Visual hallucinations after resection of cerebral metastases: two patients with complex phantom images.

PURPOSE: Complex visual hallucinations are rarely seen in neurooncology. They are commonly observed alongside psychotic symptoms in schizophrenia or dementia, in Parkinson's or Lewy-body disease, after opioid medications or anesthesia, and, in particular, they appear with visual impairments. METHODS: Here we report two normal-sighted and mentally healthy patients with unusual visual hallucinations after the resection and irradiation of brain metastases, the main features of which were persistent colorful and meaningful images with hallucinatory perseveration. RESULTS: These cases demonstrate the occurrence of complex visual hallucinations after resection of visual cortices as an effect of deafferentation, so-called visual release hallucinations or phantom images, similar to phantom pain after amputation of a limb. CONCLUSION: This case serves to heighten awareness in the radiooncology practitioner of the occurrence of visual release hallucinations (Charles Bonnet syndrome) related to multidisciplinary treatment of brain metastases.

Explanatory power by vagueness. Challenges to the strong prior hypothesis on hallucinations exemplified by the Charles-Bonnet-Syndrome.

Predictive processing models are often ascribed a certain generality in conceptually unifying the relationships between perception, action, and cognition or the potential to posit a 'grand unified theory' of the mind. The limitations of this unification can be seen when these models are applied to specific cognitive phenomena or phenomenal consciousness. Our article discusses these shortcomings for predictive processing models of hallucinations by the example of the Charles-Bonnet-Syndrome. This case study shows that the current predictive processing account omits essential characteristics of stimulus-independent perception in general, which has critical phenomenological implications. We argue that the most popular predictive processing model of hallucinatory conditions - the strong prior hypothesis - fails to fully account for the characteristics of nonveridical perceptual experiences associated with Charles-Bonnet-Syndrome. To fill this explanatory gap, we propose that the strong prior hypothesis needs to include reality monitoring to apply to more than just veridical percepts.

Epidemiology and phenomenology of the Charles Bonnet syndrome in low-vision patients.

BACKGROUND: The occurrence of visual hallucinations in visually impaired people without mental impairment is known as Charles Bonnet Syndrome (CBS). To date, the prevalence of CBS has been reported with high variance. The present study aims at evaluating the prevalence of CBS among low-vision patients. METHODS: From March 2018 to February 2022, 194 patients with a visual acuity ≥ 0.5 logMAR approached the low vision section of the Eye Clinic Sulzbach. Of these, 50 patients were found eligible, agreed to participate in the study and were screened for CBS. The course of the disease, its phenomenology and characteristics, the circumstance of onset, the ability to manipulate and resolve the hallucinations, and the psychosocial aspects of CBS were investigated. RESULTS: 26% of patients with low vision suffered from CBS. Women did not suffer from CBS significantly more often than men. Often, insight into the unreality of the images is not achieved immediately. Patterns or so-called "simple" hallucinations occurred just as frequently as other types of images such as people, body parts or faces. The most frequent images were animals. Visual hallucinations, lasting only for seconds in most cases, occurred more frequently during the day and in bright surroundings. All patients experienced the hallucinations exclusively with their eyes open. The hallucinations generally did not move with the eyes. Many sufferers did neither communicate about their hallucinations nor consult any physician. CONCLUSIONS: CBS among low-vision patients is common. Its prevalence constitutes clinical relevance. Future management of CBS may benefit from encouraging patients to share their experiences and consult a physician.

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.

How do the blind 'see'? The role of spontaneous brain activity in self-generated perception.

