Transient Global Amnesia (TGA)

KEY FACTS

Terminology

• Sudden memory loss without other signs of cognitive or neurologic impairment; usually resolves within 24 h

Imaging

• NECT, CECT almost invariably normal

• MR

  • T2/FLAIR usually normal

  • DWI: Focal dot-like area of diffusion restriction in hippocampus

    • –

      Single (55%)

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      Multiple (45%)

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      Unilateral (50-55%)

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      Bilateral (45-50%)

  • DWI abnormalities increase with time

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      From 35% at 0-6 h to 65-70% by 12-24 h

    • –

      Complete resolution by day 10

• PWI, PET/CT may show hippocampal hypoperfusion/hypometabolism

Top Differential Diagnoses

• Cerebral ischemia-infarction

• Seizure/postictal state

• Hypoglycemia

Pathology

• Underlying pathophysiology still unknown

• Functional, reversible modification of hippocampus

Clinical Issues

• Most common in middle aged, elderly patients (rare < 40 years)

  • Younger patients with physical/emotional stress, trauma, migraine (rare)

• Abrupt onset of massive episodic memory impairment

  • Both anterograde and retrograde

  • Often accompanied by repetitive questioning

  • Other neurologic functions intact

• Self-limited (spontaneous resolution within 24 h)

TERMINOLOGY