[GABAB receptor autoimmune encephalitis presenting as transient epileptic amnesia].

This case was a 50-year-old healthy woman. After repeated transient amnesia, she developed tonic-clonic seizures and was admitted to our hospital. The brain MRI showed FLAIR hyperintensities in the left temporal lobe and EEG showed an epileptic discharge starting from the left temporal region. Based on these findings, we diagnosed temporal lobe epilepsy associated with acute limbic encephalitis. While she experienced recurrent transient amnesia, her cognitive functions were preserved except for her memory. These symptoms and EEG findings were consistent with transient epileptic amnesia (TEA). Acute limbic encephalitis that occurred in a healthy middle-aged woman may be antibody-mediated encephalitis, requiring immediate immunotherapies. In this case, GABAB receptor antibodies in cerebrospinal fluid were found positive. This is the first report showing that TEA was caused by GABAB receptor autoimmune encephalitis.

[Ictal EEG pattern of transient epileptic amnesia in acute phase of non-herpetic limbic encephalitis].

A 60-year-old, right-handed woman was admitted to our hospital for amnesia as the only neurological abnormal findings following the autonomic symptoms and transient episodes of loss of awareness. EEG during the amnesia showed rhythmic alpha activity arising from the left mid-temporal region. Although this ictal activity showed evolution in the frequency and amplitude, the location was limited in the bilateral temporal areas. After the EEG evaluation, her amnesia was resolved immediately, suggesting that her presentation was transient epileptic amnesia (TEA). Meanwhile, given the clinical course and MRI findings (high intensity in the bilateral mesial temporal areas, more on the left), she was diagnosed with non-herpetic limbic encephalitis and treated with steroid and anti-epileptic drugs, leading to the positive outcome. The ictal EEG findings during TEA as the one of the presentation in acute phase of non-herpetic limbic encephalitis may contribute to further investigation of underlying mechanism of TEA.

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

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

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

Transient global amnesia in immediate postoperative period: A diagnostic dilemma.

INTRODUCTION: Transient Global Amnesia (TGA) is short-term inability to form new memories despite otherwise normal neurological function. There is associated anterograde and retrograde amnesia. The memory loss is often accompanied by repetitive questioning and temporal disorientation while higher cognitive functions are preserved. The symptoms usually resolve by 24h. CASE REPORT: We present an interesting case of 31year old female who was planned for robotically assisted right sided pyeloplasty. 30min after emergence from anaesthesia patient was disoriented, with retrograde and anterograde amnesia, but neurological function was intact. Neurologic imaging revealed no abnormality. 36h later patient was able to recall everything. DISCUSSION: The pathogenesis of TGA has more recently been attributed to cerebral venous hypertension resulting from retrograde jugular venous flow. Precipitating events are Valsalva manoeuvre, emotion/stress/pain, Excessive exertion, sexual intercourse and swimming in cold water. CONCLUSION: TGA presents dramatically, it needs to be differentiated from cerebral event. It resolves on its own. But one needs to be aware of existence of such an entity.

Persistência de imagem de hiperintensidade no hipocampo após episódio de amnésia global transitória / Persistence of hyperintensity image in the hippocampus after an episode of transient global amnesia

A patogenia da amnésia global transitória (AGT) continua obscura. Estudos recentes demonstraram que, em alguns pacientes, a sequência de difusão (DWI) da ressonância magnética pode revelar apresença de sinal pequeno e pontual hipersinal no hipocampo, após a fase aguda do episódio. Esse sinal é principalmente visualizado nas primeiras 6 horas do início do evento, sendo 114 horas o tempo máximo que foi registrado até o momento. Estamos apresentando um caso em que essa imagem persistiu por 11 dias após o episódio. Discutem-se as conhecidas causas, as teorias da patogenia da AGT e a possível conexão entre um efeito vascular e a depressão alastrante, como relatada na enxaqueca com aura.