Spontaneous activity of the human brain has been well documented, but little is known about the functional role of this ubiquitous neural phenomenon. It has previously been hypothesized that spontaneous brain activity underlies unprompted (internally generated) behaviour. We tested whether spontaneous brain activity might underlie internally-generated vision by studying the cortical visual system of five blind/visually-impaired individuals who experience vivid visual hallucinations (Charles Bonnet syndrome). Neural populations in the visual system of these individuals are deprived of external input, which may lead to their hyper-sensitization to spontaneous activity fluctuations. To test whether these spontaneous fluctuations can subserve visual hallucinations, the functional MRI brain activity of participants with Charles Bonnet syndrome obtained while they reported their hallucinations (spontaneous internally-generated vision) was compared to the: (i) brain activity evoked by veridical vision (externally-triggered vision) in sighted controls who were presented with a visual simulation of the hallucinatory streams; and (ii) brain activity of non-hallucinating blind controls during visual imagery (cued internally-generated vision). All conditions showed activity spanning large portions of the visual system. However, only the hallucination condition in the Charles Bonnet syndrome participants demonstrated unique temporal dynamics, characterized by a slow build-up of neural activity prior to the reported onset of hallucinations. This build-up was most pronounced in early visual cortex and then decayed along the visual hierarchy. These results suggest that, in the absence of external visual input, a build-up of spontaneous fluctuations in early visual cortex may activate the visual hierarchy, thereby triggering the experience of vision.

Atypical Charles Bonnet syndrome secondary to frontal meningioma: a case report.

BACKGROUND: Charles Bonnet Syndrome (CBS) is a rare clinical entity that is classically composed of visual hallucinations in the context of an altered optic pathway with preservation of reality judgment. This case aims to present the association of visual hallucinations with complex alterations of the nervous structures adjacent to the visual pathway and an atypical clinical presentation, thus explaining the possible mechanisms involved in the generation of these symptoms. CASE PRESENTATION: A 43-year-old man presents seeking care due to visual hallucinations with partial preservation of reality judgment and symptoms compatible with a major depressive disorder, including irritability and diminished hygiene habits. He has a history of complete gradual loss of vision and hyposmia. Due to poor treatment response during hospitalization, an MRI was obtained, which showed a frontal tumor lesion with meningioma characteristics adjacent to the olfactory groove and compression of the optic chiasm. He underwent surgical resection of the lesion, which remitted the psychotic symptoms, but preserving the visual limitation and depressive symptoms. CONCLUSIONS: The presence of visual hallucinations, without other psychotic features as delusions, is a focus of attention for basic structural pathologies in the central nervous system. Affection at any level of the visual pathway can cause CBS. When finding atypical symptoms, a more in-depth evaluation should be made to allow optimization of the diagnosis and treatment.

Charles Bonnet Syndrome Prevalence in a Younger Ophtalmology Outpatient Population.

BACKGROUND: In the literature, most of the studies on Charles Bonnet Syndrome (CBS) were performed on older populations. This study aims to determine the prevalence and epidemiology of CBS and the nature of the hallucinations of the younger group of patients from an ophthalmology outpatient clinic of a university hospital. SUBJECTS AND METHODS: Twenty-eight patients were randomly chosen from the outpatient ophthalmology clinic of a university hospital, and those who agreed to participate in the study were included. First, the patients were asked if they had ever seen visions that other people cannot when they were fully awake. The patients who were experiencing this symptom were given sociodemographic questionnaire and Psychiatry Institute Visual Hallucination Questionnaire, and asked to explain their hallucinations in detail. To exclude a psychiatric disorder, the participants were made a psychiatric interview as well. RESULTS: The study included 19 female (67.9%) and 9 male (32.1%) participants. Five patients (17.9%) were diagnosed with CBS. Average age of the patients diagnosed with CBS was 39.4 (min.31-max.48). Three of the 5 patients (60%) with CBS noted negative emotions (fear, wince and bewilderment) about their hallucinations. CONCLUSIONS: The prevalence of CBS (17.9%) we've found is compatible with the medical literature. CBS may also be accompanied by "relatively milder" ophthalmologic problems (myopia, astigmatism, etc.). The hallucinations which CBS patients experience could be quite distressing, and the individuals might have hard times to reveal their complaints because of the apprehension of stigmatization. To inquire this symptom during clinical examination may be the first step to help these individuals.

Case Report: Effect of a Retinal Prosthesis System on Charles Bonnet Visual Hallucinations.

