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Transient global amnesia (TGA) is one of the most severe forms of anterograde amnesia seen in clinical practice, yet patients may show evidence of spared learning during the amnesic episode. The scope of spared learning in such a severe form of amnesia remains uncertain, and it is also unclear whether findings from single-case studies hold up in group studies of TGA patients. In this group study, we found evidence that extended the domain of spared learning in TGA to include the mere exposure effect, whereby enhanced preference is primed by prior exposure to stimuli. We demonstrate this effect during an acute episode in a group of TGA patients, where they showed enhanced preference for previously exposed faces, despite markedly impaired performance on standard anterograde memory tests.

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.

Introduction: Transient global amnesia (TGA) is a syndrome characterised by the rapid onset of antero- and retrograde amnesia, accompanied by temporal disorientation and iterative questioning. It is now established that the acute phase is associated with a raised level of anxiety and a depressed mood. We conducted a thorough investigation of patients' perceptions of their disease state, focusing on the links between their lack of explicit knowledge of amnesia during the acute phase and their emotional experience., Method: Explicit knowledge of memory deficits was assessed during TGA by means of an original scale inspired by Bisiach et al. (1986) and self-reported scales measuring patients' perceptions of their current memory and their cognitive and behavioural functioning. At the same time, we probed the patients' emotional experience (sources of worry, and levels of worry, anxiety and depression) via questionnaires. Data were collected from 20 patients in the acute phase, 16 in the peri-acute phase, 16 who were assessed the day after the episode and 14 healthy controls. Each patient underwent a follow-up examination 2 months later., Results: Patients in the acute phase displayed a lack of explicit knowledge of their amnesia and overestimated their memory performances. They also expressed higher levels of worry and anxiety than controls, and a more depressed mood., Conclusions: Although they were aware of their disease state, the TGA patients were unable to identify the nature of their memory deficits and overestimated their memory performances. These memory misperceptions and the inability to acknowledge memory failure occurred concomitantly with changes in the patients' emotional state. This particular pattern of awareness could be regarded as a reaction to the suddenness and massiveness of the amnesia., (Copyright © 2012 Elsevier Srl. All rights reserved.)

Introduction: Transient global amnesia (TGA) is a perfectly well defined clinical picture, but nevertheless even today its aetiology remains unknown. The three most widely accepted theories suggest it has a vascular origin, it is related with the pathophysiology of migraine or it is of an epileptiform nature., Aim: To analyse whether there is an electroencephalographic pattern that is consistently repeated in a series of electro-encephalograms (EEG) carried out on patients with TGA., Patients and Methods: The study consists in a retrospective analysis of a sample of 345 patients referred to have an EEG after an episode of TGA., Results: In almost 20% of the EEGs something that could be considered abnormal was found, although most of these findings (64%) were of little pathological significance. Of the remaining 26%, attention should be drawn to the cases of two patients with subclinical rhythmic electroencephalogram discharges of adults (a pattern with a meaning that is not altogether clear and which has previously been associated with TGA)., Conclusions: A considerable percentage of patients have TGA and EEG alterations, although most of them are of scarce pathological significance or can be attributed to some other underlying condition. We have not succeeded in identifying any pattern that is consistently repeated. Our results suggest that the EEG is a test with low diagnostic effectiveness in this pathology and it is necessary to reconsider the need to systematically perform such tests in suspected cases of TGA.

Transient global amnesia is a neurological syndrome in which there is a sudden and brief inability to form new memories, as well as an intense retrograde amnesia. However, awareness, personal identity and attention remain intact. It is an uncommon condition seen after an anaesthetic procedure. There are several aetiopathogenic hypotheses (epileptic, migrainous or ischaemic origin) and triggering factors (pain, anxiety, temperature changes, exercise, Valsalva manoeuvres, diagnostic tests or certain drugs). We describe the case of a patient with a high level of pre-operative anxiety who suffered an episode of transient global amnesia after undergoing otolaryngology surgery. With an acute and continued amnesia after general anaesthesia, the first thing that must be done is to establish a suitable differencial diagnosis, which should include transient global amnesia, as this is mainly an exclusion diagnosis. Preoperative anxiety may be a triggering factor to take into account in this condition, with anxiolytic treatment prior to the surgery being important., (Copyright © 2010 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Published by Elsevier España. All rights reserved.)

