Cognitive

Transient Global Amnesia

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Transient Global Amnesia

  • Definitions
  1. Transient Global Amnesia
    1. Transient inability to form new memories (Anterograde Amnesia) in episode lasting minutes to hours
  • Epidemiology
  1. Incidence 5-10 per 100,000 per year (23 to 32 per 100,000 per year in age over 50 years)
  2. Age: Over age 50 years (typical age range 50 to 80 years)
  • Pathophysiology
  1. Dysfunction of bilateral medial Temporal Lobes, and hippocampus
    1. MRI Brain DWI has shown bright punctate foci in hippocampus of TGA patients
    2. Jain (2018) Indian J Radiol Imaging 28(1): 6-9 PMID: 29692518 [PubMed]
  2. Associations with Migraine Headache, Temporal Lobe ischemia or partial complex Seizures have been postulated
  3. Venous congestion and venous reflux is also postulated as cause
    1. May explain why some TGA episodes are preceded by straining or Valsalva Maneuver
    2. Lewis (1998) Lancet 352(9125):397-9 [PubMed]
  • Symptoms
  1. Previously well person becomes confused and amnestic
    1. Transient inability to form new memories (esp. immediate and recent)
    2. Episode lasts for minutes to hours (typically up to 12-24 hours)
  2. Spontaneous onset is typical, however is associated with triggers in some cases
    1. Emotional stress
    2. Physical exertion
    3. Sexual intercourse
    4. Water immersion
  • Exam
  1. Normal Level of Consciousness and orientation
  2. Impaired ability to form new memories
  3. Other intellectual tasks preserved
  4. No other neurologic deficits
  • Diagnosis
  1. Witnessed abrupt onset of Anterograde Amnesia (mild Retrograde Amnesia may also be present) AND
  2. Otherwise normal other cognition including normal level of conciousness, orientation and attention AND
  3. No history of Head Injury or Seizures AND
  4. Non-focal Neurologic Exam during and after the episode AND
  5. Personal identity intact (contrast with Dissociative Amnesia or Fugue State)
  • Evaluation
  1. Exclude Cerebrovascular Accident with neuroimaging
  2. Consider EEG
  3. Observe (typically in hospital until resolution)
  • Prognosis
  1. Complete recovery is typical
  2. Rarely recurrs
  • Resources
  1. Nehring, Spurling and Kumar (2020) Transient Global Amnesia, Stat Pearls (accessed 6/1/2021)
  • References
  1. Brown and Hachinski in Wilson et. al. (1991) Harrison's Internal Medicine, Twelfth Edition, McGraw-Hill, St. Louis, p.188-9
  2. Pensa and Swaminathan in Herbert (2021) EM:Rap 21(6): 1-2