Transient global amnesia and transient ischemic attack. Natural history, vascular risk factors, and associated conditions

Cognitive deficits and course of recovery in transient global amnesia: a systematic review

OBJECTIVE

Published evidence suggests that cognitive impairment during a TGA (transient global amnesia) spell may not be confined to episodic memory. We undertook a systematic review to determine the pattern of cognitive deficits during a TGA episode. As a secondary objective, we aimed to delineate the course of cognitive recovery.

METHODS

MEDLINE, EMBASE, CENTRAL, and Google scholar were systematically searched up to October 2023. Observational controlled studies including 10 or more TGA patients (Hodges and Warlow criteria) were retrieved. Data from case-control, cross-sectional, and cohort studies were reviewed and qualitatively synthesized.

RESULTS

Literature search yielded 1302 articles. After the screening of titles and abstracts, 115 full texts were retrieved and 17 of them were included in the present systematic review. During the acute phase, spatiotemporal disorientation, dense anterograde and variable retrograde amnesia, semantic memory retrieval difficulties, and working memory deficits comprised the neuropsychological profile of patients with TGA. Visuospatial abilities, attention and psychomotor speed, semantic memory, confrontation naming, and other measures of executive function (apart from semantic fluency and working memory) were consistently found normal. In the course of recovery, after the resolution of repetitive questioning, the restoration of spatiotemporal orientation follows, working memory and semantic memory retrieval ensue, while episodic memory impairment persists for longer. Meticulous evaluations may reveal subtle residual memory (especially recognition) deficits even after 24 h.

CONCLUSIONS

Μemory impairment, spatiotemporal disorientation, and working memory deficits constitute the pattern of cognitive impairment during a TGA spell. Residual memory deficits may persist even after 24 h.

Clinical Course and Recurrence in Transient Global Amnesia: A Study From the TEMPiS Telestroke Network

BACKGROUND AND PURPOSE

While the clinical hallmarks of transient global amnesia (TGA) are well defined, its pathophysiological causes are poorly understood. Specifically, risk factors for recurrences are yet to be determined.

METHODS

This retrospective study analyzed TGA cases diagnosed and treated within the TEMPiS telestroke network and a university stroke center in Germany. Demographic and clinical data were assessed and characteristics of TGA episodes were recorded, such as season of occurrence, trigger factors, duration, and concomitant symptoms. Follow-up of the potential recurrence of TGA was performed using a standardized questionnaire.

RESULTS

Overall 109 patients were included (age 64±8 years [mean±SD], 59.6% female). The most common vascular risk factor was arterial hypertension (60.6%), and other concomitant conditions included migraine (11.9%), hypothyroidism (22.9%), and atrial fibrillation (4.6%). The most frequent concomitant clinical feature accompanying the TGA episode at admission was elevated blood pressure (48.6%). Nineteen patients experienced at least one recurrent TGA episode. Migraine and hypothyroidism were only observed in subjects with a single TGA episode without recurrence (migraine: 14.4% without recurrence vs. none in the recurrence group, p=0.02; hypothyroidism: 27.8% without recurrence vs. none in the recurrence group, p=0.009). In contrast, atrial fibrillation was more common in subjects with TGA recurrence (p<0.001).

CONCLUSIONS

Arterial hypertension is prevalent in TGA patients, with elevated blood pressure being the most-frequent concomitant condition. In our cohort, recurrence of TGA occurred in approximately one-fifth of patients. Concomitant conditions such as migraine, hypothyroidism, and atrial fibrillation occurred at different frequencies in the two groups.

Transient global amnesia: Uncommon diagnosis of exclusion

Transient global amnesia (TGA) is an uncommon clinical syndrome characterized by short-term memory loss and disorientation that resolves in 24 h. Here, we report a 60-year-old male patient who presented with a sudden onset of disorientation and short-term memory loss and started to ask about his whereabouts and what happened. He had no significant past medical or psychiatric disorder. Likewise, the patient did not have a recent history of head trauma, substance abuse, loss of consciousness, seizure disorder, or migraine. Neurologic examination was normal except for mild disorientation and short-term memory impairment. He had a score of 18/30 on the mini-mental state examination. Extensive laboratory investigations did not show any abnormal findings. Brain MRI and EEG were normal. His memory improved and returned to a normal baseline within 24 h from the onset. After the exclusion of potential causes and the patient returned to a normal state of memory, the diagnosis of transient global amnesia was made. At the follow-up visit, the patient was in a state of normal function without a recurrence of memory impairment. Here, we presented this interesting case of transient global amnesia. TGA is a diagnosis of exclusion and is essential to keep in mind when evaluating a patient with acute onset of short-term memory impairment, especially when etiological investigations reveal no potential cause.

Transient Global Amnesia (TGA): Sex-Specific Differences in Blood Pressure and Cerebral Microangiopathy in Patients with TGA

Transient global amnesia (TGA) is defined by an acute memory disturbance of unclear aetiology for a period of less than 24 h. Observed psychological, neuroanatomical and hormonal differences between the sexes in episodic memory suggest sex-specific differences in memory disorders such as TGA. The aim of this study was to determine sex-specific differences in cardiovascular risk profiles, recurrences and magnetic resonance imaging (MRI). In total, 372 hospitalised TGA patients between 01/2011 and 10/2021 were retrospectively analysed. Comparisons were made between female and male TGA patients and compared to 216 patients with acute stroke. In our sample, women were overrepresented (61.8%), especially compared to the general population in the 65−74 age category (χ2 = 10.6, p < 0.02). On admission, female TGA patients had significantly higher systolic blood pressure values and a higher degree of cerebral microangiopathy compared to male TGA patients, whereas acute stroke patients did not. No sex-specific differences were observed with respect to recurrences or hippocampal DWI lesions. Our data demonstrate sex-specific differences in TGA. The higher blood pressure on admission and different degree of cerebral microangiopathy in female TGA patients supports the theory of blood pressure dysregulation as a disease trigger. Distinct precipitating events in female and male patients could lead to differences in the severity and duration of blood pressure abnormalities, possibly explaining the higher incidence in female patients.