Transient global amnesia (TGA) is a clinical syndrome characterized by the abrupt onset of a massive episodic memory deficit that spares other cognitive functions. If the anterograde dimension is known to be impaired in TGA, researchers have yet to investigate prospective memory (PM)--which involves remembering to perform an intended action at some point in the future--in this syndrome. Furthermore, as executive functions are thought to be spared in this syndrome, TGA provides an opportunity to examine the impact of a massive "pure" memory impairment on PM. We assessed 38 patients with a newly designed protocol that distinguished between the prospective (remembering to do something at the appropriate time) and retrospective (remembering what has to be done) components of PM. Moreover, we investigated episodic memory with an anterograde memory task and assessed executive functions, anxiety and mood, as well as their links with PM. We demonstrated that PM is impaired during TGA, with a greater deficit for the retrospective component than for the prospective component. Furthermore, we highlighted a strong link between these two components. Anterograde episodic memory impairments were correlated with retrospective component deficits in TGA patients, although we were able to confirm that executive functions are globally spared. We discuss this pattern of results within the theoretical framework of PM, putting forward new arguments in favor of the idea that PM deficits can occur mainly because of a massive anterograde memory deficit. The clinical consequences of PM impairment in TGA are examined.

Transient global amnesia syndrome was initially described more than a century ago. Although the clinical syndrome is easily recognized and highly consistent in its characteristic features, the underlying pathophysiology has remained elusive. Proposed mechanisms include focal ischemic lesions or local nonischemic energy failures. Diffusion-weighted imaging has been able to demonstrate focal areas of restricted diffusion. Nonetheless, the mechanism of this diffusion restriction is uncertain and does not necessarily indicate ischemia, leaving the exact nature of this seemingly benign disorder in doubt. This review summarizes the pertinent clinical features, proposed pathophysiology, epidemiology, imaging, and future directions in understanding transient global amnesia., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Autobiographical memories in our lives are critically dependent on temporal lobe structures. However, the contribution of CA1 neurons in the human hippocampus to the retrieval of episodic autobiographical memory remains elusive. In patients with a rare acute transient global amnesia, highly focal lesions confined to the CA1 field of the hippocampus can be detected on MRI. We studied the effect of these lesions on autobiographical memory using a detailed autobiographical interview including the remember/know procedure. In 14 of 16 patients, focal lesions in the CA1 sector of the hippocampal cornu ammonis were detected. Autobiographical memory was significantly affected over all time periods, including memory for remote periods. Impairment of episodic memory and autonoetic consciousness exhibited a strong temporal gradient extending 30 to 40 y into the past. These results highlight the distinct and critical role of human hippocampal CA1 neurons in autobiographical memory retrieval and for re-experiencing detailed episodic memories.

Introduction: Diagnostic criteria of transient global amnesia (TGA) establishes that memory functioning has to be recovered in 24 hours. However, there are contradictory data about the existence of long-term sequelae. Furthermore, there is no consensus about which is the most suitable tool in order to use in the assessment of the follow up of these patients., Aims: To assess episodic memory of TGA patients during amnesic episode and 7, 30 and 90 days after with free recall and Mini-Mental tasks. Moreover, it has been measured patient's metamemory., Subjects and Methods: 17 TGA patients and 17 healthy volunteers, matched by age, sex, and educational level were assessed. A longitudinal (four assessments) and factorial (patients and control group) study was carried out., Results: During TGA, free recall and Mini-Mental tasks were significantly affected. However, only free recall task showed improvement along time and impairment after three months. It has been also detected that metamemory of TGA patients is imprecise., Conclusions: Comparing with control group, both free recall and Mini-Mental tasks have significant lower levels during TGA, but only the first one is sensitive enough to show long-term disturbance associated with this amnesia.

Background: Hippocampal sulcal cavities (HSC) have been speculated to contribute to a higher vulnerability of memory pathways and might be a possible etiological factor in transient global amnesia (TGA). Therefore, we evaluated the influence of HSC on cognitive long-term outcome in TGA-patients., Methods: Fourteen otherwise healthy patients with the clinical syndrome of TGA in their history underwent a high-resolution magnetic resolution imaging and a comprehensive neuropsychological test battery. The neuropsychological control group consisted of 15 healthy subjects and was balanced for age, sex and other risk factors as well as intellectual and social status., Results: Magnetic resolution imaging and neuropsychological testing have been performed 1128 days (median) after the TGA. HSC have been detected in nine of the 14 patients and have been bilateral in eight of them. There were no differences in cognitive performance in patients with and without HSC as well as compared to healthy subjects. Even in patients with greater lesion load, only a slight visuospatial deficit was found., Conclusions: Although an increased incidence of HSCs is detected in TGA patients, cavities are not obligatorily in TGA. Moreover, even patients with hippocampal cavities achieve a full neuropsychological recovery independent of the frequency and size of the hippocampal lesions., (© 2010 The Author(s). European Journal of Neurology © 2010 EFNS.)

