Focal MR spectroscopy of hippocampal CA-1 lesions in transient global amnesia.
OBJECTIVE
The pathomechanisms of transient global amnesia (TGA) remain enigmatic. Focal MR signal diffusion changes in the CA-1 sector of the hippocampus have been described in transient global amnesia, but the pathophysiologic correlate of these lesions is unknown.


METHODS
We studied the metabolic spectra of diffusion lesions in the CA-1 sector hippocampus of seven patients with TGA using MR spectroscopy (MRS) between 24 and 72 hours after onset and 2 to 5 months later. The amnestic deficit was studied using a neuropsychometric test battery.


RESULTS
Four out of seven patients with an acute TGA showed a diffusion lesion with a corresponding T2 lesion in the CA-1 sector of the hippocampus. Selective hippocampal MRS of diffusion lesions showed a lactate peak in three of four patients, but not in patients without a diffusion lesion. The NAA/creatine ratio was normal.


CONCLUSIONS
Lactate as a marker of anaerobic glycolysis indicates acute metabolic stress of CA-1 neurons in TGA whereas long-term neuronal metabolic changes are not found. This implies that the acute effect on hippocampal CA-1 neurons is the functional correlate of a transient global amnesia reflecting a transient perturbation of memory relevant circuits in the hippocampus.
Bartsch
T
T
Dept. of Neurology, University Hospital Schleswig-Holstein, Kiel, Schittenhelmstr. 10, 24105 Kiel, Germany. t.bartsch@neurologie.uni-kiel.de
Alfke
K
K
Wolff
S
S
Rohr
A
A
Jansen
O
O
Deuschl
G
G
D000368:Aged; D020236:Amnesia, Transient Global / Q000175:diagnosis* / Q000378:metabolism / Q000503:physiopathology*; D015415:Biomarkers / Q000378:metabolism; D038524:Diffusion Magnetic Resonance Imaging; D018450:Disease Progression; D004734:Energy Metabolism; D006019:Glycolysis; D006624:Hippocampus / Q000378:metabolism* / Q000473:pathology*; D006801:Humans; D019344:Lactic Acid / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008875:Middle Aged; D009434:Neural Pathways / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D009483:Neuropsychological Tests; D018384:Oxidative Stress; D011237:Predictive Value of Tests; D012075:Remission, Spontaneous
D015415:Biomarkers; D019344:Lactic Acid