[123I]-FP-CIT-SPECT demonstrates dopaminergic deficit in orthostatic tremor

Ann Neurol. 2003 Apr;53(4):489-96. doi: 10.1002/ana.10475.


There is increasing evidence of a potential role of the dopaminergic system in orthostatic tremor (OT): Association with parkinsonism and treatment effects of L-dopa and dopamine agonists have been reported. Eleven patients with isolated OT had single-photon emission computed tomography (SPECT) using (123)I-FP-CIT ([(123)I]-2 beta-carbomethoxy-3beta-(-4-iodophenyl)-N-(3-fluoropropyl)-nortropane) as dopamine transporter tracer. Results were compared with 12 age-matched normal controls and 12 patients with Parkinson's disease (PD). A marked reduction in striatal tracer binding was found in OT compared to normal controls (p < 0.001). Tracer uptake was significantly higher and more symmetrical than in PD, and caudate and putamen were equally affected. L-dopa challenges, performed in seven patients, showed a small but non-significant improvement on EMG and a small but significant improvement in clinical parameters on blinded video rating. Two-month open-label L-dopa treatment (600 mg/day) led to a small improvement in two of five patients but no significant overall change. Olfactory function on University of Pennsylvania Smell Identification Test was normal. Our finding of a marked tracer uptake reduction on dopamine transporter SPECT supports a role of the dopaminergic system in OT. Lack of evidence of a clinically relevant therapeutic response to L-dopa suggests that other mechanisms must also be involved in the pathogenesis.

Publication types

  • Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Dopamine / physiology*
  • Dopamine Agents / administration & dosage
  • Electromyography
  • Female
  • Humans
  • Iodine Radioisotopes
  • Levodopa / administration & dosage
  • Male
  • Middle Aged
  • Smell / physiology
  • Tomography, Emission-Computed, Single-Photon*
  • Tremor / diagnostic imaging*
  • Tremor / drug therapy
  • Tremor / physiopathology*
  • Tropanes
  • Videotape Recording


  • Dopamine Agents
  • Iodine Radioisotopes
  • Tropanes
  • 2-carbomethoxy-8-(3-fluoropropyl)-3-(4-iodophenyl)tropane
  • Levodopa
  • Dopamine