In late stage Parkinson patients there is an unmet need for new treatments to adequately control dyskinesias, a long-term side effect of dopaminergic treatment. Low frequency repetitive transcranial stimulation (LF rTMS), a noninvasive stimulation technique, applied to motor cortical areas has in preliminary studies been used to treat dyskinesias with variable success. In our studies we examined the effect of one or multiple sham controlled LF rTMS session(s) applied to both motor cortices on dyskinesias, and one session to the right pre-supplementary motor area (pre-SMA) on dyskinesias, brain metabolism and functional connectivity. Although we did not observe a long-lasting effect on dyskinesias, we did observe a trend for improvement in the multiple session motor cortex protocol. Moreover, we demonstrated that one session of pre-SMA LF rTMS has an effect on pre-SMA metabolism dependent on disease duration, not dyskinesias. The shorter the disease duration, the stronger the observed effect, implying that some brain plasticity could still be present earlier on in the disease. Finally, we showed that one session of pre-SMA LF rTMS had different effects on functional connectivity with the ipsilateral putamen and the cerebellum depending on the dyskinesia state of the patient. We conclude that, although not very successful until now, rTMS is indeed a technique that merits to be further explored for the treatment of dyskinesias in late stage PD patients, using novel rTMS techniques and protocols, targeting prefrontal areas and the cerebellum.
- Dyskinesias in Parkinson disease
- Transcranial Magnetic Stimulation