[Chronic visual hallucinations and illusions following brain lesions. A single case study].

Lesions of the visual system do not necessarily lead to deficits in visual function. In some cases, there may even occur Positive Spontaneous Visual Phenomena (PSVP) following cerebral damage. We present data from a male patient with continuous, long-term visual illusions after having experienced cerebral infarction at the age of 56. Basing on conventional Magnetic Resonance Imaging, lesions could be located in areas supported by the lateral and medial occipital artery. Initially, homonymous hemianopsia of the right visual field was found in perimetric examinations, but in the course of six months, visual function recovered completely. Ever since the incident, the patient has been suffering from permanent photopsia, intense colourful visual hallucinations and perseverations located in the former defective area which continued unabated even after the remission of his visual field defects. While many authors have published data on PSVP lasting for several seconds, usually vanishing completely within days or weeks after cerebral lesion, in our patient the symptoms continued over a period of so far nine months. Surprisingly, he was even able to make drawings of his illusions so that we were able to include some of his pictures.