Isolated retrograde amnesia for autobiographical material associated with acute left temporal lobe encephalitis

Retrograde amnesia for autobiographical material in the absence of anterograde amnesia or other memory disturbances was found in a patient with acute viral encephalitis. Memory loss showed a temporal gradient, but new learning was spared. Both brain perfusion imaging with 99mTc-HMPAO SPECT, and EEG localized the lesion in the left temporal lobe while CT and MRI were normal. This observation supports the anatomical differentiation between the different memory functions. The uncommon combination of isolated retrograde amnesia without other neuropsychological findings may raise the doubt of psychogenic aetiology, which in this case was refuted.     

Is anterograde amnesia a special case of retrograde amnesia?

In anterograde amnesia (AA), memory loss is obtained for events that occur subsequent to the traumatic insult. But because the effects of an anterograde agent or treatment usually last for minutes or even hours after the nominal training event, processing of information may be altered during the postacquisition period as well as during acquisition. Since posttraining manipulations are themselves capable of modulating memory or inducing retrograde amnesia, the memory loss due to a putative anterograde treatment may instead represent retrograde processes. The present experiment examined this source of confounding by using an amnestic treatment that can be quickly reversed after training to remove postacquisition effects. The presence of amnesia would isolate anterograde contributions as the source of loss. For induction of AA, 56 male albino Sprague-Dawley rats were trained while at reduced body temperature (29°C). A rapid rewarming procedure was introduced for some immediately after training to ensure that the hypothermic state did not extend into the postacquisition period. Other Ss were rapidly rewarmed 1 hr after training to control for any effects of the rewarming manipulation. Both groups showed severe AA that was indistinguishable from that obtained in the gradually rewarmed controls. Data provide an empirical example of an anterograde-induced memory deficit that is independent of retrograde influences. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Focal retrograde amnesia associated with vascular headache

We report the case of a 42-year-old man with repeated attacks of headache associated with retrograde amnesia. Neuropsychological tests before and after the major episode of amnesia showed mild neuropsychological deficits but with spared anterograde memory and learning functions. The amnesia was dense for a period of 15-20 years and included people and events (public and private). There was also a suggestion of amnesia for learned skills. Neurologically he had mild clinical signs and focal EEG-abnormalities in the left fronto-temporal region, but CT, MRI, and SPECT showed no abnormality. Five years after the onset of amnesia there was no recovery of the retrograde memory deficit, but a PET (glucose) scan was normal and neuropsychological testing showed no deficits. An association with migraine has been reported for some non-classical amnesias, but this is the first case of selective retrograde amnesia in a patient with headache as a primary neurological diagnosis.     

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

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

Radiological diagnosis of viral encephalitis

Most of viral encephalitis may demonstrate no specific change on CT and MR images. Brain swelling, edema, abnormal density (CT) and abnormal intensity (MR) can be detected in herpes simplex encephalitis and enterovirus encephalitis (coxsackie, echo, polio). The common finding on CT and MRI in patients with HIV encephalopathy are atrophy, leukomalacia. Progressive multifocal leukoencephalopathy (PML) shows multifocal oval or round white matter T2-hyperintensities on MR images. Subacute sclerosing panencephalitis (SSPE) may present slight changes in the subcortical and periventricular white matter, as well as basal ganglia. Progressive disorder makes widespread T1-low, T2-high intensity area and atrophy. MRI of acute disseminated encephalomyelitis (ADEM) shows multifocal subcortical hyper intense foci on T2-weighted studies. The deep white matter, brainstem, thalamus and cerebellum can be affected. Most of ADEM lesions resolve. Imaging findings of acute lymphocytic meningitis by echovirus and coxsackievirus are usually normal.     

Syndromes of retrograde amnesia: A conceptual and empirical synthesis.

