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PubMed1992

Anterograde amnesia linked to benzodiazepines.

Benzodiazepines, shown to affect memory, can produce anterograde amnesia (i.e., a loss of memory for events occurring forward in time). Following the ingestion of a benzodiazepine, short-term memory is not affected, but long-term memory is impaired. The memory loss may occur because events are not transferred from short-term memory to long-term memory and thus not consolidated into memory storage. Information stored prior to the ingestion of a benzodiazepine is not affected. Memory impairment is more likely in benzodiazepines that have a high benzodiazepine-receptor affinity, that accumulate in the body, that are given in high doses or intravenously, or that are eliminated slowly. Individuals taking benzodiazepines are often unaware of their memory impairment unless it is pointed out to them. Elderly clients experiencing memory impairment may be embarrassed to mention the problem. Alternatives to prescribing benzodiazepines include antidepressant medications, exercise or psychotherapy. When prescribing a benzodiazepine, it is important to fully inform patients of the drug's potential side effects and to maintain the lowest effective dose for the shortest period of time.

Adult↗
PubMed2002

Severe amnesia associated with human herpesvirus 6 encephalitis after bone marrow transplantation.

BACKGROUND: Human herpesvirus 6 (HHV-6) appears to have a predilection for immunocompromised patients and has been implicated as a cause of posttransplant encephalitis. However, the pathogenesis, as well as the appropriate means of diagnosis and treatment of HHV-6 encephalitis is unclear. METHOD: We describe a case of a 20-year-old male university student with anemia who presented with an acute, severe amnesia 1 month after bone marrow transplantation. His illness was subsequently attributed to HHV-6 encephalitis. RESULTS: Cerebrospinal fluid analysis was consistent with encephalitis and polymerase chain reaction confirmed the presence of HHV-6 DNA in both cerebrospinal fluid and serum. No other herpes virus particles were detected. MRI showed bilateral hippocampal involvement. Treatment with acyclovir resulted in a decrease in serum HHV-6 DNA to undetectable levels, coincident with improvement of both memory and lesions on MRI. CONCLUSIONS: This case provides strong clinical and radiological evidence of the reversibility of this disease process and supports the recommendations for empiric treatment of post transplant patients with laboratory evidence of HHV-6 infection, culture or polymerase chain reaction, plus clinical symptoms compatible with HHV-6 infection.

Adult↗
PubMed2000

Acquisition deficit and time-dependent retrograde amnesia for contextual fear conditioning in agmatine-treated rats.

Cumulative evidence indicates that the hippocampus plays a time-limited role in contextual learning paradigms. Pharmacological studies have indicated that acquisition of background contextual cues during Pavlovian fear conditioning is dependent upon hippocampal function, whereas early inactivation of the hippocampus after training produces retrograde amnesia. When administered prior to contextual fear conditioning, agmatine (5 and 10 mg/kg, i.p.), an endogenous polyamine and N-methyl-D-aspartate (NMDA) receptor ligand found at excitatory synapses in the hippocampus, impaired the acquisition of contextual fear (measured as defensive freezing 26 hours later) without a reduction in baseline motor activity during training. Furthermore, ascending doses of agmatine were found not to exert analgesic effects on response thresholds to peripheral shock. This negated the possibility that the observed learning deficit resulted from a difference in perceived shock intensity. Post-training agmatine treatment produced a time-dependent impairment of consolidation, with subjects approaching a level of fear equivalent to that of a reference group as the delay of treatment increased (up to 6 hours). Since physiologically high levels of agmatine are able to inhibit NMDA receptor activity, these results suggest that polyamine modulation of NMDA receptors, most likely within the hippocampus, is required for the acquisition and consolidation of contextual fear stimuli.

Agmatine↗
PubMed2001

Nitroprusside and ECS-induced retrograde amnesia.