SIGNIFICANCE: Charles Bonnet syndrome is commonly encountered and diagnosed in low-vision patients. It can be distressing for some of them, as there is no known effective treatment of this condition. Although there is a growing interest in retinal implants for blind patients with severe retinal diseases, the effect of these devices on Charles Bonnet syndrome visual hallucinations remains undocumented. PURPOSE: The aim of this study was to report changes in the Charles Bonnet syndrome of a patient with retinitis pigmentosa after implantation of the Argus II retinal prosthesis. CASE REPORT: A 65-year-old patient with retinitis pigmentosa and no light perception was frequently experiencing Charles Bonnet syndrome. In the hope of improving his vision, he received an Argus II retinal prosthesis in 2018 and participated in a 10-week rehabilitation program at the Institut Nazareth et Louis-Braille. The nature and the frequency of his Charles Bonnet syndrome were documented with the Questionnaire de repérage du syndrome de Charles Bonnet (a French questionnaire used to screen for Charles Bonnet syndrome) before the surgery and for 70 weeks after it. The patient's visual acuity and visual fields were monitored during the same period. Additional tests were administered to document the visual, psychological, and cognitive states of the patient throughout the study. CONCLUSIONS: Although this case report confirmed that Argus II retinal prosthesis improves the performance of blind patients in visual tests, the improvement was not associated with a decrease in the symptoms of Charles Bonnet syndrome.

Clinical Characteristics of the Charles Bonnet Syndrome in Patients with Neovascular Age-Related Macular Degeneration: The Importance of Early Detection.

PURPOSE: We investigated the characteristics, prognosis, and clinical outcome of the Charles Bonnet syndrome (CBS) in patients with neovascular age-related macular degeneration (AMD). METHODS: Five hundred psychiatrically healthy patients with neovascular AMD were screened for CBS. The individuals that fulfilled the inclusion criteria were systematically interviewed using a structured questionnaire that covered the impact, prognosis, risk factors, phenomenology, symptoms, and knowledge about the syndrome. A control group of 45 patients was used for comparison. Demographic data, current medication, and ocular risk factors were collected in all patients. RESULTS: Forty-five patients with CBS were identified. The majority of patients reported images that consisted of colored (62%) animals (44%) or faces (42%) that lasted for seconds (53%). Most patients reported a self-limited disease with a median duration of symptoms between 9 and 11.5 months, with only 7% knowing about CBS at symptom onset. The degree of visual deficit did not predict the characteristics, complexity, frequency, duration, or impact of visual hallucinations. One-third of patients reported negative outcome, which was associated with shorter duration of CBS (p = 0.023), fear-inducing images (p < 0.001), and impact on daily activities (p = 0.015). CONCLUSION: The prevalence of CBS in neovascular AMD patients is high and clinically relevant. Patients with recent onset of visual hallucinations and describing fear-inducing images are at greater risk for negative outcome. Periodic screening may minimize the negative consequences of this disease.

Reversible Charles Bonnet syndrome secondary to upper lid ptosis.

Complex visual hallucinations can occur in visually impaired individuals with no underlying psychiatric disorder. This phenomenon is known as Charles Bonnet syndrome (CBS). It is more common in elderly patients who are suffering from impaired vision due to ocular or neurological disease processes, resulting in sensory deprivation. We report a case of CBS in an elderly female with marked ptosis, which was exacerbated following a knee replacement surgery under general anaesthesia. Her CBS symptoms persisted until surgical correction of the ptosis, with a rapid and dramatic resolution of her hallucinations. Although CBS is typically a chronic condition, unusually in this case it was acute and reversible.

Functional MRI study in a case of Charles Bonnet syndrome related to LHON.