The pathogenesis of transient global amnesia (TGA) remains obscure.Recent studies revealed that small and punctate signal on diffusion-weighted imaging (DWI) in the hippocampus after the post-acute phase. This signal is mainly seen in the first 6 hours of the onset of the event, and so far the maximum time registered was 114 hours. We present one case where this image persisted for 11 days after the episode. Known causes, theories on pathogenesis of TGA and a possible relation between a vascular mechanism and the spreading depression, as reported in migraine with aura, are discussed.

[Usefulness of electroencephalograms in evaluating transient global amnesia]. / Utilidad de la electroencefalografia en la valoracion de la amnesia global transitoria.

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 after general anaesthesia]. / Amnesia global transitoria en el contexto de una anestesia general.

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.

Transient global amnesia as a revealing sign of giant transtentorial meningioma: case report and review of the literature.

Since 1974, only 14 papers in MEDLINE-indexed journals have linked transient global amnesia (TGA) to a brain tumor. Among these, two described the entity of transient epileptic amnesia (TEA), whereas most reports lacked the functional investigations that might differentiate the two conditions. Only six cases have linked TGA or TEA to a meningioma, and none of them were transtentorial. We report the case of a 75-year-old woman who presented with one episode of TGA as a sole symptom of a giant transtentorial meningioma in the right hemisphere. A sudden attack of TGA with a rather typical clinical presentation--anterograde amnesia with selective retrograde features that lasted for a few hours, with stereotypic questions, no associated symptoms or neurological impairment, and no recurrence--occurred while she was at home; this was witnessed by her husband. The neurological examination was unremarkable, with the exception of a slight left homonymous superior quadrantonopia. Brain imaging (computed tomography and magnetic resonance imaging) showed a huge meningioma originating from the right tentorium, extending from the cerebellar hemisphere to the midst of the temporal lobe. An electroencephalogram did not reveal temporal spikes. The tumor was completely excised, and she has remained asymptomatic for 6 months. Although TGA is generally a functional entity, without an organic substrate to prompt surgical sanction, a full investigation may be warranted to rule out the possibility of a silent intracranial tumor.

Transient global amnesia in a collegiate baseball player with type I diabetes mellitus: a case report.

OBJECTIVE: To present the case of a collegiate pitcher with type I diabetes mellitus who developed transient global amnesia and to characterize the acute onset of symptoms and clinical diagnosis of this rarely reported neurologic condition in the student-athlete population. BACKGROUND: A 21-year-old collegiate pitcher with type I diabetes mellitus was found by his roommate to have acute-onset memory loss. The athletic trainer identified normal blood glucose levels and normal vital signs but profound amnesia. The patient was evaluated by his team physician and referred to the local emergency department for acute-onset memory disturbance. DIFFERENTIAL DIAGNOSIS: Hypoglycemia, ketoacidosis, adverse drug reaction, infectious disease, transient epileptic amnesia, transient ischemic attack, acute confusional state, complex partial seizure, psychogenic amnesia, migraine, intracerebral hemorrhage, traumatic brain injury, tumor, and transient global amnesia. TREATMENT: Diagnostic studies included computed tomography of the head, urine and serum toxicology, urinalysis, blood glucose level, electrolytes, blood urea nitrogen level, creatinine level, complete blood count, and electroencephalography. The patient was admitted overnight to the neurology service. The next morning, electroencephalography was repeated, and magnetic resonance imaging of the head with contrast was performed. The patient was discharged with the diagnosis of transient global amnesia. UNIQUENESS: Transient global amnesia is considered a benign condition characterized by an acute episode of memory disturbance involving the inability to form new memories and recall recent events. It is rare in young people, with only 3 case reports involving young athletes published in the literature. CONCLUSIONS: Transient global amnesia is a rarely diagnosed neurologic disturbance that may present acutely in student-athletes, although most reported cases affect older adults. Unfamiliarity with the symptoms may cause anxiety for the athlete and bystanders. Transient global amnesia does not result in long-term neurologic deficit, and neurologic function will return to baseline.

Transient global amnesia as the presenting feature of heparin-induced thrombocytopenia.

