Neuroradiology

, Volume 49, Issue 6, pp 481–487

Diffusion-weighted imaging in transient global amnesia exposes the CA1 region of the hippocampus

  • Ho Yun Lee
  • Jae Hyoung Kim
  • Young-Cheol Weon
  • Jung Seok Lee
  • Sang Yun Kim
  • Sung Won Youn
  • Sung Hyun Kim
Diagnostic Neuroradiology
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Abstract

Introduction

Transient global amnesia (TGA) is characterized by a sudden onset of anterograde amnesia without alteration of consciousness or personal identity. Interestingly, recent studies have reported a high frequency of small high-signal abnormalities in the hippocampus with diffusion-weighted (DW) imaging, and ischemia has been proposed as an etiology of TGA. We hypothesized that TGA lesions occur preferentially in the CA1 region of the hippocampus, known to be susceptible to ischemia.

Methods

Over a 30-month period 34 patients with TGA underwent MRI including DW imaging within 4 days of symptom onset. Patients with high-signal abnormalities in the hippocampus on the initial DW images underwent subsequent DW and T2-weighted imaging in the coronal plane to identify the precise lesion locations.

Results

Fourteen patients had small (1–3 mm) high-signal abnormalities in the hippocampus unilaterally on DW images. One of these patients had two lesions in one hippocampus and therefore in total 15 lesions were identified: four in the hippocampal head, and 11 in the body. Eleven lesions in ten patients with available coronal images were clearly demonstrated on both coronal DW and T2-weighted images and were localized to the lateral portion of the hippocampus, corresponding to the CA1 region.

Conclusion

Lesions associated with TGA were localized exclusively to the lateral portion of the hippocampus corresponding to the CA1 region. This finding supports the ischemic etiology of TGA; however, the pathophysiological mechanism involved requires further study.

Keywords

Magnetic resonance Diffusion MR Transient global amnesia 

Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  • Ho Yun Lee
    • 1
  • Jae Hyoung Kim
    • 1
  • Young-Cheol Weon
    • 1
  • Jung Seok Lee
    • 2
  • Sang Yun Kim
    • 2
  • Sung Won Youn
    • 1
  • Sung Hyun Kim
    • 1
  1. 1.Department of Radiology, Seoul National University College of MedicineSeoul National University Bundang HospitalSeongnam-siSouth Korea
  2. 2.Department of Neurology, Seoul National University College of MedicineSeoul National University Bundang HospitalSeongnam-siSouth Korea

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