[Transcranial magnetic stimulation for psychogenic tremor - a pilot study].

Psychogenic tremor is the most common psychogenic movement disorder. Its prognosis is widely held to be poor and strongly depends on the patient's insight into the psychogenicity of the syndrome. The clinical value of transcranial magnetic stimulation (TMS) for (i) establishing the diagnosis with a high level of certainty, (ii) modulating symptom severity and (iii) facilitating patients' insight into psychogenicity was tested in 11 patients with psychogenic tremor of the upper limb. After explaining the psychogenic origin of the syndrome and providing a neurobiological model, 30 TMS pulses were applied over the hand area of the primary motor cortex contralateral to the affected hand(s) at a rate of 0.2 Hz. 15 pulses were administered at intensities of 120 % and 140 % of the resting motor threshold, respectively. Kinematic motion analysis was used to document the effectiveness of the TMS procedure. All patients met the diagnostic criteria of conversion disorder. Time elapsed since symptom onset was on average 48 to 57 months. Tremor affected both hands in 8 patients, one patient had additional head tremor. The TMS procedure caused a significant reduction of tremor frequency and thus established the diagnosis of documented psychogenic tremor according to the criteria proposed by Fahn and Williams (1988) in each patient. The duration of symptom relief was transient in 7 patients, 4 patients had lasting symptom relief. The present pilot study demonstrates that TMS is a helpful tool to (i) establish the diagnosis of psychogenic hand tremor with a high level of certainty, (ii) reduce tremor intensity and (iii) facilitate the patient's insight into the psychogenic origin of the syndrome as a prerequisite to obtain adherence to psychotherapy.