This article attempts a synthesis of the range of disorders that have been subsumed under the rubric of retrograde amnesia. At a functional level, it is possible to make distinctions between various forms of retrograde amnesia, including a distinction between episodic amnesia for personally experienced events and semantic retrograde amnesia for components of knowledge, such as those relating to people and events. At an anatomical level, discrete lesions to limbic-diencephalic structures usually result in a limited degree of retrograde amnesia. Marked episodic or marked semantic retrograde amnesia is usually associated with significant involvement of cortical and neocortical structures. Retrograde amnesia is a functionally heterogeneous rather than a unitary phenomenon. Discontinuities and dissociations found in published studies point to the potential fractionation of retrograde amnesia into component disorders, each with its own neural profile. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Motivational control of retrograde amnesia: Further explorations and effects.

Reports 5 investigations of variables related to the motivational control of retrograde amnesias for long-term habits which result from single ECS treatments. Ss were 176 Long-Evans rats. In terms of the paradigms of M. J. Robbins and D. R. Meyer (see record 1970-11961-001), habits that were 3rd in a series were generally resistant to the treatment, were moderately impaired if the ECS treatments were delayed, and were markedly impaired if the tests for retention were carried out in changed motivational contexts. The latter result is discussed in relation to the view that long-term habits are affected by the treatments if and only if they operate as punishments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Duration of transient amnesia correlates with cognitive outcome in acute encephalitis

Temporary periods of amnesia are encountered in acute encephalitides. We investigated the association between transient encephalitic amnesia (TENA) and outcome in 60 patients. Twenty-six patients had TENA lasting < or = 1 day (short TENA), 17 had TENA lasting 2-7 days, and 17 had TENA for > 7 days (long TENA). The long TENA group had more neuropsychological impairment, larger brain lesions, and more difficulty in daily activities than the short TENA group. The findings were not explained by the number of epileptic seizures, delay of acyclovir medication, or the aetiology of encephalitis. TENA is a useful new clinical tool in predicting the outcome of acute encephalitis and selecting patients who are in need of detailed neuropsychological evaluation.     

Reexamination of role of familiarization in retrograde amnesia in the rat.

28 male Wistar rats were given a single familiarization (FAM) session before training in a 1-trial passive-avoidance task and were then submitted to hypoxia or ECS to produce retrograde amnesia (RA). 19 Ss received the same training and posttraining treatment but not prior FAM, and 10 control Ss received only FAM and training. Results indicate that under these training conditions, prior FAM is a necessary condition for both hypoxia and ECS to produce RA. Results are considered to underline the need to modify the consolidation hypothesis. Memory for an event is not fixated in isolation, but is incorporated into already existing dynamic systems; thus, the strength of the new memory is determined in part by the prior experience of the animal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential susceptibility to anterograde and retrograde amnesia treatments in preweanling rats.

Although there have been several reports that preweanling rats and mice are relatively resistant to experimentally induced retrograde amnesia, there is virtually no information concerning susceptibility to anterograde amnesia in subjects of this age. Therefore, in the present experiment, 23-day-old rats received hypothermia either prior to, or immediately after, punishment training in an attempt to induce anterograde and retrograde amnesia, respectively. When tested 24 hrs later, only those subjects given hypothermia prior to training exhibited any loss of retention. Thus these results confirmed previous evidence of resistance to retrograde amnesia in preweanling rats and further demonstrated that substantial anterograde amnesia could be obtained in these subjects. Performance of subjects tested after a 5-min retention interval revealed that the poor retention performance in subjects cooled prior to training and tested 24 hrs later was not due to a learning deficit. These results are also discussed with respect to the issue of the independence of anterograde and retrograde amnesia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Brain stem encephalitis related with viral infection

There is no definite classification of brainstem encephalitis, its etiology is not clear. Bickerstaff's brainstem encephalitis (BBE) was established by clinical diagnosis without etiology. Recently there are great progression to identify a virus by using immunological methods and PCR (polymerase chain reaction) methods. Sometimes the progression of MRI revealed subdiagnostic images of brainstem lesion. Nowadays we can investigate anti-ganglioside antibodies in some BBE patients but not all. High IgG anti-GQ1b antibody titers were present in some BBE sera samples but decreased with the clinical course of illness. A girl was suffered from BBE whose Cytomegarovirus-DNA was detected in the CSF by PCR. Serum anti-GQ1b antibody was positive. The neurological symptoms disappeared with decreasing of anti-GQ1b antibody. Immuno adsorption therapy is effective for BBE with anti-GQ1b antibody positive patients.     

