Abstract WP230: No Difference of Cerebral Perfusion Between Transient Global Amnesia With and Without Acute Focal Lesion in Hippocampus

Abstract

Introduction: In transient global amnesia (TGA), the etiology or pathogenesis is still in debate. It has been commonly suggested that TGA might be related to an ischemic event, migraine, or epileptic seizures. With the characteristic findings of diffusion-weighted images (DWI), cerebrovascular disease can be regarded as a cause of TGA. Hypothesis: Transient global amnesia may be associated with regional cerebral perfusion, especially in patients with DWI lesions. The aim of the present study is to reveal the clinical or radiological difference between TGA patients with and without acute lesions. Methods: We identified retrospectively TGA patients who fulfilled the standard criteria from January 2010 through March 2015. Within 72 hours from symptom onset, all patients were evaluated with brain MR images and an electroencephalography. According to the presence of acute lesion in the hippocampus, clinical features, vascular risk factors, and regional perfusion status with SPECT images were compared. Results: Of 61 TGA patients (mean age 60.6, female 18 patients), 20 patients had acute focal lesions in the hippocampus (size: 3.36 ± 0.64mm, 7 in the right, 9 in the left, and 2 in bilateral lesions). All lesions were located in the lateral border (CA1 region) of the hippocampus. In the comparison of clinical features, the duration of amnestic symptom was shorter in the lesion negative group than in the lesion positive group (5 hours, IQR 2.5-8.8 vs. 8 hours, IQR 5-13.5, p=0.07). However, there was no difference between TGA patients with and without DWI lesions in cerebrovascular risk factors or laboratory results. Of 23 patients underwent a cerebral SPECT, 6 patients who had DWI lesions had no abnormal findings. Of 17 patients without lesions, only 3 patients exhibited mild focal perfusion defect in both medial temporal, left frontal, and left fronto-temporal region, respectively. Conclusions: Except amnestic symptom duration, we failed to reveal any clinical difference including perfusion defect between TGA patients with and without DWI lesion. It might suggest the low probability of hypoperfusion in the hippocampus regardless of the presence of brain DWI lesions.