Download Transient Global Amnesia

Name of Disorder: Transient Global Amnesia
Essay Title: Transient Global Amnesia
Author: Amee Baird, PhD, MPsych (Clinical Neuropsychology), BA(Hons).
Institution: ARC Centre for Excellence in Cognition & its Disorders, Macquarie University
Date: 25/06/2014
Transient Global Amnesia
Transient global amnesia (TGA) is a sudden and temporary impairment of memory that lasts
up to 24 hours. During TGA a person is not able to recall new information (anterograde
amnesia), and may also have difficulty recalling old memories (retrograde amnesia). The
main symptom of TGA is repetitive questioning and disorientation (Szabo, 2014). During the
attack the person is alert and able to communicate and remains aware of their personal
identity (Peer et al., 2014). It is important to provide psychological support to the individual
and their family members during a TGA attack as it can be highly distressing to witness a
previously competent person suddenly lose their ability to remember something that was said
only a minute ago (Harrison & Williams, 2007).
In order to diagnose TGA, the following criteria outlined by Hodges & Warlow (1990) must
be met:
1. The attack was witnessed and reported.
2. There was obvious anterograde amnesia (impaired ability to learn new information) during
the attack.
3. There was no clouding of consciousness.
4. There was no focal neurological signs or deficits (such as impaired language or weakness
of limbs) during or after the attack.
5. There were no features of epilepsy.
6. The attack resolved within 24 hours.
7. The patient did not have any recent head injury or active epilepsy.
TGA typically occurs as a single episode and is considered a ‘benign’ disorder as the memory
deficits resolve completely and there are no long-term effects. Pre-attack factors that have
been associated with TGA include physical and/or emotional stress, swimming, sexual
intercourse, and use of marijuana or Viagra. The most common risk factor is a history of
migraines (Harrison & Williams, 2007).
Although there have been hundreds of reported cases of TGA, the cause is still unknown, and
it is regarded as one of the most mysterious neurological conditions. (Peer et al., 2014). A
number of possible causes have been proposed, including migraine and a disturbance of
venous blood flow in the brain (Szabo, 2014). A recent neuroimaging study using functional
Magnetic Resonance Imaging (fMRI) found that there was a significant reduction in
connectivity between brain regions controlling memory functions in individuals during a
TGA attack (Peer et al., 2014).
References
Harrison, M & Williams, M (2007). The diagnosis and management of Transient Global
Amnesia in the emergency department. Emerj Med J, 24, 444-445.
Hodges, JR & Warlow CP (1990). Syndromes of transient amnesia: towards a classification.
A study of 153 cases. J Neurol Neurosurg Psychiatry, 53, 834-843.
Peer, M et al. (2014). Reversible functional connectivity disturbances during Transient
Global Amnesia. Ann Neurol, 75, 634 – 643.
Szabo, K. (2014). Transient Global Amnesia. Front Neurol Neurosci. 2014;34:143-9.