A reappraisal of acute doses of benzodiazepines as a model of anterograde amnesia.

OBJECTIVE: Acute administration of benzodiazepines is considered a pharmacological model of general organic anterograde amnesias (OAA). We sought to determine which type of amnesia these drugs best model by comparing the effects of diazepam with those reported in amnesiacs regarding working memory capacity (WMC), susceptibility to retroactive interference (RI), and accelerated forgetting. METHODS: In this double-blind, parallel-group design study, 30 undergraduates were randomly allocated to acute oral treatments with 15 mg diazepam or placebo. WMC and story recall were assessed pre- and post-treatment. Story presentation was succeeded by 10 min of RI (spotting differences in pictures) or minimal RI (doing nothing in a darkened room). Delayed story recall was assessed under diazepam and 7 days later in a drug-free session to assess accelerated forgetting. RESULTS: Recall of stories encoded under diazepam, whether reactivated or not, was severely impaired (anterograde amnesia). However, diazepam did not impair WMC, increase susceptibility to RI, or accelerate forgetting. CONCLUSIONS: Diazepam's amnestic effects mirror those in patients with probable severe medial temporal damage, mostly restricted to initial consolidation and differ from other OAA (Korsakoff syndrome, frontal, transient epileptic, posttraumatic amnesia, and most progressive amnesias) in terms of WMC, susceptibility to RI and accelerated forgetting.

A Teenager With Acute Anterograde Amnesia.

Isolated amnesia is an uncommon presenting complaint in the pediatric age group. We report the case of an 18-year-old woman who presented with the acute onset of memory difficulty and an otherwise normal neurologic examination. Brain magnetic resonance imaging demonstrated inflammation in the bilateral temporal lobes. Serum and cerebrospinal fluid testing ultimately revealed a diagnosis of autoimmune encephalitis. Although rare, the acute onset of isolated amnesia deserves a prompt, comprehensive evaluation.

Pure topographical disorientation in novel environments without anterograde amnesia: a case study.

Topographical disorientation (TD) in novel environments is considered to be a part of anterograde amnesia. A 56-year-old woman presented with pure TD only in novel environments following limbic encephalitis. She could not remember directions inside the hospital on weekly outpatient visits; however, her verbal and visual anterograde memories were normal. In the test of learning photographs of scenes, faces, and objects, only her scores for landscapes were worse than those in healthy controls. These findings suggested that her TD specific to landscapes and directions in novel environments was caused by category-specific memory impairment related to bilateral hippocampal and parahippocampal dysfunction.

Transient epileptic and global amnesia: Real-life differential diagnosis.

OBJECTIVE: Transient epileptic amnesia (TEA) is an underestimated condition in emergency clinical setting, where most of transient amnesic episodes tend to be classified as transient global amnesia (TGA). We designed this study to evaluate the actual frequency of TEA in a real-life scenario and to highlight the features that can help clinicians distinguishing it from TGA. METHODS: We retrospectively collected clinical data of 83 patients who accessed our emergency ward for an abrupt onset of amnesic disorder, initially interpreted as TGA. All patients underwent neurological evaluation, magnetic resonance imaging (MRI) scan, and standard 21-channel scalp electroencephalography (EEG) recording (standard EEG [st-EEG]). Moreover, patients with borderline epileptiform abnormalities on st-EEG or with normal st-EEG but high clinical suspicion for TEA underwent a 16-channel 24-hour ambulatory EEG (24-h EEG). Clinical features, neurophysiological, and neuroimaging data were analyzed and compared in the two groups (TEA and TGA). RESULTS: Diagnosis of TEA, according to Zeman's criteria, was made in 15 patients (18%). From a clinical point of view recurrence (p < .001) and atypical symptoms such as confusion or language disorder (TGA plus manifestations), appear to be key elements in order to discriminate between TEA and TGA (80% of patients with TEA vs 7.8% of patients with TGA; p < .001). In our sample, duration of the episodes did not significantly differ between TGA and TEA, even though it is usually described as shorter for TEA. This result could be related with a prolonged postictal state in these patients. The analysis of st-EEG results evidenced low sensitivity for interictal epileptiform abnormalities (IEAs) detection (52.3%), with not conclusive data in distinguishing TEA from TGA. On the contrary, 24-h EEG showed IEAs in all patients with epilepsy, mostly during sleep, suggesting an essential diagnostic role of long-lasting EEG recording for TEA. Finally, structural abnormalities were more frequent in patients with TEA (26.6%). In the group with TGA, the only imaging alteration found was diffusion weighted imaging (DWI) hippocampal hyperintensity. CONCLUSION: Our findings show that in a real-life clinical scenario, TEA is frequent but often overlooked. However, simple clinical data and widely available neurophysiological examinations can truly help to effectively distinguish TEA from TGA.

