Conventional cardiovascular risk factors in Transient Global Amnesia: Systematic review and proposition of a novel hypothesis.

Transient Global Amnesia (TGA) is an enigmatic amnestic syndrome. We conducted a systematic review to investigate the relationship between the conventional cardiovascular risk factors and TGA. MEDLINE, CENTRAL, EMBASE and PsycINFO were comprehensively searched and 23 controlled observational studies were retrieved. The prevalence of hypertension, diabetes mellitus, dyslipidemia and smoking was lower among patients with TGA compared to Transient Ischemic Attack. Regarding the comparison of TGA with healthy individuals, there was strong evidence suggesting a protective effect of diabetes mellitus on TGA and weaker evidence for a protective effect of smoking. Hypertension was associated with TGA only in more severe stages, while dyslipidemia was not related. In view of these findings, a novel pathophysiological hypothesis is proposed, in which the functional interactions of Angiotensin-II type-1 and N-methyl-D-aspartate receptors are of pivotal importance. The whole body of clinical evidence (nature of precipitating events, associations with migraine, gender-based association patterns) was integrated.

Long-Term Risk of Stroke After Transient Global Amnesia in Two Prospective Cohorts.

Background and Purpose- Transient global amnesia (TGA) is known as a benign syndrome, but recent data from neuroradiological studies support an ischemic cause in some cases, which might suggest an increased susceptibility to cerebrovascular events. We determined the long-term risk of stroke after a first TGA in 2 independent prospective cohorts. Methods- In 2 independent prospective cohorts of patients with TGA (OXVASC [Oxford Vascular Study], population-based; NU (Northern Umbria) cohort, TGA registry), cardiovascular risk factors and long-term outcomes, including stroke and major cardiovascular events, were identified on follow-up. Cardiovascular risk factors were treated according to primary prevention guidelines. In OXVASC, the age-/sex-adjusted risk of stroke during follow-up was compared with that expected from the rate in the underlying study population. Results- Among 525 patients with TGA (425 NU and 100 OXVASC), mean (SD) age was 65.1 (9.5) years and 42.5% male. Hypertension (58.1%), dyslipidemia (40.4%), and smoking (36.4%) were the most frequent cardiovascular risk factors. The risk of stroke was similar in the 2 cohorts, with a pooled annual risk of 0.6% (95% CI, 0.4-0.9) and a 5-year cumulative risk of 2.7% (1.1-4.3). Moreover, the stroke risk in OXVASC cases was no greater than that expected in the underlying study population (adjusted relative risk=0.73; 0.12-4.54; P=0.74). Conclusions- TGA does not carry an increased risk of stroke, at least when cardiovascular risk factors are treated according to primary prevention guidelines.

Medical Procedure-Related Transient Global Amnesia.

BACKGROUND: Transient global amnesia (TGA) is an interesting clinical syndrome characterized by sudden memory loss for recent events and an inability to retain new memories usually lasting several hours and recovering spontaneously. We conducted a literature search of medical procedure-related TGA and its predisposing conditions. METHODS: We performed PubMed searches using the keyword "transient global amnesia" combined with "procedure," "test," "therapy," or various other individual medical procedures. In addition, we described 2 cases of gastroscopy-related TGA. RESULTS: Eighty-nine patients with medical procedure-related TGA in 49 articles were summarized. The most common procedure was cerebral angiography (n = 45), followed by coronary angiography (n = 10) and general anesthesia (n = 9). After categorization, neurological procedures were most common (n = 46, 51.7%), followed by cardiac (n = 17, 19.1%), anesthetic (n = 11, 12.4%), gastrointestinal (n = 4, 4.5%), and pulmonary (n = 2, 2.2%) procedures. CONCLUSIONS: Diverse cases of medical procedure-related TGA have been reported in the literature. Valsalva-associated activities, emotional stress with anxiety, and acute pain were predisposing conditions. An understanding of medical procedure-related TGA may be important for clinicians who perform such medical procedures.

Amnésia global transitória: epidemiologia, fisiopatologia, clínica e terapêutica / Global transient amnesia: epidemiology, pathophysiology, clinical features and therapeutics

A amnésia global transitória (AGT) é um quadro súbito de amnésia global, não acompanhada de outros déficits neurológicos, com duração de duas a 24 horas e cuja recuperação se dá espontaneamente. A incidência na população geral está estimada em 5-10 casos/100.000 pessoas/ano. Diferentes mecanismos fisiopatológicos, como fatores vasculares ou epiléticos, têm sido propostos para explicar a AGT, sendo consensual que haja acometimento transitório de regiões do hipocampo e do giro para-hipocampal. Além da amnésia anterógrada acompanhada por amnésia retrógrada, o paciente apresenta desorientação (tempo/espaço), estando preservadas outras habilidades cognitivas, como memória semântica e capacidades visuo-construtivas. Esses déficits tendem a remitir após 24h, sendo o prognóstico favorável na maioria dos casos. O diagnóstico diferencial de AGT é amplo e diversas condições clínicas, como eventos cérebro-vasculares, epilepsias, infecções e intoxicações podem mimetizá-lo, de modo que uma investigação clínica cuidadosa é imperativa. As recorrências não são frequentes nos quadros típicos. A AGT não requer tratamento específico, mas devem ser tratados fatores de risco cardiovascular eventualmente identificados durante a propedêutica de AGT. O clínico deve esclarecer o paciente a respeito do caráter benigno da AGT. Estudos com seguimento longitudinal dos pacientes são necessários para maior compreensão dos mecanismos fisiopatológicos da AGT e para melhor compreensão clínica e neuro- biológica dos déficits cognitivos apresentados por esses pacientes.

