Aneurysm of vessels of a brain - a local arteriectasia, more often an arterial circle of the big brain.

Etiology. As a rule, an aneurysm - congenital defect, sometimes consequence of an infection. The trauma, an atherosclerosis, an idiopathic hypertensia play a role.

Pathogenesis. Objective neurologic frustration at not broken off an aneurysm are observed seldom and caused by mechanical pressure upon adjoining intracranial structures.

Aneurysm many years can proceed asymptomatically. In 25 % of cases of patients suffer incidental cephalalgias which in half of cases are similar to clinic of a migraine. The paralytic type aneurysms is characterized by slowly progressing lesion of separate cranial nerves, more often oculomotor and visual, and sometimes hemispheres of a brain or its trunk. As a rule, at patients suspect a tumour of a brain or a basal arachnoiditis.