Neuropsychiatric Manifestations of Colloid Cysts: a review of the literature.

Colloid cysts account for approximately 2% of primary brain tumours and the majority of cases are identified in the fourth and fifth decade. They are small, gelatinous neoplasms lined by a single layer of mucin-secreting columnar epithelium that are thought to arise from errors in folding of the primitive neuroepithelium. They develop in the rostral aspect of the third ventricle in the foramen of Monro in 99% of cases and despite their benign histology carry a poor prognosis, with a mortality greater than 10% in symptomatic cases. The location of colloid cysts within the ventricular system results in obstruction of the foramen of Monro as the cyst grows, disrupting the circulation of cerebrospinal fluid (CSF) and causing hydrocephalus. This is the mechanism behind the most common presenting symptoms of postural headache, nausea and vomiting - a clinical picture synonymous with hydrocephalus and intracranial pathology. In addition to these classical neurological symptoms, there is a high prevalence of psychiatric symptoms in the patient population, with symptoms ranging from anterograde amnesia to gustatory hallucination. These symptoms can occur with or without the presence of hydrocephalus, and are thought to be secondary to compression of connecting pathways between the mesocortices and subcortical limbic regions. These symptoms have been shown to be comparative in frequency to the classical symptoms, yet are rarely the reason for referral to a neurological or neurosurgical service for investigation.

Clinical, neuropsychological, and metabolic characteristics of transient epileptic amnesia syndrome.

OBJECTIVE: Transient epileptic amnesia (TEA) is a recently individualized syndrome occurring in adult patients that includes epileptic seizures with amnestic features and interictal memory disturbances. METHODS: We investigated the clinical, neuropsychological, and 18F-FDG positron emission tomography (18F-FDG-PET) features of 30 consecutive cases of TEA in our center. RESULTS: The mean age of onset of amnestic seizures was 59 years. Pure acute amnesia was the only epileptic manifestation in 17% of cases. Interictal electroencephalography (EEG) abnormalities were present in 57% on awake recording and in most patients in whom sleep EEG was performed (96%). Nine of 30 patients showed anterograde memory deficit and six of 30 exhibited mild executive functioning impairment. On the autobiographical memory interview (AMI), patients showed a significant deficit for the recent period of the episodic subscale. Outcome under treatment was favorable in the majority of cases. A significant improvement was noted on recollection of autobiographical memory. 18F-FDG-PET (22 cases) showed positive correlations between left mesial temporal metabolism levels and anterograde and retrograde memory scores. SIGNIFICANCE: TEA is an emerging epileptic syndrome that likely remains misidentified and misdiagnosed. Neurometabolic data support a dysfunction of a hippocampal-neocortical network sustaining episodic memory.

Retrosplenial amnesia without topographic disorientation caused by a lesion in the nondominant hemisphere.

We report the case of a 68-year-old right-handed man who was admitted to our hospital because of sudden onset of headache. On admission, he presented with left homonymous hemianopsia, disorientation, and recent memory disturbance; however, he had normal remote memory and digit span. He was able to recall the room layout of his house and describe the route from the nearest station to his home on a map. However, at the hospital, he sometimes lost his way because of amnesia. Computed tomography (CT) and magnetic resonance imaging revealed a subcortical hematoma in the right occipital forceps and the parietal lobe, involving the cingulate isthmus. Single-photon emission CT imaging showed reduced perfusion not only in the retrosplenial region but also in the right thalamus. These findings suggested that the retrosplenial amnesia might have been caused by the interruption of hippocampal input into the anterior thalamus.

[Left mesiotemporal lesions and anterograde memory impairement: a case of neurosyphilis]. / Lésions mésiotemporales gauches et amnésie antérograde: un cas de neurosyphilis.

INTRODUCTION: Neurosyphilis has become uncommun in the developed countries. OBSERVATION: We report a case of neurosyphilis with limbic presentation, left mesiotemporal lesions on MRI and severe anterograde amnesia. DISCUSSION: Pathogeneses of MRI findings are unknown. We suggest the implication of arteritis wich affects small vessels, parenchymatous and excitotoxic lesions. The absence of mesiotemporal lesion in immunodeficient patients, the limbic systematization of pathology underlines the involvement of probably auto-immune process. Neurosyphilis should always be considered in the differential diagnosis of limbic encephalitis in order to initiate treatment and to prevent cognitives sequelaes. At last, partial status epilepticus should be diagnosed and excitotoxicity lesions prevents with antiepileptic treatment.

Limbic encephalitis presenting with seizures, anterograde amnesia, and psychosis in a patient seven weeks status post immature ovarian teratoma removal.

