Charles Bonnet Syndrome

Classification according to ICD-10
F06.0	Organic hallucinosis
ICD-10 online (WHO version 2019)

The Charles Bonnet syndrome is a neurological and psychiatric syndrome . Due to a chronic deterioration of vision in normal consciousness , visual deceptions ( illusions and pseudo-hallucinations ) occur without an acute psychiatric illness in the actual sense being present. The syndrome is named after the Swiss scientist and philosopher Charles Bonnet , who first described it in 1760.

causes

Charles Bonnet syndrome can result from damage to the visual pathway or the eye . The damage can be in the front part of the visual pathway (for example in the eye) or in the back part (for example in the primary visual cortex ). Diseases such as macular degeneration , diabetic retinopathy or cataracts occur in the front part of the visual pathway . Damage to the visual radiation (including the primary visual cortex) occurs in the rear part of the visual pathway due to, for example, a cerebral infarction , bleeding or a brain tumor . This can lead to Charles Bonnet syndrome with visual phenomena in the anopic (blind) visual field area.

Charles Bonnet syndrome appears to be related to the presence of the visual association cortex . Hallucinations do not occur if this has been destroyed. The visual imagination is also preserved in the case of defects in the primary visual cortex, and impaired in the case of damage to higher visual areas, particularly the lower temporo-occipital junction.

Symptoms

The deterioration in vision leads to productive visual phenomena in the case of Charles Bonnet Syndrome. These include, for example

• Phosphene : indefinable light phenomena,
• Photopsias : outlined, writable, mostly geometric figures,
• Tesselopsia : connected repetitive patterns, mostly described as tiles,
• Palinopsia : persistent or reappearing objects that have already been seen but are no longer in the field of view
• Metamorphopsia : distortions, reductions and enlargements of what is seen,
• complex hallucinations : developed images and scenes of objects and fantasy figures,
• Heautoscopies : mirror image double hallucinations

Those affected always experience the appearances as not real and distance themselves from them. That is why the appearances are also called illusions or pseudo-hallucinations.

diagnosis

To be diagnosed with Charles Bonnet Syndrome, the following criteria must be met:

• Stereotypical optical hallucinations
• Distancing oneself from the authenticity of the perceptions
• No hallucinations in other qualities (for example acoustic)
• No delusional experience

Charles Bonnet syndrome must be differentiated from diseases such as Lewy body dementia , migraine attacks, delirium , side effects of Parkinson’s medication, drug use ( hallucinogens ) and others.

therapy

The therapy of Charles Bonnet syndrome is based on the causes. The aim is to improve eyesight. If this is not possible (for example in anopic visual field quadrants after a cerebral infarction), pharmacological therapy is considered. Approaches to rehabilitation through social connection are discussed.

Eyesight improvement

If a cataract is the cause of Charles Bonnet syndrome, a lens operation can cause the symptoms to completely disappear. Similar successes have been reported after improving eyesight with glasses. If hallucinations occur at night, room lighting can improve the symptoms.

Medical therapy

Successes in therapy have been reported by:

• Neuroleptics such as melperone or risperidone
• Anticonvulsants such as carbamazepine or clonazepam
• Serotonin antagonists such as ondansetron

Improvement of the social connection

This therapeutic approach is based on the observation that socially isolated people are more likely to develop Charles Bonnet syndrome. However, since there is a high number of unreported cases who do not report the symptoms because they fear being stigmatized as mentally ill, this observation should be treated with caution. On the other hand, no worsening of the symptoms is to be expected from an improved social connection and possibly a connection to a self-help group.

Frequency and prognosis

It is reported that between 10% and 57% of all people with decreased visual acuity will experience Charles Bonnet syndrome. Depending on the possibility of improving eyesight and drug and supportive social measures, a large proportion of those affected can be treated.

It is important to emphasize that Charles Bonnet Syndrome is a harmless condition. Drug therapy should therefore only take place after a strict risk-benefit assessment.

Historical

After Charles Lullin, the grandfather of Charles Bonnets, suffered from a cloudy lens (cataract or "cataract") at the age of 77, he underwent an operation. Still, he almost went blind. He had vivid hallucinations 12 years after the operation, at the age of 89, which he reported with amusement. He saw men and women, carriages and houses, probably even a mirror-image double hallucination ( heautoscopy ), whereby he was always aware that he was hallucinating and that these things did not exist. In his later life, Charles Bonnet eventually developed his syndrome himself.

In addition to being a neuropsychiatrist, Bonnet was also known as a naturalist and researched the parthenogenesis of aphids and intestinal parasites.

swell

1. ^ Bonnet C .: Essai Analytique sur les Facultés de l'Âme. C. & A. Philibert, Copenhagen 1760.
2. ↑ ffytche DH and Howard RJ ( 1999 ): The perceptual consequences of visual loss: 'positive' pathologies of vision , Brain 122 (7): 1247-1260 (pdf)
3. ↑ ^{a b} Vaphiades MS et al. ( 1996 ): Positive spontaneous visual phenomena limited to the hemianopic field in lesions of central visual pathways , Neurology 47 : 408-417
4. ↑ ^{a b} Schnider A ( 1997 ): Behavioral Neurology , Georg Thieme Verlag, ISBN 3-13-109782-5
5. ↑ Chatterjee A and Southwood MH ( 1995 ): Cortical blindness and visual imagery , Neurology 45 : 2189-2195
6. ^ Gold K and Rabins PV (1989): Isolated visual hallucinations and the Charles Bonnet Syndrome: a review of the literature and presentation of six cases , Compr Psychiatry 30 : 90-98
7. ↑ Manford M and Andermann F (1998): Complex visual hallucinations, Clinical and neurobiological insights , Brain 121 : 1819-1840
8. ↑ ^{a b c d e} Eperjesi F and Akbarali N ( 2004 ): Rehabilitation in Charles Bonnet syndrome: a review of treatment options , Clinical and Experimental Optometry 87 (3): 149-152
9. ↑ Ramachandran VS and Blakeslee S ( 2001 ): The blind woman who can see , Rowohlt, ISBN 3-499-61381-6
10. ↑ Damas-Mora et al. ( 1982 ): The Charles Bonnet syndrome in perspective , Psychol Med 12 : 251-261
11. ^ Arenz ( 2001 ): Eponyms and Syndromes in Psychiatry: Biographical-Clinical Contributions. Viavital Verlag Cologne

This article is about a health issue. It is not used for self-diagnosis and does not replace a diagnosis by a doctor. Please note the information on health issues !