Olanzapine therapy in hallucinatory visions related to Bonnet syndrome.

Charles Bonnet syndrome (CBS) is characterised by the triad of complex visual hallucinations, ocular pathology causing visual deterioration and preserved cognitive status. We report a case of a 62-year-old man with a brief history of visual hallucinations. The patient complained of amaurosis with optic nerve atrophy in his left eye and a severe impairment of visual acuity in the right and suddenly experienced complex, vivid, elaborate and coloured visual hallucinations persisting long after eye closure and stopping during sleep. The patient maintained his insight, criticising these visions as unreal and felt distressed by them. Hallucination onset was 3 days before hospital admission. No cognitive impairment and no diseases apart from prostatic adenoma treated with alpha-lythic therapy were reported. Neurological examination and neuroimaging data were normal. Therapy with olanzapine (OLZ) 5 mg/day led to a progressive clearance of visual hallucinations in seven days and was gradually reduced and withdrawn. Three months later the visions reappeared and OLZ 5 mg/day yielded a persisting remission so that at the follow-up examination after 1 year on therapy the patient is still asymptomatic. To date, no established treatment for CBS is stated and in some patients the hallucinations fade spontaneously; in our case an antipsychotic therapy with OLZ was effective while generally anticonvulsant drugs with different mechanism of action such as carbamazepine, valproate and gabapentin are proposed.