Forgetting the Unforgettable: Transient Global Amnesia Part II: A Clinical Road Map

Transient global amnesia (TGA) is a clinical syndrome characterized by the sudden onset of a temporary memory disorder with profound anterograde amnesia and a variable impairment of the past memory. Usually, the attacks are preceded by a precipitating event, last up to 24 h and are not associated with other neurological deficits. Diagnosis can be challenging because the identification of TGA requires the exclusion of some acute amnestic syndromes that occur in emergency situations and share structural or functional alterations of memory circuits. Magnetic Resonance Imaging (MRI) studies performed 24–96 h after symptom onset can help to confirm the diagnosis by identifying lesions in the CA1 field of the hippocampal cornu ammonis, but their practical utility in changing the management of patients is a matter of discussion. In this review, we aim to provide a practical approach to early recognition of this condition in daily practice, highlighting both the lights and the shadows of the diagnostic criteria. For this purpose, we summarize current knowledge about the clinical presentation, diagnostic pathways, differential diagnosis, and the expected long-term outcome of TGA.

Forgetting the Unforgettable: Transient Global Amnesia Part I: Pathophysiology and Etiology

Transient global amnesia (TGA) is a clinical syndrome characterized by the sudden onset of a temporary memory disorder with a profound anterograde amnesia and a variable impairment of the past memory. Since the first description, dating back over 60 years, several cases have beenreported in the literature. Nevertheless, TGA remains one of the most mysterious diseases in clinical neurology. The debate regarding the etiology of this disease has focused mainly on three different mechanisms: vascular (due to venous flow changes or focal arterial ischemia), epileptic, and migraine related. However, to date there is no scientific proof of any of these mechanisms. Furthermore, the demonstration by diffusion-weighted MRI of lesions in the CA1 field of the hippocampus cornu ammonis led us to hypothesize that the selective vulnerability of CA1 neurons to metabolic stress could play a role in the pathophysiology of TGA. In this review, we summarize current knowledge on the anatomy, vascularization and function of the hippocampus. Furthermore, we discuss the emerging theories on the etiology and the pathophysiological cascade leading to an impairment of hippocampal function during the attacks.

Hot off the Press: MRI Sensitivity for Transient Global Amnesia

Transient global amnesia (TGA) is a rare and fascinating acute neurological disorder. It is characterized by idiopathic sudden onset anterograde memory loss that resolves within 24 hours of onset and results in no long-term sequelae. The gold standard diagnostic testing for this disorder are clinical criteria. Common emergency department investigations such as bloodwork and computed tomography scans are unremarkable. This paper reviews the yield of diffusion-weighted magnetic resonance imaging (DW-MRI) in the acute setting for the diagnosis of TGA.

Transient Global Amnesia Recurrence: Prevalence and Risk Factor Meta-analysis

Background:

Transient global amnesia (TGA) is an acute amnestic disorder with unclear pathophysiology. Although considered a benign phenomenon, the possibility of a recurrence is a major concern for the patient. Our objective is to identify the prevalence and risk factors of relapse, to help clinicians counsel patients about it.

Methods:

According to PRISMA guidance, we screened 1658 studies from MEDLINE, Lilacs and Embase databases, published from 1985 to April 2021, in English or Spanish. We included 36 observational case-control and cohort studies that included patients with TGA according to Caplan’s or Hodges and Warlow’s diagnostic criteria. We performed a meta-analysis with a random effect model for proportions and calculation of odds ratio for identified risk factors. Methodological quality was assessed according to the Newcastle-Ottawa Scale.

Results:

We identified 4514 TGA and 544 recurrence events (12.73%). Follow-up had no impact on its variance. We identified a statistically significant association between recurrence and sexual activity as a trigger, past or present personal history of migraine and depression (OR 1,481 95%CI [1,0341; 2,1222] p=0,04; OR=2,0795 IC95% [1,3892; 3,1128] p=0,003; and OR=4,487195%CI [1,890; 10,651] p=0,0288, respectively).

Conclusions:

The analysis showed that about 1 out of 8 subjects may have recurrence, with an increased risk in case of past or present history of migraine, depression or sexual intercourse prior to the event. Personal history of migraine and depression are associated with two and four times risk, respectively.

Acute-onset amnesia: transient global amnesia and other causes

Acute-onset amnesia is a dramatic neurological presentation that can cause considerable concern to both patient and clinician. The patient typically presents with an inability not only to retain new memories but also to access previously acquired memories, suggesting disturbance of hippocampal function. Transient global amnesia (TGA) is the most common cause of acute-onset amnesia, and is characterised by a profound anterograde and retrograde amnesia that typically lasts for up to 24 hours. Although TGA has a strikingly stereotypical presentation, it can be challenging to distinguish from other causes of acute-onset amnesia, including posterior circulation strokes, transient epileptic amnesia, psychogenic amnesia, post-traumatic amnesia, and toxic/drug-related amnesia. Here, we describe the general approach to the patient with acute amnesia; summarise the clinical and neuropsychological differences between the potential causes; and, provide practical recommendations to aid diagnosis and management of acute amnesia. Regardless of cause and the dramatic presentation, non-ischaemic acute-onset amnesia generally has a favourable prognosis.

Risk of ischaemic stroke in patients with transient global amnesia: a propensity-matched cohort study

BACKGROUND

The exact pathophysiological mechanism of transient global amnesia (TGA) is unknown. It is debatable whether TGA is a risk factor for stroke. Therefore, here we investigated the possibility of TGA as a risk factor for stroke in a real-world setting using large-scale nationwide health claims data.

METHODS

We used health claims data from the Korean National Health Insurance Service (NHIS). Patients diagnosed with TGA between 2007 and 2013 were selected. We initially extracted patients without TGA who were preferentially matched for age and sex with the patients with TGA at a ratio of 10:1 from the whole dataset. Further, we performed 1:2 propensity score matching analysis to balance the baseline characteristics between the two groups. In the propensity score-matched dataset, we performed multivariable Cox regression analysis to investigate the association between TGA and stroke type, including ischaemic, haemorrhagic and all stroke types.

RESULTS

Patients with TGA (n=14 673) were selected from the NHIS database. After extracting from the whole database (n=140 486) and propensity score matching their data at a 1:2 ratio, a total of 10 448 and 20 442 patients were finally assigned to the TGA and control groups, respectively. The multivariable Cox regression analysis demonstrated that the TGA group had a higher risk of ischaemic stroke and all types of stroke (adjusted HR=1.194; 95% CI: 1.043 to 1.368; and HR=1.197; 95% CI: 1.056 to 1.357, respectively).

CONCLUSIONS

Analysis of the nationwide claims database showed that TGA could be an important risk factor for stroke, especially for ischaemic stroke.

