[Bilateral vertebral artery occlusion].

We studied 9 patients with bilateral vertebral artery occlusion (BVAO). BVAO was confirmed using angiography in order to clarify its clinical feature, mechanism, and long term prognosis. Three patients showed bilateral intra-cranial occlusion, 3 bilateral extra-cranial occlusion, and 3 intra and extra-cranial occlusion. The basilar artery was fed by the posterior communicating artery in 8 out of 9 patients. In one of the 8, reconstitution of the thyrocervical artery was seen. We divided the patients into 4 groups according to MRI findings, as follows: Group 1 with no abnormal finding on MRI (N = 2); Group 2 with deep pontine infarcts and non-territorial small cerebellar infarcts (N = 2); Group 3 with extended pontine infarcts (N = 3); and Group 4 with cerebellar cortical artery infarcts, deep pontine infarcts, and non-territorial small cerebellar infarcts (N = 2). Transient episodes were seen in all patients, 8 patients out of 9 had vertigo/dizziness, 3 tinnitus, 2 diplopia, 2 headache, 2 numbness, and 1 hearing disturbance. These episodes preceded a final attack or complete stroke 2 days to 5 months, and those who had a longer period of episodes in the preceding term tended to have less severe deficits. Six of the patients had vertebro-basiler symptoms after being in the upright position, including all the patients in Groups 2 and 4, which had cerebellar border zone/terminal zone infarcts. These results indicate that the hemodynamic mechanism plays an important role in BVAO. The prognosis was not always grave. Four of the patients could walk independently, 2 could walk with a cane, and 3 were bed ridden (2 of which died). Long-term follow-up data (a mean of 5 years) were obtained in all patients. In the patients who could walk, one had asymptomatic cerebellar infarcts, and one had TIAs frequently. Patients with BVAO often also have TIAs and/or preceding episode and show cerebellar border zone/terminal zone infarcts. This research strongly suggests that hemodynamic mechanism might play an important role in BVAO, and that paying attention to border zone infarction in MRI and transient episodes can lead to earlier diagnosis and treatment.