What should be the focus of history in the evaluation of transient global amnesia (TGA)?

Updated: Jul 27, 2018
  • Author: Roy Sucholeiki, MD; Chief Editor: Helmi L Lutsep, MD  more...
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Answer

Transient global amnesia (TGA) is a well-described syndrome, but one whose exact etiology is not yet completely understood.

TGA specifically affects memory function. As mentioned previously, patients can register information, but retentive memory ability is affected dramatically.

Many mechanisms have been proposed, but no single cause can explain fully all the features of TGA. These include migraine variant, temporal lobe seizure, and TIA. If a patient is young or has repeated attacks, then the possibility of seizure or even migraine is higher. Some authors have stated that patients with TGA have age and risk factor profiles similar to those of patients with stroke or TIA, [12] but patients with TGA have a low incidence of strokes on follow-up.

There is a demonstrated association between TGA and migraine. In one nationwide cohort study, migraine was associated with an increased risk of TGA, particularly in female patients aged 40-60 years. [13]

Precipitants of TGA frequently include physical exertion, overwhelming emotional stress, pain, cold-water exposure, sexual intercourse, and Valsalva maneuver. These triggers may have a common physiologic feature: increased venous return to the superior vena cava.

The effects of drugs must be considered. For instance, sedative-hypnotic medications, either over-the-counter or prescribed for sleep (especially if used in conjunction with a transoceanic flight), or premedication with midazolam for medical procedures, may cause similar symptoms. Excessive alcohol can cause a blackout phenomenon. Hence, any history of drug-related amnesia may help clarify mitigating causes.

Sporadic reports of TGA occur very rarely in a variety of circumstances such as dobutamine-atropine stress echocardiography, infusion of DMSO-cryopreserved autologous peripheral blood stem cells, breathing of hyperoxic mixtures (Nitrox) in diving, intrathecal baclofen treatments, and withdrawal symptoms from a beta-blocker. In this report, the authors suggest that vasospasm might be an etiology versus venous conjestion. [14]

Social history and family history is relevant. Pantoni et al found that patients with TGA have a higher incidence of personal or family background of psychiatric conditions compared with patients who have had a TIA. [15] Prognostically, patients with TGA are less likely to experience a cardiovascular or cerebrovascular event compared with patients who have had a TIA.


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