Transient Global Amnesia (TGA): Younger Age and Absence of Cerebral Microangiopathy Are Potentially Predisposing Factors for TGA Recurrence

Background: Transient global amnesia (TGA) is defined by an acute memory disturbance of unclear etiology for a period of less than 24 h. TGA occurs as a single event in most cases. Prevalence rates of recurrent TGA vary widely from 5.4 to 27.1%. This retrospective study aimed to determine predictors for TGA recurrence.

Methods: Cardiovascular risk profile and magnetic resonance imaging (MRI) of 340 hospitalized TGA patients between 2011 and 2020 were retrospectively analyzed. The median follow-up period amounted to 4.5 ± 2.7 years. Comparisons were made between TGA patients with and without subsequent recurrence.

Results: TGA patients with subsequent recurrence were significantly younger (recurrent vs. single episode, 63.6 ± 8.6 years vs. 67.3 ± 10.5 years, p = 0.032) and showed a lower degree of cerebral microangiopathy compared to TGA patients without recurrence. The mean latency to recurrence was 3.0 years ± 2.1 years after the first episode. In a subgroup analysis, patients with at least five years of follow-up (N = 160, median follow-up period 7.0 ± 1.4 years) had a recurrence rate of 11.3%. A 24.5% risk of subsequent TGA recurrence in the following five years was determined for TGA patients up to 70 years of age without microangiopathic changes on MRI (Fazekas' score 0).

Conclusion: Younger TGA patients without significant microangiopathy do have an increased recurrence risk. In turn, pre-existing cerebrovascular pathology, in the form of chronic hypertension and cerebral microangiopathy, seems to counteract TGA recurrence.

Transient Global Amnesia (TGA): Influence of Acute Hypertension in Patients Not Adapted to Chronic Hypertension

Objective: Transient global amnesia (TGA) is defined by an acute memory disturbance of unclear etiology for a period of <24 h. Several studies showed differences in vascular risk factors between TGA compared to transient ischemic attack (TIA) or healthy controls with varying results. This retrospective and cross-sectional study compares the cardiovascular risk profile of TGA patients with that of acute stroke patients.

Methods: Cardiovascular risk profile and MR imaging of 277 TGA patients was retrospectively analyzed and compared to 216 acute ischemic stroke patients (26% TIA).

Results: TGA patients were significantly younger and predominantly female compared to stroke patients. A total of 90.6% of TGA patients underwent MRI, and 53% of those showed hippocampal diffusion-weighted imaging (DWI) lesions. Scores for cerebral microangiopathy were lower in TGA patients compared to stroke patients. After statistical correction for age, TGA patients had higher systolic and diastolic blood pressure, higher cholesterol levels, lower HbA1c, as well as blood glucose levels, and lower CHA₂DS₂-VASc scores. Stroke patients initially displayed higher CRP levels than TIA and TGA patients. TGA patients without DWI lesions were older and showed higher CHA₂DS₂-VASc scores compared to TGA patients with DWI lesions.

Conclusion: This study revealed significant differences between TGA and stroke patients in regard to the cardiovascular risk profile. Our main findings show a strong association between acute hypertensive peaks and TGA in patients not adapted to chronic hypertension, indicating a vascular cause of the disease.

Factors Associated With Risk of Recurrent Transient Global Amnesia

Importance

Transient global amnesia (TGA) is usually considered a benign event with a low recurrence rate. However, recurrence rates vary considerably among studies and there are no known risk factors for TGA.

Objective

To examine risk factors for the recurrence of TGA.

Design, Setting, and Participants

This retrospective cohort study involved medical record review of patients with isolated or recurrent TGA presenting to the Mayo Clinic in Rochester, Minnesota, between August 1, 1992, and February 28, 2018. A total of 1491 cases were reviewed and 1044 met diagnostic inclusion criteria for TGA, with the remainder excluded owing to indeterminate or alternate diagnoses or limited information available in the medical record.

Exposures

Single vs recurrent episodes of TGA.

Main Outcomes and Measures

Demographics, precipitating factors, migraine history, imaging and electrodiagnostic findings, and family history of TGA were collected. The main outcome measure was TGA recurrence.

Results

Of 1044 included patients, 575 (55.1%) were male, and the mean (SD) age at inclusion was 75.0 (11.5) years. A total of 901 patients (86.3%) had a single episode of TGA and 143 (13.7%) had recurrent episodes of TGA. The 2 groups were similar in age at inclusion, sex, identifiable triggers, and duration of anterograde amnesia. The number of recurrences ranged from 1 to 9, with 137 individuals (95.8%) having 3 or fewer recurrences. The mean (SD) age at first episode of TGA was 65.2 (10.0) years for individuals with a single episode vs 58.8 (10.3) years for those with recurrent episodes (P < .001). There was a personal history of migraine in 180 individuals (20.0%) with a single episode of TGA and 52 individuals (36.4%) with recurrent episodes of TGA (P < .001), and a family history of migraine in 167 individuals (18.5%) with a single episode of TGA and 44 individuals (30.8%) with recurrent episodes of TGA (P = .001). There were no electroencephalographic findings associated with increased risk of TGA recurrence. Acute and subacute temporal lobe abnormalities on results of magnetic resonance imaging were seen rarely and did not require intervention. A family history of TGA was identified in 12 individuals (1.3%) with a single episode of TGA and 4 individuals (2.8%) with recurrent episodes of TGA.

Conclusions and Relevance

This study suggests that, in this large cohort of patients with TGA, recurrent TGA was associated with earlier age at the time of first TGA episode and higher prevalence of both personal and family history of migraine compared with isolated cases. These results can be used to counsel patients about risks of recurrence and may have implications for the understanding of TGA pathophysiology.

Transient Global Amnesia - Risk Factors and Putative Background

Objectives

Transient global amnesia (TGA) is a temporary short-term reversible memory loss. Etiology of TGA remains unclear with various hypotheses. We analyzed clinical characteristics, neuroimaging, and electrophysiological findings as well as comorbidities and seasonal variation in TGA patients with regard to possible background of the syndrome.

Materials and Methods

A total of 56 patients (42 women and 14 men) with TGA hospitalized from 2008 to 2016 in the Department of Neurology, Wrocław Medical University.

Results

A total of 52 patients (92.9%) underwent their first-ever episode of TGA. The potential triggers or events before episode could be recognized in 22 patients (39.3%). 35.7% patients had TGA in summer and 26.8% in winter months. In 92.9% patients chronic diseases were found, included: Hypertension (60.7%), dyslipidemia (48.2%), autoimmune thyroiditis (17.9%), and ischemic heart disease (14.3%). One patient (1,8%) suffered from migraine. Doppler ultrasonography of carotid arteries revealed abnormalities in 29 patients (51.8%). Electroencephalography abnormalities were observed in 10 (17.6%) of patients.