Background/aim: Transient global amnesia (TGA) could be related to acute ischemic disturbances in mesial parts of temporal lobes, which are important for memory. Incompetence of internal jugular vein (IJV) valve with venous congestion causes venous microthrombosis of hippocampus. The aim of this study was to investigate the frequency of IJV valve incompetence, as well as other hemodynamic and structural properties of cerebral circulation in TGA patients., Methods: IJV valve competence was investigated in 40 TGA patients and 30 persons of the control group (matched by age and sex), as well as detection of microembolic signals and detection of right to left cardiopulmonal shunt, cerebral vasomotor reactivity and echocardiography by color triplex ultrasonography and transcranial doppler., Results: A significant difference in frequency of IJV valve incompetence was found between the TGA patients and the control persons (55% TGA vs. 30% controls; p < 0.001). We did not find a significant structural (plaques frequency) or hemodynamic (flow velocity, pulsatility index) differences on arteries of the neck and cerebral arteries between the TGA patients and the controls, except for the increased pulsatility index on the basilar artery (40% TGA vs. 16.6% controls; p < 0.01) and decreased vasomotor reactivity in TGA patients (50% TGA vs 26.6% controls;p < 0.001). Microembolic signals were detected very rarely (17.5% TGA patients vs. 13.3% controls; p > 0.05), as well as right to left cardiopulmonal shunt (15% TGA vs. 16.6% controls; p > 0.05), indicating that embolism was not important for pathogenesis of TGA. Transesophageal echocardiography confirmed it, because only one TGA patient had a potent foramen ovale., Conclusion: We found a significantly increased frequency of IJV incompetence in the TGA patients, which confirmed the role of vein drainage disturbances in pathogenesis of TGA.

Subclinical rhythmic electrographic discharges of adults (SREDA) is an uncommon distinctive EEG rhythmic pattern with uncertain significance. We report a patient with transient global amnesia in whom an EEG recording, performed after the acute phase of the neurological event, showed SREDA. Based on this EEG finding, we discuss about a possible correlation between SREDA and transient global amnesia. The presence of SREDA in our patient with transient global amnesia seems to be incidental. When described in association with transient global amnesia, SREDA should be recognized in order to avoid misdiagnosis. Although SREDA has been fortuitously described in association with transient global amnesia, a patho-physiological correlation with mechanisms which produce it seems unlikely.

Objective: The aim of the present study was to investigate the pattern of recollection and familiarity deficits and the modulation of recognition memory performance by the depth of encoding (deep vs. shallow) in transient global amnesia (TGA)., Method: Ten patients with TGA and 11 control subjects were assessed during the acute stage and after recovery 7 to 19 days later., Results: Both recollection and familiarity were impaired in the acute stage and showed significant, albeit not complete, recovery by the time of the postacute assessment. The patients did, however, show a significant levels-of-processing effect, which was significantly reduced in acute TGA, but not at follow-up., Conclusion: The significant levels-of-processing effect during acute TGA might be linked to recruitment of the prefrontal cortex., ((c) 2010 APA, all rights reserved)

We report a 55-year-old woman, who presented with transient amnesia for 7h following underwater swimming. There was no evidence of neurological disturbance except global amnesia. Sharp waves in both temporal regions were registered during the initial EEG recording, which was accentuated by hyperventilation. Right hippocampal high signal intensity was observed in DWI performed 56 h after symptom onset. The sharp waves were all disappeared on follow-up EEG recordings., (Copyright © 2010 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.)

A critical role in place learning has been attributed to place cells within the cornu ammonis 1 (CA1) sector of the hippocampus in rodents. The role of CA1 cells in the human hippocampus with regard to place learning remains elusive. Using a virtual Morris water maze, we investigated patients with acute transient global amnesia (TGA), a rare self-limiting dysfunction of the hippocampal system. Fourteen individuals with selective and focal lesions in the CA1 sector of the hippocampus showed a profound impairment in place learning. The size of the lesions and the duration of the TGA correlated with the deficit in the performance.

