Transcranial Direct Current Stimulation in the Treatment of Visual Hallucinations in Charles Bonnet Syndrome: A Randomized Placebo-Controlled Crossover Trial.

OBJECTIVE: To investigate the potential therapeutic benefits and tolerability of inhibitory transcranial direct current stimulation (tDCS) on the remediation of visual hallucinations in Charles Bonnet syndrome (CBS). DESIGN: Randomized, double-masked, placebo-controlled crossover trial. PARTICIPANTS: Sixteen individuals diagnosed with CBS secondary to visual impairment caused by eye disease experiencing recurrent visual hallucinations. INTERVENTION: All participants received 4 consecutive days of active and placebo cathodal stimulation (current density: 0.29 mA/cm2) to the visual cortex (Oz) over 2 defined treatment weeks, separated by a 4-week washout period. MAIN OUTCOME MEASURES: Ratings of visual hallucination frequency and duration following active and placebo stimulation, accounting for treatment order, using a 2 × 2 repeated-measures model. Secondary outcomes included impact ratings of visual hallucinations and electrophysiological measures. RESULTS: When compared with placebo treatment, active inhibitory stimulation of visual cortex resulted in a significant reduction in the frequency of visual hallucinations measured by the North East Visual Hallucinations Interview, with a moderate-to-large effect size. Impact measures of visual hallucinations improved in both placebo and active conditions, suggesting support and education for CBS may have therapeutic benefits. 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 preexisting visual impairment. CONCLUSIONS: Findings indicate that inhibitory tDCS of visual cortex may reduce the frequency of visual hallucinations in people with CBS, particularly individuals who demonstrate greater occipital excitability prior to stimulation. tDCS may offer a feasible intervention option for CBS with no significant side effects, warranting larger-scale clinical trials to further characterize its efficacy.

Evaluation of the Clinical Features, Management, and Prognoses of Patients With Charles Bonnet Syndrome.

Charles Bonnet syndrome (CBS) is characterized by visual hallucinations with preservation of cognitive abilities. The hallucinations consist mostly of vivid (realistic) objects and tend to reoccur. Here, we evaluate the etiologies, symptoms, treatments, and prognoses of 13 CBS cases. All patients had visual hallucinations but were normal on cognitive and psychiatric assessments. Patient demographic and clinical characteristics, treatment options, and 3-month follow-up data were retrospectively reviewed. The possible causes of CBS and what the patients perceived during their hallucinations were recorded. Antipsychotic agents, such as risperidone and quetiapine, and anticonvulsants, such as levetiracetam, may be effective in some cases.

[Complex visual hallucinations in the visually impaired, the Charles Bonnet syndrome]. / Charles Bonnets syndrom: synhallucinationer hos synskadade - Svagt seende patienter bör informeras om detta benigna tillstånd, som kan vålla oro.

Charles Bonnet syndrome (CBS) is characterised by recurrent, complex and vivid visual hallucinations in the absence of cognitive dysfunction. Individuals with CBS usually maintain insight into the unreal nature of their hallucinatory experiences. There is a strong association between CBS and acquired visual loss and the most commonly described ocular pathology is age-related macular degeneration. However, CBS has been described in the context of visual impairment due to pathologies anywhere along the visual pathway. It is widely agreed that CBS is an underreported diagnosis caused by patients' reluctance to admit their hallucinatory experience because of fear of being labelled mentally ill. CBS is a diagnosis of exclusion and careful assessment must be made to ensure that other etiologies causing the symptoms are ruled out. Knowledge of CBS is nonetheless important, as it constitutes a benign differential diagnosis to diseases presenting themselves with visual hallucinations. In many patients the hallucinations generate considerable anxiety aggravated by the lack of awareness of CBS. Thus, a major part of the treatment is careful information about the benign nature of the condition. Optimizing visual function also has beneficial effects on the hallucinations. This is conducted by optical means such as visual aids and the employment of different types of surgical procedures.

Hallucinatory experiences in visually impaired individuals: Charles Bonnet syndrome - implications for research and clinical practice.

BACKGROUND: Charles Bonnet syndrome (CBS) refers to visual hallucinations that occur in individuals with preserved cognitive functions associated with visual impairment. METHODS: This article reviews occurence of visual hallucinations in subjects with CBS by journals published in English in the Pubmed database in the period 1992-2018. Criteria for selection of appropriate papers were sufficient information and perspicuous view on pathogenesis, epidemiology, clinical presentation and treatment possibilities of CBS. RESULTS: Most commonly, visual hallucinations in patients with CBS are complex, repetitive and stereotyped. Such individuals have preserved insight that those percepts are not real, and there is an absence of secondary explanatory delusions and hallucinations within other modalities. Seeing as the aforementioned percepts do not share all the characteristics of hallucinations, it remains unresolved how they should be referred to. Terms as release hallucinations, one that is reflecting its underlying pathogenesis, or confabulatory hallucinatory experiences have been proposed. Moreover, CBS has also been referred to as phantom vision syndrome and may occur in any ophthalmological disease. It is not particularly connected with loss of function along any level of the visual pathway. Although this syndrome is mostly associated with age-related macular degeneration, glaucoma and cataract, it could be related to almost any other ophthalmological conditions. The incidence of CBS alongside with mostly other ocular pathology is rising as population is ageing. CONCLUSIONS: Nonetheless, CBS remains commonly underreported, under recognized and/or misrecognized. Albeit the treatment recommendations and guidelines are not yet fully established, it is important to raise awareness of this specific and distinct condition, which inevitably implicates many differential diagnostic deliberations.