Charles-Bonnet Syndrome (CBS) is a clinical entity characterized for visual hallucinations in patients with severe vision impairment and preserved cognitive state. Its pathogeny is still unknown, limiting management options. For diagnosis neurological and psychiatric disorders must be discarded. Treatment is based in three pillars: explaining to the patient the origin and nature of the symptoms, treating the visual deficit when possible, and pharmacotherapy with anti-psychotics.

To outline the main characteristics and etiopathogenic theories of the CBS, so as to improve diagnosis and treatment.

Basing on a case followed in mental health consults, we made a systematic review of the articles published in Medline (PubMed) in the last 5 years, with the following keywords, Charles-Bonnet Syndrome, hallucinations, deafferentation, visual impairment.

We found that all our case and the reported ones had in common the nature and characteristics of the hallucinations, the presence of a trigger, usually a new medicament, and the functional MRI patrons of activity; those patrons located the loss of input prior to the association cortex, which appeared hyper-excitable in functional MRI.

Although the aetiology and pathogeny of CBS is still unclear, present data suggests that the key mechanism may be a dysregulation in the homeostatic adaptation of the neural pathway when it is left without external input, traducing a hyper-function of a physiological process, probably mediated by acetylcholine, as opposed with other neuropsychiatric pathologies, in which the cortex is the primary affected area.

The authors have not supplied their declaration of competing interest.