Transient Global Amnesia
Overview
Acute onset anterograde amnesia
Normal cognition
Episodes are self limited and resolve within 24 hours
No single definite aetiology
Incidence
1 in 10k per year
Risk factors
Age 50 to 80
HTN = 2 x risk
^ Lipids = 3 x risk
Migraines associated
Pathophysiology
Evidence suggest vascular, migraine, epileptic and psychogenic causes
Clinical
Immediate recall intact
Delayed recall following several minutes is impaired
Appear disorganised, confused, perserverative
Cognition spared
10 to 40% have headache
Nausea, dizziness, anxiety, paraesthesia
Duration
Mean is 6 hours
Most symptoms resolve within 24 hours
Triggers
Occur 30 to 90% of patients
Acute on chronic emotional events
Physical activity
Sex = 10%
Stress = 20%
Valsalva = 40%
Pain
Posture change
Medical procedure
High altitude
Hot or cold water contact
Body temperature changes
Imaging
CT n emergency
MRI may be normal or show incidental findings within first few hours
MRI can show hippocampus punctuate lesions
Peaks between 12 and 72 hours
Resolve within 1 to 6 months
Management
Exclude other diagnoses
Fever is not seen in TGA
Detailed neuro exam
Test cognition
Thaimine 500mg IV
Ddx
TIA / Stroke
Seizure
Psychogenic
Long term Management
TGA usually does not recur
Rates 2 to 26%
Manage stroke risk factors
No increased risk of mortality, epliepsy, stroke or dementia