Read this topic

Picture the hippocampusA brain structure central to forming new memories.Read more → as the brain's memory 'recording head' that briefly jams under a burst of physiological stress (a cold plunge, straining, emotional shock) so that although the person is fully awake and knows exactly who they are, nothing new gets written to memory until the jam clears — hence the loop of asking the same question over and over.

• Transient global amnesia (TGA) is a syndrome of sudden-onset, isolated anterograde amnesia (with variable retrograde amnesia for recent events) lasting minutes to up to 24 hours, with full recovery.
• Classic precipitants include emotional stress, physical exertion, Valsalva manoeuvres (e.g., heavy lifting, sexual intercourse), sudden immersion in cold or hot water, and pain.
• The leading pathophysiological theory implicates transient dysfunction of the hippocampusA brain structure central to forming new memories.Read more →, particularly the CA1 region, visible as small punctate diffusion-weighted MRI lesions that typically appear with a delay of 24-48 hours and resolve.
• Patients remain alert, retain personal identity, and show no other focal neurological signs — the defining feature is the pure, isolated memory disturbance with repetitive questioning as the hallmark clinical sign.

• Watch for sudden repetitive questioning ('Why are we here? What happened?') with full alertness and preserved identity.
• A preceding trigger such as emotional stress, exertion, Valsalva manoeuvre, or cold-water immersion strongly supports the diagnosis.
• Absence of focal neurological signs (no weakness, no dysarthria, no visual field loss) helps distinguish TGA from a TIA or stroke.
• Full resolution within 24 hours without recurrence is the expected natural history to confirm the diagnosis in retrospect.

• TGA vs TIA — TGA is a pure amnestic syndrome without other focal deficits and carries a much lower subsequent stroke risk; a TIA typically causes additional focal signs (weakness, dysarthria, visual loss) and carries the standard vascular risk requiring urgent work-up.
• TGA vs dissociative amnesia — TGA preserves personal identity and procedural knowledge, affecting only new memory formation; dissociative amnesia often involves loss of autobiographical identity and is linked to psychological trauma, without the hippocampal MRI changes.
• TGA vs complex partial seizure — TGA episodes last longer (up to 24 hours) with continuous alertness and no automatisms; seizures are briefer (minutes) with possible automatisms and post-ictal confusion or drowsiness.
• TGA vs Wernicke's encephalopathyAn acute brain condition from thiamine deficiency causing confusion, ataxia, and abnormal eye movements.Read more → — TGA is an isolated, self-resolving amnestic event in an otherwise well patient; Wernicke's presents with the additional triad of ataxiaLoss of full control of body movements, causing an unsteady, uncoordinated gait or actions.Read more → and ophthalmoplegiaWeakness or paralysis of the muscles that move the eyes.Read more → in a thiamine-deficient (often alcohol-dependent) patient and requires urgent thiamine replacement.

• Treating every sudden amnesia as a TIA requiring the identical urgent vascular pathway — TGA has a distinctly lower stroke recurrence risk and a different (benign) natural history.
• Missing the classic precipitants (cold water immersion, Valsalva, emotional stress, exertion) that strongly support TGA over other causes in the vignette.
• Assuming repeated questioning implies a psychiatric or dissociative cause — the preserved identity and typical trigger context point instead to a benign, self-limiting organic (hippocampal) mechanism.
• Over-interpreting a single TGA episode as heralding dementia or epilepsy — reassurance and observation, not anticonvulsants, are appropriate for a classic isolated episode.

• Localise the clue to the relevant anatomical level, cell type, pathway or molecular process.
• Map that structure or process to its normal function.
• Predict the deficit or clinical sign produced when it is disrupted.
• Reject options that belong to a neighbouring structure, pathway or level of explanation.