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 too Family history ?2% Incidence 5 - 30 per 100,000 Recurrence 5 - 8% per year Apparent 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 MRI in 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?