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Abstract
Objective To analyze how the evidence of hippocampal diffusion-weighted imaging (DWI) lesions may support the clinical diagnosis of transient global amnesia (TGA).
Methods In this retrospective observational study, 390 consecutive patients with isolated TGA were analyzed, who were evaluated at our institution between July 1999 and August 2018. The size, location, and number of lesions and time-dependent lesion detectability were examined. The incidence of DWI lesions was reviewed with regard to different levels of clinical diagnostic certainty upon presentation to the emergency department.
Results Hippocampal DWI lesions were detected in 272 (70.6%) patients with TGA, with a mean of 1.05 ± 0.98 (range 0–6) and a mean lesion size of 4.01 ± 1.22 mm (range 1.7–8.6 mm). In the subgroups of lower diagnostic certainty (amnesia witnessed by layperson or self-reported amnestic gap), DWI was helpful in supporting the diagnosis of TGA in 76 (69.1%) patients. In 187 patients with information about the exact onset, DWI lesions were analyzed in relation to latency between onset and MRI. Lesions could be detected at all time points and up to 6 days after symptom onset in individual patients; the highest rate of DWI-positive MRI (93%) was in the 12–24 hours time window.
Conclusion MRI findings can support the diagnosis of TGA and may be particularly valuable in situations of low clinical certainty. DWI—ideally performed with a minimum delay of 20 hours after onset—should therefore be considered a useful adjunct to the diagnosis of TGA.
Glossary
- DWI=
- diffusion-weighted imaging;
- ED=
- emergency department;
- TEA=
- transient epileptic amnesia;
- TGA=
- transient global amnesia
Footnotes
Go to Neurology.org/N for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article.
↵* These authors contributed equally to this work.
CME Course: NPub.org/cmelist
- Received November 11, 2019.
- Accepted in final form February 5, 2020.
- © 2020 American Academy of Neurology
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