Impaired Smooth Pursuit During Transient Global Amnesia

BACKGROUND AND PURPOSE: During transient global amnesia (TGA), selective impairment of episodic memory is assumed to occur due to alteration in the neuronal network between the hippocampus and parietooccipital cortices that also include a hub for smooth pursuit (SP) eye movements. This study aimed to determine whether SP is impaired during TGA, and to identify any anatomical and functional linkage present between the oculomotor and memory systems. METHODS: Within a median of 1.0 day of TGA, horizontal SP was evaluated in 145 patients with a target moving at peak velocities of 10°/s and 20°/s. The average SP gains of patients were compared with those of the age-matched controls. RESULTS: The patients with TGA showed lower SP gains in both directions for both peak target velocities. While the normal controls showed symmetric SP in the rightward and leftward directions, in the TGA patients the SP gain was lower during rightward than leftward SP regardless of bilaterality or the side of the lesions. CONCLUSIONS: The cortical regions processing information about visual motion appeared to be affected during or soon after an amnestic episode of TGA, and more so in the right hemisphere. This means that disturbed processing of dynamic visual information may be related to the impaired spatial orientation observed during TGA.

Clinics in diagnostic imaging (188). Transient global amnesia (TGA)

A 60-year-old woman was travelling on a plane with her spouse when she suddenly developed acute-onset disorientation to time and space. According to her husband, she repetitively questioned her whereabouts and complained of a minor headache. Upon landing, she was immediately brought to the emergency room and subsequent magnetic resonance imaging was performed, which showed multiple punctate 2-3 mm regions of diffusion-weighted imaging hyperintensity in the medial aspects of both temporal lobes. The conglomeration of clinical history and radiological findings was most suggestive of transient global amnesia. This article discussed the background, proposed mechanisms, diagnosis, radiological characteristics and management of transient global amnesia.

Transient Global Amnesia after Gastroscopy

No abstract available.

Hippocampal Lesions of Diffusion Weighted Magnetic Resonance Image in Patients with Headache without Symptoms of Transient Global Amnesia

BACKGROUND: The dot-like hippocampal signal intensity in diffusion-weighted MR images is well-known as a characteristic imaging feature in transient global amnesia, a neurological syndrome in which sudden forward-and-backward memory loss occurs that is slowly recovered within 24 hours. We here report on patients with this dot-like hippocampal hyperintensity who did not present with anterograde amnesia except for headaches. CASE REPORT: Two women without a specific medical history presented with sudden-onset headaches on the same day. Neither had any trauma or infection history before the symptom or any sudden emotional or postural changes. Brain MRI showed tiny hippocampal high signal intensity on diffusion-weighted images (DWI). CONCLUSIONS: Dot-like hippocampal lesions seen on DWI may be present without memory impairment, and more studies are needed to determine whether there is any association with headache as in this case.

Comparison of Clinical Characteristics between Transient Global Amnesia with and without Acute Focal Lesion in Hippocampus

BACKGROUND: Transient global amnesia (TGA) might be related to an ischemic event with characteristic findings in diffusion-weighted images (DWIs). However, acute lesions are uncommon. The aim of this study was to identify any clinical or radiological differences between TGA patients with and without acute lesions. METHODS: From January 2010 through March 2015, we identified retrospectively TGA patients with DWIs within 7 days from onset. According to the presence of an acute lesion in the hippocampus, clinical features, vascular risk factors, electroencephalography (EEG) findings, and the regional perfusion status in single-photon-emission computed tomography (SPECT) images were compared. RESULTS: Of 57 TGA patients (mean age=60.5 years; 40 females), 19 patients (33.3%) had acute focal lesions in the hippocampus (3.53±0.74 mm, mean±SD). In terms of clinical features, the symptom duration was shorter in the lesion-negative group than in the lesion-positive group (mean=5 hours, interquartile range [IQR]=2-9 hours vs. mean=8 hours, IQR=5-13.5 hours; p=0.072). However, there were no differences between TGA patients with and without DWI lesions in cerebrovascular risk factors, laboratory results, or EEG findings. In 6 of 22 patients who underwent cerebral SPECT (2 of 9 DWI lesions and 4 of 13 without lesions), mild perfusion defects were exhibited without significant differences in both medial temporal regions and in the left frontal and left frontotemporal regions. CONCLUSIONS: Symptom duration was the only clinical difference-including perfusion defects and epileptic evidence-between TGA patients with and without DWI lesions. This suggests that there is a low probability of hypoperfusion or focal seizure in TGA patients without acute lesions.

