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. From birth we have a visual capacity that allows us to detect the stimuli around us and react to them.
Sight, however, is a sense that evolves, developing mainly throughout the first year of life. From certain ages onwards, it is common for visual capacity to be reduced and problems such as eyestrain to appear.cataracts and even glaucoma. Likewise, it is possible that the areas of the brain responsible for vision stop functioning with the usual precision, or that visual connections with other sensory and even intellectual processes may weaken.
This type of problem can cause our visual system to perceive stimuli that are not present, as occurs in the case of Charles Bonnet syndrome.
Charles Bonnet Syndrome is understood as the clinical condition characterized by the appearance of visual hallucinations in patients with problems in the visual pathway, whether these problems are located in the visual organs, their connections to the brain or the brain areas involved in vision.
The main diagnostic criteria for this syndrome are the aforementioned presence of visual hallucinations and that these occur in the total absence of cognitive and consciousness alterations, psychiatric, neurological or substance use disorders that could explain their appearance.
In other words, These hallucinations occur in healthy subjects with no other problem than visual problems.having to rule out the presence of dementia (a condition that sometimes also presents visual hallucinations), poisoning and other disorders.
Thus, Charles Bonnet Syndrome would appear mainly in healthy individuals who do not suffer any other alteration than vision loss. 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 very variable.although they present a series of common characteristics such as occurring with clarity of consciousness, without the illusion of reality being present (that is, the patient knows that it is something not real), they combine with normal perceptions, they appear and disappear without there being a clear cause for it and they represent a phenomenon that surprises those who suffer from them, although there is usually no great fear regarding them.
Regarding the content of the hallucinations that occur in Charles Bonnet Syndrome, the perception of small human figures or animals is common (type of hallucination called lilliputian), as well as sparkles or bright colors.
The perception itself is clear and vivid, located in the space external to the person himself (that is, 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 in to a large extent with real perception (remember that this syndrome occurs in individuals with visual loss, who therefore see real stimuli more blurred).
These hallucinations occur without a clear cause that triggers them.; although stress, excessive or poor lighting or lack or overload of sensory stimulation facilitate its appearance. The duration of hallucinations is usually short, and can vary between seconds and hours, and they usually disappear spontaneously when you close your eyes or redirect your gaze towards them or towards another point.
The causes of this syndrome, as already mentioned, are found in vision loss. This loss usually occurs due to damage to the visual system, 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 makes the connection between the eye and the occipital lobe difficult.
But, although an eye disease causes vision loss, 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 topic, one of the most accepted being the Neuronal Deafferentation Theory.
This theory is based on the consideration that due to eye disease there is a loss of nerve impulses that should reach the occipital cortex, the area of the brain responsible for processing visual information. This causes the brain to become especially sensitive to the stimuli that reach 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
With respect to the treatment of Charles Bonnet Syndrome, on a psychological level the first thing that must be done is to reassure and provide information to the patient, who may present great distress by not knowing what is happening and believing that he or she has some type of dementia or disorder. mental. It must be explained that the visions experienced are a consequence of vision lossit was recommended that ophthalmologists report the possibility of this phenomenon appearing as a consequence of loss of sight in patients with diseases that degenerate this sense, encouraging patients to tell their experiences.
At a pharmacological level, in general this type of disorder does not usually respond positively to neuroleptics, although in some cases haloperidol and risperidone have shown some effectiveness. Anticonvulsants such as carbamazapine have also been proposed.
However, the most useful thing in this syndrome is to treat the medical cause that causes vision loss, increasing visual acuity as much as possible. It has been proven that some patients with this syndrome have not had hallucinations again after undergoing surgery or treatment for their visual problem.
Bibliographic references:
Santhouse, A.M.; Howard, R.J. & Ffytche, D.H. (2000). Visual hallucinatory syndromes and the anatomy of visual brain. Brain; 123: 2055-2064.
Lapid, MI; Burton. MC; Chang, M.T. et al. (2013) Clinical Phenomenology and Mortality in Charles Bonnet Syndrome. J Geriatr Psychiatry Neurol; 26(1):3-9.
Tan, C.S.; Yong, VK & Au Eong, KG (2004) Onset of Charles Bonnet Syndrome (formed visual hallucinations) following bilateral laser peripheral iridotomies. Eye; 18: 647-649.
Yacoub, R. & Ferruci, S. (2011). Charles Bonnet syndrome. Optometry; 82: 421-427.