Introduction: Transient global amnesia (TGA) is a disorder of unknown aetiology. In recent studies, TGA was associated with a right to left shunt (RLS). We studied the presence of the RLS in patients with TGA and we compared this series with patients who had suffered a transient ischaemic attack (TIA)., Patients and Methods: We included 66 consecutive TGA patients. In these patients a transcranial Doppler was performed to determine the presence of a RLS. We collected data on the TGA episode, vascular risk factors, migraine history, recurrence of TGA and neuroimaging in patients with and without RLS. We compared the prevalence of the RLS in TGA series with 59 patients with TIA., Results: The prevalence of RLS was 21.2% in patients with TGA. The RLS was associated with the migraine history (40% versus 13%; p = 0.014) and a Valsalva manoeuvre as a triggering factor (50% versus 14.5%; p = 0.022). A greater prevalence of RLS was detected in patients with TIA (55.9% versus 21.2%; p < 0.001)., Conclusions: The RLS prevalence in TGA patients is similar to the general population but significantly lower than the prevalence in TIA patients. The association with a Valsalva manoeuvre as a precipitating factor in the TGA patients with RLS could play a role in the aetiopathogenesis of the TGA.

A 43-year-old woman one day experienced a dissociative fugue which she could not recall. She was married, nulliparous, with no history of dissociative disorder or other psychiatric disorders. She had been sexually abused during late childhood-early adolescence. She was examined thoroughly from both psychiatric and medical standpoints to exclude organic causes for her condition. Magnetic Resonance Imaging showed only some non-specific abnormalities. On personality tests, a histrionic structure of personality emerged, with obsessive and narcissistic traits accompanied by rigidity and anxiety, dysphoria and high risk for depression; some impairment was found in executive function tests. Final diagnosis was one of dissociative fugue. In fact, organic traits were not sufficient to establish a diagnosis of Transient Global Amnesia.

More than 50 years after its initial description, transient global amnesia (TGA) remains one of the most enigmatic syndromes in clinical neurology. Recent MRI data suggest that a transient perturbation of hippocampal function is the functional correlate of TGA because focal diffusion lesions can be selectively detected in the CA1 field of the hippocampal cornu ammonis. Although various factors, such as migraine, focal ischaemia, venous flow abnormalities, and epileptic phenomena, have been suggested to be involved in the pathophysiology 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., (Copyright (c) 2010 Elsevier Ltd. All rights reserved.)

A patient who suffered a transient global amnesia (TGA) attack underwent regional cerebral blood flow (rCBF) SPECT imaging and neuropsychological testing in the acute phase, after one month and after one year. Neuropsychological testing in the acute phase showed a pattern of anterograde and retrograde amnesia, whereas memory was within age normal limits at follow up. SPECT data were analysed with a within subject comparison and also compared with those of a group of healthy controls. Within subject comparison between the one month follow up and the acute phase detected increases in rCBF in the hippocampus bilaterally; further rCBF increases in the right hippocampus were detected after one year. Compared to controls, significant hypoperfusion was found in the right precentral, cingulate and medial frontal gyri in the acute phase; after one month significant hypoperfusion was detected in the right precentral and cingulate gyri and the left postcentral gyrus; after one year no significant hypoperfusion appeared. The restoration of memory was paralleled by rCBF increases in the hippocampus and fronto-limbic-parietal cortex; after one year neither significant rCBF differences nor cognitive deficits were detectable. In conclusion, these data indicate that TGA had no long lasting cognitive and neural alterations in this patient.

