Charles Bonnet Syndrome following enucleation

Visual system plasticity in mammals: the story of monocular enucleation-induced vision loss

The groundbreaking work of Hubel and Wiesel in the 1960’s on ocular dominance plasticity instigated many studies of the visual system of mammals, enriching our understanding of how the development of its structure and function depends on high quality visual input through both eyes. These studies have mainly employed lid suturing, dark rearing and eye patching applied to different species to reduce or impair visual input, and have created extensive knowledge on binocular vision. However, not all aspects and types of plasticity in the visual cortex have been covered in full detail. In that regard, a more drastic deprivation method like enucleation, leading to complete vision loss appears useful as it has more widespread effects on the afferent visual pathway and even on non-visual brain regions. One-eyed vision due to monocular enucleation (ME) profoundly affects the contralateral retinorecipient subcortical and cortical structures thereby creating a powerful means to investigate cortical plasticity phenomena in which binocular competition has no vote.In this review, we will present current knowledge about the specific application of ME as an experimental tool to study visual and cross-modal brain plasticity and compare early postnatal stages up into adulthood. The structural and physiological consequences of this type of extensive sensory loss as documented and studied in several animal species and human patients will be discussed. We will summarize how ME studies have been instrumental to our current understanding of the differentiation of sensory systems and how the structure and function of cortical circuits in mammals are shaped in response to such an extensive alteration in experience. In conclusion, we will highlight future perspectives and the clinical relevance of adding ME to the list of more longstanding deprivation models in visual system research.

Charles Bonnet syndrome in cranio-maxillofacial surgery: case report

BACKGROUND

Complex visual hallucinations in the presence of a clear mental state and in the absence of underlying neurological disorders have received increased recognition since Charles Bonnet reported visual hallucinations secondary to mature cataracts in 1760. The prevalence of Charles Bonnet syndrome (CBS) varies widely in the literature and might be underestimated in most settings. The current paper presents a case of acute-onset CBS due to a unilateral Frost suture after revision of an orbit floor fracture.

CASE REPORT

A 68-year-old male patient underwent an operation to repair a unilateral orbital floor fracture and subsequent eye patching by a Frost suture. The patient complained of complex, colored visual hallucinations ∼3 h after waking from general anesthesia. The visual hallucinations stopped during sleep and reappeared in the morning. The symptoms disappeared completely ∼2 h after removal of the Frost suture.

DISCUSSION

Frost sutures are commonly used in oculoplastic surgery and may result in acute onset of visual hallucinations. CBS is often neglected, and clinicians must be aware of the association between acute visual deprivation and CBS.

Clinical phenomenology and mortality in Charles Bonnet syndrome

BACKGROUND/AIM

Despite existing diagnostic criteria for Charles Bonnet syndrome (CBS), clinical manifestations vary greatly. We examined the clinical course and mortality of patients diagnosed with CBS.

METHODS

We conducted a retrospective chart review of patients with CBS. We collected demographic and clinical information and medical burden scores. Kaplan-Meier mortality curves were compared using log-rank test. Cox proportional hazard model was used for multivariate analysis and hazard ratio (HR). Mortality was compared to expected mortality from Minnesota population.

RESULTS

Seventy-seven patients with CBS had a mean age of 79.5 (standard deviation ± 13.0) and were predominantly Caucasian (97%) and female (73%). In all, 20 (26%) subsequently developed a dementia syndrome, most often Lewy body. A total of 46 (60%) deaths occurred with an average follow-up time of 33.0 months. Characteristics associated with mortality included older age (75-84 [HR 3.34, P = .029], >85 [HR 4.58, P = .007]) and renal disease (HR 3.39 with 95% confidence interval 1.31-8.80, P = .012). Medical burden scores were not associated with overall mortality. Mortality was high compared to Minnesota population (P < .0001).

CONCLUSIONS

A large proportion of patients with CBS developed dementia, and there was a high mortality rate associated with older age and renal disease. Medical burden was not associated with mortality.

Acute Charles Bonnet syndrome secondary to eye patching

OBJECTIVE

The aim of this study was to report a case of Charles Bonnet syndrome secondary to eye patching following eyelid reconstruction with an unusually acute onset.

METHOD

An observational case report was conducted.

RESULTS

The patient reported complex visual hallucinations that started less than 10 minutes after patching of her right eye (the left eye had poor vision from previous trauma). The patch was removed after 2 days, and the hallucinations gradually stopped over the subsequent 2 days.

CONCLUSION

This case of Charles Bonnet syndrome describes an unusually acute onset of hallucinations and is only the second reported case following eye patching. Eye patching is commonly used in a number of situations, and it is important to be aware of this association, as the diagnosis of Charles Bonnet syndrome is often overlooked.

A case of acute reversible Charles Bonnet syndrome following postsurgical unilateral eye patch placement

A fully alert 70-year-old male with no significant medical or psychiatric history presented for surgical follow-up after uncomplicated right lower eyelid cicatricial ectropion surgery with postoperative unilateral, eye patch placement complaining of visual hallucinations. Preoperative unaided visual acuity was 20/20 in each eye. The patient described simple, nonformed and complex, formed images that were both static and animated. The images included crystal-like formations that appeared to bubble, green leaves against a vivid magenta backdrop, and an isolated hallucination of a lifelike plant with trembling leaves. These hallucinations began 2 days postoperatively and persisted 2 days following eye patch removal. The patient perceived the hallucinations multiple times a day over the 7-day period, without a stereotyped pattern. The images occurred when the eyes were open and ceased when they were closed. They were prompted by looking at a blank wall or white surface. The patient consistently recognized these images as unreal. They typically persisted for 1 to 2 minutes and could be extinguished by looking away. There were no associated auditory hallucinations, psychosis, or delirium and no history of visual, cognitive, or neurological deficit. The patient denied the use of hallucinogenic medications, including analgesics, or the initiation of any new medications. To the authors' knowledge, this is the first reported case of acute reversible CBS following unilateral eye patch placement. CBS may be a frightening postsurgical consequence of eye patch placement. It is important that the ophthalmic surgeon be aware of the potential for development of CBS and offer appropriate referral and reassurance should it occur.

Complex visual hallucinations (Charles Bonnet syndrome) in the hemianopic visual field following occipital infarction

Charles Bonnet syndrome is characterised by the occurrence of complex visual hallucinations in the presence of normal cognition in elderly individuals. It commonly happens following conditions where there has been a profound loss of vision or interruption of visual input into the occipital cortex. It is important to distinguish this largely innocuous condition from psychiatric conditions that exist in the same age group. This article describes a rare variant of this condition where such hallucinations occur in the hemianopic visual field of a patient with an occipital infarct whose visual acuity is largely unimpaired. The article details the various conditions where this phenomenon has been experienced; the theories that have been postulated for its aetiology and the treatment options. The variations of this case from the commonly observed scenarios are highlighted questioning previously held convictions as well as providing an insight into the widening spectrum of the phenomenon as more cases are described. The article hopes to raise awareness of this condition, which is much commoner than perceived by healthcare practitioners, as most patients in that age group are reluctant to be forthcoming with their symptoms for fear of being diagnosed with a psychiatric disorder.