INTRODUCTION: Charles Bonnet syndrome is characterized by simple or complex visual hallucinations (VH) due to damage along the visual pathways. We report a functional MRI study of brain correlates of VH in the context of a severe optic atrophy in a patient with Leber's Hereditary Optic Neuropathy (LHON). CASE REPORT: A 62-year-old man was diagnosed with LHON (11778/ND4 mtDNA mutation) after subacute visual loss in left eye (right eye was amblyopic). One month later, he experienced VH of a few seconds consisting in "moving red and blue miniature cartoons". One year later VH content changed in colored mosaic (10-15 s duration), usually stress-related, and blue and white flashes (2-5 s), triggered by unexpected auditory stimuli. Audiometry revealed mild sensorineural hearing loss. Three block design functional MRI paradigms were administrated: 1) random "clap", 2) "checkerboard" and 3) non-random "beep". After random "claps" simple flashes were evoked with bilateral activation of primary and secondary visual cortex, cuneus, precuneus and insula. Neither hallucinations nor cortex activation were registered after "checkerboard" stimulation, due to the severe visual impairment. Primary and secondary auditory cortices were "beep"-activated, without eliciting VH by non-random "beep". CONCLUSIONS: The peculiarity of our case is that VH were triggered by random auditory stimuli, possibly due to a cross-modal plasticity between visual and auditory networks, likely influenced by the sensorineural deafness. Functional alterations of both networks in resting conditions have been demonstrated in LHON patients, even without an auditory deficit. Finally, the absence of VH triggered by expected stimuli is consistent with the "expectation suppression theory", based on increased neural activations after unexpected but not by predicted events.

The sound of music: A rare case of auditory Charles Bonnet syndrome in an elderly male.

BACKGROUND: Auditory Charles Bonnet syndrome describes a rare condition that presents with sensorineural hearing loss, which can result in musical hallucinations. METHODS: A Hispanic man, age 78, with no previous psychiatric history was evaluated at our clinic with a complaint of hearing voices and music. The patient was noted to have received cochlear implantation in his right ear in 2013, due to bilateral sensorineural hearing loss. He had auditometric testing completed in 2013 following the onset of hallucinations. RESULTS: Routine laboratory workup was unremarkable. Computed tomography of the brain revealed mucosal thickening in the left maxillary sinus and mild generalized cerebral atrophy. Over the course of 4 months, treatment with donepezil led to improvement in symptomatology. The Brief Psychiatric Rating Scale score decreased substantially from 15 to 6 over an 8-week period. The Clinical Global Impression-Severity scale score decreased from 4 to 2 and the Clinical Global Impression-Improvement scale score increased from 0 to 1 over the same period. CONCLUSIONS: Auditory Charles Bonnet syndrome should be considered in patients endorsing auditory hallucinations with hearing loss in whom the etiology is not clearly due to a psychiatric condition. The role of acetylcholine requires further elucidation; however, donepezil demonstrated efficacy in the treatment of musical hallucinations in our patient.

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.

The elephant in the room: understanding the pathogenesis of Charles Bonnet syndrome.

PURPOSE: Charles Bonnet syndrome (CBS) is a syndrome characterised by complex visual hallucinations in individuals who are cognitively normal, though often elderly and visually impaired. Although first described over 250 years ago, the condition remains poorly understood and difficult to treat. RECENT FINDINGS: Our understanding of CBS pathogenesis has advanced little since it was first described, and much of the recent literature consists of case studies strikingly similar to the first published account of CBS. However, imaging studies have provided some indication as to the cortical areas implicated in the genesis of complex visual hallucinations, and the existence of similar hallucinatory syndromes in other sensory modalities suggests a common underlying mechanism. SUMMARY: This review begins by describing what is currently known about CBS, focusing on epidemiology, clinical presentation and diagnosis. It then explores potential starting points for better understanding the pathogenesis of CBS, namely the existence of similar conditions in other sensory modalities and the reproduction of complex visual hallucinations in sensory deprivation scenarios. Finally, it discusses how CBS should be approached in clinical practice.

"Playthings of the Brain": Phantom Visions in Charles Bonnet Syndrome.

Charles Bonnet Syndrome (CBS) is a condition of the visually impaired, in which hallucinations - or, more appropriately, visions - of geometric patterns, people, and objects appear within the visual field. Most people with CBS are older adults, a function of increased likelihood of visual deterioration in later life, but the condition can occur at any age. Diagnostic criteria vary among professions, but generally includes awareness that the visions are not real, the absence of other accompanying sensory hallucinations, and the absence of dementia or other neurological condition. The mechanism by which the phenomenon occurs is not well understood, although some speculation exists that it is akin to phantom limb syndrome. Although there has recently been increasing awareness about the condition, many in the fields of medicine, optometry, and social work have not heard of it. As front-line providers for clients, it is important that social workers be well informed about the condition to alleviate anxiety our clients may have about expressing their experiences with the condition.