Hippocampal Hyperintensities on Diffusion-Weighted MRI without Transient Global Amnesia

Dot-like hippocampal hyperintensities on diffusion-weighted magnetic resonance imaging (MRI) have been reported as an interesting imaging finding of transient global amnesia (TGA). We report three patients with such dot-like hippocampal hyperintensities who did not present with anterograde amnesia. Episodes associated with the Valsalva maneuver such as nausea or vomiting might have produced the dot-like hippocampal hyperintensities in these patients. However, depending on the individual susceptibility to hippocampal lesions, clinical symptoms of TGA might not be present even when hippocampal lesions are present.

Seasonal Changes in the Incidence of Transient Global Amnesia

BACKGROUND AND PURPOSE: Transient global amnesia (TGA) is a stereotypic condition characterized by anterograde and retrograde amnesia that typically resolves within 24 hours. The pathophysiology of TGA is still unclear. We noted that patients hospitalized with TGA tend to appear in seasonal clusters, and decided to investigate this phenomenon. METHODS: Every patient with acute presentation of amnesia at our medical center is hospitalized for observation and evaluation. We reviewed the monthly occurrence of TGA in our patient population between 2000 and 2014, and compared this to non-TGA hospitalizations during the same time period. RESULTS: During the analysis period, 154 patients who met the criteria for TGA were hospitalized, as well as 259,007 non-TGA hospitalizations. The annual occurrence of TGA ranged from 5 to 16 hospitalizations. There were 91 TGA events in women and 63 in men, in subjects aged 62.8±10.6 years (mean±SD). The incidence was maximal during December [odds ratio (OR)=2.83, 95% confidence interval (CI)=1.20–6.67] and March (OR=2.77, 95% CI=1.17–6.56), and minimal from April to August. The incidence exhibited an increase followed by a decrease from October to February. A seasonal trend was observed as well, with incidence peaks occurring in winter (OR=1.82, 95% CI=1.12–2.96) and spring (OR=1.80, 95% CI=1.10–2.94). CONCLUSIONS: Our findings suggest that the incidence of TGA exhibits seasonal variations. This observation may help to improve the understanding of the pathophysiology underlying TGA.

Recurrent Transient Global Amnesia in a Hot and Humid Machinery Room

Transient global amnesia (TGA) is characterized by abrupt onset temporary dysfunction of anterograde and retrograde amnesia without other neurologic deficits. We encountered a 53-year-old man who developed recurrent TGA while working in a hot and humid machinery room (33degrees C and 64% relative humidity). Heat exposure and physical exertion may facilitate the leakage of cytokines into the systemic circulation so as to cause a cerebral endothelial insult. Functional insufficiency of the hippocampus and its connections caused by physical and environmental factors may be related to recurrent attacks.

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.

Anterior portion of the cingulate gyrus: A novel location for transient global amnesia? / Porção anterior do giro do cíngulo: Uma nova localização para amnésia global transitória?

Transient global amnesia (TGA) is characterized by abrupt transient loss of anterograde memory, lasting up to 24 hours, and no other focal neurological signs. We report the case of a right-handed 71-year-old female patient who presented temporal-spatial disorientation 5 minutes after ingestion of 1000 ml of iodinated contrast. The patient had mild temporal-spatial disorientation, with significant deficit in anterograde memory. After 12 hours under observation, the patient progressed to gradual improvement and was discharged. A reevaluation after 15 days showed normal cortical functions, score on mini-mental state exam of 30, and unaffected working and recall memory. MRI performed 48 hours after the event showed hypersignal in the diffusion sequence in the anterior portion of the cingulate gyrus, with hypointense signal in MAP/ ADC, confirming a finding consistent with TGA. No previous reports in the literature have described the location affected in this patient, rendering it a novel site consistent with this diagnosis.

Amnésia global transitória (TGA) é caracterizada por perda transitória abrupta de memória anterógrada, com duração de até 24 horas e sem outros sinais neurológicos focais. Relatamos o caso de uma paciente de 71 anos de idade, destra, que apresentou desorientação temporal e espacial depois de 5 minutos após a ingestão de 1.000 ml de contraste iodado. A paciente teve desorientação temporoespacial moderada, com déficit significativo de memória anterógrada. Depois de permanecer 12 horas sob observação, progrediu para melhoria gradual e recebeu alta. A nova avaliação após 15 dias mostrou funções corticais normais, com mini-exame mental de 30, com memória executiva e de evocação preservadas. A ressonância magnética realizada 48 horas após o evento mostrou hipersinal na sequência difusão na porção anterior do giro do cíngulo, com hipossinal em MAPA/ADC, confirmando achado compatível com TGA. Não há relato na literatura descrevendo alteração no mesmo local que esta paciente, tornando-se, portanto, um possível novo local compatível com diagnóstico de TGA.

