Annals of Long Term Care

Key words: Charles Bonnet syndrome, visual hallucinations, age-related macular degeneration.

We report the case of a nonagenarian who started reporting hallucinations shortly after being admitted to a long-term care (LTC) facility for frailty and generalized weakness after being hospitalized for pneumonia. These hallucinations were disconcerting to her, particularly because she realized that they were not real. Once her poor vision was identified as the source of the hallucinations and she was informed of this, she was no longer as troubled by them and took measures to curtail them.

Case Presentation

A 93-year-old woman was admitted to a skilled nursing facility after being hospitalized for pneumonia and generalized weakness. Her chronic medical conditions included age-related macular degeneration, osteoporosis, myelodysplastic syndrome with resultant anemia, and hypothyroidism. Because of her poor vision and increased frailty, she was transferred to an LTC facility. Her medications included levothyroxine 25 µg daily for her hypothyroidism, sulfamethoxazole/trimethoprim double strength (800/160 mg) twice daily for her pneumonia, and ferrous sulfate 325 mg daily for her anemia.

At the LTC facility, the patient reported spiders falling from the ceiling, which was an episodic but frequent event that mostly occurred when she looked up. She also reported seeing a small cat, a dog, and, occasionally, a fox in her room. Sometimes she would see a toy train, which she described as being very colorful, moving across the room. No auditory hallucinations or delusions were noted, and she demonstrated good insight, stating that she did not believe these images to be real. Her main concern was that her mind was going, and she often asked staff “Am I really getting crazy?” Following such reports, cognitive testing was performed. On the Mini-Mental State Examination, she showed good recall, attention, and calculation skills, demonstrating intact cognition, but her ability to perform the Clock Drawing Test was limited by her poor vision.

Once cognitive assessments ruled out a cognitive deficit and the visual assessments showed her to be legally blind, vision impairment was considered the source of her hallucinations—a condition known as Charles Bonnet syndrome—and we provided her with reassurance that she was not going crazy. In addition, the lighting in her room was improved, which reduced glare, and supportive counseling was provided. She was also encouraged to participate in social and recreational activities at the nursing home. Because knowledge of the source of the hallucinations greatly reduced her distress over them, pharmacologic treatment was not considered or needed, and use of such agents would not have been preferable given her frail status, which would have increased her risk of adverse effects and drug-drug interactions. Furthermore, the patient has made greater effort to keep her mind occupied, such as by listening to the news on the radio, which she says has led to considerable improvement, providing further evidence that mind-altering agents are not always needed or optimal.

Discussion

CBS, which is characterized by complex visual hallucinations in individuals with visual impairment, is named after Swiss naturalist Charles Bonnet, who described the condition in the 1760s.¹ Bonnet first noted the syndrome in his 89-year-old grandfather, who was nearly blind from cataracts in both eyes, yet reported seeing a variety of apparitions, including people, birds, carriages, buildings, and tapestries.² Like Bonnet’s grandfather, most patients with CBS are elderly persons, with various large case series showing a mean age between 70 and 85 years.³

CBS predominantly affects people with severe visual impairments due to old age (eg, macular degeneration, glaucoma, cataracts) or from damage to the eyes or optic pathways, such as may occur from a stroke.^4,5 In particular, central vision loss from macular degeneration or another condition combined with peripheral vision loss from glaucoma may predispose to CBS, although many people with such deficits do not develop the syndrome. In the literature, CBS has a reported prevalence between 10% and 40%.⁶ Although these data reveal the syndrome to be fairly common, it frequently goes unrecognized, partially because of a lack of awareness of the condition among physicians and other healthcare providers and a reluctance by patients to report the condition, which may stem from their fear of being labeled mentally unstable.⁷ Yet in addition to severely impaired vision, an understanding that the hallucinations are not real is a diagnostic criterion for CBS, as this realization helps distinguish this condition from delusional syndromes. See Table 1 for the full diagnostic criteria.

