Pseudo-hallucinations following heart surgery in patients with normal vision

Sporadically patients complain visual pseudo-hallucinations following major cardiac surgery. We examined 100 patients following surgery with extracorporeal circulation to determine the incidence of this phenomenon.

We interviewed 100 patients with a short screening questionnaire. Patients that reported pseudo-hallucinations received neurologic and psychiatric examination, visual screening, neuropsychological assessment (Mini Mental Status Test, Confusion Assessment Method) and – if possible – cranial MRI between day 4 and 9 after surgery.

We identified 11 non-delirious patients (3 female, 8 male; 64.8±12.3y) with pseudo-hallucinations after coronary artery bypass grafting or aortic valve replacement.

Patients described vivid, typically coloured images of animate or inanimate objects (i.e. meshes, posies, persons, paint splatters). Pseudo-hallucinations were first noted several days after surgery. They typically appeared several times per day and lasted from several seconds to hours. Frequency, duration and luminosity decreased over time and disappeared within 3 days to 3 weeks. The phenomenon did not occur in relation to time of day, activity or room lighting. At any time the patients were aware of the unreal nature of the illusions. No patient showed psychiatric or neurologic symptoms or suffered from migraine or severely impaired vision. MRI was done in 5/11 patients. Only 1 patient showed multiple small infarcts within the middle and posterior cerebral artery territory.

Visual pseudo-hallucinations occur frequently after cardiac surgery and seem not to be related to postoperative delirium or structural brain damage. Further studies are required to determine the underlying pathophysiology.