The therapeutic role of repetitive transcranial magnetic stimulation (rTMS) in parkinsonian visual hallucinations: Electrophysiological correlates

Abstract

We have evaluated an 82 years old PD patient who has acutely developed VH secondary to acute visual loss that was associated with increased electroencephalographic activity in the gamma range over the parietal, occipital and frontal regions. In this respect, we have tested the therapeutic effect of occipital lobe oriented rTMS application and its electrophysiological correlates that led to significant improvement in the hallucinatory symptomatology of the patient after two weeks. We have revealed that the improved hallucinatory symptoms after rTMS application resolved completely after switching from the pramipexole treatment to L-Dopa indicating that there could be a combined therapeutic effect of L-Dopa and rTMS. Furthermore, Quantitative-Electroencephalography analysis has shown that the therapeutic effects of rTMS and L-Dopa were seen with the improvement of impaired gamma power spectrum. Although the main limitation of this report is that this a single case study and that these findings need to be replicated in a larger sample, e.g., as part of a controlled trial, our present findings help us to enlighten the unknown pathophysiological overlapping between the visual hallucinations in PD and Charles Bonnet Syndrome. Finally, our study revealed increased gamma coherence and power spectrum which is seen with visual hallucinations and improved after the application of 1 Hz rTMS on the occipital lobe. These findings together suggest that rTMS could be used as a therapeutic tool for parkinsonian complex VH and probably due affecting gamma coherence and power spectrum.