Peduncular hallucinosis after a thalamic stroke

Abstract

Peduncular hallucinosis is a rare form of hallucinations consisting of vivid and nonthreatening colourful visual hallucinations. It was first described by French neurologist Jean Lhermitte in 1922. It sometimes includes distorted images of animals and people. Peduncular hallucinosis has been described after vascular and infective lesions of the mesencephalon and thalamus.We present a case of peduncular hallucinosis after a right thalamic infarction. This is a case of a 75-year-old Caucasian man with a previous medical history of hypertension and hyperlipidaemia who presented as a transfer from an outside hospital with transient left facial palsy, upper and lower extremity weakness. His symptoms resolved on arrival. CTA head and neck revealed focal filling defect in the basilar artery and a right posterior cerebral artery (PCA) occlusion at its origin. MRI brain without contrast revealed a right thalamic infarct. The patient had vivid hallucinations including his wife sleeping on his hospital bed, seeing his favourite book on the table while he had left it at home, seeing his dogs and a TV show on his room television while it was off. He was easily redirectable, and the hallucinations resolved over 2 days without pharmacological intervention. In cases of thalamic, midbrain or peduncular infarctions, physicians should be cognizant of the possibility of peduncular hallucinosis and inquire about hallucinations. New onset hallucinations in a patient with no prior psychiatric history presenting with concerns for stroke should prompt physicians to strongly consider peduncular hallucinosis.

Keywords: neuroimaging; neurology; stroke.