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|LETTER TO EDITOR
|Year : 2015 | Volume
| Issue : 4 | Page : 604-605
Transient global amnesia with intracranial vertebral artery dissection and hippocampal CA1 lesion
Hiroshi Yokota1, Kazuhiro Yokoyama1, Satoru Iwasaki2
1 Department of Neurosurgery, Higashiosaka City General Hospital, Osaka, Japan
2 Department of Radiology, Higashiosaka City General Hospital, Osaka, Japan
|Date of Web Publication||4-Aug-2015|
Department of Neurosurgery, Higashiosaka City General Hospital, Osaka
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Yokota H, Yokoyama K, Iwasaki S. Transient global amnesia with intracranial vertebral artery dissection and hippocampal CA1 lesion. Neurol India 2015;63:604-5
A 58-year-old man with a medical history of hypertension suddenly showed abnormal behavior. His wife noticed that he was unable to use his mobile phone and had memory impairment. His neurological examination was normal except for disorientation with regard to time and place. The blood pressure was 176/97 mmHg. After admission, he could not recall that he had been admitted to the hospital and repeatedly asked for confirmation of that fact. We made a diagnosis of transient global amnesia (TGA) and the symptoms were nearly completely resolved on the same day.
Axial diffusion-weighted (DW) magnetic resonance (MR) imaging performed 2 days after the onset of illness disclosed a small rounded high signal intensity lesion in the right hippocampal head and an apparent diffusion coefficient (ADC) map demonstrated a decreased value of the lesion [Figure 1]. Coronal DW-MR imaging performed 4 days after the onset revealed the high intensity persisting in the lateral portion of the hippocampus corresponding to the CA1 area along with a decreased ADC value [Figure 1]. Furthermore, dissection of the right vertebral artery in the fourth segment was visualized by MR angiography and confirmed by cerebral angiography [Figure 2]. Electrocardiography and trans-thoracic echocardiography demonstrated no abnormalities. The follow-up MR imaging performed 13 days after the onset did not reveal any signal or structural changes corresponding to the area of the lesion.
|Figure 1: Diffusion-weighted-magnetic resonance (DW-MR) images showing hyperintensity with decreased apparent diffusion coefficient (ADC) in the right hippocampus corresponding to the CA1 area (arrows). Axial DW-MR image (a) Coronal DW-MR image, (c) ADC map (b, d)|
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|Figure 2: Dissection of right vertebral artery (arrows). Magnetic resonance angiogram. Inset, shows axial source image (a); Right vertbral angiogram (b)|
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Transient global amnesia is a syndrome that resolves within 24 h and is characterized by sudden onset of antero- and retro-grade amnesia without focal neurological or epileptic signs, consciousness disturbance, or a recent history of head trauma, although the ability to identify individuals is preserved. Although the pathogenesis is considered to be multifactorial and remains controversial, ischemia in the hippocampus, especially in the CA1 area, has been reported in DW-MR imaging studies.  It is not clear if the ischemic pathogenesis of TGA is due to a hypoxia-ischemic insult caused by an embolic or hemodynamic arterial mechanism; or, it is a consequence of the venous ischemic mechanism.  Three cases of TGA with vertebral artery dissection have been reported. , However, 1 of those patients demonstrated an ischemic lesion in the left thalamus,  while the other 2 had additional neurological deficits due to cerebellar and cerebral ischemic lesions.  It is possible that in the present case also, the intracranial vertebral artery dissection and hippocampal CA1 lesion was only a coincidental finding, and a distal embolism following vertebral artery dissection might have been the possible cause of TGA.
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[Figure 1], [Figure 2]