Patients with CBS generally have vivid, complex, and recurrent hallucinations, which are often described as “fictive visual percepts,” meaning patients’ visual perceptions of their surrounding environment are fictionalized by the objects and people that their mind creates.⁸ One common characteristic is that the visualized persons or objects appear smaller than they would in reality, a phenomenon referred to in the medical literature as Lilliputian hallucinations, making reference to the fictional little people who resided on the island of Lilliput in Jonathan Swift’s 1726 novel Gulliver’s Travels.^7,9,10 Patients with CBS often report seeing faces or cartoons, and these hallucinations are strictly visual, with no effect on other senses, such as hearing, smell, or taste, which is another hallmark of CBS.¹¹

The etiology of hallucinations in patients with CBS is not completely understood. A possible explanation is that the nerve cells in the retina, which send a constant stream of impulses to the visual cortex, cannot send the same stream of impulses to the brain when they become damaged, causing the brain in some persons to respond by increasing its own activity.^7,9,12 Brain scanning experiments have provided evidence to support this explanation by showing increased activity in various regions of the visual cortex in severely visually impaired persons.^13,14 In addition, what a person hallucinates depends on where in the brain the increased activity is happening.^4,14 If the increased activity is located in the part of the visual cortex used to process and see colors, the hallucination will be of a color; if it is in the part used to process or see objects, the hallucination will be of an object; and if it is in the part used to process or see faces, the hallucination will be of a face.¹⁴ Because patients often report experiencing these hallucinations when the brain is not occupied by other stimuli, social and sensory isolation has also been explored as a contributing factor.⁶

Treatment

The best treatment for patients with CBS is assurance that their hallucinations are a result of their visual impairment and not a manifestation of a mental illness, as this generally alleviates any fear or distress that they may have regarding these events (Table 2).^9,15 Patients’ caregivers and family members should be informed of this as well so that they can provide additional support and reassurance. Because most cases of CBS occur in elderly persons, a population with much comorbidity and on multiple medications, pharmacologic approaches should be avoided to prevent adverse effects. Instead, a multidisciplinary approach that focuses on encouragement and addresses visual issues to the extent possible is optimal, such as recommending the use of corrective lenses and taking measures to minimize glare and increase color contrast in the environment. Frequent supportive counseling is also beneficial, especially in the beginning as the person acclimates to the condition. Reports indicate that increasing social contact reduces visual hallucinations in some patients, which could be why participation in social and recreational activities has shown benefit among LTC residents with CBS.^9,16-19

Pharmacologic treatments should be considered only for patients who are truly distressed by their visual hallucinations despite receiving reassurance and other nonpharmacologic interventions, who experience concomitant behavioral problems, or who are depressed because of their CBS. In such cases, anticonvulsants, antianxiety agents, and antipsychotics can be considered (Table 2). Anticonvulsants have been shown to curb the hallucinations in some patients,⁹ whereas antianxiety agents can be used to lessen distress over the hallucinations. Antipsychotics can be used when hallucinations are so disturbing that they affect the patient’s quality of life; however, these agents should be used at lower doses, enabling an anxiolytic mechanism rather than an antipsychotic one.²⁰ Regardless of which pharmacologic treatment is used, these agents are only modestly effective in suppressing visual hallucinations and mostly help reduce the emotional toll of the hallucinations.¹²

Before initiating any pharmacologic treatments, the potential for adverse effects, particularly sedation, extrapyramidal effects, and an increased risk of stroke and all-cause mortality, need to be discussed with patients and their families. In addition, the minimum effective dose should be used to ensure patient comfort and quality of life. Although there is not much literature available on its use for CBS, another agent that can be considered is donepezil, a cholinesterase inhibitor. In a case report from Japan, the authors report successfully using donepezil to treat CBS in an elderly woman without any symptoms of Alzheimer’s disease or Lewy body dementia.²¹ They conclude that “because donepezil has fewer adverse effects than anticonvulsants and neuroleptic drugs, it may be a safer option for the treatment of CBS in the elderly.”

For most patients, pharmacologic treatments are unnecessary. Just knowing that they aren’t becoming mentally ill and that the symptoms will eventually subside is all the treatment they need.^22,23 A study by Jackson and Bassett²⁴ showed that 28% of patients with CBS cease experiencing the hallucinations after 1 year.It appears that as the brain adjusts to the person’s vision loss over time, the hallucinations begin to recede. Therefore, when medications are prescribed to help patients cope with CBS, the need for these agents must be closely reviewed on follow-up visits, as improvement in hallucinations might be a sign of brain adjustment, rather than of a benefit of using these agents.^5,10,25