Diffusion-weighted MRI in transient global amnesia and its diagnostic implications.

Area of Science:

• Neurology
• Radiology
• Medical Imaging

Background:

• Transient global amnesia (TGA) is a distinct clinical syndrome characterized by sudden, temporary memory loss.
• Accurate diagnosis of TGA can be challenging, particularly in cases with ambiguous clinical presentation.
• Diffusion-weighted imaging (DWI) has emerged as a sensitive technique for detecting subtle brain abnormalities.

Purpose of the Study:

• To evaluate the diagnostic utility of hippocampal diffusion-weighted imaging (DWI) lesions in transient global amnesia (TGA).
• To determine the effectiveness of DWI in supporting TGA diagnosis, especially in cases with low initial clinical certainty.

Main Methods:

• Retrospective analysis of 390 patients with isolated TGA evaluated between 1999 and 2018.
• Examination of lesion characteristics (size, location, number) and time-dependent detectability on DWI MRI.
• Review of DWI lesion incidence in relation to varying levels of clinical diagnostic certainty.

Main Results:

• Hippocampal DWI lesions were identified in 70.6% of TGA patients.
• DWI was crucial for diagnosis in 69.1% of cases with lower clinical certainty.
• Lesions were detectable up to 6 days post-onset, with the highest detection rate (93%) between 12-24 hours.

Conclusions:

• MRI findings, specifically hippocampal DWI lesions, significantly aid in TGA diagnosis.
• DWI MRI is particularly valuable in ambiguous TGA cases, enhancing diagnostic confidence.
• Performing DWI ideally within 20 hours of symptom onset is recommended for optimal diagnostic yield in TGA.