Clinical Characteristics of 372 Cases of Transient Global Amnesia in the Emergency Department: A Single Center Study

PURPOSE: Transient global amnesia (TGA) is characterized by abrupt onset of antegrade amnesia usually seeking emergency care. We analyzed the clinical characteristics of TGA patients and the significance of diffusion weighted imaging (DWI) in the diagnosis of TGA. METHODS: Retrospective analysis was performed using electronic medical records of patients diagnosed as TGA in the emergency departments from January 2003 to December 2013. The patient's clinical characteristics and precipitants were analyzed, and detection rate of hippocampal lesion was compared according to the time to DWI after symptom onset (24 h). RESULTS: Of 372 consecutive TGA patients studied, 27 had a positive DWI lesion in hippocampus. Demographics and vascular risk profile were not significantly different between those in DWI (+) and DWI (-), and neither was duration of amnesia (p=0.076). However, the median time interval to DWI was significantly longer in DWI (+) than DWI (-) [7.5 (5.5~15.0) h vs. 6.0 (3.5~9.0) h, p=0.011]. In addition, the detection rate of hippocampal lesion increased with the time interval [0-6 h (4.1%), 6~12 h (10.7%), 12~24 h (11.1%), and >24 h (16.1%), p=0.004]. CONCLUSION: Positive hippocampal lesion on DWI can confirm the diagnosis of TGA; however, difference in lesion detectability in regard to time interval from symptom onset to DWI should be considered in diagnosis of TGA with DWI.

Vertebral Artery Dissection Presenting as Transient Global Amnesia: A Case Report and Review of Literature

Vertebral artery dissection is one of the most common causes of stroke in young adults. The course of the vertebral artery dissection is usually benign, and pure transient amnesia as an initial symptom has been rarely reported. We describe a patient with vertebral artery dissection who presented with acute transient amnesia, and review the medical literatures about the pathophysiological mechanism of transient global amenesia (TGA). This case could be a one of evidence which supports the cerebrovascular mechanism of TGA.

Transient Global Amnesia Developed in a 14-Year Old Girl during Cellular Phone Texting

A 14-year-old-girl developed sudden amnesia upon study for semester examination. She was using cellular phone texting when he realized amnesia and texted to her friend about the amnesia. On the captured texting messages, she showed grammatical errors and spelling errors. Diffusion-weighted brain MRI showed tiny lesions in left hippocampus consistent with transient global amnesia. EEG and other laboratory tests were normal. The amnesia recovered within 24 hours and did not recur during one and half year of follow up period.

Transient Global Amnesia Associated With Coil Embolization of Cerebral Aneurysm

A 50-year-old woman who had chronic headache was admitted to the hospital. Stent-assisted coil embolization of the aneurysm in the right vertebral artery was performed. After the procedure, the patient experienced a transient memory impairment. A microembolic lesion in the right medial temporal lobe and cerebral hemisphere was observed on diffusion-weighted imaging. We report a case of transient global amnesia caused by microembolus in the medial temporal lobe after embolization of an aneurysm.

Comparison of Electroencephalography and Diffusion-Weighted MR Findings in Transient Global Amnesia Patients

BACKGROUND: The etiology of transient global amnesia (TGA) is uncertain. Recent studies have demonstrated a high signal intensity on diffusion MRI in TGA patients. In this study we reviewed and compared the use of electroencephalography (EEG) and diffusion-weighted imaging (DWI) in TGA in order to determine their sensitivity and to reveal clues about the etiology of this condition. METHODS: Twenty patients (7 males and 13 females; aged 58.0+/-12.1 years, mean+/-SD) who had been diagnosed with TGA at Dongguk University International Hospital within a 2-year period (2007 and 2008) were included in the study. All patients underwent EEG and DWI. RESULTS: The EEG of 12 of the 20 patients (60.0%) exhibited abnormalities; all 12 exhibited slowing on either the left side (n=6) or bilaterally (n=6). Spikes or sharp waves were detected in two patients. DWI revealed unilateral high signal intensities in the hippocampus of eight patients; five of these patients had left hippocampal lesions, and the other three had right hippocampal lesions. Four patients with a unilateral DWI lesion exhibited bilateral EEG abnormalities, and six patients exhibited only EEG abnormalities (without DWI abnormalities). Three patients had a high-signal-intensity lesion on DWI without EEG abnormalities. Five patients had normal EEG and DWI results. Interestingly, no patient had EEG abnormalities confined to the right temporal area. CONCLUSIONS: These findings suggest that left temporal dysfunction is important for the development of TGA. EEG might be complementary to DWI in TGA investigations, and may be superior at illustrating the associated memory dysfunction.

