Case of the Month – April 2018
By Dr Morgan McMeniman
This month’s patient is a 46-year-old male who presented to his referring clinician with severe, sudden onset amnestic symptoms but no other complaints. He had no relevant medical history, history of trauma or prior surgery.
By the time he presented for MRI to Queensland X-Ray his symptoms had resolved however he underwent the scan to exclude any underlying ischemia.
3T axial diffusion weighted image (DWI) through the temporal lobes. Diffusion weighted sequences have many uses but are particularly important in identifying acute ischemic change. They are a routine sequence on all of our MRI brain scans.
The finding is subtle but specific for transient global amnesia- a small focus of true restricted diffusion in the left mesial temporal lobe at the hippocampus.
Transient Global Amnesia is characterised by sudden onset of memory loss and repetitive questioning without other neurologic signs. It is self limiting. It is most common in men of middle age and the elderly. The underlying aetiology remains controversial with uncertainty as to whether it reflects a vascular process, seizure activity or a migrainous phenomenon. Thankfully recovery is full and the process has a low recurrence rate. Active management is not required.