Transient global amnesia
Classification according to ICD-10 | |
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G45.4 | Transient global amnesia (amnesiac episode) |
ICD-10 online (WHO version 2019) |
The Transient Global Amnesia (TGA) or amnesic episode is a neurological disorder that frequently occurs in the elderly and a temporary disturbance of memory leads. It is considered harmless, but repeatedly leads to great concern among those affected and their relatives. The cause is a temporary dysfunction of the mediobasal temporal lobe (including both hippocampi ), the pathogenesis of which is not known.
Epidemiology
The annual new disease rate ( incidence ) is estimated at 3 / 100,000 inhabitants. Men and women are equally affected. The second half of life is clearly overrepresented, with transient global amnesia most common in the sixth decade of life.
Symptoms
There is a disturbance of memory that lasts up to 24 hours with a corresponding disorientation regarding time, situation and place ( anterograde amnesia ). The old memory remains largely intact; as far as the recent past is concerned, however, limitations are quite typical ( retrograde amnesia ) - hence “global” amnesia. Those affected make a perplexed impression. The constant repetition of the same questions, although they have already been answered several times, is very characteristic. The procedural memory , i.e. the ability to call up automated motor skills such as driving a car, is not disturbed. The symptoms appear abruptly and gradually and completely resolve after a few hours. It only leaves a memory gap for the time of the memory impairment .
Diagnosis
The diagnosis can usually be made clinically (without additional examinations) according to the criteria of Caplan (1985) and Hodges and Warlow (1990):
- sudden and severe memory impairment
- Preservation of procedural memory (e.g. continuation of complex activities such as playing the piano)
- Duration 1 to 24 hours
- no further abnormalities in the neurological examination
- especially no impaired consciousness or disorientation towards the person
- no previous trauma or epilepsy
The transient global amnesia must be differentiated, in particular, from memory disorders caused by:
- Epilepsy , especially transient epileptic amnesia
- Stroke , especially amnesic strokes
- traumatic brain injury
- Poisoning (including alcohol)
- Inflammation of the brain (especially in the context of herpes simplex encephalitis )
- functional disorders after emotionally stressful experiences
treatment
Inpatient admission is always required if the diagnosis cannot be made clearly or if adequate care is not guaranteed at home. Ultimately, however, it is used to monitor the progress (waiting for improvement) and to carry out examinations ( EEG , MRT ) to rule out the above-mentioned serious diseases.
A rational therapy is not possible because the cause of the disease is not known. It does not seem necessary either, as there are no further consequences beyond the memory gap. Only the risk of a new transient global amnesia is slightly increased after a single episode.
Cause considerations
A transient circulatory disorder was primarily suspected. In the majority of patients, punctiform diffusion disorders in the lateral hippocampus can be detected in magnetic resonance imaging . However, this is contradicted by the fact that transient global amnesia, unlike other short-term ischemias of the head ( TIA , amaurosis fugax ), is not a risk factor for suffering a stroke .
Further, due to the association was to migraine a cortical spreading depression adopted as a common basis of both diseases. However, this could not be further substantiated in practice, and the age at the time it first appeared does not speak in favor of it.
Venous congestion of the blood flow from the head was also suspected. This is supported by studies on the venous valves of the jugular vein of TGA patients. However, there are no reports to date that such patients could induce transient global amnesia using a Valsalva maneuver . As with most diseases, the cause of which is not known, functional (psychogenic / dissociative) causes were also discussed, as with the rather longer-lasting and non-age-related dissociative amnesia . Ultimately, the cause is still not clear.
literature
- L. Caplan: Transient global amnesia . In: JAM Frederiks (ed.): Clinical Neuropsychology (= Pierre J. Vinken, GW Bruyn, Harold L. Klawans [ed.]: Handbook of Clinical Neurology . Volume 45 ). Elsevier, Amsterdam 1985, ISBN 0-444-90356-9 , pp. 205-218 (English).
- JR Hodges, CP Warlow: Syndromes of transient amnesia - Towards a classification. A study of 153 cases . In: Journal of Neurology, Neurosurgery, and Psychiatry . tape 53 , no. 10 . BMJ Publishing Group, October 1990, ISSN 0022-3050 , p. 834-843 , doi : 10.1136 / jnnp.53.10.834 (English).
- C. Gandolfo, C. Caponnetto, M. Conti, N. Dagnino, M. Del Sette, A. Primavera: Prognosis of transient global amnesia - A long-term follow-up study . In: European Neurology . tape 32 , no. 1 . Karger, 1992, ISSN 0014-3022 , pp. 52-57 , doi : 10.1159 / 000116787 (English).
- Harald Kerbel: Transient Global Amnesia. Clinical course and follow-up . A study on 51 patients. University of Heidelberg, 1990, DNB 911131795 (dissertation).
- Martina Gertrudis Ramspott: Transient Global Amnesia and Jugular Venous Insufficiency . Ulm University, 2007, DNB 987857118 , urn : nbn: de: bsz: 289-vts-63026 ( online dissertation).
- O. Sedlaczek, JG Hirsch, E. Grips, CN Peters, A. Gass, J. Wohrle, M. Hennerici: Detection of delayed focal MR changes in the lateral hippocampus in transient global amnesia . In: Neurology . tape 62 , no. 12 . Lippincott Williams & Wilkins, June 22, 2004, ISSN 0028-3878 , pp. 2165–2170 , doi : 10.1212 / 01.WNL.0000130504.88404.C9 (English).
- S1 guideline for transient global amnesia (= amnesiac episode) of the German Society for Neurology (DGN). In: AWMF online (as of 2012)