Global transient amnesia (GTA) is a clinical syndrome characterized by the sudden onset of anterograde and retrograde amnesia, without permanent neurological deficits, and which presents complete remission spontaneously within 2 to 24 hours. The incidence of GTA in the general population ranges from 5 to 10 cases per 100.000 individuals/ year. Different pathophysiological mechanisms have been proposed for GTA, such as vascular or epileptic factors, and it is consensual that there is transitory involvement of hippocampal and parahippocampal gyri in this condition. In addition to anterograde and retrograde amnesia, GTA patients typically present time-space disorientation, with the preservation of other cognitive abilities, such as semantic memory and visuoconstructive capacities. The differential diagnosis includes stroke, epilepsy, infections and intoxication, and a careful clinical investigation is essential to establish the GTA diagnosis. Recurrence is uncommon in typical cases and, in general, no specific treatment is required. However, clinical investigation of GTA may eventually disclose cardiovascular risk factors; these factors should be treated when identified. GTA is considered a benign condition, with good clinical and cognitive prognostics in most of the cases. More studies are needed to advance the current knowledge on the pathophysiology and on the neural basis of the transitory cognitive impairment observed in GTA.

[Transient global amnesia: A descriptive study of 12 Polynesian patients]. / Ictus amnésique: étude descriptive de 12 patients polynésiens.

INTRODUCTION: According to the criteria of Hodges and Warlow, transient global amnesia is defined by sudden onset of isolated anterograde amnesia of spontaneous resolution within one to twenty-four hours. Its pathophysiological mechanisms are still uncertain. METHODS: In a retrospective study, we have analyzed epidemiological, clinical and MRI data from twelve patients admitted to the only neurological department of French Polynesia for transient global amnesia corresponding to the criteria of Hodges and Warlow between January 2010 and December 2013. RESULTS: The median age of the cohort was 61.5 (53-72), the sex ratio was 1. Ten patients had one or more cardiovascular risk factors, 3 had migraine headaches and 3 had anxiodepressive disorders. Among triggers found, the occurrence during the rest was noted in one case. Retrograde amnesia was observed in 42% of cases, repetitive questioning in 75% of cases, anxious bewilderment in 67% of cases and disorientation in 33% of cases. The median episode duration was 9 hours and the duration of hospitalization was 3 days. Three patients had a recurrence. MRI was abnormal in all patients and showed diffusion-weighted hyperintensities in right (n=8), left (n=3) and bilateral (n=1) hippocampi. CONCLUSION: Epidemiological, clinical and MRI data from our cohort are similar to those from the literature except for the highest prevalence of cardiovascular risk factors and the most frequent right hippocampus involvement. Transient global amnesia occurring exceptionally while sleeping was also observed in one of our patients.

Is a cancer diagnosis associated with subsequent risk of transient global amnesia?

BACKGROUND: Psychological stress has been associated with transient global amnesia (TGA). Whether a cancer diagnosis, a severely stressful life event, is associated with subsequent risk of TGA has not been studied. METHODS: Based on the Swedish Cancer Register and Patient Register, we conducted a prospective cohort study including 5,365,608 Swedes at age 30 and above during 2001-2009 to examine the relative risk of TGA among cancer patients, as compared to cancer-free individuals. Incidence rate ratios (IRRs) and their 95% confidence intervals (CIs) derived from Poisson regression were used as estimates of the association between cancer diagnosis and the risk of TGA. RESULTS: During the study 322,558 individuals (6.01%) received a first diagnosis of cancer. We identified 210 cases of TGA among the cancer patients (incidence rate, 0.22 per 1000 person-years) and 4,887 TGA cases among the cancer-free individuals (incidence rate, 0.12 per 1000 person-years). Overall, after adjustment for age, sex, calendar year, socioeconomic status, education and civil status, cancer patients had no increased risk of TGA than the cancer-free individuals (IRR, 0.99; 95% CI, 0.86-1.13). The IRRs did not differ over time since cancer diagnosis or across individual cancer types. The null association was neither modified by sex, calendar period or age. CONCLUSION: Our study did not provide support for the hypothesis that patients with a new diagnosis of cancer display a higher risk of TGA than cancer-free individuals.

High-field, T2 reversed MRI of the hippocampus in transient global amnesia.

OBJECTIVE: To investigate the fine structural integrity of the hippocampus in patients with transient global amnesia (TGA) using high-resolution T2 reversed (T2R) MRI. METHODS: The authors performed detailed structural analysis of the hippocampus in 15 patients who had recovered from an episode of TGA and 150 randomly recruited normal volunteers across the adult age spectrum using high-resolution T2R MRI obtained on a 3.0-T system. An additional 100 subjects, with stroke or tumor, were similarly studied and served as disease controls. RESULTS: The overall incidence of hippocampal cavities detected in normal volunteers increased with age but never exceeded 40%, whereas the incidence in disease control group was 31%. They were always unilateral. In contrast, cavities were found in all 15 patients with TGA (100%), an incidence higher than in normal or disease controls (p < 0.05; Ryan's multiple comparison test), and were bilateral in eight patients (53%). The cavities in all but one of the normal volunteers (99%) and all disease controls (100%) were crescent shaped and < or =2 mm in width. The cavities in 14 of 15 patients with TGA (93%) were considerably larger (>3 mm in width), and five of the patients had giant cavities (>5 mm in width). Most of the cavities in patients with TGA had a rounded shape and resembled pathologic cavities described in specimens of hypoxia-related CA1 necrosis. CONCLUSION: The data indicate that transient global amnesia may not be a benign entity. Delayed neuronal loss within CA1 area of Lorente de No may represent its important sequel.