[Pure Amnesia].

Pure amnesia (amnesic syndrome) is an organic brain syndrome characterized by impairment in episodic memory, with either an anterograde or sometimes retrograde loss of memories. Although episodic memory is impaired, semantic memory, immediate memory, and procedural memory are preserved. The Papez circuit is a network of nerve fibers and nerve centers that starts and ends in the hippocampus travelling by way of the fornix, mammillary bodies, anterior thalamic nuclei, cingulate gyrus, and parahippocampal gyrus. A lesion restricted to this circuit often produces pure amnesia. Regions concerned with the Yakovlev circuit also have an important role in memory. Clinical cases of pure amnesia caused by cerebrovascular disease presented following brain imaging and resulted from various different lesions. The cases identified were predominantly thalamic amnesia and hippocampal amnesia. Thalamic amnesia often resulted from an infarction in the territory of the thalamotuberal artery and paramedian thalamic artery although thalamic hemorrhage in medial portion of thalamus also produced pure amnesia. Hippocampal amnesia usually occurred following an infarction in the temporal branches of posterior cerebral artery. Cases of retrosplenial amnesia caused by subcortical hematoma and infarction in the retrosplenial region are also described. In addition, cases of pure amnesia resulting from an infarction in the fornix, mammillary body hemorrhage, and caudate hemorrhage are also shown.

Lateral geniculate body presenting only hemorrhage homonymous hemianopia-A case report.

We report a case of a 55-year-old man who developed acute-onset narrowing of his visual field. He showed right homonymous hemianopsia without any other neurological symptoms and signs. Brain CT and MRI showed localized hemorrhage (about 1.6 ml) in the left lateral geniculate body (LGB). A cerebral angiography showed no vascular anomalies of cerebral vessels, and the left anterior choroidal artery and left lateral posterior choroidal artery could be visualized well. He had hypertension, polycythemia and dyslipidemia and was a habitual smoker and an alcoholic. In the literature, various kinds of visual field defects including hemianopsia, upper quadrant hemianopsia, lower quadrant hemianopsia, and horizontal sectoranopia have been reported in eight cases of LGB hemorrhage. Localized LGB hemorrhage was found in only one case out of 2,763 cerebral hemorrhage patients enrolled in our stroke registry for 11 years from 2005 to 2016. Localized hemorrhage of LGB very rarely occurred.

[A case of unilateral ischemic stroke with ipsilateral limb-kinetic apraxia].

A 74-year-old man developed aphasia, weakness of the right upper extremity and left limb-kinetic apraxia. Brain MRI showed an infarct in the area supplied by the left middle cerebral artery. Cerebral angiography revealed high grade stenosis with plaques of bilateral proximal internal carotid arteries. The carotid endarterectomy of the left carotid artery was performed three months later. After this operation his left limb-kinetic apraxia improved. We considered transhemispheric diaschisis, callosal apraxia or diagonistic dyspraxia as a possible cause of this rare symptom.

[A case of representational dysgraphia and object representational disorder with unilateral spatial neglect].

We describe the case of a 48-year-old left-handed woman with unilateral neglect from a brain infarction in the area of the right basal ganglia and temporo-parieto-occipital lobe. When a Kanji character was dictated to her, she wrote only the right side (tukuri) of the character. When copying a picture from the visual image of a left-right asymmetrical object, such as the side view of the dog, she drew the tail and a hind leg immediately but was unable to draw a picture of the dog from the left side. We asked her to imagine going around to the opposite side of the imaginary dog and to draw it from that perspective. She easily drew the left side first, resulting in a left-right inverted picture of what she had previously drawn. She then tried to slowly visualize the missing part of her imagery, and was able to draw only the right tip of the missing part. She could not compose a complete picture of the dog. These findings suggested that the impairment was in the imaging of the left side of a character or object and that this was a case of representational dysgraphia and object representational disorder with unilateral spatial neglect.