Conclusion

Our findings suggest a putative cerebrovascular background of transient global amnesia. No evidence has been provided for the association between TGA and epilepsy or migraine. Among comorbidities, autoimmune thyroiditis deserves further investigation with regard to its potential links with TGA.

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.

Factors associated with recurrent transient global amnesia: systematic review and pathophysiological insights

The examination of the risk factors that affect the recurrence of transient global amnesia (TGA) may shed light on the pathophysiological substrate of the disease. A systematic review was performed to identify the factors associated with the recurrence of TGA. MEDLINE, EMBASE, CENTRAL and PsycINFO were meticulously searched. Observational controlled studies involving patients with single (s-TGA) and recurrent TGA (r-TGA) according to Hodges and Warlow's criteria were retrieved. Differences in the demographic characteristics, personal and family medical history, previous exposure to precipitating events and laboratory findings were examined. Retrieved evidence was assessed in the context of the individual article validity, based on the numerical power and methodological quality of each study. Nine cohort studies with retrospective, prospective or mixed design were retrieved. In total, 1989 patients with TGA were included, 269 of whom suffered from r-TGA (13.5%). R-TGA presented an earlier age of onset. Evidence was suggestive of a relationship between recurrence and a family or personal history of migraine, as well as a personal history of depression. There was weaker evidence that associated recurrence with a positive family history of dementia, a personal history of head injury and hippocampal lesions in diffusion-weighted MRI. On the other hand, no connection was found between recurrence and electroencephalographic abnormalities, impaired jugular venous drainage, cardiovascular risk factors, atrial fibrillation, previous cerebrovascular events, exposure to precipitating events, a positive family history of TGA and hypothyroidism. Important pathophysiological insights that arised from these findings were discussed.

Transient global amnesia does not increase the risk of subsequent ischemic stroke: a propensity score-matched analysis

INTRODUCTION

Data regarding the risk of cerebrovascular events following transient global amnesia (TGA) remain controversial. While some neuroradiological studies suggest an underlying cerebrovascular etiology, results from the clinical studies have been largely conflicting. We, therefore, aimed to evaluate the risk of ischemic stroke in a large, nationally representative sample of patients with TGA.

METHODS

We utilized the Nationwide Readmissions Database 2010-2015 to identify all hospitalizations with the primary discharge diagnosis of TGA. We selected a 2% random sample of all elective admissions to be included as controls. A propensity score-matched analysis was performed to match patients with TGA and the controls. The primary outcome was readmission due to ischemic stroke up to 1 year following discharge from the index hospitalization, assessed using the Kaplan-Meier survival analysis in the propensity-matched groups.

RESULTS

There were 24,803 weighted hospitalizations due to TGA (mean ± SD age: 65.6 ± 10.4 years, female: 54.9%) and 699,644 corresponding controls. At baseline, patients with TGA were significantly older, more likely to be male, and had a higher prevalence of hypertension, hyperlipidemia, coronary artery disease, cerebrovascular disease, and migraine, as compared to the controls. However, after propensity score matching, we obtained 21,202 cases and 21,293 well-matched corresponding controls, and the risk of readmission due to ischemic stroke in patients with TGA was not different compared to the control group (HR: 1.13, 95% CI 0.62-2.05, P 0.686) during the mean (SD) follow-up period of 192.2 (102.4) days.

CONCLUSIONS

After adjustment for demographics and cerebrovascular risk factors, TGA is not associated with an increased risk of subsequent ischemic stroke.

The long-term prognosis of Transient Global Amnesia: a systematic review

Transient Global Amnesia (TGA) constitutes an enigmatic amnestic condition. In view of the admittedly limited knowledge regarding the nature of TGA, we decided to systematically review existing evidence for the generally regarded benign course of the disease. MEDLINE, EMBASE, CENTRAL and PsycINFO were searched for relevant articles. Observational (case-control, cross-sectional and cohort) controlled studies were retrieved. TGA diagnosis was made according to the diagnostic criteria of Caplan, validated by Hodges and Warlow. The TGA group was compared with either healthy controls (HC) or/and individuals with transient ischaemic attacks (TIA). The long-term risks of dementia, epilepsy, psychological-emotional disturbances, as well as long-term vascular and (vascular or nonvascular) mortality risks, were evaluated. Quality assessment was based on the Newcastle-Ottawa Scale. Literature search provided 12 eligible articles. Retrospective, prospective or mixed cohort designs were implemented in every study. Five articles registered a high quality, five registered a moderate quality, while two articles were assessed as part of the grey literature (conference abstract, abstract in English-article in Spanish). Overall, retrieved evidence was suggestive of similar vascular and mortality risks in TGA patients and HC, while TIA individuals exhibited elevated risks. Moreover, psychological disturbances were comparable between TGA and healthy individuals. On the other hand, studies for dementia and epilepsy obtained contradictory results, indicating both a similar and an increased risk in the TGA group compared to the HC group. Therefore, additional high-quality studies are warranted for the acquisition of more determining conclusions regarding the long-term risk of dementia and epilepsy in TGA.

Migraine in transient global amnesia: a meta-analysis of observational studies

BACKGROUND

PURPOSE: Although many studies have investigated the relationship between transient global amnesia (TGA) and migraine, to date, no meta-analysis has confirmed the existence and size of their association.

METHODOLOGY

Literature search involved MEDLINE, EMBASE, CENTRAL and PsycINFO. Observational controlled studies including TGA patients (Caplan, Hodges and Warlow) were retrieved. Quality evaluation was based on the Newcastle-Ottawa scale. The prevalence of migraine was compared in TGA patients vs. healthy controls (HC), as well as in TGA against TIA individuals. Data from case-control, cross-sectional and cohort studies were pooled separately.

