Network localization of transient global amnesia beyond the hippocampus

Area of Science:

• Neuroscience
• Neurology
• Neuroimaging

Background:

• Transient global amnesia (TGA) is a common neurological condition in older adults with unclear causes.
• Understanding the neuroanatomical basis of TGA is crucial for diagnosis and treatment.
• Focal brain lesions provide insights into the causal relationship between brain structure and neurological symptoms.

Purpose of the Study:

• To investigate the neuroanatomical substrate of TGA using lesion network mapping.
• To identify specific brain regions and networks associated with TGA-causing lesions.

Main Methods:

• A literature review identified 51 cases of TGA with DWI lesions.
• Clinical data were extracted and analyzed.
• Lesion mapping and functional connectivity analysis using a normative connectome dataset were performed.

Main Results:

• Hippocampal lesions were most frequently reported in TGA.
• Other TGA-causing lesion locations included the cingulate gyrus, anterior thalamic nucleus (ATN), putamen, caudate nucleus, corpus callosum, and fornix.
• Over 90% of hippocampal TGA lesions showed functional connectivity with the default mode network (DMN).

Conclusions:

• Hippocampal structural abnormalities are consistently implicated in TGA.
• Lesions in multiple brain locations can precipitate TGA, indicating a complex etiology.
• The default mode network (DMN) may play a role in TGA pathophysiology, suggesting TGA is a syndrome with diverse causes rather than a transient ischemic attack (TIA) subtype.