Charles Bonnet Syndrome: Definition, Causes and Symptoms

Among the various perceptual systems, the visual system is the main tool through which our species perceives and reacts to its environment. Since birth we have a visual capacity that allows us to detect the stimuli that surround us and react to them.

Sight, however, is a sense that is evolving, developing mainly throughout the first year of life. From certain ages, it is common for visual capacity to be reduced and problems such as eye strain to appear, cataracts and even glaucoma. Also, it is possible that areas of the brain responsible for vision cease to function with the usual precision, or that the visual connections with those of other sensory and even intellectual processes are weakened.

This type of problem can cause our visual system to perceive stimuli that are not present, as in the case of Charles Bonnett syndrome.

What is Charles Bonnet Syndrome?

The Charles Bonnet Syndrome is understood as the clinical picture characterized by the appearance of visual hallucinations in patients with problems in the visual pathway, whether these are problems located in the visual organs, their connections to the brain, or the brain areas involved in the vision.

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The main diagnostic criteria of this syndrome are the aforementioned presence of visual hallucinations and that these occur in the total absence of cognitive and consciousness alterations, disorders psychiatric, neurological or substance use disorders that could explain its appearance.

In other words, these hallucinations occur in healthy subjects with no other problem than the visual itself, having to rule out the presence of dementia (a condition that sometimes also presents visual hallucinations), poisoning and other disorders.

Thus, the Charles Bonnet Syndrome would appear mainly in healthy individuals who do not suffer from any other alteration than loss of vision. Since a large proportion of visual problems appear during old age, it is especially prevalent in the elderly population.

visual hallucinations

The hallucinations present in this type of disorder are highly variable., although they present a series of common characteristics such as occurring with clarity of conscience, without the illusion of reality (i.e., the patient knows that it is not real), combine with normal perceptions, appear and disappear without that there is a clear cause for it and they represent a phenomenon that surprises the sufferer, although there is usually no great fear regarding they.

Regarding the content of the hallucinations that occur in the Charles Bonnet Syndrome, the perception of human figures or small animals is frequent (type of hallucination called lilliputian), as well as sparkles or bright colors.

The perception itself is clear and vivid, situated in space external to the person himself (i.e., false perceptions are perceived as if they were elements of the environment, although they are recognized as unreal), with a high level of definition that contrasts to a great extent with the real perception (remember that this syndrome occurs in individuals with visual loss, who therefore see the stimuli more blurred real).

These hallucinations occur without a clear cause that triggers them; although he stress, excessive or poor lighting or the lack or overload of sensory stimulation facilitate its appearance. The duration of the hallucinations is usually short, and can vary between seconds and hours, and they tend to vanish spontaneously when you close your eyes or redirect your gaze towards them or towards another spot.

Causes (etiology)

The causes of this syndrome, as already mentioned, are found in the loss of vision. This loss usually occurs due to damage to the visual system, being generally due to macular degeneration or glaucoma and appearing mainly in elderly subjects. However, it is also possible that this loss of vision is due to the presence of a brain pathology that hinders the connection between the eye and the brain. occipital lobe.

But, although an eye disease causes loss of vision, it is worth asking why hallucinations and Charles Bonnet Syndrome appear. In this sense, there is a wide diversity of theories that work on the subject, one of the most accepted being the Neuronal Deafferentation Theory.

This theory is based on the consideration that due to the eye disease there is a loss of impulses nerve cells that should reach the occipital cortex, the area of the brain responsible for processing information visual. This causes the brain to become especially sensitive to the stimuli that come to it., being also affected by other sensory stimulations that, given the hypersensitivity of the receptors, could form the perception of hallucinations, activating the visual area.

Treatment

Regarding the treatment of Charles Bonnet Syndrome, at a psychological level the first thing that must be done is calming down and providing information to the patient, who can present great anguish by not knowing what is happening and believing that he has some type of dementia or disorder mental. It should be explained that the visions you experience are a consequence of vision loss, and it is recommended that ophthalmologists report the possibility of the appearance of this phenomenon as a consequence of the loss of sight in patients with diseases that degenerate this sense, encouraging patients to count their experiences.

At the pharmacological level, in general this type of disorder does not usually respond to neuroleptics positively, although in some cases haloperidol and risperidone have shown some efficacy. Anticonvulsants such as carbamazapine have also been proposed.

However, the most useful in this syndrome is to treat the medical cause that causes the loss of vision, increasing visual acuity as much as possible. It has been verified that some patients with this syndrome have not returned to hallucinations after being operated on or treated for their visual problem.

Bibliographic references:

Belloch, A., Baños, R. and Perpigná, C. (2008) Psychopathology of perception and imagination. in a. Belloch, B. Sandin and F. Ramos (Eds.) Manual of Psychopathology (2nd edition). Vol I Madrid: McGraw Hill Interamericana.

Burke, W. (2002). The neural basis of Charles Bonnet hallucinations: a hypothesis. J Neurol Neurosurg Psychiatry; 73: 535–541

Morsier, G. (1936) Pathogenie de l'halluci-nose pédonculaire. A propos d'un nouveau cas. Schweizerische Medizinische Wochenschrift; 27: 645-646.

Luke, R. (2007). Hallucinations: Historical and clinical review. Psychiatric information, nº189.

Podoll, K.; Osterheider, M. & Noth, J. (1989). The Charles Bonnet syndrome. Fortschritte der Neurologie und Psychiatrie; 57: 43-60.

Santhouse, A.M.; Howard, R.J. & Ffytche, D.H. (2000). Visual hallucinatory syndromes and the anatomy of visual brain. brain; 123: 2055-2064.

Lapid, M.I.; Burton. M.C.; Chang, M.T. et al. (2013) Clinical Phenomenology and Mortality in Charles Bonnet Syndrome. J Geriatric Psychiatry Neurol; 26(1):3-9.

Tan, C.S.; Yong, V.K. & Au Eong, K.G. (2004) Onset of Charles Bonnet Syndrome (formed visual hallucinations) following bilateral laser peripheral iridotomies. eye; 18: 647-649.