RESULTS

Literature search yielded 1178 articles, 12 of which were included in the present meta-analysis. Results from case-control (ten), cohort (one) and cross-sectional (one) studies were compatible with an association between TGA and migraine. The nationwide inpatient cross-sectional study was of lesser value due to its inpatient orientation. The high-quality, population-based, retrospective cohort (158,301 participants per group) determined a higher relative-risk (RR) of TGA for migraine vs. non-migraine individuals [RR = 2.48, 95%confidence-interval (95% CI) = (1.32, 4.87)]. Sensitivity testing based on stricter diagnostic criteria strengthened the estimated association [RR = 3.84, 95% CI = (1.57, 9.38)]. Additionally, pooled data from eight case-control studies (700 TGA, 746 HC) yielded similar results [Odds-Ratio, OR = 2.51, 95% CI = (1.85, 3.41)], with the association mainly driven by the three high-quality studies, rather than the five articles of moderate quality. Finally, pooled findings from four case-control studies of moderate-quality revealed a higher prevalence of migraine among TGA compared to TIA patients [OR = 1.82, 95% CI = (1.22, 2.73)].

CONCLUSIONS

A significant association between TGA and migraine was established. The underlying connecting mechanism remains undetermined, yet.

Factors determining recurrence in transient global amnesia

Background

Aetiology of transient global amnesia (TGA) remains uncertain, though many have been proposed, including ischaemic, migrainous or epileptic pathologies.

Methods

We attempted to determine risk factors for TGA, as well as prognostic factors that may cause recurrence. We evaluated clinical history, family history and magnetic resonance diffusion-weighted imaging (DWI) studies of 93 prospective patients with TGA. Patients were followed from 2004 to 2016. Fifteen of 93 (16%) patients experienced a recurrence of TGA.

Results

Among precipitating events, physical activities inducing Valsalva-like manoeuvres were most common, followed by emotional stress. Eighty-four patients had possible comorbidities or risk factors for TGA, though no single risk factor was ubiquitous. Risk factors associated with recurrence were head injury (isolated vs. recurrent, 16.7% vs. 53.5%, p &lt; 0.01), depression (isolated vs. recurrent, 15.4% vs 46.7%, p = 0.01) and family history of dementia (isolated vs. recurrent, 20.5% vs. 46.7%, p = 0.03). Of 15 patients with confirmed recurrent TGA, two developed dementia and four subjective memory impairment. DWI lesions were observed in 24 patients and were located anywhere within the hippocampus.

Conclusions

DWI lesions were not significantly associated with outcomes (recurrence, subjective memory impairment, dementia). We have found that depression, previous head injury and family history of dementia may predict TGA recurrence.

Transient global amnesia: clinical features and prognostic factors suggesting recurrence

OBJECTIVE

The risk of recurrence of new amnesia events in patients having previously experienced transient global amnesia (TGA) ranges between 2.9-23.8%. Our objective was to search for recurrence predictors in TGA patients.

METHODS

Retrospective analysis to identify recurrence predictors in a cohort of 203 TGA patients from a single center in Buenos Aires, Argentina, diagnosed between January 2011 and March 2017 Clinical features and complementary studies (laboratory results, jugular vein Doppler ultrasound and brain MRI) were analyzed. Comparison between patients with recurrent versus single episode TGA was performed, applying a multivariate logistic regression model.

RESULTS

Mean age at presentation was 65 years (20-84); 52% were female. Median time elapsed between symptom onset and ER visit was two hours, with the average episode duration lasting four hours. Mean follow-up was 22 months. Sixty-six percent of patients referred to an identifiable trigger. Jugular reflux was present in 66% of patients; and 22% showed images with hippocampus restriction on diffusion-weighted MRI. Eight percent of patients had TGA recurrence. Patients with recurrent TGA had a more frequent history of migraine than patients without recurrence (37.5% vs. 14%; p = 0.03). None of the other clinical characteristics and complementary studies were predictors of increased risk of recurrence.

CONCLUSIONS

Patients with migraine may have a higher risk of recurrent TGA. None of the other clinical characteristics evaluated allowed us to predict an increased risk of recurrence. Although the complementary studies allowed us to guide the diagnosis, they did not appear to have a significant impact on the prediction of recurrence risk.

Enhanced cortisol secretion in acute transient global amnesia

INTRODUCTION

Stress-related transient inhibition of memory formation in the hippocampus has been hypothesized as one of the underlying pathomechanisms of transient global amnesia (TGA). TGA episodes, during which patients cannot encode and recall new information (anterograde amnesia affecting episodic long-term memory), are frequently preceded by a psychologically or physically stressful event.

METHODS

We measured salivary cortisol during acute TGA in 14 patients, as well as cortisol day-profiles and the effect of experimental exposure to stress (using the socially evaluated cold pressor test) on cortisol levels during the subacute phase. We assessed psychiatric comorbidity as well as depression, trait anxiety and chronic stress. These findings were compared with data of 20 healthy controls.

FINDINGS

Nine patients reported a precipitating stressor and all 14 developed typical hippocampal lesions on follow-up MRI. During TGA, salivary cortisol levels were more than 3-fold higher compared to time-matched day levels. While there was no difference in mean cortisol levels of the diurnal rhythm, we found a significant interaction between groups during experimental stress exposure (p = 0.049) with the TGA group revealing a higher cortisol increase. The TGA group reported higher levels of depressive symptomatology (CES-D) and higher scores of chronic stress (TICS) compared with the control group and there was a significant correlation between cortisol increase during TGA and the results of self-rating according to the CES-D (r = 0.615; p = 0.004), as well as to the STAI (r = 0.702; p = 0.001).

CONCLUSION

Our findings of enhanced secretion of cortisol in acute TGA patients correlating with symptoms of depression and anxiety and a persisting hyperreactivity to experimental stress in the subacute phase support the hypothesis that stress might be significant for the pathogenesis of TGA.

Transient global amnesia: current perspectives

Transient global amnesia (TGA) is a clinical syndrome characterized by the sudden onset of an extraordinarily large reduction of anterograde and a somewhat milder reduction of retrograde episodic long-term memory. Additionally, executive functions are described as diminished. Although it is suggested that various factors, such as migraine, focal ischemia, venous flow abnormalities, and epileptic phenomena, are involved in the pathophysiology and differential diagnosis of TGA, the factors triggering the emergence of these lesions are still elusive. Recent data suggest that the vulnerability of CA1 neurons to metabolic stress plays a pivotal part in the pathophysiological cascade, leading to an impairment of hippocampal function during TGA. In this review, we discuss clinical aspects, new imaging findings, and recent clinical-epidemiological data with regard to the phenotype, functional anatomy, and putative cellular mechanisms of TGA.

Vascular Risk Factors and Internal Jugular Venous Flow in Transient Global Amnesia: A Study of 165 Japanese Patients

BACKGROUND

The etiology of transient global amnesia (TGA) remains unclear. We studied the pathophysiology of TGA in 165 Japanese patients.

