A 96 year old woman with history of hypertension, hypothyroidism, cerebral vascular accident, senile nuclear sclerosis with low vision of the left eye, central retinal artery occlusion of the right eye, and primary open angle glaucoma of bilateral eyes, was admitted for evaluation of new onset visual hallucinations. She reported seeing “beautiful flowers, faces, piles of wood, and wood chips.” She denied headache, eye pain, fever, or dizziness, and endorsed chronic weakness of her left side. Physical exam was within normal limit with no focal neurologic deficits. Non-contrast CT of the head in the ED demonstrated old lacunar infarction but no acute findings. The patient refused magnetic resonance imaging.
On hospital day (HD) 1, the patient reported continued visual hallucinations which would disappear if she closed her eyes. Ophthalmology was consulted. Opthalmic exam revealed stable decreased vision of the left eye, bilateral eye pressure within normal limits, and cupping of the left optic nerve related to glaucoma. Given the history of long-standing poor vision with normal neurologic exam and imaging, the diagnosis of Charles Bonnet Syndrome was made. The patient received no further workup or intervention, and was discharged to home on HD 2.
Discussion:
Charles Bonnet Syndrome, also known as visual release hallucinations, refers to visual hallucinations seen in patients with low visual acuity from any cause. Common underlying conditions include age-related macular degeneration, glaucoma, diabetic retinopathy, and cerebral infarction. Reported prevalence of visual hallucinations in older patients with impaired vision is 11-15%, and is even higher (39%) in macular disease. In conditions of low vision, visual sensory deafferentation leads to disinhibition of visual cortical regions leading to spontaneous firing and hallucinations. Hallucinations can be simple or complex, with reports of formed images of people, animals, or scenes. Treatment includes increasing visual stimuli and reducing social deprivation. Blinking or rapid eye movements can help suppress hallucinations when they occur. Patients with unremitting hallucinations or with disturbing images may require treatment with antipsychotics or donepezil. Hallucinations may persist for days to weeks or even years. In all cases, correcting the etiology of visual loss (e.g. cataract surgery) causes resolution of symptoms.
Conclusions:
Given the expanding aging population it is imperative for the hospitalist to be familiar with conditions generally afflicting the geriatric population. The presentation of visual hallucinations would typically trigger extensive neurologic, infectious, and psychiatric evaluations. In patients with low visual acuity and new onset visual hallucinations, it is important to consider the Charles Bonnet Syndrome as a potential etiology in the absence of neurologic findings and if initial neurologic workup is negative to save patients from unnecessary testing and protracted hospitalization.