From the Guidelines
For a patient presenting with Transient Global Amnesia (TGA), the initial workup should focus on ruling out other potential causes of acute memory loss and assessing for any underlying conditions that may have triggered the episode, as the pathophysiological mechanism responsible for TGA has not been elucidated and its relationship to extracranial carotid and vertebral artery disease is unclear 1.
Diagnostic Recommendations
- Immediate neurological examination to assess for any focal neurological deficits.
- Laboratory tests such as complete blood count, electrolyte panel, blood glucose, and renal function tests to evaluate for metabolic causes.
- Electrocardiogram (ECG) to assess for cardiac arrhythmias or other cardiac issues.
- Imaging studies, specifically a non-contrast computed tomography (CT) scan of the head, to rule out intracranial hemorrhage or other structural abnormalities.
- Consideration of magnetic resonance imaging (MRI) of the brain, particularly if the CT scan is normal, to further evaluate for ischemic changes or other abnormalities.
- Assessment for recent head trauma, infection, or other potential triggers.
Management and Prevention
Medications that may be considered in the management or prevention of future episodes, though not typically initiated during the acute phase of TGA, include aspirin for its antiplatelet effects, if no contraindications exist 1. The dose would typically be 81 mg daily, but this should be individualized based on patient risk factors and medical history.
Monitoring and Follow-up
It's crucial to monitor the patient closely during the episode, as TGA typically resolves within 24 hours. Follow-up appointments should be scheduled to reassess the patient after the episode has resolved, to discuss the results of any diagnostic tests, and to provide guidance on reducing the risk of future episodes, if applicable. Patients with transient neurological attacks, including TGA, face an increased risk of stroke compared with those without symptoms 1.
From the Research
Diagnostic Criteria for Transient Global Amnesia (TGA)
The diagnostic criteria for TGA, as established in 1985 and elaborated in 1990, include:
- A sudden and severe anterograde memory disturbance
- Various degrees of retrograde amnesia
- No clouding of consciousness
- No other impairments of cognition
- No history of epilepsy or head trauma
- Resolution of the episode within 24 hours, leaving a memory gap for the length of the attack 2, 3
Diagnostic Workup for TGA
The diagnostic workup for TGA involves:
- Witnessed episode of memory loss
- Anterograde amnesia
- No evidence of neurological signs or deficits
- No features of epilepsy or active epilepsy
- No recent head injury
- Resolution of the episode within 24 hours 3
- Magnetic resonance imaging (MRI) may be used to rule out other potential causes, with punctate lesions in the hippocampus detected in some cases 2, 4, 5
- Computerized tomography (CT) may also be used to rule out other potential causes 5
Importance of Ruling Out Other Conditions
It is essential to rule out other acutely morbid conditions when addressing TGA, such as transient ischemic attacks (TIA) or cerebral vasculitis 3, 5 The timing of imaging is also crucial, with MRI and CT scans typically performed after the episode has resolved to rule out other potential causes 5
Recurrence of TGA
Recurrence of TGA is more likely in younger patients without significant microangiopathy, with a 24.5% risk of subsequent TGA recurrence in the following five years for patients up to 70 years of age without microangiopathic changes on MRI 6