Charles Bonnet syndrome

The Charles Bonnet syndrome is a neurological and psychiatric syndrome. It is due to chronic visual impairment in normal awareness to visual hallucinations ( illusions and pseudo hallucinations) without indicating an acute psychiatric disorder in the strict sense. The syndrome is named after the Swiss naturalist Charles Bonnet and philosophers.

Causes

The Charles Bonnet syndrome can occur as a result of damage to the visual pathway or the eye. The damage can be in the front part of the visual pathway (eg, in the eye), as well as in the rear part ( for example, in the primary visual cortex ) are. In the front part of the visual pathway occur in diseases such as macular degeneration, diabetic retinopathy or cataracts. In the rear part of the visual pathway damage the optic radiation (including the primary visual cortex ) occur for example due to cerebral infarction, hemorrhage or brain tumor. This can lead to a Charles Bonnet syndrome with visual phenomena in anopischen ( blind ) visual field.

The Charles Bonnet syndrome appears to be linked to the presence of the visual association cortex. Then hallucinations do not occur when it has been destroyed. The visual imagination is obtained from defects in the primary visual cortex, and higher visual areas affected in case of damage, especially of the lower temporo- occipital junction.

Symptoms

The visual impairment leads in case of Charles Bonnet syndrome to productive visual phenomena. These include, for example,

• Phosphenes: indefinable light phenomena,
• Photopsias: outlined, recordable, mostly geometric figures
• Palinopsien: Persistent or re- appearing objects that have already been seen, but are no longer present in the visual field.
• Metamorphopsy: distortions, reductions and enlargements of the seen.
• Complex hallucinations: embodied images and scenes of objects and fantasy figures.
• Heautoskopien: mirror-image double hallucinations

Sufferers experience the phenomena always as not genuine and to distance themselves from it. Therefore, we call the phenomena also illusions or pseudo-hallucinations.

Diagnosis

To make the diagnosis of Charles Bonnet syndrome, the following criteria must be met:

• Stereotypes visual hallucinations
• Distancing from the authenticity of the perceptions
• No hallucinations in other qualities (eg, acoustic)
• No delusional Experience

The Charles Bonnet syndrome must be distinguished from diseases such as Lewy body dementia, migraine attacks, delirium, side effect of Parkinson's drugs, drug intake ( hallucinogens ) and others.

Therapy

The treatment of Charles Bonnet syndrome - oriented to the causes. The aim is to improve the eyesight. If this is not possible ( for example in anopischen visual field quadrant after infarction), a pharmacological therapy is being considered. Approaches to rehabilitation through social connections are discussed.

Improve eyesight

If a cataract the Charles Bonnet syndrome is based, then a lens surgery cause a complete disappearance of symptoms. Similar results have been reported by improving eyesight by glasses. In nocturnal hallucinations occurrence may be a symptom improving lighting.

Drug therapy

Success in therapy have been reported by:

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

Improvement of social connection

This therapy approach is based on the observation that it often comes at a Charles Bonnet syndrome in socially isolated people. However, since a high estimated number of sufferers out there who do not report the symptoms, because they fear being stigmatized as mentally ill, this observation should however be treated with caution. On the other hand, from an improved social connection and possibly expect a connection to a support group no worsening of symptoms.

Incidence and prognosis

It is reported that suffer a Charles Bonnet syndrome between 10% and 57 % of all people with reduced visual acuity. Depending on the possibility of improving the eyesight and medical and supportive social measures is a large proportion of those treated.

It is important to emphasize that the Charles Bonnet Syndrome is a harmless condition. Drug therapy should be made only after strict risk-benefit assessment.

Historical

After Charles Lullin, the grandfather of Charles Bonnet, at the age of 77 years was diagnosed with a lens opacity (cataract or " Cataracts " ), he underwent an operation. Still, he went blind almost. 12 years after surgery, at the age of 89 years there has been vivid hallucinations, which he reported in amusement. He saw men and women, carriages and houses, probably even a mirror image Doppelgängerhalluzination ( Heautoskopie ), where he was always aware that he was hallucinating and these things did not exist. In his later life Charles Bonnet ill eventually even to his syndrome

Except as neuropsychiatrist Bonnet was also known as a naturalist and conducted research on the parthenogenesis of aphids and intestinal parasites ..

Swell

• Neuropsychological syndrome
• Disease in neurology