Previous research found that the administration of verapamil and felodipine immediately before electroconvulsive shocks (ECS) attenuated ECS-induced retrograde amnesia. This study examined whether sodium nitroprusside, an antihypertensive drug that does not affect calcium channels, has a similar action. Adult male Sprague-Dawley rats received nitroprusside (0.5 mg/kg ip) or saline 3 minutes before each of three once-daily true or sham ECS. Retention of pre-ECS learning was studied 1 day after ECS using a passive avoidance task. Nitroprusside was associated with increased seizure duration in ECS-treated rats, and with enhanced recall in both true and sham ECS groups. The latter finding suggests that nitroprusside nonspecifically improves cognitive functions, and does not support the hypothesis that ECS-induced cognitive impairment is a result of blood-brain barrier breach. Nitric oxide mechanisms may underlie the benefits purveyed by nitroprusside.

Amnesia, Retrograde↗
PubMed2001

Phenylephrine and ECS-induced retrograde amnesia.

Phenylephrine is a nonselective alpha-receptor agonist. This study examined whether the administration of phenylephrine immediately before electroconvulsive shocks (ECS) attenuated ECS-induced retrograde amnesia. Adult male Wistar rats received phenylephrine (0.25 mg/kg i.p.) or saline 3 min before each of three once-daily true or sham ECS. Retention of pre-ECS learning was studied 1 day after the ECS course using a passive avoidance task. Phenylephrine increased seizure duration in ECS-treated rats, and also enhanced recall in both true and sham ECS groups. The latter finding suggests that phenylephrine nonspecifically improves cognitive functions, perhaps through adrenergic mechanisms that improve memory consolidation and storage. Since phenylephrine increases blood pressure, its cognitive effects also weaken the hypothesis that ECT-induced cognitive impairment results from the seizure-related hypertensive surge.

Adrenergic alpha-Agonists↗
PubMed2002

Effects of stimulus parameters on seizure duration and ECS-induced retrograde amnesia.

A selected electroconvulsive therapy stimulus dose can result from different combinations of pulse amplitude, pulse width, pulse frequency, and stimulus duration; however, the roles of these stimulus variables in the effects of the overall stimulus dose are not clearly understood. A series of studies on Wistar rats was therefore conducted to assess the effects of different stimulus compositions at constant stimulus charge. In the first two studies, two differently composed 60 mC charge unidirectional electroconvulsive shock (ECS) stimuli were administered once daily for 3 days, while in the third study three differently composed 120 mC charge unidirectional ECS stimuli were administered on a single occasion. At constant charge, a markedly longer stimulus duration was associated with ear burns and an approximately 12.5% longer seizure duration. At constant charge, however, different stimulus compositions were not associated with different degrees of impairment in two passive avoidance models of ECS-induced retrograde amnesia. These preliminary findings have implications for the choice of stimulus settings during dose titration and dose selection procedures. While the findings encourage further investigation, it appears that variations in stimulus duration are biologically significant, but minor variations in other stimulus elements may not influence the effects of electrically induced seizures very much.

Amnesia, Retrograde↗
PubMed1988

Memory impairments: forgetfulness versus amnesia.

Two varieties of memory disorders can be distinguished--those characterized by the phenomenon of forgetfulness and those characterized by the presence of an amnesic state. Although these two conditions may appear similar, they have different anatomical correlates and functional significance. States of forgetfulness and amnesia arise from different etiologies, have different prognoses and require different therapeutic regimes. The purpose of this article is to distinguish these two varieties of memory disorders and contrast them as to anatomical features, functional differences, etiologies, prognoses and therapeutic management regimes. This should assist the neuroscience nurse to better understand relevant nursing assessment features and plan appropriate therapeutic nursing interventions for the client. Teaching protocols for families and significant others as well as clients with memory impairments should also be enhanced.

Amnesia↗
PubMed2000

Medial temporal lobe amnesia: a case study for nursing.

Maintaining and enhancing cognitive function is a crucial but challenging intervention for patients with memory problems. Research on the medial temporal lobe (MTL) memory system has yielded much information that can guide nurses in planning, evaluating, and performing effective interventions. A patient, Mrs. N, with a diagnosis of anaplastic astrocytoma of the left medial temporal lobe provides an example. Information from research guides assessment of Mrs. N and affords development of specific patient-centered interventions to maintain function, cope, and compensate. Data have been gathered from the patient, relatives, and caregivers to compare with and augment existing research, because few nursing case studies of amnesia involving patients with left medial temporal lobe tumors are available for analysis.

