Neuroscience · Year 2 · from Neuroscience
Case 3: Transient Global Amnesia
Patient Presentation
Demographics: 62-year-old male
Chief Complaint: Wife reports patient has been "asking the same questions over and over" for 4 hours
History of Present Illness: The patient's wife reports that they were gardening this morning when her husband suddenly began asking "What are we doing?" repeatedly. Despite answering him multiple times, he would ask again within minutes. He knows who he is and recognizes family members but cannot recall what he did this morning or why he is at the hospital. He has asked "Why are we here?" approximately 15 times during the emergency department evaluation. He denies headache, and there was no witnessed seizure activity. He was straining while lifting heavy bags of mulch just before symptom onset.
Physical Examination:
- Vital signs: BP 154/88, HR 72, T 36.8C
- General: Anxious appearing, well-groomed male
- Neurological:
- Mental status: Alert; oriented to person and place; knows the year but not the exact date; cannot recall any of three objects at 5 minutes despite multiple trials; long-term memory intact (recalls wedding date, children's names, career history); repeatedly asks "What happened to me?"
- Cranial nerves: Intact
- Motor: 5/5 throughout
- Sensory: Intact
- Coordination and gait: Normal
Workup:
- CT head without contrast: No acute abnormality
- MRI brain with DWI: Small punctate areas of restricted diffusion in bilateral hippocampi (particularly CA1 regions), each measuring approximately 2-3 mm
- Basic metabolic panel: Normal
- ECG: Normal sinus rhythm
Diagnosis: Transient global amnesia (TGA)
Treatment:
- Observation and reassurance
- No specific treatment required
Clinical Course: Over the next 6 hours, the patient gradually began retaining new information. By 8 hours after onset, he could recall three objects at 5 minutes. At discharge 10 hours after symptom onset, he had returned to baseline cognitive function. He had complete amnesia for the episode itself and approximately 2 hours before onset (the gardening). At 1-month follow-up, neurological examination was normal and the patient had returned to all usual activities.
Clinical Pearl: TGA is a benign, self-limited episode of anterograde amnesia typically lasting 4-8 hours (maximum 24 hours). Patients characteristically ask repetitive questions while retaining personal identity and procedural abilities. The hippocampus (particularly CA1, which is vulnerable to metabolic stress) shows transient dysfunction. Precipitants may include physical exertion, emotional stress, immersion in cold water, or Valsalva maneuver. The condition is not associated with increased stroke risk, and recurrence is uncommon (approximately 5-25%).
Clinical Image
Image Description: Axial FLAIR MRI demonstrating symmetric hyperintensity in the bilateral medial thalami, a characteristic finding in Wernicke encephalopathy due to thiamine deficiency. This pattern reflects the selective vulnerability of mammillary bodies, medial thalami, and periaqueductal gray matter - key structures in the Papez circuit essential for memory formation.
Attribution: Image from Radiopaedia (https://radiopaedia.org/), Creative Commons Attribution-NonCommercial-ShareAlike 3.0 license.