The Charles Bonnet Syndrome: a Systematic Review of Diagnostic Criteria

Charles Bonnet Syndrome as Sequelae of Occipital Lobe Infarct With Hemorrhagic Conversion: A Case Report

Charles Bonnet syndrome occurs in the setting of visual impairment with subsequent complex and repetitive visual hallucinations confined in the area of visual loss, with intact cognition and insight. It has been described as a sequelae of ischemic stroke affecting the visual pathway. We report a case of a male presenting with right homonymous hemianopsia secondary to acute left occipital lobe infarct of cardioembolic etiology. He then developed visual hallucinations on the side of the visual loss. MRI showed hemorrhagic conversion of the occipital lobe infarct. Electroencephalogram showed focal and intermittent slowing of the anterior temporal and frontal region. Charles Bonnet syndrome may signify the worsening or progression of a structural lesion affecting the visual pathway, such as hemorrhagic conversion, and warrants prompt and thorough evaluation. Understanding these conditions is crucial for healthcare professionals and caregivers to provide effective support and interventions for those affected.

Association between visual impairment and psychosis: A longitudinal study and nested case-control study of adults

BACKGROUND

Theories propose that visual impairment might increase the risk of psychosis, and vice versa. We aimed to investigate the relationship between visual impairment and psychosis in the UK Biobank cohort.

STUDY DESIGN

In a nested case control study of ~116,000 adults, we tested whether a Schizophrenia Spectrum Disorder (SSD) diagnosis as exposure was associated with visual impairment. We also tested longitudinally whether poorer visual acuity, and thinner retinal structures on Optical Coherence Tomography (OCT) scans in 2009 were associated with psychotic experiences in 2016. We adjusted for age, sex, depression and anxiety symptoms; and socioeconomic variables and vascular risk factors where appropriate. We compared complete case with multiple imputation models, designed to reduce bias potentially introduced by missing data.

RESULTS

People with visual impairment had greater odds of SSD than controls in multiply imputed data (Adjusted Odds Ratio [AOR] 1.42, 95 % Confidence Interval [CI] 1.05-1.93, p = 0.021). We also found evidence that poorer visual acuity was associated with psychotic experiences during follow-up (AOR per 0.1 point worse visual acuity score 1.06, 95 % CI 1.01-1.11, p = 0.020; and 1.04, 95 % CI 1.00-1.08, p = 0.037 in right and left eye respectively). In complete case data (15 % of this cohort) we found no clear association, although confidence intervals included the multiple imputation effect estimates. OCT measures were not associated with psychotic experiences.

CONCLUSIONS

Our findings highlight the importance of eye care for people with psychotic illnesses. We could not conclude whether visual impairment is a likely causal risk factor for psychosis.

Migraine with aura

This chapter describes the different types of aura including rare aura subtypes such as retinal aura. In addition, aura manifestations not classified in the International Classification of Headache Disorders and auras in headache disorders others than migraine are also described. The differential diagnosis of migraine aura comprises several neurological disorders which should be known to specialists. Migraine aura also has impact on the choice of migraine treatment; recommendations for the treatment of the migraine aura itself are also presented in this chapter.

Impact of Charles Bonnet Syndrome on visually impaired older adults’ ability to engage in physical activity: A scoping review

Charles Bonnet syndrome (CBS) is a condition associated with sight loss, characterised by vivid, spontaneous visual hallucinations. Currently, it is unclear whether CBS presents challenges to participation in physical activities, in addition to barriers attributed to sight loss alone. The purpose of this scoping review was to establish the extent of the literature, and gaps in the knowledge base, concerning the impact of CBS on older adults’ engagement in physical activities. Review conduct was informed by Arksey and O’Malley and Levac et al.’s scoping review methodologies. Six academic databases were searched during May 2021, yielding 2709 results: eight articles met eligibility criteria. Two additional sources were located via a reference check of included papers and stakeholder consultation. Quantitative cross-sectional studies ( n = 3) indicate that CBS may interfere with the ability to move around, while qualitative sources (case report/series n = 6; autobiography n = 1) show that sudden presentation of hallucinations in a person’s pathway, or threatening content, may jeopardise safety while walking. Moving to avoid a hallucination could present a fall risk if attention is diverted from environmental hazards. One case report stated that CBS did not affect personal care activities. Due to a limited evidence base, further empirical research is needed to achieve a comprehensive understanding about how CBS affects older adults’ participation in physical activities.

Charles Bonnet Syndrome With Superimposed Delirium

Charles Bonnet Syndrome (CBS) is diagnosed when a patient who is psychiatrically intact experiences visual hallucinations in the setting of significant visual acuity or field loss. The exact pathophysiology of the CBS hallucinations remains largely unknown. The main theories include the deafferentation theory and perceptual release theory. There are suspected neurotransmitters involved, including acetylcholine and dopamine. There is no defined treatment protocol with medication for CBS, but various psychotropic medications have been used with varying degrees of remission of symptoms.

