Introduction: Primary orthostatic tremor (OT) is defined as a clinical syndrome with high frequency (13-18 Hz) tremor when standing predominantly involving legs and trunk. OT is thought to be driven by an unique supraspinal tremor generator. Previous studies suggest that the nigrostriatal dopaminergic transmission is impaired in patients with OT.
Clinical case: All three patients at an age of 56, 45 and 72 years fulfilled the diagnosis criteria of primary OT. The duration of illness amounted to 4, 3 and 1 year, respectively. The three patients had single-photon emission computed tomography (SPECT) using 123-I-FP-CIT as dopamine transporter tracer (DatSCAN).
Results: DatSCAN was normal in every patient.
Conclusions: OT is considered to be caused by a central oscillator because high-frequency tremor bursts are time locked in arm, leg, trunk, and even facial muscles and peripheral stimulation does not reset the tremor. Some reports suggest that the central generator may be located in the posterior fossa. In our patients presynaptic nigrostriatal pathway was normal.