High-field, T2 reversed MRI of the hippocampus in transient global amnesia.
OBJECTIVE
To investigate the fine structural integrity of the hippocampus in patients with transient global amnesia (TGA) using high-resolution T2 reversed (T2R) MRI.


METHODS
The authors performed detailed structural analysis of the hippocampus in 15 patients who had recovered from an episode of TGA and 150 randomly recruited normal volunteers across the adult age spectrum using high-resolution T2R MRI obtained on a 3.0-T system. An additional 100 subjects, with stroke or tumor, were similarly studied and served as disease controls.


RESULTS
The overall incidence of hippocampal cavities detected in normal volunteers increased with age but never exceeded 40%, whereas the incidence in disease control group was 31%. They were always unilateral. In contrast, cavities were found in all 15 patients with TGA (100%), an incidence higher than in normal or disease controls (p < 0.05; Ryan's multiple comparison test), and were bilateral in eight patients (53%). The cavities in all but one of the normal volunteers (99%) and all disease controls (100%) were crescent shaped and < or =2 mm in width. The cavities in 14 of 15 patients with TGA (93%) were considerably larger (>3 mm in width), and five of the patients had giant cavities (>5 mm in width). Most of the cavities in patients with TGA had a rounded shape and resembled pathologic cavities described in specimens of hypoxia-related CA1 necrosis.


CONCLUSIONS
The data indicate that transient global amnesia may not be a benign entity. Delayed neuronal loss within CA1 area of Lorente de No may represent its important sequel.
Nakada
Tsutomu
T
Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, 1 Asahimachi, Niigata 951, Japan. tnakada@bri.niigata-u.ac.jp
Kwee
Ingrid L
IL
Fujii
Yukihiko
Y
Knight
Robert T
RT
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D020236:Amnesia, Transient Global / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D001284:Atrophy / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D001925:Brain Damage, Chronic / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D001932:Brain Neoplasms / Q000175:diagnosis; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods / Q000592:standards*; D018450:Disease Progression; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006624:Hippocampus / Q000473:pathology* / Q000503:physiopathology; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009410:Nerve Degeneration / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology; D011237:Predictive Value of Tests; D012016:Reference Values; D020521:Stroke / Q000175:diagnosis