Lack of a temporal gradient of retrograde amnesia following NMDA-induced lesions of the basolateral anygdala assessed with the fear-potentiated startle paradigm.

M. Kim and M. Davis (see record 1994-28571-001) previously reported that electrolytic lesions of the central nucleus of the amygdala, made 6 or 30 days after training, complctcly blockcd the expression of fear potentiated startle in rats. The present study shows that excitotoxic lesions of the basolateral amygdala also block fear-potentiated startle and do so whether the lesions are made soon (i.e., 6 days) or long (i.e., 30 days) after training. The relevance of these findings to various theories of amygdala function is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Assessment of retrograde amnesia: Findings with a new public events procedure.

Existing public events tests for retrograde amnesia quickly become out of date and require frequent restandardization. The initial development of the Oscar Test is reported, which requires Ss to match the titles of Academy Award winning movies with the years in which they were made, a procedure that updates itself automatically every year. Data from 25 normal Ss and 7 patients with severe anterograde amnesia are presented. As a group, the patients demonstrated significant impairment, misdating movies by an average of 14 yrs. Several individual amnesic patients were much more impaired and produced profiles similar to those found on other remote memory tests. Performance on the Oscar Test tended to parallel performance on the Autobiographical Memory Interview in revealing mild, time-limited retrograde amnesia in some patients and severe, temporally extensive retrograde amnesia in others. Neuropathology outside the classical memory system may be required for the latter type. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dissociation of implicit and explicit knowledge in a case of psychogenic retrograde amnesia

There have been few studies of psychogenic amnesia based on a cognitive or neuropsychological framework. In the present study, a patient with acute onset of profound psychogenic retrograde amnesia was examined. Although her performance on neuropsychological tasks revealed intact anterograde memory, language functioning, visuospatial and constructional skills, and mental speed and flexibility, she displayed severe impairments on a variety of retrograde memory tasks. Furthermore, initial observations revealed inconsistencies between the patient's recall of semantic knowledge on direct questioning and her ability to demonstrate the use of this knowledge on indirect tasks. To test this formally, we devised an indirect remote knowledge task to examine a possible dissociation between explicit and implicit memory. Two healthy subjects matched for age, gender, education, occupation, and estimated IQ were also tested. As predicted, the findings demonstrate implicit knowledge despite impaired explicit recall for the same material.     

Polymicrobial sepsis following endoscopic retrograde cholangiopancreatography

Cholangitis with polymicrobial sepsis followed endoscopic retrograde cholangiopancreatography in a patient without biliary tract obstruction. Inadequately disinfected endoscopy equipment was strongly implicated as the source of infection. Results with a new method of disinfection using gluteraldehyde are given.     

Role of ACTH in recovery from retrograde amnesia induced by hypothermia in rats.

The present investigation assessed whether increased congruency between ACTH state present shortly after training and that at testing contributed to memory recovery. If recovery were related to an increased correspondence between internal state present after training and that at testing, then suppressing ACTH release should block memory recovery. This was the hypothesis that was examined in the present investigation. Specifically, animals were trained on a passive avoidance task, administered hypothermia (the amnestic agent) and, shortly prior to testing, given treatments known to be effective in reversing memory loss induced by hypothermia. Before training (Experiment 1) or testing (Experiment 2) animals were injected with either dexamethasone (an agent that suppresses ACTH release) or saline. Results, in general, indicated that when ACTH release was suppressed, a blunted recovery effect was obtained. This reduction in the extent of memory recovery was observed when ACTH was suppressed either at training or at testing. These data are interpreted as providing support for an ACTH-related, state-dependent retention mechanism contributing to recovery from hypothermia-induced retrograde amnesia in rats. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prolonged twilight state in the course of viral encephalitis

A marked prophylactic effect of dibasole and ascorbic acid in influenza and other acute respiratory diseases (ARD) is described. The analysis was based on comparison with a control group observed for the same period and being at the same risk of contracting infection with influenza or other ARD. The control group was given glucose according to the same procedure.