Background/aims: Different etiologies for transient global amnesia (TGA) have been proposed, such as venous flow abnormalities, spreading depression and migraine-related mechanisms like focal ischemia. Jugular vein valve incompetence (JVI) is commonly described in TGA patients, but its contributing role in TGA pathogenesis is still unknown. We investigated the possible relationship between JVI and pathogenetic mechanisms in TGA., Methods: 243 TGA patients underwent clinical and neurological assessment. Demographic characteristics, TGA-precipitating factors and vascular comorbidities were carefully recorded. In each patient, JVI was assessed by Doppler ultrasonography., Results: TGA patients were grouped according to the presence (n = 171, 70.4%) or absence (n = 72, 29.6%) of JVI. TGA patients with JVI showed a higher presence of precipitating factors, namely a Valsalva-like maneuver (JVI-positive vs. JVI-negative, 35.8 vs. 17.1%, p = 0.004) and emotional stress (36.6 vs. 21.4%, p = 0.023), but had fewer vascular comorbidities, namely hypertension (37.2 vs. 51.4%, p = 0.047) and carotid arteriosclerosis (20.5 vs. 31.9%, p = 0.050)., Conclusions: These findings support the argument for the existence of at least 2 different TGA-associated mechanisms defined by JVI. On the one hand, JVI associated with a Valsalva-like maneuver and emotional stress supported the venous blood congestion hypothesis, and on the other, the JVI-negative group may have another vascular basis, unrelated to venous congestion., ((c) 2010 S. Karger AG, Basel.)

Memory flashbacks are usually attributed to recreational drugs or psychiatric conditions. The differential diagnosis for memory flashbacks is diverse and challenging; moreover, management is influenced by the working diagnosis. We describe the case of a 35-year-old man who presented with memory flashbacks secondary to temporal lobe seizures from an unruptured aneurysm of the posterior cerebral artery. To our knowledge, a case of this nature has not been previously reported. This case demonstrates the need to recognize that, on rare occasions, a complaint of memory flashbacks can be the result of an organic etiology. We also discuss the challenging presentations of temporal lobe seizures, as they can easily be misdiagnosed as a psychiatric condition.

Transient global amnesia (TGA) is characterized by the abrupt onset of severe amnesia without concomitant focal neurological symptoms. Recent studies revealed that small and punctate MR-signal diffusion-weighted imaging (DWI) lesions can be found within the hippocampus of TGA patients during the post-acute phase. On the basis of dual-process models of recognition memory, the present study examined the hypothesis that hippocampal dysfunction as suggested by these DWI lesions disrupts hippocampus-mediated recollection in patients with TGA, whereas familiarity-based recognition memory that is assumed to be supported by extra-hippocampal brain regions should be unaffected. We administered a recognition memory task for faces and words to eleven TGA patients during the post-acute phase and to eleven matched controls. Receiver operating characteristics (ROCs) were obtained in order to derive estimates of familiarity and recollection by applying a formal dual-process model of recognition memory. Analyses of ROC curves revealed a disruption of recollection in TGA patients' memory for words [t(20)=2.70, p<.05], but no difference in familiarity-based recognition memory between patients and controls [t(20)=-1.10, p=.284]. Post hoc analyses indicated that the deficit in recollection is more pronounced in TGA patients who show visible hippocampal lesions on diffusion-weighted MR imaging compared to those without detectable hippocampal lesions. In conclusion, consistent with recent neuroanatomical dual-process models of recognition memory, hippocampal dysfunction in patients with TGA is associated with a selective effect on specific recognition memory subprocesses.

Transient global amnesia (TGA) is a common paroxysmal disorder of episodic memory. The aetiology of TGA is still unknown. Brain ischaemia, migraine, epileptic seizure, venous congestion and psychological disturbances have been proposed as pathological mechanisms. Moreover, different precipitating events are recognised in most TGA patients including physical activity, severe emotional stress, painful experiences, immersion in cold water and sexual intercourse. We describe a 54-year-old woman who presented a TGA immediately after right-left shunt of saline contrast during the execution of transoesophageal echocardiography. Aetiopathological considerations for this uncommon presentation are discussed.

Transient global amnesia (TGA) is characterized by a severe disturbance of memory, occurring rapidly, lasting less than a day and mainly affecting elderly subjects. During its acute phase, it is characterized by a severe anterograde amnesia, partial retrograde amnesia and anxiety with repetition of the same questions. The diagnosis is purely based on patient's clinical features. Complimentary examinations are only requested when atypical symptoms are present. The pathophysiology of TGA remains unknown, but it appears to be related to transient disturbances of the perfusion and oxygenation of the hippocampal structures, following a precipitating factor (stress, effort...). Spontaneous recovery is usual in less than 24 hours and without sequelae. Relapse is rare. Nevertheless, TGA represents a psychological traumatism pathology for the patients and their family.