Aged↗
PubMed2001

Dissociations in cognitive memory: the syndrome of developmental amnesia.

The dearth of studies on amnesia in children has led to the assumption that when damage to the medial temporal lobe system occurs early in life, the compensatory capacity of the immature brain rescues memory functions. An alternative view is that such damage so interferes with the development of learning and memory that it results not in selective cognitive impairments but in general mental retardation. Data will be presented to counter both of these arguments. Results obtained from a series of 11 amnesic patients with a history of hypoxic ischaemic damage sustained perinatally or during childhood indicate that regardless of age at onset of hippocampal pathology, there is a pronounced dissociation between episodic memory, which is severely impaired, and semantic memory, which is relatively preserved. A second dissociation is characterized by markedly impaired recall and relatively spared recognition leading to a distinction between recollection-based versus familiarity-based judgements. These findings are discussed in terms of the locus and extent of neuropathology associated with hypoxic ischaemic damage, the neural basis of 'remembering' versus 'knowing', and a hierarchical model of cognitive memory.

Amnesia↗
PubMed2000

Amnesia is a deficit in relational memory.

Eye movements were monitored to assess memory for scenes indirectly (implicitly). Two eye movement-based memory phenomena were observed: (a) the repetition effect, a decrease in sampling of previously viewed scenes compared with new scenes, reflecting memory for those scenes, and (b) the relational manipulation effect, an increase in viewing of the regions where manipulations of relations among scene elements had occurred. In normal control subjects, the relational manipulation effect was expressed only in the absence of explicit awareness of the scene manipulations. Thus, memory representations of scenes contain information about relations among elements of the scenes, at least some of which is not accessible to verbal report. But amnesic patients with severe memory impairment failed to show the relational manipulation effect. Their failure to show any demonstrable memory for relations among the constituent elements of scenes suggests that amnesia involves a fundamental deficit in relational (declarative) memory processing.

Adult↗
PubMed2006

Amnesia for electric dental pulp stimulation and picture recall test under different levels of propofol or midazolam sedation.

AIM: To compare the amnesic effect of propofol and midazolam to electric dental pulp stimulation (invasive) and picture recall test (non-invasive) at two sedation levels with the aid of bispectral index (BIS) monitoring. METHODS: The subjects were 10 male volunteers (24-34 years) classified as ASA physical status I. Propofol was administered to achieve a sedation score of three with a target-controlled infusion technique; it was then regulated to give a sedation score of two (P group). Midazolam was administered by a titration dosage to achieve a sedation score of three (M group). It then gradually decreased to give a sedation score of two. The BIS score, sedation score, plasma/serum concentration of propofol and midazolam, blood pressure, pulse rate, respiratory rate, end-tidal CO(2) tension and arterial oxygen saturation were observed at each sedation level in both groups. Amnesic effects were evaluated using a picture recall test and electric dental pulp stimulation. RESULT: No difference was observed in the amnesic effect evaluated by picture recall test at the two sedation levels. Likewise, there was no difference at a sedation score of three when the amnesic effect was evaluated by electric dental pulp stimulation. In contrast, a significant difference was observed at a sedation score of two; midazolam produced amnesia in more subjects than did propofol. CONCLUSION: Propofol and midazolam did not show any significant difference in amnesic effects to non-invasive stimuli. For invasive stimuli, midazolam showed a stronger amnesic effect at the moderate sedation level, but not at the deeper sedation level.

Adult↗
PubMed1994

Transient global amnesia following cerebral angiography with non-ionic contrast medium.

Transient global amnesia (TGA) is an uncommon syndrome of recent memory deficit and inability to learn new data, usually resolving within 24 h. Two cases following use of non-ionic contrast media in cerebral angiography are described. The neuroanatomy of memory is reviewed. Possible aetiologies of TGA in relation to cerebral angiography include ischaemia (embolic, arterial spasm), epilepsy that may be primary or tumour-related and direct toxic effects of contrast media.

Adult↗
PubMed1994

Transient global amnesia in a young child.

Unprovoked and unexplained sudden loss of memory and inappropriate behaviour in a 5 year old child is described as fitting into the clinical picture of 'transient global amnesia'. The likely pathophysiology of this condition is discussed with some support for Fisher's suggestion of 'hippocampal-fornical' dysfunction.

