abrantes
authors: Rhode Island Hospital, 2 Dudley Street Suite #555, Providence, RI 02905, USA.
authors: Brigid
authors: B
authors: Crabtree
authors: Rhode Island Hospital, 2 Dudley Street Suite #555, Providence, RI 02905, USA.
authors: Jonathan
authors: J
authors: Cahill
authors: Butler Hospital/Alpert Medical School of Brown University, 345 Blackstone Blvd., Providence, RI 02906, USA. Electronic address: Joseph_Friedman@brown.edu.
authors: Joseph H
authors: JH
authors: Friedman
mesh_terms: D000368:Aged; D020329:Essential Tremor / Q000150:complications*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000150:complications*; D010300:Parkinson Disease / Q000150:complications*; D015995:Prevalence; D014202:Tremor / Q000453:epidemiology* / Q000209:etiology
keywords: Essential tremor; Internal tremors; Multiple sclerosis; Parkinson's disease