Background: Some studies have shown the presence of psychopathological disorders in transient global amnesia., Aims: To determine whether transient global amnesia is associated with psychopathological disorders and to assess the influence of these psychopathological disorders on memory impairments., Method: Levels of anxiety and depression before and during transient global amnesia were rated. Memory performances were assessed by means of original episodic memory tasks and working memory tasks. These data were collected in 17 individuals observed during the very acute phase, 18 individuals examined in the peri-acute phase and 26 controls., Results: During the acute phase, participants with transient global amnesia displayed a higher level of anxiety and a more depressed mood than controls. An alteration of emotional state, as measured by the Adjective Mood Scale, was correlated with deficits in anterograde memory., Conclusions: Transient global amnesia comprises sudden changes in people's emotional state, which has a major impact on and interacts with episodic memory impairment.

We report a 64-year-old male patient with pure transient global amnesia (TGA) who exhibited global cerebral hypoperfusion during an amnesia attack. Initial single photon emission computed tomography (SPECT) performed 3 hours after the onset of the amnesic attack revealed diffuse hypoperfusion in the cerebrum, whereas a second SPECT study, 1 month later, revealed improvement of cerebral blood flow. This case suggests that SPECT study is useful in revealing the pathophysiological mechanism of TGA and that TGA attacks are associated with global cerebral blood flow change.

Background: An isolated prolonged episode of transient amnesia can be a major manifestation of transient global amnesia (TGA) and transient epileptic amnesia (TEA). We report a case of transient amnesia associated with a left temporal tumor and try to elucidate the possible mechanism of the amnesia., Case Report: A 67-year-old right-handed man with the past history of migraine developed a transient declarative amnesia with a permanent memory gap for 5 hours. During the attack, he drove for 100 km flawlessly, but was not aware of his memory deficit. Selective retrograde amnesia during the episode was also observed. Investigations revealed an impaired verbal memory on neuropsychological tests, a possible metastatic tumor in the left temporal lobe by cerebral MRI, isolated wicket temporal spikes in the left mesial temporal area by sphenoidal electroencephalogram (EEG), and an additional brief phase of confusion. No recurrence of a similar attack occurred by 17 months after treatment with radiotherapy and chemotherapy., Discussion: This case serves to emphasize that transient dense anterograde amnesia resembling TGA might possibly occur as a manifestation of TEA and that there is a risk of subsequent epileptic features. The amnesia in this case also supports the hypothesis of spreading depression in patients with TGA and migraine and could support the epileptic hypothesis for the pathogenesis of TGA.

Objective: The pathomechanisms of transient global amnesia (TGA) remain enigmatic. Focal MR signal diffusion changes in the CA-1 sector of the hippocampus have been described in transient global amnesia, but the pathophysiologic correlate of these lesions is unknown., Methods: We studied the metabolic spectra of diffusion lesions in the CA-1 sector hippocampus of seven patients with TGA using MR spectroscopy (MRS) between 24 and 72 hours after onset and 2 to 5 months later. The amnestic deficit was studied using a neuropsychometric test battery., Results: Four out of seven patients with an acute TGA showed a diffusion lesion with a corresponding T2 lesion in the CA-1 sector of the hippocampus. Selective hippocampal MRS of diffusion lesions showed a lactate peak in three of four patients, but not in patients without a diffusion lesion. The NAA/creatine ratio was normal., Conclusion: Lactate as a marker of anaerobic glycolysis indicates acute metabolic stress of CA-1 neurons in TGA whereas long-term neuronal metabolic changes are not found. This implies that the acute effect on hippocampal CA-1 neurons is the functional correlate of a transient global amnesia reflecting a transient perturbation of memory relevant circuits in the hippocampus.

Introduction: Sexual activity may on occasion be complicated by neurologic syndromes of headache and amnesia. These syndromes may be alarming not only to patients but also to medical practitioners unfamiliar with them, initiating inappropriate investigations or advice., Aims: To review the clinical features, differential diagnosis, investigation, pathophysiology, and treatment of primary headache associated with sexual activity and of transient global amnesia precipitated by sexual activity., Methods: Selective literature review., Conclusion: Transient headache and amnesia associated with sexual activity are generally benign, self-limited syndromes of presumed vascular origin. The most important differential diagnosis in both instances is subarachnoid hemorrhage, but this may be readily excluded on the basis of clinical and investigational findings. Reassurance, based on clear diagnosis, is the most important treatment.