A 57-year-old man developed transient global amnesia within an hour of bolus unfractionated heparin administration on day 4 post-mitral valve replacement. Both immunoglobulin G-specific enzyme-linked immunosorbent assay and serotonin release assay were strongly positive for the antibodies that cause heparin-induced thrombocytopenia. The patient's cognitive functions returned to normal following discontinuation of unfractionated heparin and warfarin and commencement of lepirudin infusion.

Transient amnesia in a patient with left temporal tumor: symptomatic transient global amnesia or an epileptic amnesia?

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.

Is anterior temporal lobectomy a precipitating factor for transient global amnesia?

Little is known about the pathophysiology of transient global amnesia (TGA) and how it is related to epilepsy. We report here five typical episodes of TGA, each occurring several years after surgery for epilepsy. In all cases, patients were seizure-free after a surgery consisting of anterior temporal lobectomy for refractory medial temporal lobe epilepsy associated with hippocampal sclerosis (n = 4) or linked with a dysembryoplastic neuroepithelial tumour (n = 1). Investigations, including MRI or CT scan, angio-MRI or echocardiogram or vascular echo Doppler, excluded a vascular origin. Using accepted criteria to distinguish between TGA and epileptic amnesic attacks--the typical clinical presentation, the long duration of the episode, the absence of other symptoms associated with seizures and the absence of recurrence--it is evident that these patients suffered a TGA. These studies suggest that hippocampal resection carried out therapeutically in some epileptic patients may be a precipitating factor for TGA.

[Polycythaemia as a ready factor of transitory global amnesia]. / La policitemia como factor predisponente de amnesia global transitoria.

Transitory global amnesia (TGA) is an upheaval where the patient has anterograde memory lost of abrupt beginning and an inferior duration to 24 h, that has been related to ischaemic, epileptogenic and migranous ethiology. On the other hand polycythaemia is classified like a prothrombotic disorder that can produce manifold manifestations in the central nervous system, from strokes to psychiatric disturbances of anxious type, and all related to the secondary cerebral hipoperfusión due to hyperviscosity. Two patients, who had a previous diagnostic of polycythaemia suffered an episode of TGA, in addition in one of the two cases a cerebellar hemangioblastoma was found. There are numerous cases reported of brain tumors and other CNS findings diagnosed as a result of an episode of TGA, nevertheless on has not described to the relation between polycythaemia and the TGA. In the TGA a hypoperfusion of the temporal brain hemisphere has been documented and this can be a leading mechanism, so we propose that polycythaemia could ready to suffer a TGA.

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

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

Transient global amnesia or subarachnoid haemorrhage? Clinical and laboratory findings in a particular type of acute global amnesia.

Acute global amnesia may be due to several causes, such as transient global amnesia (TGA), acute drug-related confusional state, toxic substances, metabolic abnormalities, infective diseases, cerebral tumours, cerebrovascular accidents, subarachnoid haemorrhage and epilepsy. In particular both TGA and subarachnoid haemorrhage may be precipitated by sexual activity; by contrast the two diseases are quite different in prognosis and treatment. Ten subjects were admitted in the period 1997-99 to our emergency department for acute global amnesia related to sexual activity. They represented 18% of total acute global amnesias observed in the same period. All patients were males, aged between 41 and 64 years. TGA was found in nine cases, while one patient had subarachnoid haemorrhage, due to rupture of an aneurysm of the right middle cerebral artery. The patient with subarachnoid haemorrhage showed neurologic defects (second-degree nystagmus and retropulsion), while no major neurologic abnormalities were found in TGA. Likewise computerized tomography (CT) scan was positive only in the case of subarachnoid haemorrhage. Patients and relatives in most cases left out sexual activity as a trigger factor. This experience indicates that acute global amnesia related to sexual activity is mostly due to TGA. Major neurologic signs are suggestive of subarachnoid haemorrhage and an immediate CT scan is recommended. Targeted questions are needed to identify the cause of the event.