Visual release hallucinations (Charles Bonnet syndrome)
- Victoria S Pelak, MD
Victoria S Pelak, MD
- Associate Professor of Neurology and Ophthalmology
- Director, Neurology Residency Program
- University of Colorado Denver, School of Medicine, Department of Neurology
The Charles Bonnet syndrome refers to symptoms of visual hallucinations that occur in patients with visual acuity loss or visual field loss. These are often called release hallucinations, reflecting the most widely accepted theory of their pathogenesis.
Underlying conditions of vision loss associated with the Charles Bonnet syndrome affect the eye, optic nerve, or brain and include a diverse set of pathologies, such as macular degeneration and stroke. While often not functionally disabling, the hallucinations can be distressing to patients and negatively impact quality of life . Published case reports suggest that the syndrome is not well recognized by clinicians and may often be misdiagnosed as psychosis or early dementia [2,3].
The pathophysiology, causes, clinical features, diagnosis, and treatment of the Charles Bonnet syndrome will be reviewed here. Other causes and the overall approach to visual hallucinations are discussed separately. (See "Approach to the patient with visual hallucinations".)
The Charles Bonnet syndrome (CBS) may be more common than is generally appreciated. Visual hallucinations are often unreported by patients because they fear that they represent psychiatric disease [1,4,5]. When this symptom is specifically solicited in older patients with impaired vision, 11 to 15 percent admit to having visual hallucinations [1,5-11]. The reported prevalence was even higher, 39 percent, in one survey of patients diagnosed with macular disease . These surveys also reveal that most patients had failed to report these symptoms to their physician or to family members. One study found that only 12 percent of patients attending a retinal clinic were aware of the condition .
Release hallucinations have been reported in all age groups, including children [8,14]. However, most patients with CBS are elderly; in large case series, the mean age is between 70 and 85 years [4,8,15,16]. This probably reflects the mean age at which the most common underlying conditions causing vision loss are seen. Some investigators, but not others, have found that advanced age is a risk factor for release hallucinations within their study population [6,11,17].To continue reading this article, you must log in with your personal, hospital, or group practice subscription. For more information on subscription options, click below on the option that best describes you:
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