[Primary orthostatic tremor].

Primary orthostatic tremor is a particular tremor exclusively present when a subject is standing. Patients experience a severe disabling sense of unsteadiness. Walking, sitting and lying down are unaffected Neurological examination and cerebral imagery are normal most of the time. Electromyography in standing position confirms the diagnosis in showing a regular rapid tremor with a frequency of 12 to 18 Hz. Its physiopathology is partially unknown. A few symptomatic therapies can be proposed.