Report of six cases of hemodynamic TIA and its causal relations among hemodynamic parameters

Transient ischemic attacks (TIA) following hypotension are thought to be very rarer than TIA of microembolic cause. Six cases of hemodynamic TIA which occurred following hypotension were reported and its causal relations among various cerebral hemodynamic parameters were analyzed. Mean age of four male and two female cases was 73 years old. Mean value of habitual mean arterial blood pressure was 113 mmHg and mean value of arterial blood pressure at the time of the attacks was 83 mmHg. 23% fall of mean arterial blood pressure occurred at the time of the attacks. The causes of hypotension were vasovagal reflex in one case, complete atrioventricular conduction block in two, orthostatic hypotension in one, and antihypertensive medication in the other two. Cerebral angiography revealed large vessel occulsion or severe stenosis of the brain in five cases. Mean hematocrit value at the time of the attack was 44% and was significantly elevated as compared to the value of interictal state (38%). From these evidences it was suggested that the occurrence of hemodynamic TIA was closely connected to the hemorheological factors as well as systemic hypotension and large cerebral vessel occlusions.