Suluma Aslan

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INTRODUCTIONCharles Bonnet Syndrome(CBS) was first described in 1760 by Naturalist and philosopher Charles Bonnet, who first observed lifelike complex visual hallucinations in his grandfather Charles Lullis after bilateral cataract surgery(1); it was a neurologist George de Morsier who coined the term in 1938 after Charles Bonnet himself developed the condition(2). CBS, also known as ”phantom image”, is characterized by recurrent or persistent complex visual hallucinations in people with a disease of the visual system with intact insight, intellectual function and normal cognitive functioning without primary psychiatric disorders(3,4). With limited knowledge of CBS among physicians, the prevalence of CBS is underreported(4) even though 41-59% of the visually impaired experience elementary visual phenomena, and 11-15% exhibit complex hallucinations, due to a medical condition or artificially produced, such as in preparation for cataract surgery(5,6). The presence of varying inclusion criteria, inconsistent depth of questioning and limited patient disclosure for fear of being ridiculed may all contribute to underreporting(3,5). Visual hallucinations could be a sign of psychiatric disorders, neurological diseases, metabolic abnormalities, and the use or abuse of specific drugs(7). Both elementary forms(3) and complex visual hallucinations are reported in CBS(8); while glaucoma,cataract and age-related macular degeneration are the most common associated disorders, any ophthalmological conditions can lead to CBS(7), especially in significant visual impairment(9). A pituitary adenoma is rarely associated with CBS (10); however, reduced visual acuity or a visual field deficit can occur from the benign tumour’s compressing optic chiasm affecting one or both eyes(11).There are three main theories associated with the pathogenesis of CBS, and these are; the sensory deprivation or deafferentiation theory related to spontaneous excitation due to a loss of visual input to the brain(12), the release theory associated with excessive excitation and the consequent release of visual hallucinations(13,14), and the ”irritative theory” due to distal provocative injuries transmit abnormal input to the visual cortex leading to abnormal excitatory activity to the temporal and occipital lobes(15,16).Charles Bonnet syndrome is treated multifacetedly with pharmacotherapy, psychosocial therapy, maintaining appropriate eye care, and sensory stimulation. Generally, CBS is treated with antipsychotics and antidepressants(5), and in some cases, antiepileptic medications have also been used with variable benefits (17).An 81-year-old blind male presented with a three-year history of visual hallucinations after a recurrence of pituitary macroadenoma. His past psychiatric history is uneventful, and he has intact insight with no cognitive impairment. He improved on a low haloperidol dosage, with a few relapses, when he stops the medications.