Transient global amnesia

Significance of serum neuron-specific enolase in transient global amnesia

Neuron-specific enolase (NSE) is a glycolytic enzyme, which is associated with neuronal cell dysfunction in the brain. This study evaluated the role of serum NSE levels of patients with transient global amnesia (TGA). In addition, the relationship between serum NSE levels and the clinical features of TGA was explored. Forty-eight patients with TGA were prospectively included, and their serum NSE levels were measured. We investigated serum NSE levels in patients with TGA. In addition, we analyzed the differences in clinical characteristics between patients with elevated and normal serum NSE levels. Of the 48 patients with TGA, 16 patients (33.3%) had elevated serum NSE levels (25.0 ± 11.5 ng/mL), whereas 32 patients (66.7%) showed normal serum NSE levels (12.8 ± 2.1 ng/mL). The patients with elevated serum NSE levels exhibited higher levels of cognitive impairment than those with normal serum NSE levels (4/16 vs. 1/32, p = 0.036). The serum NSE levels showed a relatively high discrimination (AUC 0.684) between patients with and without cognitive impairment, with 80.0% sensitivity and 74.4% specificity at a cut-off value 17.3 ng/mL. A third of all patients with TGA carry elevated serum NSE levels, which suggests that the neuronal cell dysfunction could be associated with TGA pathogenesis. In addition, it might be correlated with cognitive impairment.

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.

Implicit Learning in Transient Global Amnesia and the Role of Stress

Transient global amnesia (TGA) is a disorder with reversible anterograde disturbance of explicit memory, frequently preceded by an emotionally or physically stressful event. By using magnetic resonance imaging (MRI) following an episode of TGA, small hippocampal lesions have been observed. Hence it has been postulated that the disorder is caused by the stress-related transient inhibition of memory formation in the hippocampus. In experimental studies, stress has been shown to affect both explicit and implicit learning—the latter defined as learning and memory processes that lack conscious awareness of the information acquired. To test the hypothesis that impairment of implicit learning in TGA is present and related to stress, we determined the effect of experimental exposure to stress on hippocampal activation patterns during an implicit learning paradigm in patients who suffered a recent TGA and healthy matched control subjects. We used a hippocampus-dependent aversive learning procedure (context conditioning with the phases habituation, acquisition, and extinction) during functional MRI following experimental stress exposure (socially evaluated cold pressor test). After a control procedure, controls showed successful learning during the acquisition phase, indicated by increased valence, arousal and contingency ratings to the paired (CON+) vs. the non-paired (CON−) conditioned stimulus, and successful extinction of the conditioned responses. Following stress, acquisition was still successful, however extinction was impaired with persistently increased contingency ratings. In contrast, TGA patients showed impairment of conditioned responses and insufficient extinction after the control procedure, indicated by a lack of significant differences between CON+ and CON− for valence and arousal ratings after the acquisition phase and by significantly increased contingency ratings after the extinction. After stress, aversive learning was not successful with non-significant ratings of all parameters. Concerning brain activation patterns after the control procedure, controls showed increased hippocampal response during acquisition after the control procedure. This was not seen after stress exposure. In TGA patients, we observed an increased response in the right ventral striatum in the acquisition phase following stress. These findings suggest that alterations in implicit learning processes, including impaired hippocampal and increased striatal responses, might play a role in TGA pathophysiology, partly related to acute stress.

Hippocampal modifications in transient global amnesia

Transient global amnesia (TGA) is an acute and transient syndrome with a remarkably stereotypical set of signs and symptoms. It is characterized by the abrupt onset (no forewarning) of massive episodic memory impairment, both anterograde and retrograde. Ever since it was first described, TGA has fascinated neurologists and other memory experts, and in recent years, there has been a surge of neuroimaging studies seeking to pin down the brain dysfunction responsible for it. Several pathophysiological hypotheses have been put forward, including the short-lived suggestion of an epileptic mechanism. All the available data indicate that the brain modifications are reversible, and that the mechanism behind TGA is of a functional nature. However, while diffusion-weighted imaging studies have clearly identified the hippocampus and, more specifically, the CA1 area, as the locus of brain modifications associated with TGA, researchers have yet to determine whether the origin of the mechanism is vascular or neurochemical. Spectroscopy may provide a means of settling this issue once and for all.

