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Charles Bonnet Syndrome
Published in Alexander R. Toftness, Incredible Consequences of Brain Injury, 2023
The leading theory about why Charles Bonnet syndrome occurs is that because the visual centers in the brain aren't receiving as much input from the eyes anymore, they begin making up images instead. In technical terms, the loss of input to the visual regions of the brain leads these regions to spontaneously generate neuronal discharges that can be interpreted by the person as pseudohallucinations. This is called the “deafferentation theory” by Charles Bonnet syndrome researchers (Stojanov, 2016, p. 883).
Dementia
Published in Henry J. Woodford, Essential Geriatrics, 2022
Visual hallucinations with progressive cognitive impairment suggest DLB. Alternative diagnoses include delirium and psychotic depression, and they can sometimes occur in other dementias. Charles Bonnet syndrome is a condition in which cognitively intact people develop visual hallucinations in association with chronic visual impairment. Auditory hallucinations are more compatible with schizophrenia. Delusions are common in advanced AD but may be an early feature of DLB.
MRCPsych Paper A1 Mock Examination 5: Answers
Published in Melvyn WB Zhang, Cyrus SH Ho, Roger Ho, Ian H Treasaden, Basant K Puri, Get Through, 2016
Melvyn WB Zhang, Cyrus SH Ho, Roger CM Ho, Ian H Treasaden, Basant K Puri
Explanation: Charles Bonnet syndrome is characterized by the presence of complex visual hallucinations occurring in persons with visual impairment and no demonstrable psychopathology. The hallucinations vary from elementary (geometric figures) to complex hallucinations (seeing human figures or animals) and are more vivid than the limits of their impaired vision. There is usually insight that the hallucinations are not ‘real’ and the percepts may be modified by voluntary control. The syndrome is also associated with some fears of developing a mental illness.
Neuro-Ophthalmic Literature Review
Published in Neuro-Ophthalmology, 2023
David A. Bellows, John J. Chen, Hui-Chen Cheng, Panitha Jindahra, Collin McClelland, Michael S. Vaphiades, Xiaojun Zhang
The authors report a randomised, double-masked, placebo-controlled crossover trial of 16 individuals diagnosed with Charles Bonnet syndrome (CBS) secondary to visual impairment caused by eye disease who experienced recurrent visual hallucinations. All participants received four consecutive days of active or placebo transcranial direct current stimulation (tDCS) to the visual cortex over two defined treatment weeks, separated by a 4-week washout period. When compared with placebo treatment, active inhibitory stimulation of visual cortex resulted in a significant reduction in the frequency of visual hallucinations. Participants who demonstrated greater occipital excitability on electroencephalography assessment at the start of treatment were more likely to report a positive treatment response. Stimulation was found to be tolerable in all participants, with no significant adverse effects reported, including no deterioration in pre-existing visual impairment. The authors concluded that inhibitory tDCS of the visual cortex may reduce the frequency of visual hallucinations in people with CBS, particularly individuals who demonstrate greater occipital excitability prior to stimulation.
Suppressing visual hallucinations in an adolescent by occipital transcranial magnetic stimulation: A single-case experimental research design
Published in Neuropsychological Rehabilitation, 2023
Robert Bodén, Josefin Nilsson, Ida Walles, Eva Larsson, Ingela Kristiansen, David Fällmar, Jonas Persson
While the exact mechanisms underlying Charles Bonnet syndrome remain elusive one theory posits that they result from a release phenomenon (Cogan, 1973) in this case a disinhibition of secondary visual cortex due to damage of the primary visual cortex. The observed normalization of increased activity in the lateral visual network is in line with this. An alternative explanation is that increased excitatory activity at the border of the lesion drives downstream regions as has also previously been reported (Passera et al., 2020), which is in line with both the findings of increased activity at baseline in primary visual regions, suppression of lateral regions following treatment, and reduction of symptoms using an inhibitory protocol. However, we did not observe any direct effect of cTBS on the stimulated region as reflected in unchanged flash VEPs recorded over the treatment target, and activity in primary visual regions.
“Playthings of the Brain”: Phantom Visions in Charles Bonnet Syndrome
Published in Journal of Gerontological Social Work, 2019
Charles Bonnet Syndrome is a condition that can occur in the visually impaired population, characterized by visions that are thought to be the result of deafferentation. The condition occurs in the absence of other explanatory circumstances – neurological disease, mental illness, deficit of cognition, medicinal side effects/polypharmacy, etc. – with insight as to the impossibility of the visions’ reality. Prevalence estimates are extremely varied and are therefore unable to give a good indication of the true number of people with the condition. Underreporting is thought to play a large role in those unreliable estimates, with one of the major contributing factors being the fear of being mistaken for suffering from mental illness, which can carry with it a substantial amount of social stigma even in so-called “developed” societies. Without prior knowledge of the condition, it can be the cause of a great deal of anxiety at onset. Social workers, both in practice and in research, stand in a unique position to extend awareness of the condition, help clients manage it, and also to add to the research literature, thereby improving outcomes for the people we serve.