Vasospasm and adrenergic innervation of circle of Willis.

Cerebral vasospasm following the rupture of intracranial aneurysm presents perplexing situation, i.e. prolonged vasospasm results in cerebral infarct and too early relief causes recurrence of the bleeding. To understand mechanism underlying the cerebral vasospasm, catecholamine-containing sympathetic nerve plexus was examined in the arterial walls of the circle of Willis using rat, cat, dog and monkey using Falck-Hillarp's fluorescence method. The distribution of fluorescing nerve plexus was found to be essentially the same in the examination of all species. The distribution of the fluorescing fibers decreases in the following order; proximal anterior cerebral, internal carotid, distal anterior or proximal middle cerebral, and distal middle cerebral artery. The origin of the nerve plexus accompanying the basal cerebral arteries and the relation to the experimental cerebral vasospasm was investigated as detailed as they could.