SUBJECTS AND METHODS

TGA was diagnosed in hospitalized patients from 2004 to 2015. We analyzed clinical characteristics, magnetic resonance imaging findings, and maximum intima-media thickness of the common carotid artery, and the reflux of internal jugular venous (IJV) flow by ultrasonography, and statistically compared patients with TGA with age-matched and sex-matched patients who have had a transient ischemic attack (TIA), small-vessel occlusion (SVO), and normal controls (each group, N = 165).

RESULTS

Patients with TGA showed lower prevalence of vascular risk factors than patients with TIA and SVO did. Eleven patients (6.7%) had 2 episodes of TAG, but specific clinical variables could not be recognized in these patients. The maximum intima-media thickness was significantly thinner in TGA (1.1 ± .7 mm) than in SVO (1.6 ± .9 mm; P = .001). The percentages of cases whose IJV flow reflux was increased by Valsalva maneuver showed no difference (P = .573) between TGA (26.0 %) and SVO (29.4%). MR diffusion-weighted imaging yielded small hyperintense signals in the hippocampus in 64 of 90 (71.1%) patients between 24 and 72 hours. Potential precipitating specific factors or events before the attacks could be recognized in 40 cases (24.2%) of 165 patients.

CONCLUSION

Arterial ischemia and IJV flow reflux might not contribute to TGA pathophysiology. The vulnerability of the hippocampus to physical or emotional stress might be suspected as an underlying mechanism in some patients with TGA.

Long-Term Outcome in Patients With Transient Global Amnesia: A Population-Based Study

OBJECTIVE

To study the long-term risk of cerebrovascular events, seizures, and cognitive impairment in patients with transient global amnesia (TGA).

PATIENTS AND METHODS

Data for all patients diagnosed with possible TGA in Olmsted County, Minnesota, between January 1, 1985, through December 31, 2010, were retrieved from the Rochester Epidemiology Project database. Transient global amnesia was defined clinically. End points were cerebrovascular event (stroke or transient ischemic attack), seizure, or cognitive impairment (mild cognitive impairment or dementia) during follow-up. End points were studied using Kaplan-Meier survival plots and log-rank test.

RESULTS

A total of 221 patients with TGA were identified and 221 age- and sex-matched controls were included in the analysis. The mean duration of follow-up was 12 years in both groups (range, 0.07-29.93). Prevalence of vascular risk factors and history of seizures were similar between both groups. Previous migraine was more common in the TGA group (42 patients [19.1%] vs 12 patients [5.4%]; P<.001). There was no statistically significant difference between survival curves for the TGA group and the control group using time to any type of cerebrovascular event (log-rank P=.30), time to seizures event (log-rank P=.55), and time to cognitive impair event (log-rank P=.88) as end points. The TGA recurrence occurred in 5.4% of patients after a median interval of 4.21 years (interquartile range, 2.82-8.44). Modified Rankin scale and death rates at last follow-up were also similar between both groups.

CONCLUSION

Our findings indicate that having an episode of TGA does not increase the risk of subsequent cerebrovascular events, seizures, or cognitive impairment.

Seasonal Changes in the Incidence of Transient Global Amnesia

Background and Purpose

Transient global amnesia (TGA) is a stereotypic condition characterized by anterograde and retrograde amnesia that typically resolves within 24 hours. The pathophysiology of TGA is still unclear. We noted that patients hospitalized with TGA tend to appear in seasonal clusters, and decided to investigate this phenomenon.

Methods

Every patient with acute presentation of amnesia at our medical center is hospitalized for observation and evaluation. We reviewed the monthly occurrence of TGA in our patient population between 2000 and 2014, and compared this to non-TGA hospitalizations during the same time period.

Results

During the analysis period, 154 patients who met the criteria for TGA were hospitalized, as well as 259,007 non-TGA hospitalizations. The annual occurrence of TGA ranged from 5 to 16 hospitalizations. There were 91 TGA events in women and 63 in men, in subjects aged 62.8±10.6 years (mean±SD). The incidence was maximal during December [odds ratio (OR)=2.83, 95% confidence interval (CI)=1.20–6.67] and March (OR=2.77, 95% CI=1.17–6.56), and minimal from April to August. The incidence exhibited an increase followed by a decrease from October to February. A seasonal trend was observed as well, with incidence peaks occurring in winter (OR=1.82, 95% CI=1.12–2.96) and spring (OR=1.80, 95% CI=1.10–2.94).

Conclusions

Our findings suggest that the incidence of TGA exhibits seasonal variations. This observation may help to improve the understanding of the pathophysiology underlying TGA.

Longitudinal Cerebral Perfusion Change in Transient Global Amnesia Related to Left Posterior Medial Network Disruption

BACKGROUND

The pathophysiology of transient global amnesia (TGA) is not fully understood. Previous studies using single photon emission computed tomography (SPECT) have reported inconclusive results regarding cerebral perfusion. This study was conducted to identify the patterns of regional cerebral blood flow (rCBF) in TGA patients via longitudinal SPECT analysis. An association between the observed SPECT patterns and a pathophysiological mechanism was considered.

METHODS

Based on the TGA registry database of Seoul National University Bundang Hospital, 22 TGA patients were retrospectively identified. The subjects underwent initial Tc-99m-ethyl cysteinate dimer (ECD) SPECT within 4 days of an amnestic event and underwent follow-up scans approximately 6 months later. The difference in ECD uptake between the two scans was measured via voxel-based whole brain analysis, and the quantified ECD uptake was tested using a paired t-test.

RESULTS

The TGA patients had significantly decreased cerebral perfusion at the left precuneus (P<0.001, uncorrected) and at the left superior parietal and inferior temporal gyrus according to the voxel-based whole brain analysis (P<0.005, uncorrected). A difference in the quantified ECD uptake between the 2 scans was also found at the left precuneus among the 62 cortical volumes of interest (P = 0.018, Cohen's d = -0.25).

CONCLUSION

We identified left hemispheric lateralized hypoperfusion that may be related to posterior medial network disruption. These findings may be a contributing factor to the pathophysiology of TGA.

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.

