Transient global amnesia (TGA) has been a well-described phenomenon for more than 40 years. Clinically, it manifests with a paroxysmal, transient loss of memory function. Immediate recall ability is preserved, as is remote memory; however, patients experience striking loss of memory for recent events and an impaired ability to retain new information. In some cases, the degree of retrograde memory loss is mild.
Bartsch et al found that in 7 patients with TGA, 4 had a diffusion abnormality corresponding with a T2 lesion in the CA-1 sector of the hippocampus. In 3 of these patients, MRS revealed a lactate peak. The authors suggest that this represents an acute stress reaction of this particular area and indicates the pathological substrate of TGA. The incidence has been estimated 8.3 per 100,000 per annum. Avoid activities that could produce an unusual increase in intrathoracic pressure.