[Simple partial seizure consisting of complex visual hallucinations due to left temporo-occipital lesion].

We report a case of simple partial seizure consisting of elementary visual hallucinations and complex visual hallucinations due to left temporo-occipital lesion. The patient was a 45-year-old right-handed female who has been suffering from paroxysmal visual hallucinations in her right visual field for 15 days before admission. The properties of the hallucinations included several round colorful figures, the upper torsos of people in red, and green trees. CT scan showed a small low density area which, limited to the basal part of the left temporal and occipital lobes, was complicated partially by a high density area that was thought to be calcified. On T2-weighted MRI images, the lesion was shown as a small oval-shaped high signal intensity area surrounded by a low signal intensity area, and from its characteristic findings, a cavernous angioma was suspected. On the EEG, epileptic discharge was observed in the area limited to the left occipital region when elementary visual hallucinations occurred, and high amplitude diffuse slow waves were revealed predominantly on the left when complex visual hallucinations developed. It was thought that elementary visual hallucinations occurred in this patient following epileptic discharge of the occipital lobe, and complex visual hallucinations developed secondarily to the discharge which expanded from the occipital lobe to the surrounding area. Considering the investigation of non-epileptic visual hallucinations that are observed in the hemianopic visual field, we believe that disturbances of function of the temporo-parietal lobes around the occipital visual cortex has an important role in causing the development of complex visual hallucinations.