This case report describes a 64-year-old male with Charles Bonnet Syndrome in the setting of superimposed delirium. We note the different medications that were trialed to reduce his CBS symptoms and decrease episodes of behavioral disturbances. Clinical features of this rare syndrome with superimposed delirium are summarized in hopes of providing directions for management and future study.

Clinical Reasoning: A 48-Year-Old Woman With 6 Months of Vivid Visual Hallucinations

Visual hallucinations are frequently encountered in clinical practice. It is critical for neurologists, particularly those in training, to develop a systematic approach for evaluating patients presenting with such unique and often perplexing symptoms. In this study, we present the case of a 48-year-old woman who developed vivid visual hallucinations after receiving nivolumab for melanoma. We discuss the broad differential diagnosis for visual hallucinations and how history and examination can guide one's evaluation.

Medicare Claims Data Underestimate Hallucinations in Older Adults With Dementia

OBJECTIVE

Administrative claims data are used to study the incidence and outcomes of dementia-related hallucinations, but the validity of International Classification of Diseases (ICD) codes for identifying dementia-related hallucinations is unknown.

METHODS

We analyzed Medicare-linked survey data from 2 nationally representative studies of U.S. older adults (the National Health and Aging Trends Study and the Health and Retirement Study) which contain validated cognitive assessments and a screening question for hallucinations. We identified older adults who had dementia or were permanent nursing home residents, and we combined this with questionnaire responses to define dementia-related hallucinations. Using Medicare claims data, we calculated the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of ICD codes for dementia-related hallucinations overall and within prespecified strata of age, neurologic comorbidity, and health care utilization.

RESULTS

We included 2,337 older adults with dementia in our cohort. Among 3,789 person-years of data, 1,249 (33.0%) had hallucations, and of these 286 had a qualifying ICD code for dementia-related hallucinations or psychosis (sensitivity 22.9%). Of 2,540 person-years of dementia without hallucinations, 284 had a diagnosis code for hallucinations (specificity 88.8%). PPV was 50.2%, and NPV was 70.1%. Sensitivity was greatest (57.0%) among those seeing a psychiatrist. Otherwise, there were no significant differences in sensitivity, specificity, PPV, or NPV by age, neurologic diagnosis, or neurologist care.

CONCLUSION

Dementia-related hallucinations are poorly captured in administrative claims data, and estimates of their prevalence and outcomes using these data are likely to be biased.

Charles Bonnet syndrome as first manifestation of occipital infarction

PURPOSE

To describe a case of Charles Bonnet syndrome as the first manifestation of occipital infarction in a patient with preserved visual acuity.

OBSERVATIONS

We report a 78-year-old man followed in our department with a two-month-long history of visual hallucinations based on the vision of flowers and fruits intermittently, being perceived as unreal images. Best-corrected visual acuity was stable in the follow-up time being 20/20 in the right eye and 20/25 in the left eye. Extraocular muscle function testing, pupillary reflexes, biomicroscopy, fundus and optical coherence tomography examinations did not reveal any interesting findings. In order to rule out occipital pathology, orbital-cerebral magnetic resonance imaging was performed, showing an image compatible with the chronic ischemic right occipital lesion. The patient was diagnosed with Charles Bonnet syndrome secondary to occipital infarction and neurology decided that no treatment was required. 24-2 and 10-2 visual field tests showed no remarkable alterations and Full-field 120 point screening test showed nonspecific peripheral defects. Hallucinations improved over the months, being described as not annoying and increasingly infrequent.

CONCLUSIONS AND IMPORTANCE

Charles Bonnet syndrome is a condition characterized by the presence of recurrent and complex visual hallucinations in patients with visual pathway pathologic defects. Visual acuity or visual field loss is not a requirement for diagnosis. Charles Bonnet syndrome should be suspected in all patients with non-disturbing visual hallucinations, even though they present good visual acuteness. It will be essential to perform complementary explorations to identify the underlying pathology that allows the starting of a correct treatment option.

Vision loss and hallucinations: perspectives from neurology and ophthalmology

PURPOSE OF REVIEW

The aim of this article is to summarize the evidence for visual impairment as a risk factor for visual hallucinations in neurologic disease and recent advances in our understanding of the central visual pathways that mediate this association.

RECENT FINDINGS

Recent studies have described the prevalence Charles Bonnet syndrome and questioned its lack of association with cognitive impairment, used advanced neuroimaging to show that disinhibition of the occipital lobe is involved in the pathogenesis of visual hallucinations in Parkinson's disease, and demonstrated that visual impairment because of eye disease is a consistent risk factor for visual hallucinations across a number of different neurodegenerative disease populations.

SUMMARY

Through connections between the primary visual cortex and other brain structures, visual function is closely tied to visual hallucinations. Given that the vast majority of vision loss is caused by ophthalmic disease, much of which is preventable or treatable, the detection and treatment of vision loss in at-risk populations may reduce the burden and consequences of visual hallucinations in older adults.

