Psychogenic movement disorders recover following transcranial magnetic stimulation

Nathalie Chastan, MD-PHD,

Other Contributors:

April 17, 2013

Introduction- We read the article written by Garcin et al. (4) about transcranial magnetic stimulation (TMS) as an efficient treatment for psychogenic movement disorders (PMD) with great interest. The authors report the efficacy of TMS on 24 adult patients with chronic PMD. Twenty low frequency stimuli were delivered over the motor cortex with a circular coil. The authors observed an immediate significant improvement in 75% of patients treated with complete resolution in a third of these patients. We would like to relate our similar experience with TMS for patients with PMD.

Patients and methods- We retrospectively reviewed the medical records of 19 patients (14 females, 5 males) with PMD who received TMS in Rouen University Hospital's Neurophysiology Department between January 2004 and September 2010. Average age was 29.7 +- 15.3 years (mean +- SD, min-max: 8-61 years). Symptoms were tremor (n=10), myoclonia (n=5), or dystonia (n=4). Movement disorders affected either one upper limb (n=10), one lower limb (n=3), both upper limbs (n=1), both lower limbs (n=2), the face (n=2), or hemibody (n=1). Median symptom duration at the time of consultation was 21 days (min-max: 1-2000). Symptoms were acute (<30 days) in 12 patients, subacute (between 30 days and 6 months) in 3 patients, or chronic (>6 months) in 4 patients. Thirty stimuli were delivered over the motor cortex (contralaterally to symptoms or bilaterally in case of bilateral movement disorders), with a circular coil at low frequency (0.2 Hz) with a maximum intensity of 2.5 Tesla. If symptoms persisted 2 days after the first treatment (n=3), a second stimulation session was carried out between the 2nd and 7th days using the same parameters. The diagnosis of PMD which presents as a neurologic disease but without any organic damage to the nervous system was explained to each patient. TMS efficacy was classified in two groups according to subjective evaluations realized by both the patient and the neurologist: Patients were classified in the "effective" group if recovery was complete or if the patient presented a dramatic improvement and in the "ineffective" group if mild or no improvement was observed. The local ethics committee approved this retrospective study.

Results- TMS was effective in 95% of the 19 patients with PMD. A complete recovery was observed in 15 patients (79%). Ten patients recovered immediately after TMS, 2 patients recovered almost immediately after TMS (within a few minutes or hours, but less than 24 hours), and 3 patients recovered after the second TMS session. TMS was ineffective in 1 patient, a 49-year-old woman with a right-hand tremor that had appeared after an armed robbery three years earlier. No side effects were noted. The initial symptoms recurred in 4 patients: One patient experienced a single recurrence of her PMD one month after treatment. Three patients had multiple recurrences between one month and one year after treatment. TMS was once again used to treat these recurrences and was immediatly and entirely effective for all recurrences. At least one precipitating event was identified in 12 patients. Nine patients described precipitating events that were psychosocial in nature (work-related stress, personal conflict, the death of family member). A physically traumatic event in the affected limb occured in 4 patients, and, in 2 of these patients, the injury was considered particularly minor. No precipitating event was found in 7 patients. Seven patients had psychiatric comorbidities such as anxiety and depressive disorders.

Discussion- We find TMS to be effective in treating PMD, confirming the results of Garcin et al. (4). We observed a much higher response rate among our patients, but this was to be expected as very few chronic patients were included (4 patients) in our study. In the study of Garcin et al., the population was composed solely of chronic patients who are thought to be more difficult to treat. Treatment is less effective the later it is implemented, suggesting that PMD should be diagnosed and treated as quickly as possible (5). Dafotakis et al. found that tremor decreased in 11 patients with psychogenic tremor after one TMS session with similar parameters, but Dafotakis et al. used a figure-eight coil for their protocol (3). The two techniques differ in terms of the stimulated cortical volume. (A circular coil stimulates a larger cortical volume than a figure-eight coil.) The TMS procedure used in our protocol (the same as that of Garcin et al.(4)) has proven to be safe in other psychogenic disorders (1,2). Our TMS procedure is widely available since even modest neurophysiology departments have a circular coil on hand that is used for motor evoked potentials. The efficacy mechanisms of TMS stimulation are unknown. One possible explanation is that TMS stimulation modifies cortical excitability or connectivity. A small number of stimuli applied with a figure-eight coil are known to not modify cortical excitability, but the studies that illustrate this lake of modification were not done with a circular coil. In addition, a placebo effect cannot be ruled out. A multicentric randomized controlled trial versus placebo is ongoing (NCT01352910) to measure the importance of the placebo effect.

Conclusion- A majority of patients with PMD recover following transcranial magnetic stimulation suggesting that TMS should be used in PMD.

Conflict of Interest:

None declared

Conflict of Interest

None declared