Background and purpose: Transient global amnesia (TGA) is a rare amnestic syndrome characterized by the sudden onset of a selective anterograde and retrograde amnesia with a time course of up to 24 hours. Recent studies have found a high frequency of small high-signal abnormalities in the hippocampus on diffusion-weighted imaging (DWI), and accordingly ischemia has been proposed as an etiology of TGA. We hypothesized that TGA lesions occur preferentially in the CA1 region of the hippocampus, which is known to be susceptible to ischemia. Methods: Twenty consecutive patients with a clinical diagnosis of TGA underwent DWI both within 24 hours of symptom onset and 3 days later. Twenty patients with high-signal abnormalities in the hippocampus on the initial DWI underwent subsequent DWI and T2-weighted imaging in the coronal plane to precisely localize the lesions. Results: Seventeen patients had small high-signal abnormalities (with diameters of 1-3 mm) in the hippocampus unilaterally on DWI. One of these patients had two lesions in one hippocampus. Three of the 20 patients had lesions bilaterally in the hippocampus, 1 of whom had 3 bilateral lesions. A total of 25 lesions were identified: 5 in the hippocampal head, 19 in the body, and 1 in the tail. Six patients had unilateral lesions on the left,11 patients had them on the right, and 3 patients had bilateral lesions. Conclusions: In this study, lesions associated with TGA were localized mostly to the lateral portion of the hippocampus, corresponding to CA1. This finding supports the ischemic etiology of TGA, but the underlying pathophysiologic mechanism requires further investigation.
Amnesia, Retrograde ; Amnesia, Transient Global ; Head ; Hippocampus ; Humans ; Ischemia

Cases showing memory disturbances with isolated retrograde memory without any definitive brain lesions are classified as dissociative amnesia. Improvements in imaging techniques have allowed the organic causes of this disease to be identified in several recent cases. Several studies have diagnosed cases of memory disorders as pure retrograde amnesia (PRA). The patient reported here had no psychiatric disorder and had normal MRI results, but showed hypometabolism in PET that met the criteria for PRA.
Amnesia ; Amnesia, Retrograde ; Brain ; Humans ; Memory ; Memory Disorders

A 44-year-old man showed recurrent paroxysmal amnesic attacks following viral encephalitis which, despite antiepileptic treatment, developed into status epilepticus. Interestingly, the amnesic attacks mainly consisted of amnesia for retrograde events. After recovery from status, he showed a persistent amnesia which was characterized as disproportionate retrograde amnesia for the past 20 years. We attribute the amnesic attacks in the acute stage to a transient epileptic amnesia and the profound retrograde amnesia in the chronic stage to status- or infection-related focal brain damage.
Adult ; Amnesia ; Amnesia, Retrograde* ; Brain ; Encephalitis, Viral* ; Humans ; Status Epilepticus

We report a case of profound amnesia, anterograde and retrograde, in a patient, who had been premedicated with midazolam and underwent a posterior fusion of the cervical spine under inhalation anesthesia. The patient's memory was restored immediately after intravenous injections of the benzodiazepine antagonist flumazenil.
Amnesia ; Amnesia, Anterograde ; Amnesia, Retrograde* ; Anesthesia, Inhalation ; Benzodiazepines ; Flumazenil* ; Humans ; Injections, Intravenous ; Memory ; Midazolam* ; Spine

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.
Amnesia ; Amnesia, Retrograde ; Amnesia, Transient Global* ; Female ; Hospitalization ; Humans ; Incidence* ; Male ; Seasons*

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.
Amnesia ; Amnesia, Retrograde ; Amnesia, Transient Global ; Brain ; Hippocampus ; Humans ; Magnetic Resonance Imaging ; Male ; Middle Aged ; Perfusion ; Tomography, Emission-Computed

We describe a case of anterograde and retrograde amnesia resulting from probable herpes simplex encephalitis. In retrograde amnesia, dissociations not only between episodic and semantic memories, but also between semantic memories for personal and public things were observed. We postulated, using FDG-PET, that the former was caused by mesial temporal lesions, based on `multiple trace theory', and the latter, by bilateral lateral temporal lesions, which were probably related to the retrieval of semantic memory, especially for public things.
Amnesia, Retrograde* ; Encephalitis, Herpes Simplex ; Encephalitis, Viral* ; Humans ; Memory ; Semantics

