Transient global amnesia - not so rare after all

Transient global amnesia (TGA) is characterised by the sudden occurrence of amnesia while lacking other neurological symptoms. Complete remission occurs within 24 hours. The pathogenesis remains unknown. The objective of this study was to evaluate the prevalence of TGA in a primary referral hospital in Uster, Switzerland and examine the accuracy of the diagnostic procedure and outcome.

We conducted a retrospective review of patients with TGA admitted to the Uster hospital, Switzerland between 1/2005 and 10/2007. Of 8166 patients, 20 consecutive cases fulfilled the diagnostic criteria and were further analysed. We included presenting symptoms, diagnostic tests performed, treatment and outcome. A questionnaire to investigate the treating doctor's knowledge of TGA was conducted. A follow up was conducted in all patients at 19.1 +/- 7.1 months after presentation.

The incidence was 6.8/100 000/year. In all patients the symptoms resolved within 24 hours and all patients were seen by a consultant neurologist. Drug related causes were excluded. 25% episodes started after some form of exercise, 20% after emotional distress. All patients underwent cerebral imaging. 76% of the questionnaires sent to in-hospital physicians were returned. Diagnostic criteria of TGA were fully known in 75%. In 30% the diagnosis on admission was not TGA and had to be adjusted during the hospital stay. Follow up showed relapse in 10%.

TGA is a syndrome of which emergency physicians should be aware. The diagnosis is made clinically and the prognosis is good, although relapses may occur. Missed diagnoses may lead to uncertainty in patients and their relatives.