The observation of memory recovery following post-training amnestic interventions has historically caused controversy over the meaning of this finding, leading some authors to question the paradigm of a consolidation period for memories. Similarly, recent demonstrations of transient amnesia caused by interventions following memory reactivation have been used to question the existence of a retrieval-driven reconsolidation process. The present work aims to approach the phenomenon of transient amnesia following disruptions of consolidation and reconsolidation, discussing how memory recovery might be explained within a framework of systems consolidation, persistent synaptic reinforcement, and multiple memory traces. With these concepts in mind, we propose that long-term consolidation processes can underlie recovery from amnesia, demonstrating the feasibility of such a hypothesis in a two-structure computational model of learning in which consolidation is dependent upon synaptic reentry reinforcement. On the basis of this, we suggest that prolonged consolidation can account for experimental findings of transient amnesia, in a way that explains differences between disruptions of consolidation and reconsolidation without the need to dwell into the discussion between storage- and retrieval-based explanations for memory impairment., ((c) 2008 Wiley-Liss, Inc.)

We used fMRI to examine the activation patterns of patient AE during encoding and recognition of visual scenes during an episode of transient global amnesia (TGA) and 3 months later. Controls (n = 5) showed bilateral (R > L) activation in parahippocampal and fusiform gyri during encoding and right-sided activation in the same regions associated with recognition of previously viewed scenes. AE showed a similar pattern at follow-up. During acute TGA, when performance was profoundly impaired, AE showed no medial temporal activation associated with encoding of new scenes or recognition of old scenes. In both contrasts, the percent signal change in relevant medial temporal regions was more than three standard deviations below the control sample mean. She did, however, show striking bilateral hippocampal activation for recognition attempts (old + new scenes > baseline) even though retrieval was unsuccessful (55% recognition accuracy). This finding was unique to AE on this occasion. This is the first study to document normalization of both encoding and recognition activation patterns in TGA. Furthermore, the strong hippocampal activation during unsuccessful retrieval highlights important issues in interpreting memory-related activations, particularly in dysfunctional systems., ((c) 2007 Wiley-Liss, Inc.)

Cerebral venous reflux is found frequently in transient global amnesia (TGA) patients. The cerebral venous reflux mostly results from left brachiocephalic venous obstruction, and the level of reflux depends on different respiratory status. For further understanding of the role of venous outflow impairment in the pathogenesis of TGA, we used color duplex sonography to reveal the flow patterns in the internal jugular vein (IJV) and its branches (JB) under different respiratory conditions. We compared the frequency of abnormal venous flow of IJV and/or JB on color duplex sonography between 17 TGA patients and 17 age- and gender-matched normal individuals both at rest (regular breathing) and at deep inspiration. Further, these venous-flow abnormalities in IJV and JB were well described. Cranial 3-D time-of-flight magnetic resonance arteriography (MRA) were performed in all patients three to seven days after their TGA attacks and in all normal individuals to analyze the abnormal flow signals in the intracranial venous structures. In the result, abnormal flow-patterns in the left IJV and/or left JB during regular breathing were found more frequently in TGA patients than normal individuals (65% vs. 6%; p < 0.001). These abnormalities in TGA patients were (1) isolated reversed flow in the left JB, (2) segmental reversed flow in the left distal IJV and (3) continuous reversed flow in the left IJV and JB. The MRA study revealed that only the most severe reflux in the IJV causes intracranial venous reflux; six were in the group of continuous reversed flow in left IJV and one was in the group of segmental reversed flow in left distal IJV. These findings suggest that TGA might be one of the clinical manifestations of the "cerebral-type intermittent venous claudication," which stems from cerebral venous outflow impairment, insufficient venous collaterals and specific precipitating factors.

Objective: To investigate the neuromuscular transmission (NMT) of the patients with transient global amnesia (TGA) using single fiber electromyography (SFEMG)., Background: The pathophysiology of TGA remains unknown and several elements support the hypothesis of a shared background with migraine. Recent studies showed that some migraineurs have subclinical abnormalities of NMT by using SFEMG. We aimed to test the patients with TGA using SFEMG., Methods: We investigated 6 patients diagnosed with TGA according to published criteria and 5 healthy volunteers with similar ages. SFEMG during voluntary contraction of the extensor digitorum communis muscle, nerve conduction studies and concentric needle electromyography were performed and 20 single fiber potential pairs were recorded from each subject and individual and mean jitter values were calculated., Results: Three patients with TGA showed pronounced NMT failure by SFEMG, whereas none of the controls disclosed this abnormality. The mean jitter value of TGA patients (35+/-33) was greater than that of the control subjects (25+/-15) (P=0.006). Seventeen of the 120 individual jitter values of the TGA group and only 3 (from 3 different volunteers) of the 100 individual jitter values of the control group exceeded upper normal limit (P=0.004)., Conclusions: These results suggest that TGA shares the same type of subclinical abnormality of NMT observed in migraine patients in recent studies.