Stronger pharmacological cortisol suppression and anticipatory cortisol stress response in transient global amnesia

Transient global amnesia (TGA) is a disorder characterized by a sudden attack of severe anterograde memory disturbance that is frequently preceded by emotional or physical stress and resolves within 24 h. By using MRI following the acute episode in TGA patients, small lesions in the hippocampus have been observed. Hence, it has been hypothesized that the disorder is caused by a stress-related transient inhibition of memory formation in the hippocampus. To study the factors that may link stress and TGA, we measured the cortisol day-profile, the dexamethasone feedback inhibition and the effect of experimental exposure to stress on cortisol levels (using the socially evaluated cold pressor test and a control procedure) in 20 patients with a recent history of TGA and in 20 healthy controls. We used self-report scales of depression, anxiety and stress, and a detailed neuropsychological assessment to characterize our collective. We did not observe differences in mean cortisol levels in the cortisol day-profile between the two groups. After administration of low-dose dexamethasone, TGA patients showed significantly stronger cortisol suppression in the daytime profile compared to the control group (p = 0.027). The mean salivary cortisol level was significantly higher in the TGA group prior to and after the experimental stress exposure (p = 0.008 and 0.010 respectively), as well as prior to and after the control condition (p = 0.022 and 0.024, respectively). The TGA group had higher scores of depressive symptomatology (p = 0.021) and anxiety (p = 0.007), but the groups did not differ in the neuropsychological assessment. Our findings of a stronger pharmacological suppression and higher cortisol levels in anticipation of experimental stress in participants with a previous TGA indicate a hypersensitivity of the HPA axis. This suggests that an individual stress sensitivity might play a role in the pathophysiology of TGA.

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.

The transience and nature of cognitive impairments in transient global amnesia: a meta-analysis

Transient global amnesia (TGA) is a clinical syndrome characterized by the sudden onset of severe amnesia without concomitant focal neurological symptoms. This meta-analysis of the cognitive characteristics of TGA addressed two main issues. First, we examined the hypothesis that the acute phase of TGA is associated with changes of anterograde and retrograde episodic long-term memory sparing semantic and short-term memory, while we had no clear prediction for potential reductions of executive functions due to the relative lack of previous studies addressing this issue. Second, we analyzed the time-course of changes in cognitive functions throughout three time intervals--acute (0-24 hours after TGA onset), postacute (24 hours to 5 days), and long-term phase (5-30 days)--to reveal whether there is a fast versus a delayed recovery. The results of the meta-analysis on 152 effect sizes from 25 studies showed that TGA is characterized by an extraordinarily large reduction of anterograde (d* = 1.89) and a somewhat milder reduction of retrograde (d* = 1.28) episodic long-term memory. Moreover, our results indicate the existence of additional, nonamnestic cognitive changes during TGA, because executive functions were also diminished (d* = 0.79). Reductions in both anterograde episodic long-term memory and executive function recover slowly, as slightly poorer performance in these cognitive domains can be found in the postacute phase (d*s = 0.32 and 0.44). All cognitive diminutions resolved within the long-term phase, by this calling into question previous reports of poorer performance of TGA patients relative to comparison subjects weeks or months after the attack.

Transient global amnesia--a review

Transient global amnesia (TGA) is an isolated amnesic syndrome with normal neurological examination where patients remain alert and communicative with no loss of personal identity; however, they experience striking loss of memory for recent events and an impaired ability to retain new information. TGA could be triggered by venous congestion and there is evidence of association between younger patients and history of migraine. Most episodes last 2-12 h and the recurrence rate of future amnesic events is very low.

Classical diseases revisited: transient global amnesia

Transient global amnesia usually affects patients between the ages of 40 and 80. Patients with this condition are often described--wrongly--as being confused. It presents classically with an abrupt onset of severe anterograde amnesia. It is usually accompanied by repetitive questioning. The patient does not have any focal neurological symptoms. Patients remain alert, attentive, and cognition is not impaired. However, they are disoriented to time and place. Attacks usually last for 1-8 h but should be less than 24 h. It is possible that it may result from different mechanisms such as venous congestion with valsalva-like activities before symptom onset, arterial thromboembolic ischaemia and vasoconstriction due to hyperventilation. Diagnosis may be made safely in the presence of a characteristic collateral history. No specific treatment is indicated for a typical episode.

Transient global amnesia following a transoceanic flight

Transient global amnesia (TGA) is the abrupt onset of temporary anterograde amnesia without any focal neurological features. It is a benign condition and is completely reversible in most cases. However, the sudden occurrence of memory impairment can be especially alarming to an individual who has recently arrived in an unfamiliar setting. The cause of TGA remains unknown. Reported here is the unusual occurrence of TGA in a man following the completion of an international airplane flight. Possible etiologies of the episode are considered.