Transient global amnesia

Transient global amnesia (TGA) is a clinical syndrome characterized by the sudden onset of anterograde amnesia (the inability to encode new memories), accompanied by repetitive questioning, sometimes with a retrograde component, lasting up to 24 hours, without compromise of other neurologic functions. Herein, we review current knowledge on the epidemiology, pathophysiology, clinical diagnosis, and prognosis of TGA. For this review, we conducted a literature search of PubMed, with no date limitations, using the following search terms (or combinations of them): transient global amnesia, etiology, pathophysiology, venous hypertension, migraine, magnetic resonance imaging, computed tomography, electroencephalography, prognosis, and outcome. We also reviewed the bibliography cited in the retrieved articles. Transient global amnesia is a clinical diagnosis, and recognition of its characteristic features can avoid unnecessary testing. Several pathophysiologic mechanisms have been proposed (venous insufficiency, arterial ischemia, and migrainous or epileptic phenomena), but none of them has been proved to consistently explain cases of TGA. Brain imaging may be considered and electroencephalography is recommended when episodes are brief and recurrent, but otherwise no investigations are necessary in most cases. Data on long-term prognosis are limited, but available information suggests that the relapse rate is low, the risk of stroke and seizures is not considerably increased, and cognitive outcome is generally good.

No signs of intracranial arterial vasoconstriction in transient global amnesia

BACKGROUND AND PURPOSE

The current theories to explain the pathophysiology of transient global amnesia (TGA) involve epilepsy, migraine, and hippocampal ischemia which might be determined by venous congestion or arterial vasoconstriction triggered by Valsalva-associated maneuvers in susceptible individuals.

METHODS

Seventy-five TGA patients [mean age 60.3 ± 8.0 years, 44 (59%) females] and 75 age- and gender-matched controls were enrolled into a case-control study and underwent extracranial and transcranial arterial echo-color Doppler sonography.

RESULTS

Intracranial arterial obstructions of the posterior circulation were neither observed in TGA patients nor in controls. There was no significant difference between the two groups with regard to intima-media thickness of the common carotids (.73 ± .07 vs. .72 ± .06), cervical vessel atherosclerosis (13% vs. 15%), >50% intracranial stenosis of the anterior circulation arteries (3% vs. 3%), resistance index values of the vertebral arteries at rest and during Valsalva maneuver (.69 ± .08 vs. .67 ± .09) and pulsatility index values of the major intracranial arteries at rest and during Valsalva maneuver. No difference in all study items was found between patients assessed during or soon after the TGA episode.

CONCLUSIONS

Extra-intracranial atherosclerosis does not play a pathogenic role in TGA and no supporting evidence for the arterial vasoconstriction hypothesis of TGA emerged from this study.

Misdiagnosis of stroke

Rapid diagnosis of stroke is necessary for the timely delivery of thrombolysis and evaluation of novel therapies such as neuroprotection. An accurate clinical history and competent examination are key to identifying which patients are likely to have had a stroke and arranging and interpreting neuroimaging. Stroke symptoms are typically acute in onset, but are highly variable depending on the vascular territory affected. Common presenting symptoms are limb weakness, and speech and visual disturbances. Common stroke mimics are seizures, space occupying lesions, syncope, somatization and delirium secondary to sepsis. Stroke recognition instruments can help nonspecialists in the early diagnosis of stroke, with studies reporting sensitivity of over 90% and specificity of approximately 85% for some instruments. In patients with a clinical diagnosis of stroke, brain computed tomography or MRI is required to exclude some stroke mimics and differentiate ischemic from hemorrhagic stroke, which is key to providing appropriate therapies such as thrombolysis. In the future, plasma biomarkers may improve clinical diagnosis of stroke, but prospective studies are required to establish their utility. Clinical trials of acute stroke therapies need to ensure rapid accurate diagnosis of stroke using structured clinical assessments and appropriate imaging to achieve early treatment and avoid entry of stroke mimics into trials.

Transient global amnesia and the risk of ischemic stroke

BACKGROUND AND PURPOSE

Whether transient global amnesia (TGA) represents an arterial insult that heralds ischemic stroke remains unclear. Therefore, we examined stroke risk after TGA in a population-based cohort.

METHODS

After performing chart review at our institution to validate the International Classification of Diseases, 9th Edition, Clinical Modification diagnosis code for TGA, we used administrative claims data to identify all patients discharged from nonfederal California emergency departments or acute care hospitals between 2005 and 2010 with a primary discharge diagnosis of TGA. Patients with a primary discharge diagnosis of migraine, seizure, or transient ischemic attack were included as controls. Kaplan-Meier statistics were used to calculate rates of ischemic stroke, and Cox proportional hazards analyses were used to compare stroke risk among the 4 exposure groups while controlling for traditional stroke risk factors.

RESULTS

International Classification of Diseases, 9th Edition, Clinical Modification code 437.7 had a sensitivity of 86% and a specificity of 95% for TGA. The cumulative 1-year rate of stroke was 0.54% (95% confidence interval [CI], 0.36-0.81) after TGA, 0.22% (95% CI, 0.20-0.25) after migraine, 0.90% (95% CI, 0.83-0.97) after seizure, and 4.72% (95% CI, 4.60-4.85) after transient ischemic attack. After adjustment for demographic characteristics and stroke risk factors, TGA was not associated with stroke risk when compared with migraine (hazard ratio, 0.82; 95% CI, 0.61-1.10). The likelihood of stroke after TGA was lower than after seizure (hazard ratio, 0.57; 95% CI, 0.44-0.76) or transient ischemic attack (hazard ratio, 0.27; 95% CI, 0.20-0.35).

CONCLUSIONS

Compared with patients diagnosed with migraine or seizure, patients diagnosed with TGA do not seem to face a heightened risk of stroke.

Different risk factor profiles between transient global amnesia and transient ischemic attack: a large case-control study

BACKGROUND

The pathophysiology of transient global amnesia (TGA) is not fully understood. This study was conducted to identify the cardiovascular risk factors of TGA compared to those of transient ischemic attack (TIA) and normal controls, using a large number of subjects. In addition to the comparison of risk factors, an association between the observed cardiovascular risk factors in the current study and a pathophysiological mechanism recently investigated was speculated upon.

MATERIALS AND METHODS

We performed a retrospective case-control study that compared 293 TGA patients to 632 TIA patients and 293 age- and sex-matched normal controls. Demographic details and cardiovascular risk factors were carefully recorded.

RESULTS

TGA patients had a significantly higher prevalence of ischemic heart disease and hyperlipidemia; however, they had a lower prevalence of hypertension, diabetes mellitus, ischemic stroke and atrial fibrillation when compared to TIA patients. When compared to age- and sex-matched normal controls, TGA patients also had a significantly higher prevalence of hyperlipidemia, previous ischemic stroke and ischemic heart disease.