Visualization of hypermetabolism in the ventral visual pathway by FDG-PET in the Charles Bonnet syndrome

A 74-year-old man presented with complex visual hallucinations with a left inferior quadrantanopia. The characteristics of the visual hallucinations met the criteria for the Charles Bonnet syndrome. Brain magnetic resonance imaging (MRI) revealed a right occipital falx meningioma. Fusion images of gadolinium-enhanced MRI and ¹⁸F-fluorodeoxyglucose (FDG)-positron emission tomography (PET) of the brain demonstrated hypometabolism in the right primary and secondary visual cortices, and an ipsilateral hypermetabolism in a focal area of the medial aspect of the secondary visual cortex as well as the lateral part of the ventral visual pathway. These findings imply that hyperactivation of the ventral visual pathway, especially the lateral aspect of the ventral occipitotemporal cortex, may be related to the face hallucinations in this patient. This case highlights features of FDG-PET that can explain the pathophysiology of the Charles Bonnet syndrome.

Associations between psychosis and visual acuity impairment: A systematic review and meta-analysis

OBJECTIVES

Several theories propose that visual acuity impairment is associated with psychosis. Visual impairment could lead to psychosis or the converse, or they may share underlying pathology or risk factors. In the first evidence synthesis in this area for over 25 years, we collated studies measuring the association between visual acuity impairment and psychosis.

METHODS

We searched the MEDLINE, EMBASE, PsycINFO, and Web of Science databases for studies published from 1992 to 2020, using the Newcastle Ottawa Scale to assess risk of bias. We narratively synthesized findings and meta-analyzed sufficiently homogenous results.

RESULTS

We included 40 papers, which reported on 31 studies. Evidence from seven cohort studies was inconsistent, which precluded meta-analysis of this study design. These contradictory results also made it difficult to draw conclusions regarding a temporal association. We found evidence for an association from eight cross-sectional studies treating visual acuity impairment as the exposure and psychosis as the outcome [pooled odds ratio (OR) =1.76, 95% confidence interval (CI): 1.34-2.31], and four with the reverse exposure and outcome (OR: 1.85, 95% CI: 1.17-2.92). Seven case-control studies with mixed findings were found, but only two primarily addressed our research question, and these findings were mixed.

CONCLUSIONS

Although evidence supports a cross-sectional association between visual acuity impairment and psychosis, further research is needed to clarify the temporal direction, given the mixed findings in cohort studies. Understanding the association may give insights into prevention strategies for people at risk of visual acuity impairment and psychosis.

Visual hallucinations in psychiatric, neurologic, and ophthalmologic disease

PURPOSE OF REVIEW

Recent studies have increased our understanding of the biochemical and structural bases of visual hallucinations in patients with a variety of underlying causes.

RECENT FINDINGS

Visual hallucinations may be related to disruption of functional connectivity networks, with underlying biochemical dysfunction such as decreased in cholinergic activity. Structural abnormalities in primary and higher order visual processing areas also have been found in patients with visual hallucinations. The occurrence of visual hallucinations after vision loss, the Charles Bonnet syndrome, may have more functional similarity to psychiatric and neurodegenerative causes than previously suspected despite retained insight into the unreal nature of the phenomena.

SUMMARY

Visual hallucinations are common, and patients may not report them if specific inquiries are not made. Presence or absence of hallucinations may be of diagnostic and therapeutic importance, especially in patients with neurodegenerative conditions that have overlapping features. Treatment of visual hallucinations remains challenging and must be tailored to each patient based on the underlying cause and comorbid conditions.

Photopsia

'Photopsia' describes the symptom of visual disturbances that are typically flash-like, sudden in onset and brief, and occurring without light entering the eye. Patients reporting photopsia often pose a diagnostic challenge, given the wide range of possible neurological and ophthalmological causes. We review the common causes of photopsia, discuss the assessment and workup of this symptom, and stress the importance of close interdisciplinary liaison to help with its diagnosis and management. We discuss a patient with acute zonal occult outer retinopathy to illustrate these points.

Charles Bonnet Syndrome in a Patient with Parkinson's Disease and Bilateral Posterior Capsule Opacification

Charles Bonnet syndrome (CBS) is a condition of visual hallucinations or disturbances occurring in patients with visual pathway pathology not due to underlying psychiatric, metabolic, or neurologic disease. A patient with Parkinson’s disease experiencing visual hallucinations was evaluated by the ophthalmology service and found to have decreased vision due to bilateral reversible posterior capsular opacification. The patient’s hallucinations did not improve on clozapine, a medication requiring careful monitoring due to potentially severe systemic side effects. However, the hallucinations resolved and vision improved after bilateral treatment of the posterior capsular opacification. Clozapine was then discontinued, and the patient was able to resume his previous Parkinson’s disease therapy. This case highlights the importance of considering visual pathway pathology as a contributing factor to visual hallucinations, even in patients with previously diagnosed underlying psychiatric, metabolic, or neurologic disease that could additionally be the etiology of the visual disturbances.