The aetiology, pathomechanisms and anatomical correlates of transient global amnesia (TGA) still remain obscure. Recently, focal MR-signal diffusion-weighted imaging (DWI) changes in the hippocampus have been described in patients with TGA, but the exact localization, long term outcome and pathophysiological nature of these lesions still remain unknown. The topography and time course of hippocampal DWI lesions in 41 TGA patients was studied using serial 3 T high-resolution MR-imaging and correlated to clinical and neuropsychometric results. Of these, 29 patients showed 36 DWI lesions with corresponding T(2) lesions in the hippocampus within a time window of 48 h after onset. Almost all lesions (94%; 34/36) were selectively found in the CA-1 sector (Sommer sector) of the hippocampal cornu ammonis. Most DWI lesions (8/10) were already detectable in the peri-acute phase <6 h after onset of symptoms. A follow-up study 4-6 months after the episode did not show evidence for residual structural sequelae of these lesions (n = 20/20). A venous MR angiography of the intracranial dural sinus showed an asymmetric venous drainage in 21/24 (88%) patients. In 11/16 (69%) patients with unilateral lesions, the asymmetry corresponded to the side of the DWI lesion. Significant episodic verbal memory deficits in the acute phase (n = 14/18) were associated with lesions of the dominant hemisphere while impairment of visuospatial memory was associated with lesions of the non-dominant hemisphere. Persistent neuropsychological sequelae were not detected 4-6 months after the episode (n = 16). This is the first prospective study combining high-resolution imaging and neuropsychometry analysing the detailed functional anatomy and outcome of hippocampal DWI/T(2) lesions in TGA supporting the view the TGA being a benign transient disorder. The TGA can be considered a model for a focal transient perturbation of memory circuits in the temporo-mesial region.

Transient global amnesia (TGA) is a well-defined clinical syndrome of unknown etiology, which often occurs once in life. Several mechanisms have been proposed but only trigger events have been clearly associated with the attack such as physical exertion, emotional stress, sexual intercourse or immersion in cold water. According to our knowledge, this is the first study, which associates trigger events and TGA recurrency. The aim of this retrospective study was to evaluate the risk factors which contribute to TGA recurrency. TGA patients consecutively admitted, performed clinical and neurological evaluation, electroencephalogram and structural brain imaging scan. TGA-trigger events were evaluated and comorbidities were carefully recorded. The risk factor sum was calculated as the sum of the considered triggers. Eighty-five TGA patients were grouped according to the presence of single TGA (n = 73) or two episodes of TGA (n = 12). The 14.11% of patients experienced two episodes. A logistic regression analysis showed that the more increased number of TGA the more number of trigger events (P < 0.11; chi2 = 6.38; beta = -3.29). These observations claim that TGA may be considered a complex epiphenomenon, and the sum of the trigger factors can be responsible for recurring of this almost unique-in-life event.

Since the first reports of transient global amnesia (TGA) were published in 1956, several neuropsychological and functional imaging studies have shed light on different aspects of this neurological syndrome. By establishing diagnostic criteria, Hodges and Warlow (1990b) have made it far easier to identify clinical TGA-related features. However, no comprehensive survey has been yet carried out in order to validate their criteria/findings or provide information about previously unknown features. In the present paper, (i) we review the literature published since Hodges and Warlow's study and seek to characterize the demographic and clinical features of TGA more accurately, (ii) we report 142 personal TGA cases, with supplementary information regarding both episodes and patients, such as precipitating events, associated symptoms and personality, and (iii) we suggest the existence of different groups of TGA patients, on the basis of a hierarchical cluster analysis. This revealed that in women, episodes are mainly associated with an emotional precipitating event, a history of anxiety and a pathological personality. In men, they occur more frequently after a physical precipitating event. In younger patients, a history of headaches may constitute an important risk factor. No link was found with vascular risk factors. The relevance of each of the above-mentioned variables is discussed in the light of our classification. An extensive description of cases from both the literature and our patient population allows us to refine the characterization of clinical TGA features.