transient global amnesia
DESCRIPTION
Transient Global Amnesia. Allan B. Wolfson, MD University of Pittsburgh Department of Emergency Medicine. Presentation of TGA. Clinical features. Sudden onset Anterograde amnesia Repetitive questioning Retrograde amnesia (variable, often spotty) - PowerPoint PPT PresentationTRANSCRIPT
Transient Global Amnesia
Allan B. Wolfson, MD
University of Pittsburgh
Department of Emergency Medicine
Allan Wolfson, MD
Presentation of TGA
Allan Wolfson, MD
Clinical features
• Sudden onset• Anterograde amnesia• Repetitive questioning• Retrograde amnesia (variable, often spotty)• Normal alertness, behavior, & cognition• Non-focal neuro exam • Resolution within 24 hrs
Allan Wolfson, MD
Reported triggers
• Emotional upset
• Sexual activity
• Vigorous exercise
• Valsalva
Allan Wolfson, MD
Differential Diagnosis
• Head injury• Toxic / metabolic• Vascular / TIA – posterior circulation• Non-convulsive seizure• Post-ictal state• Migraine• Tumor• Encephalitis• AV fistula• Functional
Allan Wolfson, MD
Epidemiology of TGA
Age group usually over 50, but seen in kids tooFamily history ?2%Incidence 5 - 30 per 100,000Recurrence 5 - 8% per yearApparent triggering factors in 33 - 50%
Allan Wolfson, MD
TGA -- Criteria for Dx
• Witnessed onset• Antegrade amnesia• No clouding of consciousness or loss of personal
identity• No cognitive impairment• No focal findings• No epileptic features
• No recent head trauma, no sz within 2 yrs• Resolution within 24 hrs
Allan Wolfson, MD
Anatomy of Memory
What structures subsume memory?
• Medial temporal lobes (hippocampus)• Thalamus• “Diencephalon”• Frontal / pre-frontal• “Deep cortical structures”
Allan Wolfson, MD
Physiology of Memory
• Memory acquisition
• Memory storage or consolidation
• Memory retrieval
• 3-compartment model?
immediate, recent, remote
Allan Wolfson, MD
Emergency Dept Evaluation
• History
• Neuro exam
• “Basic labs”?
• Head CT
• EEG
• MRI
Allan Wolfson, MD
Bedside evaluation of episodic memory
• Orientation?
• Remember 3 things for 3 minutes?
• Remember what happened yesterday?
Allan Wolfson, MD
Other types of memory to check on
• Semantic memory
• Procedural memory
• Biographical memory
• Topographic memory
• Meta-memory
Allan Wolfson, MD
Etiology of TGA?
• Vascular
• Seizure
• Migraine
• Venous hypertension
(Valsalva, paradoxical embolism)
Allan Wolfson, MD
Etiology of TGA?
• Case-control studies show no association with stroke or TIA
• Sub-group with epilepsy excluded by definition
• Nonconvulsive status epilepticus?• Association with migraine• Reported precipitating factors
Allan Wolfson, MD
Differentiating features
• Repetitive questioning
• Complex acts and instructions
• Memory gap for the event
• Severity of retrograde amnesia
• Rapid onset
• Duration
Allan Wolfson, MD
Transient epileptic amnesia
• Short attacks, multiple attacks• No repetitive questioning• Anterograde amnesia may be only partial• Altered behavior• Alteration in consciousness• Other features of epilepsy (eg, automatisms, other seizures, EEG, response to anticonvulsants)
Allan Wolfson, MD
Functional Amnesia
• Severe retrograde amnesia
• Absence of anterograde amnesia
• Duration often weeks or longer
Allan Wolfson, MD
Fancy Diagnostic Studies
• EEG
• CT scanning
• SPECT scanning, PET scanning
• MRI, DW-MRI, PW-MRI
Allan Wolfson, MD
SPECT scanning
• Some studies have shown decreased perfusion in medial temporal lobes, thalamus, or frontal lobes
• Usually returns to normal after attack
• Reflection of abnormality or cause?
Allan Wolfson, MD
Diffusion-weighted MRI
• Inconsistent findings• Sometimes shows abnormalities (esp in left hippocampus)
• Sensitive for ischemia (decreased diffusibility of water)• But also consistent with “spreading depression” (rapid resolution, unlike ischemia)
Allan Wolfson, MD
Diffusion-weighted MRI
• Sensitive for ischemia
(decreased diffusibility of water)
• But also consistent with
“spreading depression”
(rapid resolution, unlike ischemia)
Allan Wolfson, MD
What is “spreading depression”?
• Wave of depolarization progressing across cortex at 3-5 mm/min
• Associated with aura of migraine
Allan Wolfson, MD
Diffusion-weighted MRIin TGA
• Inconsistent findings• Sometimes shows abnormalities, especially in left hippocampus
Bilateral or left-sided only Sometimes no changes May be time-dependent
Allan Wolfson, MD
Treatment
• None necessary
• Migraine therapy?
Allan Wolfson, MD
Prognosis
• Essentially benign
• Subclinical persistent memory deficits?
• Associated conditions?
Allan Wolfson, MD
Disposition from the ED
• Theoretically:
after amnesia resolves, can
discharge with neurology follow-up
and no immediate testing
• Actually:
admission, MRI, EEG
Allan Wolfson, MD
Unanswered questions
• Etiology? Spectrum of causes?
• True role of precipitating factors?
• Acute treatment?
• Physiology of memory?
Allan Wolfson, MD
QUESTIONS ???