Cerebral artery spasm--a possible mechanism of TIA?

The pathogenetic transitory ischemic attacks (TIA) is usually ascribed to emboli although in some 25% of TIA patients there is no source of embolism to be found in either the heart or neck vessels and angiographically visible carotid lesions are present only in about half the patients with carotid distribution TIA. A case is reported with repeated attacks of amaurosis fugax without remaining neurological symptoms in this very sensitive area. This and similar case histories raise the possibility of spasm in the cerebral arteries as the underlying cause of certain forms of TIA. As certain Ca-blocking agents, such as nifedipine and especially nimodipine, can relieve spasm, there are reasons to conduct a controlled study in man to find out if and to what extent a Ca-blocker with a verified effect on cerebral artery spasm in animal experiments has a beneficial effect on TIA in man.