Clinical phenomenology and mortality in Charles Bonnet syndrome

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.

Parasomnias Occurring in Non-Rapid Eye Movement Sleep

PURPOSE OF REVIEW

This article discusses the clinical manifestations, diagnosis and differential diagnosis, pathophysiology, and management of parasomnias occurring in non-rapid eye movement (REM) sleep.

RECENT FINDINGS

Disorders of arousal are characterized by dissociated sleep, with wake and sleep phenomena intermingling, and local sleep, in which different areas of the brain exist simultaneously in different states of wakefulness or sleep. The frequency of arousals from slow-wave sleep with delta or mixed-frequency activity has a high sensitivity but relatively low specificity for the diagnosis of arousal parasomnias.

SUMMARY

Disorders of arousal (sleepwalking, sleep terrors, and confusional arousals) are characterized by incomplete awakenings from slow-wave sleep, limited recall of imagery, and partial or complete amnesia. They occur most frequently in childhood. Management includes correction of precipitating factors, attention to safety, behavioral techniques, and medications. Sleep-related eating disorder is a variant of arousal disorders and may be associated with the use of short-acting hypnotics and restless legs syndrome. Complex nocturnal visual hallucinations can occur with visual loss, dementia with Lewy bodies, use of β-adrenergic receptor antagonists, and anxiety. Exploding head syndrome occurs at wake-sleep transition or on waking during the night, is usually benign, and requires treatment only if significant sleep disruption occurs.

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.

COGEVIS: A New Scale to Evaluate Cognition in Patients with Visual Deficiency

We evaluated the cognitive status of visually impaired patients referred to low vision rehabilitation (LVR) based on a standard cognitive battery and a new evaluation tool, named the COGEVIS, which can be used to assess patients with severe visual deficits. We studied patients aged 60 and above, referred to the LVR Hospital in Paris. Neurological and cognitive evaluations were performed in an expert memory center. Thirty-eight individuals, 17 women and 21 men with a mean age of 70.3 ± 1.3 years and a mean visual acuity of 0.12 ± 0.02, were recruited over a one-year period. Sixty-three percent of participants had normal cognitive status. Cognitive impairment was diagnosed in 37.5% of participants. The COGEVIS score cutoff point to screen for cognitive impairment was 24 (maximum score of 30) with a sensitivity of 66.7% and a specificity of 95%. Evaluation following 4 months of visual rehabilitation showed an improvement of Instrumental Activities of Daily Living (p = 0.004), National Eye Institute Visual Functioning Questionnaire (p = 0.035), and Montgomery–Åsberg Depression Rating Scale (p = 0.037). This study introduces a new short test to screen for cognitive impairment in visually impaired patients.

Hallucinations in Healthy Older Adults: An Overview of the Literature and Perspectives for Future Research

KEY POINTS

➢ Studies suggest a substantial minority of healthy older adults have hallucinatory experiences, in line with existing evidence on hallucinations in other age groups, though it is still unclear if hallucination prevalence increases or declines with age in older cohorts.

➢ Stigma attached to both hallucinations and ageing leads to considerable under-reporting of these experiences in healthy older adults and may negatively bias how professionals, family members, and the public respond.

➢ Why and when hallucinations in healthy older adults remit, persist, or progress to other clinical disorders remains poorly understood.

➢ Current evidence points to a range of factors associated with hallucinations in older adults including decline in sensory or cognitive functioning, poor sleep, and psychosocial stressors (e.g., social isolation, loneliness, and bereavement), highlighting the need for accurate assessment and tailored interventions.

Hallucinations, though common in youth and younger adults, are not the preserve of these age groups. Accumulating evidence shows that hallucinatory experiences are also present at surprisingly high rates in healthy older adults in the general community. Furthermore, stigma and misunderstanding of hallucinations, together with ageism, may lead to under-reporting of these experiences by older adults, and misdiagnosis or mismanagement by health and mental health practitioners. Consequently, improved public and professional knowledge is needed about the nature and significance of hallucinations with advancing age. The purpose of this review is to provide a comprehensive overview, and critical analysis, of research on the prevalence, psychosocial, and neurobiological factors associated with hallucinations in people aged 60 years and over. To the best of our knowledge, this is the first review of its kind in the literature. The evidence supports a dynamic conceptualization of hallucinations, in which the emergence of hallucinations is viewed as a balance between the sensory, cognitive, or social impairments accompanying advancing age and the degree to which compensatory processes elicited by these impairments are successful. We briefly summarize the implications of the literature for aged care services and interventions, and stress that far more studies are needed in this important field of research.

Minds on replay: musical hallucinations and their relationship to neurological disease

The phenomenon of musical hallucinations, in which individuals perceive music in the absence of an external auditory stimulus, has been described sparingly in the literature through small case reports and series. Musical hallucinations have been linked to multiple associated conditions, including psychiatric and neurologic disease, brain lesions, drug effect, and hearing impairment. This study aimed to review the demographics of subjects with musical hallucinations and to determine the prevalence of neurological disorders, particularly neurodegenerative disease. Through the Mayo medical record, 393 subjects with musical hallucinations were identified and divided into five categories based on comorbid conditions that have been associated with musical hallucinations: neurological, psychiatric, structural, drug effect and not otherwise classifiable. Variables, including hearing impairment and the presence of visual and other auditory hallucinations, were evaluated independently in all five groups. The mean age at onset of the hallucinations was 56 years, ranging from 18 to 98 years, and 65.4% of the subjects were female. Neurological disease and focal brain lesions were found in 25% and 9% of the total subjects, respectively. Sixty-five subjects were identified with a neurodegenerative disorder, with the Lewy body disorders being the most common. Visual hallucinations were more common in the group with neurological disease compared to the psychiatric, structural, and not otherwise classifiable groups (P < 0.001), whereas auditory hallucinations were more common in the psychiatric group compared to all other groups (P < 0.001). Structural lesions associated with musical hallucinations involved both hemispheres with a preference towards the left, and all but two included the temporal lobe. Hearing impairment was common, particularly in the not otherwise classifiable category where 67.2% had documented hearing impairment, more than in any other group (P < 0.001). Those with an underlying neurodegenerative disorder or isolated hearing impairment tended to hear more persistent music, which was often religious and patriotic compared to those with a structural lesion, where more modern music was heard, and those with psychiatric disorders where music was mood-congruent. This case series shows that musical hallucinations can occur in association with a wide variety of conditions, of which neurological disease and brain lesions represent a substantial proportion, and that Lewy body disorders are the most commonly associated neurodegenerative diseases. A future prospective study would be helpful to further delineate an association between musical hallucinations and neurodegenerative disease.