Objective: It has been emphasized that amaurosis fugax (AmF) is caused by thromboembolism due to atheromatous lesions of the extracranial carotid artery (EC-CA) in Caucasian populations. However, there have been few studies of AmF in Japan. We analyzed the clinical and pathophysiologic features of AmF in 43 Japanese AmF patients.
Subjects and methods: Forty-three patients presented with AmF from a group of 2,056 Japanese patients with acute ischemic stroke. We investigated angiographic and transcranial Doppler findings, precipitating factors, medical treatment and prognosis, to elucidate the pathogenetic mechanism of AmF.
Results: Angiographic findings revealed an intracranial lesion in 22 patients (51%), extracranial lesion in 16 (37%), and no abnormality in 5 (12%). Blood flow in the ophthalmic artery (OA) examined by the transcranial Doppler ultrasonography (TCD) showed normal antegrade flow in 24 patients and reversed flow in 7. Precipitating factors for AmF were seen in 7 out of 43 patients. Regarding the pathogenesis of AmF, the micro-thromboembolism originated from the internal carotid artery (ICA) in 25 patients, the thromboembolism was via the external carotid artery (ECA) in 7, the hemodynamic retinal vascular insufficiency in 6 patients showed various atheromatous changes in the intracranial carotid artery (IC-CA) or EC-CA, and the cause was unknown in 5.
Conclusion: In this series of patients, AmF was mainly caused by thromboembolism from IC-CA atheromatous lesions. Micro-thromboemboli from the ECA or hemodynamic retinal vascular insufficiency, although less frequent, should also be considered as possible etiologies for AmF.