Cerebral blood flow SPET in transient global amnesia with automated ROI analysis by 3DSRT

The aim of this study was to determine the areas involved in episodes of transient global amnesia (TGA) by calculation of cerebral blood flow (CBF) using 3DSRT, fully automated ROI analysis software which we recently developed. Technetium-99m L, L-ethyl cysteinate dimer single-photon emission tomography ((99m)Tc-ECD SPET) was performed during and after TGA attacks on eight patients (four men and four women; mean study interval, 34 days). The SPET images were anatomically standardized using SPM99 followed by quantification of 318 constant ROIs, grouped into 12 segments (callosomarginal, precentral, central, parietal, angular, temporal, posterior cerebral, pericallosal, lenticular nucleus, thalamus, hippocampus and cerebellum), in each hemisphere to calculate segmental CBF (sCBF) as the area-weighted mean value for each of the respective 12 segments based on the regional CBF in each ROI. Correlation of the intra- and post-episodic sCBF of each of the 12 segments of the eight patients was estimated by scatter-plot graphical analysis and Pearson's correlation test with Fisher's Z-transformation. For the control, (99m)Tc-ECD SPET was performed on eight subjects (three men and five women) and repeated within 1 month; the correlation between the first and second sCBF values of each of the 12 segments was evaluated in the same way as for patients with TGA. Excellent reproducibility between the two sCBF values was found in all 12 segments of the control subjects. However, a significant correlation between intra- and post-episodic sCBF was not shown in the thalamus or angular segments of TGA patients. The present study was preliminary, but at least suggested that thalamus and angular regions are closely involved in the symptoms of TGA.

Amnesia during cold water immersion: a case report

This report describes a case of amnesia during a cold-water experiment. The volunteer was exposed three times in 1 day (120 min duration each time) to 20 degrees C water. During the third immersion, from min 95 to min 115, the subject experienced transient global amnesia for 20 min. The rectal temperature during this time was 35.6 degrees C. This single case demonstrates that memory loss in a young individual apparently can occur after cold-water exposure and at core temperatures above 35 degrees C.

Continuing cognitive impairment after isolated transient global amnesia

Fourteen patients were investigated 3-4 days after end of their transient global amnesia (TGA) with a number of neuropsychological tests. Their performance was compared with that of a control group, matched for age, education, and profession. It was found that in spite of the common definition of TGA, impairments in both verbal and non-verbal long term memory and verbal fluency persisted and were in fact impaired to such a degree that it seemed unlikely that full recovery would have occurred within the next few days. We propose a major role of stress in the etiology and the recovery process of TGA and consider it likely that stress hormones are of major influence both in the triggering of TGA and the subsequent continuation of cognitive impairments.

Transient amnesia triggered by acute marijuana intoxication

We report an unusual case of sudden isolated transient amnesia triggered by acute marijuana use. The memory disorder, apart from the long duration, had the characteristics of a transient global amnesia-like episode. Acute marijuana intoxication can affect memory more globally and severely than previously reported.

Transient global amnesia and migraine. A case control study

This study examined the putative association of transient global amnesia (TGA) and migraine. 57 TGA patients were compared to a double-size control group of normal subjects. TGA patients who also had migraine were additionally compared to those without migraine and to a second control group of outpatients with migraine only. The prevalence of migraine, and also of episodic tension-type headache, was markedly increased among TGA patients. Precipitants and accompanying vegetative symptoms of TGA and migraine overlapped. However, there was no evidence of an interaction between TGA and migraine, in that the expression of key TGA features was not affected by comorbidity with migraine, and vice versa. The present findings argue against the hypothesis that TGA represents a type of migraine aura or migraine equivalent. They conform to the hypothesis that the two conditions are essentially independent and result from an inherited brain state that disposes to different types of paroxysmal dysregulation, presumably at the level of the brain stem.

Psychiatric and behavioral problems

In an emergency setting, many neurologic conditions present with psychiatric and behavioral symptoms. These symptoms may either be the first manifestation of the neurologic illness or a later occurrence in the progression of the disease. It is important for clinicians evaluating patients with psychiatric symptoms to identify the signs indicating associated neurologic illness and to have strategies for managing the acute, potentially dangerous, neuropsychiatric manifestations of the disease. This article addresses emergency evaluation and management of depression, anxiety, psychosis, mania, suicide attempts, neuroleptic malignant syndrome and other hypermetabolic and amnestic syndromes, somatoform disorders, aggression, and legal issues, such as capacity to accept or refuse treatment.

Vascular dementia: dead or alive?

The term 'Vascular Dementia' remains popular as a diagnostic entity, since it encompasses a variety of vascular pathologies. This is in stark contrast to many clinical classificatory systems that weight their definitions strongly towards stroke alone. A diagnosis of vascular dementia is complicated by compounding factors that reduce both the validity and specificity of diagnostic systems. This review highlights some of the problems faced in epidemiological, clinical, neuropathological and radiological studies attempting to define a clear-cut syndrome of dementia associated with cerebrovascular disease. The role of non-stroke ischaemia is also discussed. It is concluded that the term vascular dementia may have outlived its usefulness as a valid concept; alternative approaches are suggested.

