Background: Charles Bonnet Syndrome (CBS) is a rare clinical condition which is
characterized by complex hallucinations in visually impaired patients. The pathophysiology of this
disorder remains largely unknown, and there is still no proven treatment for this disease. In our study, we
aimed to investigate the neural activity through Electroencephalography (EEG) power and evaluate the
effect of rivastigmine in combination with alpha-lipoic acid on hallucination in two CBS patients with
Methods: EEG data was recorded with standard routine EEG protocols for both patients in our
electrophysiological research laboratory (REMER Clinical Electrophysiology and Neuromodulation
Research and Application Laboratory) with Brain Vision Recorder (Brainproduct, Munich, Germany).
All spectral analyses were processed by BrainVision Analyzer 2 (Brainproduct, Munich, Germany, 2.0.4
Version) in 128 Hz sample rates and the EEG recording and analysis was performed before the
administration of rivastigmine (4.5 mg/daily and five patch daily for the first and second patients,
respectively) in combination with alpha-lipoic acid (600 mg/daily) for both patients while they were not
hallucinated during the time period recordings. Based on our measurement protocol, we have compared
the patients in the study group with the three control subjects who were found to be normal except of
visual disturbances secondary to significant diabetic retinopathy.
Results: Highest theta power values were found in right occipital and left temporo-parietal regions for
first and second CBS patients, respectively. Additionally, power spectra were lower in two cases as
compared to their control groups in the alpha band for all electrodes. We have also shown that acid
rivastigmine in combination with alpha-lipoic exerted significant anti-hallucinatory efficiency.
Conclusion: Our present findings could support the hypothesis that increased activation of specific areas
in the source monitoring system plays an important role in the pathogenesis of CBS. In addition,
rivastigmine in combination with alpha-lipoic acid could be a new valuable option for CBS patients.