PO073 Peduncular hallucinations after stn-dbs: lesion or a coincidence?

Peduncular hallucinationsare known to be associated with midbrain, pontine and thalamic lesions. They can be spontaneous or in response to visual stimuli. However, ‘complex’ distortion of perception has only been reported in association with dorsomedial thalamic lesions. Delirium, psychosis and visual hallucinationshave been reported after Deep brain stimulation(DBS) of the subthalamusnucleus (STN). However,’ fantastically’ distorted Peduncular hallucinationshave not. We report the case of a 47 year old female with young onset Parkinson’s disease and intact preoperative cognition, who experienced complex visual hallucinationswithin a week of STN stimulation with no motor/sensory deficit. She was alert and oriented but described, in detail, seeing small animals and clown faces in reflective surfaces as well as creepy polar bears that sat on her legs and made them feel cold. Switching the stimulation off, altering contact sites and reducing dopaminergic drugs had little impact. The stimulation was restarted; Quetiapinewas given and she improved after 8 weeks of hospitalisation. It is possible that peduncular hallucinationsin our patient resulted from a peroperative dorsomedial thalamus micro-lesion. Given the intensity and distress of this type of hallucinations, prompt recognition and treatment with atypical antipsychoticsshould be considered.