Transient Global Amnesia
MRI Case Series
Dr Lan Nguyen (Radiology Registrar)
Dr Tarun Jain (Consultant Radiologist)

Transient global amnesia (TGA) is a sudden, temporary episode of memory loss leading to absence of recall of recent events. It results in anterograde and partial retrograde amnesia lasting less than 24 hours without any other neurological or congestive symptoms. So the patient is not able to remember where he is and how he got there. In addition, patient may not remember anything about what’s happening in the here and now. Consequently, he may keep repeating the same questions because he can’t remember the answers that have just been given.

The patients may appear outwardly normal as they know who they are, recognise people they know well and can function quite normally in complex activities such as driving a car. Understandably this is a source of lot of anxiety, both for the affected person and those around them. Thankfully, most cases show complete resolution of symptoms within a few hours from onset of symptoms.

Recently, we had experience with MRI findings in this uncommon disease. A specialised type of MRI scan called diffusion weighted imaging (DWI) can detect small punctate spots in the hippocampus of brain in patients with TGA. Hippocampus is a small part of brain which plays a role in memory formation and learning. MRI findings can help confirm the diagnosis and also helps to exclude other causes of brain pathology like stroke.

The findings in 5 patients were presented in the meeting of ACT Radiologists on 6 May 2015 (ACT branch of RANZCR – Royal College of Australian and New Zealand Radiologists).