Transient global amnesia (TGA), is an anxiety-producing temporary loss of short-term memory. Typically, patients will not be able to remember events for the past few hours, and not be able to retain new information for more than a few minutes. Patients will suffer the effects of TGA for up to 24 hours, after which symptoms resolve. Worldwide, its incidence is approximately 2.9–10/100 000 cases per year. [1]
TGA is differentiated from stroke by the lack of tingling, peripheral limb involvement, speech impairment or ability to walk. It is differentiated from subarachnoid hemorrhage from the lack of headache. [2]
Presentation
TGA does produce an inability to assimilate certain, generally current or recent, details while social skills and memories of distant past events or trivia is maintained.
-The attack was witnessed and reported as being a definite loss of recent memory (anterograde amnesia).
-There was an absence of clouding of consciousness.
-There were no focal neurological signs or deficits during or after the attack.
-There were no features of epilepsy, and the patient did not have any recent head injury or active epilepsy
-The attack resolved within 24 hours
Causes
The underlying cause of TGA is unclear. One current hypothesis is that TGA may be due to venous congestion of the brain [4], leading to ischemia of structures involved with memory, such as the hippocampus.[5] This may be triggered by performing a Valsalva maneuver in the context of various precipitating events such as immersion in cold water, sexual activity, severe emotional stress and vigorous exertion.[6][7]
Prognosis
The prognosis of TGA is very good. It does not affect mortality and has a small recurrence rate.
"The most important part of management after diagnosis is looking after the psychological needs of the patient and his or her relatives. Seeing a once competent and healthy partner, sibling or parent become incapable of remembering what was said only a minute ago is very distressing, and hence it is often the relatives who will require reassurance." [8]
^ Quinette P, Guillery-Girard B , Dayan J , et al. What does transient global amnesia really mean? Review of the literature and thorough study of 142 cases. Brain 2006;129 (Part 7) :1640–58.
^ Monzani V, Rovellini A , Schinco G , et al. Transient global amnesia or subarachnoid haemorrhage? Clinical and laboratory findings in a particular type of acute global amnesia. Eur J Emerg Med 2000;7:291–3.
^ Hodges JR, Warlow CP Syndromes of transient amnesia: towards a classification; a study of 153 cases. Neurosurg Psychiatry 1990;53:834–43
^ Lewis SL. Aetiology of transient global amnesia. Lancet.1998;352:397-399..
^ Chung CP, Hsu H , Chao A , et al. Detection of intracranial venous reflux in patients of transient global amnesia. Neurology 2006;66:1873–7.
^ UCLA Department of Medicine - wfsection-Transient Global Amnesia. Retrieved on 2007-07-25.
^ Moreno-Lugris XC, Martinez-Alvarez J , Branas F , et al. Transient global amnesia. Case–control study of 24 cases. Rev Neurol 1996;24:554–7.
^ Magnus Harrison and Mark Williams
The diagnosis and management of transient global amnesia in the emergency department
Emerg Med J 2007; 24: 444-445. doi:10.1136/emj.2007.046565