Posterior ischemia during an attack of transient global amnesia.

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Abstract
The popular concept that cerebral ischemia causes transient global amnesia has been difficult to prove by cerebral blood flow studies during attacks because the transient global amnesia attacks are so short. We performed single-photon emission computed tomography (SPECT) of the brain and neuropsychological assessment in a 37-year-old woman during a 10-hour attack and twice thereafter. A neuropsychological evaluation 3 hours after the onset of transient global amnesia revealed severe impairment of recent memory and verbal fluency, both of which returned to normal 2 and 28 days later, respectively. A 99mTc-labeled hexamethylpropyleneamine oxime SPECT of the brain performed 6 hours after the onset showed multiple perfusion defects in both occipital lobes, the medial left temporal lobe, and the left thalamus. A second brain SPECT performed 3 days later showed perfusion defects in only the occipital regions. A third brain SPECT performed 28 days later was normal. The patient's brain computed tomographic scan, electroencephalogram, duplex ultrasound of the carotid artery, and echocardiogram were normal. The perfusion defects revealed by the brain SPECT during the transient global amnesia attack indicated ischemia in the territory of the posterior cerebral arteries, which partially resolved in 3 days and completely resolved by 28 days.