Transient global amnesia and hippocampal diffusion restriction: an overlooked radiological finding

Area of Science:

• Neurology
• Radiology
• Neuroimaging

Background:

• Transient global amnesia (TGA) presents with sudden anterograde amnesia.
• Diffusion restriction in the hippocampus (HDR) is an observed finding in TGA patients on DWI-MRI.
• The pathophysiology of TGA remains unclear, with cerebrovascular causes debated.

Purpose of the Study:

• To analyze the prevalence and characteristics of hippocampal diffusion restriction (HDR) in TGA patients.
• To investigate the relationship between HDR and vascular risk factors.
• To determine the rate of HDR lesions overlooked in routine radiology reports.

Main Methods:

• Retrospective analysis of 91 TGA patients diagnosed between 2011 and 2022.
• Evaluation of DWI-MRI scans for focal diffusion restriction, particularly in the hippocampus.
• Correlation analysis with patient demographics, vascular risk factors, and symptom duration.

Main Results:

• Focal diffusion restriction was detected in 18.5% of TGA patients (17/91), predominantly in the hippocampus.
• HDR detection was highest when DWI-MRI was performed 24-48 hours after symptom onset (p=0.03).
• 53% of detected HDR cases were not specified in routine radiology reports, highlighting potential underreporting.

Conclusions:

• Hippocampal diffusion restriction is a notable finding in a subset of TGA patients.
• Vigilant examination of DWI-MRI is crucial for detecting HDR, as it may be overlooked in standard reports.
• Further research is needed to clarify the role of cerebrovascular factors in TGA and HDR.