Amnesia↗
PubMed1993

Sexual intercourse as a precipitating factor of transient global amnesia.

A Japanese female case of transient global amnesia (TGA), who developed an amnesic episode after sexual intercourse, is reported. The mechanism of how TGA in the present case is precipitated by sexual intercourse could be explained by the elevated blood pressure during sexual intercourse that drops rapidly, causing a temporal ischemia in the distribution of the basilar artery. Furthermore, the importance of sexual intercourse as a precipitating factor of TGA is stressed.

Adult↗
PubMed1995

Inhibitors of cyclooxygenases produce amnesia for a passive avoidance task in the chick.

Arachidonic acid is a putative messenger in synaptic transmission which presumably plays a role in learning and memory. Previous experiments showed that inhibitors of phospholipase A2-dependent release of arachidonic acid cause amnesia in a one-trial passive avoidance task in the chick. To test if arachidonic acid is metabolized to other messengers, the effects of inhibitors of enzymes which metabolize arachidonic acid were tested in the same task. The cyclooxygenase inhibitors indomethacin, naproxen and ibuprofen caused amnestic effects at all concentrations tested when injected intracerebrally before training. Injections were 5 microliters of 5-20 mmolar solutions per hemisphere. The onset of amnestic effects was always 2 h after training, independently of drug type, concentration, and injection time before training. The delay of 2 h after training suggests that the drugs prevent induction of cyclooxygenase synthesis. Post-training injections had no effect. Control tests showed little effect of the drugs on motor control and motivation. Caffeic acid and esculetin, inhibitors of lipoxygenases, and sodium furegrelate, a thromboxane synthase inhibitor, had no effect on performance of chicks in the task at all concentrations or time points tested. The results indicate that cyclooxygenase products, but not lipoxygenase or thromboxane synthase products, play a role in memory consolidation in the chick when learning this task.

Amnesia↗
PubMed2005

Clinical features, risk factors, and prognosis in transient global amnesia: a follow-up study.

We previously observed a high frequency of psychopathological features in transient global amnesia (TGA). We aimed at assessing differences in risk factor profile and prognosis between TGA and transient ischemic attack (TIA) patients with a focus on aspects with possible psychopathological relevance. We studied 51 TGA patients (mean age +/- SD, 62.7 +/- 6.7 years; M/F = 24/27) and 51 control patients with TIA (mean age +/- SD, 63.8 +/- 6.7 years; M/F = 41/10) and followed them up for about 7 years. Compared with TIA controls, TGA patients more frequently had a history of psychiatric diseases (age and sex-corrected OR = 2.86, 95% CI: 1.01-8.05) and alcohol use (OR = 3.26, 95% CI: 1.10-9.66) and less frequently a history of cardiac (OR = 0.29, 95% CI: 0.11-0.76) or peripheral artery disease (OR = 0.11, 95% CI: 0.01-0.96). A family history of psychiatric diseases was reported more frequently by TGA than TIA patients (OR = 2.99, 95% CI: 1.04-8.59). On follow-up, in comparison with TIA patients, TGA patients had a significantly lower risk of combined stroke, myocardial infarct, and death (log-rank test, P = 0.0059). In the multivariate analysis, the dissimilar baseline risk factor profile explained most of the difference in prognosis between the two groups. In comparison with TIA patients, patients with TGA have more frequently a personal or family history of psychiatric diseases and a more favorable vascular risk factor profile and prognosis. These results have therapeutic implications and reinforce the hypothesis that TGA is a benign disorder.

Amnesia, Transient Global↗
PubMed2006

Recurrency in transient global amnesia: a retrospective study.

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.

Aged↗
PubMed1992

Assessment of post-traumatic amnesia in young children.

To assess the duration of post-traumatic amnesia (PTA) in children, a new procedure is described, derived from a method described previously for adults. The procedure was tested on 70 healthy children between 3.5 and 10 years of age, then applied in a longitudinal prospective study of 54 children with brain damage resulting from closed head-injury. The procedure consistently measured PTA in children of various ages. The duration of PTA was found to be as good a prognostic indicator for the occurrence of long-term residual sequelae as is duration of coma.

Amnesia↗