A paraneoplastic syndrome associated with anti-N-methyl-D-asparate (NMDA) receptors can initially present as a neurologic or psychiatric disturbance. Removal of the tumor is usually curative, and the syndrome is associated with the presence, rather than the history, of tumor. We present a case in which a 25-year-old, Hispanic woman presented with seizures, memory loss, and unusual behavioral changes. The woman had a teratoma removed 2 months earlier. Because of the time course, a paraneoplastic syndrome was initially considered unlikely. Brain imaging, electroencephalography (EEG) and neurologic work-up were negative. The patient was treated for a suspected somatoform disorder and psychosis. Based on the clinical picture, the working diagnosis was changed to delirium due to paraneoplastic limbic encephalitis. A course of intravenous immunoglobins (IVIg), and high dose steroids was administered. The patient's symptoms improved, and she was discharged home. After discharge, studies came back positive for antibodies against NR1/NR2 of the NMDA receptor.

[Postictal psychosis syndrome: a clinical entity to be recognized]. / Le syndrome de psychose post-ictale : une entité clinique à connaître.

INTRODUCTION: Post-ictal psychosis syndrome (PIP) belongs to the group of epileptic psychoses which, according to the most commonly used classification, is to be distinguished from ictal psychoses, on one hand, and from inter-ictal psychoses, on the other. OBJECTIVES: The present paper aims to review recent data concerning the clinical, therapeutic and pathophysiological aspects of PIP. METHODS: We report four cases of PPI, which involved four patients hospitalized at the Salpêtrière hospital between 2001 and 2005, and discuss these cases in light of the relevant literature. RESULTS: The PIP fit generally occurs in patients suffering from intractable temporal lobe epilepsy which started several years before. The psychiatric disorders suddenly take hold after a series of complex partial seizures with frequent secondarily generalized tonic clonic seizures. During the episode, EEG recordings do not show any epileptic activity. Psychiatric symptoms consist of persecutory delusive ideas, verbal and visual hallucinations, agitation, and aggressiveness. Mood disorders are variable from one patient to another and exhibit intraindividual fluctuation. In most patients given antipsychotic drugs, the short-term outcome of PIP is favorable . In the long-term, even if recurrence is the main long-term risk, progression to severe mood disorders or to poor prognosis inter-ictal psychosis is possible. Accordingly, the clinician must be aware of this syndrome in order to correctly diagnose PIP since effective treatment with antipsychotic drugs is available. CONCLUSION: The short-term prognosis of PPI is usually favorable but this syndrome can potentially develop in the long-term to more severe psychiatric disorders. It is, therefore, important to recognize PIP syndromes which respond more readily to pharmacological treatments than other types of psychoses.

[Carbon monoxide intoxication and anterograde amnesia]. / Intoxication au monoxyde de carbone et amnésie antérograde.

BACKGROUND: Carbon monoxide (CO) intoxication is still one of the most frequent conditions causing brain damage as a result of hypoxia in Morocco, and the main area of brain damage is the hippocampus. The role of the hippocampus in the memory process has been known for long and we usually associate hippocampus damage with anterograde amnesia. Nevertheless, the pure amnesic syndrome is retrieved in the isolated damage of the hippocampus as is seen in the anoxia caused by CO intoxication. The outcome of the patterns depends on the extent of brain damage, the age of onset and the early diagnosis. CASE-REPORT: This study presents the case of a young female patient who presented with anterograde amnesia after massive and prolonged accidental exposition to CO that presented disproportional radiological and clinical outcome. Primary care was in the intensive care unit during 24 hours and based on oxygen therapy and diuretics. The psychiatric examination found an acute stress disorder and symptoms of delirium in the form of reduced awareness and memory deficit. The amnesia was anterograde and the patient exhibited diminished ability to remember time, space and persons. The Galveston orientation and amnesia test (GOAT) score on awakening in the intensive care unit was 46. The laboratory findings did not provide direct physiological disturbances. The brain computed tomography (CT) scan revealed bilateral hippocampus low-density in the cerebral white and grey matter. The clinical and the radiological outcome of this pattern were not correlated. The GOAT scores were 46 on the 10th day and 50 when the patient was discharged three weeks later, although the brain CT scan showed a decrease of the low-density in the hippocampus. Forty-five days later, the GOAT score was still 49 and the brain CT scan did not show any low-density lesion. Clinical symptoms of a major depressive episode were installed. CONCLUSION: These results are correlated to the findings of several series in which the CT scans in CO intoxication show common characteristic features that are symmetrical low-density lesions in the cerebral white matter in some specific brain structures such as the globus pallidus and the hippocampus. The early diagnosis is usually difficult because the brain CT scan findings do not always provide morphological changes and fail approximately one half of the time to detect low-density in the white matter of the hippocampus, and the use of MRI is not as easy as the CT scan. The long period of unconsciousness, the white matter damage and the late diagnosis result in complications in the outcome.

