[Aneurysm of the anterior cerebral artery disclosed by unique hemianopic scotoma].

We report the case of a 47-year-old man with an aneurysm of the anterior cerebral artery revealed by lateral homonymous hemianopic non congruent scotoma. The aneurysm was successfully treated with interventional radiology procedures. In 10p. cent of cases, intracranial aneurysms present prior to their rupture with headache or neuro-ophthalmological symptoms and signs. Isolated visual field defects are rare, and isolated compression of the optic tract is extremely unusual. Although rare, the development of a non-congruent controlateral homonymous hemianopic scotoma is highly suggestive of optic tract compression, and can be explained by the somatotopy of the fibers within the optic tract.