CONCLUSION

The cardiovascular risk factors identified in TGA patients in this study were different from those of previously reported studies. This disproportionate prevalence of cardiovascular risk factors may constitute possible evidence that TGA and TIA differ in their pathophysiological mechanism. In addition, some cardiovascular risk factors, such as hyperlipidemia and ischemic heart disease, should be regarded as possible risk factors of TGA.

Transient global amnesia and neurological events: the framingham heart study

BACKGROUND/OBJECTIVE

Transient global amnesia (TGA) is a temporary amnestic syndrome characterized by lack of other focal neurological deficits. Cerebrovascular disease, migraine and seizures have been suggested as underlying mechanisms. TGA may be a risk factor for cerebrovascular or other neurological events. We studied the relation of TGA, vascular risk factors, brain magnetic resonance imaging (MRI) indices of subclinical ischemia and neurological events in a community-based sample.

DESIGN/SETTING

A total of 12 TGA cases were ascertained using standard criteria by experienced neurologists, and matched to 41 stroke- and seizure-free controls. Vascular risk factors, brain MRI findings, and subsequent cerebrovascular or seizure events were compared in cases and controls.

PARTICIPANTS

Framingham Heart Study (FHS) original and offspring cohort participants were included.

RESULTS

No significant differences between the groups were observed in the prevalence of vascular risk factors, or brain MRI measures. Few incident stroke/transient ischemic attacks (TIA) (one event among the cases and four in controls) or subsequent seizures occurred in either group. Head CT during the acute event (n = 11) and brain MRI (n = 7) were negative for acute abnormalities. Electroencephalograms (EEG) (n = 5) were negative for epileptiform activity. Extracranial vascular studies were negative for significant stenosis in all cases.

CONCLUSION

In our community-based study TGA was not related to traditional vascular risk factors, or cerebrovascular disease. However, our study is limited by small sample size and power, and larger studies are required to exclude an association.

Transient Global Amnesia

In this case report and review of the literature, transient global amnesia (TGA) is discussed. A 72-year-old physician presented to the emergency department with sudden loss of memory. In particular, he was unable to recall recent events. Other neurological examination was intact. The loss of recent memory was completely resolved, during the next 4 hours. This event (TGA) must be distinguished from other neurological events such as transient ischemic attacks, seizures, and cerebral vascular events. A literature review suggested that TGA is related to an acute loss of function in the temporal lobe. It is important for palliative medicine physicians to have this unusual syndrome in their differential diagnosis, as this cause of memory loss must be separated from more aggressive causes of memory loss, for example, stroke and seizure. Transient global amnesia is a self-limiting disorder without late consequences.

Transient global amnesia: a case report

Introduction

Transient global amnesia is a syndrome of temporary and reversible disruption of short-term memory accompanied by repetitive questioning. Although the etiology is unknown, the prognosis usually benign, and no particular treatment is required, it is important for all involved clinicians to recognize the diagnosis and possess knowledge about the evaluation of these affected patients.

Case Presentation

A middle-aged Caucasian woman presented for neurologic evaluation for acute forgetfulness. Neurologic examination disclosed repetitive questioning with preserved orientation and no focal motor, speech, sensory, coordination, or cranial nerve deficits. Neurologic investigations did not reveal any pathologic findings. Her memory improved and reverted to normal baseline over the course of a 24-hour hospital stay.

Conclusion

Transient global amnesia is an interesting syndrome of reversible anterograde amnesia associated with repetitive questioning that occurs with an unclear etiology in middle-aged and elderly individuals. Due clinical diligence is required in the investigation of these patients. Treatment is generally not required, and the condition usually does not recur. Clinicians, including neurologists, internists, family practice physicians, and psychiatrists, need awareness of this condition.

Involvement of AMPA receptors in CSD-induced impairment of LTP in the hippocampus

OBJECTIVE

To investigate the alteration of hippocampal long-term plasticity and basal synaptic transmission induced by repetitive cortical spreading depressions (CSDs).

BACKGROUND

There is a relationship between migraine aura and amnesia attack. CSD, a state underlying migraine attacks, may be responsible for hippocampus-related symptoms. However, the precise role of CSD on hippocampal activity has not been investigated.

METHODS

Male Wistar rats were divided into CSD and control groups. Repetitive CSDs were induced in vivo by topical application of solid KCl. Forty-five minutes later, the ipsilateral hippocampus was removed, and hippocampal slices were prepared for a series of electrophysiological studies.

RESULTS

Repetitive CSDs led to a decrease in the magnitude of long-term potentiation in the hippocampus. CSD also reduced hippocampal synaptic efficacy, as shown by a reduction in post-synaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor responses. In contrast, the post-synaptic N-methyl-d-aspartate receptor responses remained unchanged. In addition, there were no changes in paired-pulse profiles between the groups, indicating that CSD did not induce any presynaptic alterations.

CONCLUSION

These findings suggest that a reduction of post-synaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor responses is the mechanism responsible for impaired hippocampal long-term potentiation induced by CSD.

Acute confusional migraine: our knowledge to date

Acute confusional migraine (ACM) is a rare migraine variant, affecting children and adolescents, as well as adults. Between 0.45 and 7.8% of children with migraine present with ACM, but the disorder may well be underdiagnosed. ACM is an exclusion diagnosis and some dangerous causes of confusion (e.g., epilepsy, ischemia, hemorrhagia, neoplasm, intoxication and encephalitis) should be ruled out. The confusional state often manifests with a wide diversity of cortical dysfunctions, such as speech difficulties, increased alertness, agitation and amnesia. Exact history taking, clinical examination, and laboratory, radiological and electroencephalographical findings lead the practitioner towards the diagnosis. Approximately half of the cases may be triggered by mild head trauma. Transient global amnesia is an important differential diagnosis, possibly caused by similar pathophysiological mechanisms. The exact pathomechanism remains unclear, with the common hypothesis comprising of the confusional state as a complex aura phenomenon, in which the cortical spreading depression wave reaches not only the occipital, but also the temporal, parietal and frontal cortex, as well as the brainstem and the hippocampi, leading to transient hypoperfusion and dysfunction of these brain areas.

Transient global amnesia: a brief review and update

Transient global amnesia (TGA) is a transitory syndrome of memory loss, lasting less than 24 h. Although there are many known causes of transient amnesia, the syndrome of TGA remains of unknown etiology. Known causes of transient amnesia, theories of pathogenesis of TGA, and recommended evaluation and treatment are discussed.