Development and initial validation of the alcohol-induced blackout measure.

BACKGROUND: Blackouts are common among young adults and predict alcohol-related harm. However, existing measures do not capture the range of alcohol-induced memory impairment involved in blackout experiences and do not differentiate between fragmentary and en bloc blackouts. This study aimed to develop and validate a brief, reliable measure of alcohol-induced blackouts among young adults. METHODS: College students reporting alcohol-induced memory impairment in the past year were recruited via Qualtrics to participate in an online survey (N = 350, 56% female). A subsample (n = 109, 67% female) completed a one-month follow-up. Principal component analysis was used to determine the structure of the Alcohol-Induced Blackout Measure (ABOM), which was designed to reflect two components (fragmentary and en bloc blackouts). The reliability and validity of the total ABOM score was assessed. RESULTS: The final five items fit in a two-component scale structure; however, a single principal component accounted for 73% of variance in blackout items, all of which demonstrated high component loadings and communalities. The total blackout score demonstrated strong internal consistency, test-retest reliability, and convergent and incremental validity. ABOM scores predicted alcohol-related consequences at baseline and one-month follow-up. CONCLUSIONS: The ABOM is a brief and reliable, self-report measure that quantifies the frequency of a range of blackout experiences in the past 30 days. Accounting for this range of experiences improved predictive validity over single-item blackout measures. Blackout frequency is a strong, unique predictor of alcohol-related problems.

Does lateral parietal cortex support episodic memory? Evidence from focal lesion patients.

Although neuroimaging and human lesion studies agree that the medial parietal region plays a critical role in episodic memory, many neuroimaging studies have also implicated lateral parietal cortex, leading some researchers to suggest that the lateral region plays a heretofore underappreciated role in episodic memory. Because there are very few extant lesion data on this matter, we examined memory in six cases of focal lateral parietal damage, using both clinical and experimental measures, in which we distinguished between recollection and familiarity. The patients did not have amnesia, but they did show evidence of disrupted recollection on an anterograde memory task. Although the exact mechanisms remain to be elucidated, lateral parietal damage appears to impair some aspects of episodic memory.

Sub-clinical checking compulsions are related to impaired prospective memory independently of depression, anxiety and distractibility.

In this study, we explored whether relationships between checking compulsions and prospective memory are a result of the increased levels of distractibility, depression, state and trait anxiety associated with checking compulsions. Students (N=126) completed a prospective memory task and questionnaires which assess the frequency of experiencing prospective memory failures. Checking compulsions were associated with failing the prospective memory task and with self-reported prospective memory failures. Elevations in distractibility, depression, state and trait anxiety associated with checking compulsions had no influence on prospective memory task performance. They contributed to, but did not completely account for, the relationship between checking and self-reported prospective memory. The results support our theory that individuals with checking compulsions have an impaired prospective memory and that their increased experiences with prospective memory failures undermines their trust in the ability to perform tasks, ultimately resulting in intrusive doubts that specific tasks were not performed and the compulsion to check.

Cerebellar lesions: is there a lateralisation effect on memory deficits?

BACKGROUND: Until recently, neurosurgeons eagerly removed cerebellar lesions without consideration of future cognitive impairment that might be caused by the resection. In children, transient cerebellar mutism after resection has lead to a diminished use of midline approaches and vermis transection, as well as reduced retraction of the cerebellar hemispheres. The role of the cerebellum in higher cognitive functions beyond coordination and motor control has recently attracted significant interest in the scientific community, and might change the neurosurgical approach to these lesions. The aim of this study was to investigate the specific effects of cerebellar lesions on memory, and to assess a possible lateralisation effect. METHODS: We studied 16 patients diagnosed with a cerebellar lesion, from January 1997 to April 2005, in the "Centre Hospitalier Universitaire Vaudois (CHUV)", Lausanne, Switzerland. Different neuropsychological tests assessing short term and anterograde memory, verbal and visuo-spatial modalities were performed pre-operatively. RESULTS: Severe memory deficits in at least one modality were identified in a majority (81%) of patients with cerebellar lesions. Only 1 patient (6%) had no memory deficit. In our series lateralisation of the lesion did not lead to a significant difference in verbal or visuo-spatial memory deficits. FINDINGS: These findings are consistent with findings in the literature concerning memory deficits in isolated cerebellar lesions. These can be explained by anatomical pathways. However, the cross-lateralisation theory cannot be demonstrated in our series. The high percentage of patients with a cerebellar lesion who demonstrate memory deficits should lead us to assess memory in all patients with cerebellar lesions.