Cognitive impairment and Charles Bonnet syndrome: a prospective study.

OBJECTIVES: Charles Bonnet syndrome (CBS) is a common cause of visual hallucinations in older people. The relationship between CBS and cognitive impairment is unclear, but anecdotal reports exist of dementia emerging in patients diagnosed with CBS. This work set out to determine if there is an increased incidence of dementia, and increased severity of cognitive impairment, in people with CBS compared to controls from the same clinical setting. METHOD: People over 65 attending low-vision and glaucoma clinics, and a cohort of age-matched controls, underwent a psychiatric assessment. The cohorts were followed up after one year. RESULTS: Mild cognitive impairment was present in 2/12 CBS participants and 2/10 controls. Partial insight was seen in nine CBS participants. Two participants with CBS, and no controls, developed dementia at follow-up. No significant differences in performance on the ACE-R were found between the groups. Both participants who developed dementia had partial insight and hallucinations of familiar figures at diagnosis of CBS, and one had mild cognitive impairment. CONCLUSIONS: Reassurance that CBS is universally benign may be misplaced. Some people given this diagnosis go on to develop dementia. Cognitive testing at the point of diagnosis was unable to identify those at risk of this outcome. Partial insight, the presence of Mild Cognitive Impairment, and hallucinations of familiar figures at diagnosis of CBS may confer an increased risk of subsequent dementia diagnosis. Copyright © 2017 John Wiley & Sons, Ltd.

Family physician awareness of Charles Bonnet syndrome.

Background: Charles Bonnet syndrome is characterized by formed visual hallucinations in individuals with vision loss. It is reported that one in five older adults with vision loss suffer from Charles Bonnet syndrome and the suspected lack of awareness amongst family physicians may lead to misdiagnosis and inappropriate treatment. Objective: To assess Canadian family physicians' awareness of Charles Bonnet syndrome. Methods: We conducted a national perception and practices survey of family physicians across Canada to assess (i) the level of awareness of Charles Bonnet syndrome amongst family physicians; (ii) the frequency of family physicians' encounters with patients with visual hallucinations and (iii) management strategies and referral patterns for patients with Charles Bonnet syndrome presenting to family physicians. Results: Four hundred and ninety-nine family physicians across Canada answered at least one question on the survey. 54.7% indicated they were not at all aware and 19.7% indicated they were slightly aware of Charles Bonnet syndrome. 72.8% of physicians had patients present with visual hallucinations once a year or less often. The frequency of patients seen in practice with visual hallucinations is significantly associated with awareness by physicians of Charles Bonnet syndrome (ß = 0.501, t(388) = 5.59, P < 0.001). Of those who encountered patients with visual hallucinations, the majority of respondents (77.4%) provided counselling or education to the patient. Conclusion: There is a great lack of knowledge about Charles Bonnet syndrome among family physicians. Awareness of Charles Bonnet syndrome is critical to appropriate diagnosis, assessment and treatment of this condition and to reassure patients that they are not suffering from a mental disorder.

Reversible Charles Bonnet Syndrome After Oculoplastic Procedures.

Individuals with Charles Bonnet syndrome (CBS) typically have severe visual loss and experience visual hallucinations yet have no psychiatric disease. Visual impairment often is due to end-stage glaucoma or macular degeneration. We report 3 cases of CBS in patients who underwent an oculoplastic surgical procedure. One patient experienced binocular visual distortion due to excessive topical ophthalmic ointment, and 2 patients experienced monocular visual impairment from patching. Visual hallucinations resolved once vision returned to baseline. We highlight the possibility of transient CBS in postoperative patients who have temporary iatrogenic vision impairment in one or both eyes.

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.