Caudate Volume Change in Transient Global Amnesia Patients; Voxel-Based Morphometric Study

BACKGROUND: Transient global amnesia (TGA) is characterized by a severe disturbance of memory, lasting less than a day, and complete resolution. However, some authors have suggested the occurrence of permanent memory impairment in such cases. In this study, we investigated whether the gray-matter structure suffers degeneration in TGA, based on the assumption that TGA attacks appear to be related to underlying permanent pathology. METHODS: T1-weighted magnetic resonance imaging data for 20 TGA and 55 normal subjects were analyzed. The gray-matter volume was measured using voxel-based morphometry. The subjects also completed the Seoul Neuropsychological Screening Battery (SNSB). RESULTS: The gray-matter volume was reduced in the left superior frontal gyrus, right precentral gyrus, right superior frontal gyrus, left caudate nucleus, left precentral gyrus, left post central gyrus, and both putamens. The SNSB revealed the presence of selective neuropsychological dysfunctions after clinical recovery. Most of the cases exhibited attention deficit, and difficulties in copying of the Rey-Osterrieth Complex Figure, and in the Seoul verbal learning test. CONCLUSIONS: Left caudate nucleus atrophy could explain the attention deficit and memory impairment experienced in these TGA patients. Many patients with TGA have neuropsychological dysfunctions even after they appear to be clinically improved.

Retrograde Amnesia as a Predominant Symptom of Transient Global Amnesia

Transient global amnesia (TGA) causes retrograde amnesia, but there have been few reports of retrograde amnesia as a presenting symptom in TGA. A 52-year-old male who had acute amnesia for the past 4 years presented with TGA and recovered within 1 day. Brain magnetic resonance imaging revealed a lesion in the left hippocampus, and brain single-photon emission computed tomography revealed decreased blood flow in the left temporal and frontal areas. We speculated that hippocampal lesion with a frontal perfusion defect can be a cause of TGA.

Cerebellar Hypoperfusion during Transient Global Amnesia: An MRI and Oculographic Study

BACKGROUND AND PURPOSE: Transient global amnesia (TGA) is characterized by sudden anterograde and retrograde amnesia lasting for up to 24 hours. Diffusion-weighted magnetic resonance imaging (DWI) in cases of TGA and ischemia demonstrates a high frequency of high signal intensities restricted to the hippocampus, and this has been proposed as an etiology of TGA. The aims of this study were to characterize the DWI and single-photon-emission computed tomography (SPECT) findings during the acute and recovered phases of TGA and to correlate the findings with oculomotor abnormalities. METHODS: Five consecutive patients with a clinical diagnosis of TGA underwent DWI and SPECT of the brain within 24 hours after symptom onset and again 3 days later. Eye movements were also recorded using three-dimensional video-oculography. RESULTS: In all patients, DWI disclosed small punctuate (1-3 mm), high-signal lesions in the lateral portion of the hippocampus. The initial SPECT also revealed hypoperfusion in the cerebellar vermis, which had recovered by the follow-up examination. Three patients showed saccadic hypermetria or impaired smooth pursuit only during the acute phase. CONCLUSIONS: Our patients with TGA showed cerebellar vermian hypoperfusion in addition to ischemic insults to the lateral hippocampus. The oculomotor abnormalities observed in our patients support the occurrence of cerebellar dysfunction during the TGA attack.

Insular Infarction Presenting With Transient Global Amnesia

The pathophysiology of transient global amnesia is uncertain. Several studies have suggested that the anatomical substrates of transient global amnesia are the limbic areas, including the hippocampus, caudate nucleus, cingulate area, and thalamus. We examined a patient who presented with transient global amnesia with left insular infarction. We believe that the insular lobe may be an important area of episodic memory formation, and infarction of this brain area may be the mechanism underlying the amnesia experienced in this case.

Transient Global Amnesia Following Subarachnoid Hemorrhage

The etiology and pathogenesis of transient global amnesia (TGA) is still unclear. Several mechanisms have been proposed, including arterial thromboembolic ischemic attacks, epilepsy, and migraine. However, TGA following severe headache has not been reported, to our knowledge. We described a patient presenting with TGA associated with the sudden onset of headache provoked by a subarachnoid hemorrhage. MRI and CT with angiography of the brain showed no abnormal findings. CSF study revealed hemorrhage. Single photon emission computed tomography revealed mild low perfusion at both hippocampal regions.