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Driving Simulation in the Clinic: Testing Visual Exploratory Behavior in Daily Life Activities in Patients with Visual Field Defects
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Published on: September 18, 2012

[Visual hallucinations: the Charles Bonnet syndrome]

Gilles Fénelon1

  • 1Service de neurologie, Hôpital Henri Mondor, Créteil. gfenelon@wanadoo.fr

Psychologie & Neuropsychiatrie Du Vieillissement
|February 3, 2005
PubMed

Insights

Charles Bonnet syndrome (CBS) causes visual hallucinations in visually impaired individuals. Risk factors include age and severe vision loss, with potential links to other neurological conditions.

Area of Science:

  • Neuroscience
  • Ophthalmology
  • Psychiatry

Context:

  • Charles Bonnet syndrome (CBS) is characterized by visual hallucinations (VH) in patients with visual impairment.
  • Diagnostic criteria for CBS lack consensus regarding the necessity of an ophthalmic disease or cognitive impairment.
  • CBS affects an estimated 12-15% of visually impaired individuals.

Purpose:

  • To summarize the current understanding of Charles Bonnet syndrome, including its definition, prevalence, characteristics, risk factors, and potential pathophysiological mechanisms.
  • To explore the relationship between CBS, visual impairment, and other neurological conditions presenting with visual hallucinations.

Summary:

  • Visual hallucinations in CBS are often repetitive, stereotyped, and may involve complex figures, with patients retaining insight into their unreality.
  • Key risk factors for CBS include advanced age and severe visual impairment.
  • Neuroimaging suggests VH in CBS correlate with activity in the ventral extrastriate visual cortex, possibly due to deafferentation of visual associative areas.
  • While no definitive treatments exist, anticonvulsants may offer some benefit, though reassurance and explanation are often sufficient.
  • VH in hemianopic fields post-stroke and in conditions like late paraphrenia, Alzheimer's, and Parkinson's disease may share pathophysiological mechanisms with CBS.

Impact:

  • Highlights the need for a consensual definition and systematic therapeutic trials for Charles Bonnet syndrome.
  • Underscores the role of visual impairment as a risk factor for visual hallucinations across various neurological and psychiatric conditions.
  • Provides insights into the neurobiological underpinnings of visual hallucinations in the context of sensory deprivation.

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