Evolution of temporal lobe hypoperfusion in transient global amnesia: a serial single photon emission computed tomography study.
Previous functional neuroimaging studies performed during transient global amnesia (TGA) have not answered the central question regarding the etiology of TGA, namely: whether the observed hypoperfusion in the mesial temporal lobe structures reflects a primarily ischemic process or whether it represents a secondary phenomenon resulting from locally decreased metabolism. The authors performed Tc 99-m-bicisate brain single photon-emission computed tomography (SPECT) scanning in a 66-year-old man during an episode of TGA, 24 hours after the episode and 3 months after the episode. To the authors' knowledge, this is the only reported study in which a follow-up SPECT scan was performed within 24 hours. The initial study showed bilateral mesial temporal lobe hypoperfusion that partially resolved after 24 hours and returned to normal at 3 months. Resolution of the SPECT scan abnormalities correlated well with resolution of the memory loss. These findings agree with previously reported SPECT, positron-emission tomography (PET), and diffusion magnetic resonance imaging (MRI) studies that indicate the mesial temporal lobe structures as the major site of pathology in TGA. The authors suggest that a process causing decreased local metabolism, such as cortical spreading depression, constitutes the primary pathophysiologic mechanism in this case.
Jovin
T G
TG
Department of Neurology, University of Pennsylvania Health System, Pennsylvania Hospital, Philadelphia, PA, USA.
Vitti
R A
RA
McCluskey
L F
LF
D000368:Aged; D020236:Amnesia, Transient Global / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology; D002545:Brain Ischemia / Q000150:complications; D002561:Cerebrovascular Disorders / Q000150:complications* / Q000000981:diagnostic imaging; D013181:Cortical Spreading Depression / Q000502:physiology; D003545:Cysteine / Q000031:analogs & derivatives*; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D013702:Temporal Lobe / Q000098:blood supply* / Q000000981:diagnostic imaging / Q000378:metabolism; D015899:Tomography, Emission-Computed, Single-Photon; D014057:Tomography, X-Ray Computed
D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C059659:technetium Tc 99m bicisate; D003545:Cysteine