Coma and confusional states: emergency diagnosis and management

Coma and confusion signal a failure of brain function with many possible causes. Since many of the potential causes may quickly lead to death or severe disability, it is important to develop a focused and ordered approach to facilitate the rapid diagnosis and early institution of proper therapies. This requires an understanding of the localizing features of the neurologic examination and of the syndromes likely to cause coma and confusion, a predetermined plan for empiric therapies in certain cases of doubt when diagnostic confirmation will be delayed, and a careful consideration of cases when the diagnosis is not revealed by the initial neuroimaging, lumbar puncture, or EEG.

Transient global amnesia and functional retrograde amnesia: contrasting examples of episodic memory loss

We studied 11 patients with transient global amnesia (TGA) and ten patients with functional retrograde amnesia (FRA). Patients with TGA had a uniform clinical picture: a severe, relatively isolated amnesic syndrome that started suddenly, persisted for 4-12 h, and then gradually improved to essentially normal over the next 12-24 h. During the episode, the patients had severe anterograde amnesia for verbal and non-verbal material and retrograde amnesia that typically covered at least two decades. Thirty hours to 42 days after the episode, the patients had recovered completely and performed normally on tests of anterograde and retrograde amnesia. By contrast, patients with FRA had a sudden onset of memory problems that were characterized by severe retrograde amnesia without associated anterograde amnesia and with a clinical presentation that otherwise varied considerably. The episodes persisted from several weeks to more than two years, and some of the patients had not recovered at the time of our last contact with them. The uniform clinical picture of TGA and the variable clinical picture of FRA presumably reflect their respective neurologic ('organic') and psychogenic ('non-organic') aetiologies.

Diffusion-weighted MRI in transient global amnesia precipitated by cerebral angiography

BACKGROUND

Transient global amnesia is a well-described complication of cerebral angiography. Speculation about the pathophysiology exists but is as yet unsubstantiated. Diffusion-weighted MRI is a new imaging technique that is very sensitive in detecting acute ischemia. Its use in the evaluation of transient amnesia precipitated by cerebral angiography has not previously been reported.

CASE DESCRIPTION

A 44-year-old man underwent posterior circulation cerebral angiography for the investigation of episodic vertigo. Shortly after completion of the procedure, he was noted to have symptoms of transient global amnesia. Diffusion-weighted MRI at 6 and 44 hours after the procedure demonstrated increased signal in the right hippocampus and other areas within the posterior circulation bilaterally consistent with ischemia from emboli. Abnormalities on conventional MRI images performed at the same time points were noted only in retrospect. A follow-up MRI at 2 months was normal.

CONCLUSIONS

Ischemia from cerebral emboli may cause transient global amnesia precipitated by cerebral angiography. Diffusion-weighted MRI may be useful in defining the pathophysiology.

Transient global amnesia and migraine in young people

Two cases of transient global amnesia (TGA) in a 16-year-old boy and in a 13-year-old girl are reported; both occurred during competitive sport and were associated with migraine. TGA in young people could provide crucial information on the still equivocal pathogenesis, a vascular thromboembolic hypothesis being untenable in such cases. A migrainous mechanism is likely to underlie TGA in young people and "pure' TGA in general. TIA or stroke, like epilepsy or other pathological conditions, should concern the differential diagnosis of transient amnestic episodes rather than the pathogenesis of TGA.

Transient global amnesia and thalamic hemorrhage

A left rostral thalamic hematoma was found in a 52-year-old hypertensive man who suffered from a 10-h episode of transient global amnesia (TGA). A neuropsychological study revealed no cognitive impairment in a follow-up period for 5 years. The left rostral part of the thalamus appears to be responsible for his TGA, due probably to an interference of the mamillothalamic tract, ventroamygdalofugal pathway or dorsal noradrenergic bundle.

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

BACKGROUND AND PURPOSE

The purpose of the present study was to make an attempt to ascertain the etiology of transient global amnesia (TGA), which is still disputed more than 30 years after the first description of this clinical entity.

METHODS

In a case-control study, we compared the prevalence of vascular risk factors in 64 TGA patients with 64 first-ever transient ischemic attack (TIA) control subjects and 108 normal community-based control subjects matched for age and sex. We prospectively studied the vascular events and mortality rates of the TGA cases and of the TIA control subjects. Then we compared the outcome of the two groups using actuarial analysis based on survival curves.

RESULTS

We did not find evidence of an increased risk of TGA associated with any vascular risk factor. In contrast to TIA control subjects, no TGA patient suffered stroke, myocardial infarction, or TIA during the follow-up period. Migraine was more common in TGA patients than in both normal and TIA control subjects. In three patients (4.5%), the TGA was eventually considered to be of epileptic origin.

CONCLUSIONS

The results of our case-control and longitudinal studies point to the conclusion that TGA and TIA do not share the same etiology. Since half of our patients had a precipitating event in their history, it is reasonable to hypothesize that spreading depression may play a role in TGA. The significant positive association between migraine and TGA may support this hypothesis. Epilepsy may mimic TGA in a minority of cases.