BACKGROUND: Patients treated with regional anesthesia often require concomitant medication for comfort and sedation. Propofol is widely used for this purpose, but studies upon awareness or post-operative retrograde amnesia are limited. So we designed this study to investigate the frequency of retrograde amnesia on various effect-site concentrations of propofol by using target controlled infusion (TCI). METHODS: Ninety patients (ASA I, II) undergoing orthopedic or urogenital surgery with spinal, epidural or axillary block were randomly assigned to one of six groups. Target concentrations of propofol in the six groups were respectively 1.0, 1.2, 1.4, 1.6, 1.8, or 2.0 microgram/ml. When the effect site concentration reached the target concentration in each group, we waited for 5 minutes and then lowered the target concentration to 0.5 microgram/ml. When the effect site concentration returned to 0.5 microgram/ml, we again waited for 5 minutes and then showed the patient number and picture cards and asked the patient to memorize them. Subsequently the target concentration was returned to the original level. In the post anesthesia care unit, retrograde amnesia was checked 2 hours after eye opening and then rechecked 24 hours later. RESULTS: The percentages of retrograde amnesia checked 2 hours after eye opening were 27%, 27%, 40%, 40%, 40%, and 53% (number card) and 27%, 27%, 40%, 47%, 53%, and 63% (picture card) for propofol dose of 1.0, 1.2, 1.4, 1.6, 1.8, and 2.0 microgram/ml. A significant correlation was found between the propofol concentration and the percentage of retrograde amnesia for picture but not for the numbered cards. The percentages of retrograde amnesia observed at 24 hours after eye opening were similar to the 2 hour results. CONCLUSIONS: When propofol is used for sedation at 1.0 2.0 microgram/ml, retrograde amnesia increases in proportion to the effect site concentration. Many patients can recall intra-operative awareness, and thus we cannot be assured of effective retrograde amnesia. Therefore although a patient is under deep sedation, careful consideration of awareness and recall is needed.
Amnesia, Retrograde* ; Anesthesia ; Anesthesia, Conduction ; Deep Sedation ; Humans ; Orthopedics ; Propofol*

Midazolam is a new water soluble benzodiazepine which used to induce anesthesia. The drug possesses properties similar to those of benzodiazepines(sedative, anxiolytic, anticonvulsant, muscle-relaxant) and has low toxicity compared with thiopental which is world-wide used for induction agent. Midazolam is characterized by slow onset of action, more gradual effects on circulation, low frequency of thrombophlebitis and greater degree of antegrade amnesia. Because of these characteristics midazolam is used as an alternative induction agent. As an induction agent, in order to evaluate the properties of midazolam compared with thiopental, 60 patients were divided into 2 groups. Group I, thiopental 5 mg/kg induction group; Group II, midazolam 0.15mg/kg induction group. Systolic and diastolic blood pressure, pulse rate, induction time and recovery time were measured in each group. Frequency of the throm bophlebitis, retrograde and antegrade amnesia were evaluated. In group I, systolic blood pressure decreased significantly and pulse rate increased signifi-cantly. In group II, diastolic pressure decreased significantly and pulse rate increased signifi-cantly. Induction time and recovery time were delayed significantly in group II than group I. In group II, frequency of the thrombophlebitis was lower and antegrade amnesia was greater than group I. Retrograde amnesia did not occured in both groups. On the basis of these data, midazolam used for induction maintains hemodynamic stability, induces anesthesia smoothly, produces low frequency of the thrombophlebitis and high frequency of antegrade amnesia. Therefore it is concluded that midazolam is safe and effective induction agent and may offers an advantage over thiopental in situations where hemodynamic stability is crucial.
Amnesia ; Amnesia, Retrograde ; Anesthesia ; Benzodiazepines ; Blood Pressure ; Heart Rate ; Hemodynamics ; Humans ; Hypnotics and Sedatives ; Midazolam* ; Thiopental* ; Thrombophlebitis

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.
Amnesia, Retrograde ; Amnesia, Transient Global* ; Cytokines ; Hippocampus ; Hot Temperature ; Humans ; Middle Aged ; Neurologic Manifestations ; Physical Exertion