French neuropsychological procedure consensus in epilepsy surgery.

INTRODUCTION: Neuropsychological assessment is an integral component of the surgical procedure in patients with epilepsy. As no French consensus for neuropsychological assessment was available, the main goal of this work was to define French neuropsychological procedure consensus in regard to literature review. METHOD: A panel of expert in neuropsychology was created within the framework of the French League Against Epilepsy. A systematic search of publications from 1950 to 2017 listed in PubMed database was conducted leading to a classification of articles according to their level of scientific evidence. French neuropsychological procedure consensus was then carried out with an expert panel of expert. RESULTS: Low scientific evidence of neuropsychological data was reported. A panel of expert proposed a comprehensive neuropsychological assessment procedure including the exploration of intellectual efficiency, long-term memory, short-term and working memory, attention, executive functions, processing speed and motor skills, language, visual processing, praxis, psychobehavioral, and social cognition. DISCUSSION: A common procedure for assessing cognitive and psychobehavioral function is now available in patients with epilepsy undergoing surgical evaluation have been established, they may help to improve the quality of care and the patient experience. This work highlights the need of furthers investigations and the necessity to develop specific tools with normative data.

Transient epileptic amnesia: Update on a slowly emerging epileptic syndrome.

Transient epileptic amnesia (TEA) is a recently individualized, late-onset, pharmaco-sensitive form of mesial temporal lobe epilepsy with recurrent episodes of acute memory loss, but also interictal memory disturbances characterized by autobiographical and topographical memory impairment and a long-term consolidation deficit. In this article, we review the main clinical and electrophysiological characteristics of TEA, discuss its putative neuroanatomical substrate and mechanisms, common features and how it differs from related concepts, with the overall aim to defend the idea that TEA deserves to be recognized as a distinct epilepsy syndrome. While the pathophysiological basis remains largely unknown, emotional and/or dysimmune factors may have a potential influence. Most importantly, the concept of TEA is highly relevant to tertiary epilepsy and memory clinics, but also to routine neurology practice, leading to an adequate diagnosis and management of epilepsy-related, acute and long-standing memory deficits.

[Interest of EEG recording during direct electrical stimulation for brain mapping function in surgery]. / Intérêt du monitoring électrophysiologique au cours d'une chirurgie éveillée en neurochirurgie.

Brain tumor surgery is at risk when lesions are located in eloquent areas. The interindividual anatomo-functional variability of the central nervous system implies that brain surgery within eloquent regions may induce neurological sequelae. Brain mapping using intraoperative direct electrical stimulation in awake patients has been for long validated as the standard for functional brain mapping. Direct electrical stimulation inducing a local transient electrical and functional disorganization is considered positive if the task performed by the patient is disturbed. The brain area stimulated is then considered as essential for the function tested. However, the exactitude of the information provided by this technique is cautious because the actual impact of cortical direct electrical stimulation is not known. Indeed, the possibility of false negative (insufficient intensity of the stimulation due to the heterogeneity of excitability threshold of different cortical areas) or false positive (current spread, interregional signal propagation responsible for remote effects, which make difficult the interpretation of positive or negative behavioural effects) constitute a limitation of this technique. To improve the sensitivity and specificity of this technique, we used an electrocorticographic recording system allowing a real time visualization of the local. We provide here evidence that direct cortical stimulation combined with electrocorticographic recording could be useful to detect remote after discharge and to adjust stimulation parameters. In addition this technique offers new perspective to better assess connectivity of cerebral networks.

[Isolated autobiographical amnesia: a neurological basis?]. / Amnésie autobiographique isolée : une origine neurologique ?

INTRODUCTION: The term "autobiographical memory" (AuM) refers to contextually bound experiences that occurred in a specific time, place, and affective setting. AuM is a component of memory commonly impaired in amnestic disorders. Alteration occurs rarely in isolation but rather in the setting of a larger memory impairment. Isolated AuM deficit is a controversial clinical entity, however, recently reported in the context of temporal lobe epilepsy. This study aims at characterizing this poorly documented clinical syndrome and at discussing its potential pathophysiological basis. PATIENTS AND METHODS: We studied a group of three subjects with a history of pharmacosensitive epilepsy and severe AuM complaints. They all were submitted to a neuropsychological evaluation that included an extensive episodic memory assessment, along with wake/sleep electroencephalogram (EEG) and brain magnetic resonance imaging (MRI). RESULTS: We observed the following findings: preserved autonomy and intact global cognitive functioning; normal performance to standardized episodic memory assessment, contrasting with decreased performance to specific AuM evaluation; frontal and/or temporal epileptic activity on EEG; and normal structural brain MRI. CONCLUSION: We reported on a group of patients exhibiting selective impairment of some components of personal memory, associated with interictal frontal and/or temporal abnormalities on EEG. To account for these findings, we hypothesise that interictal epileptic-related activity is impeding long-term consolidation or storage of autobiographical material.

[Pure progressive amnesia: an amnestic syndrome with preserved independence in daily life]. / L'amnésie pure progressive : un syndrome amnésique avec préservation de l'autonomie.

INTRODUCTION: Pure progressive amnesia, a form of progressive focal cortical atrophy is thought to represent the early stages of a rare form of Alzheimer's disease (AD). This syndrome is characterized by the insidious and slowly progressive breakdown of memory, in the absence of a significant impairment in other cognitive domains or in the realm of behavior. The aims of the present study were to contribute to the characterization of this poorly documented type of amnesia, to compare it with other forms of amnestic syndromes resulting from lesions to the medial temporal lobes and to discuss its potential pathophysiological basis. PATIENTS AND METHOD: We carried out three single case studies in patients presenting with pure progressive amnesia. They all underwent a neuropsychological evaluation that included an extensive assessment of spatial and recognition memory, along with brain magnetic resonance imaging and a cerebral blood flow study. RESULTS: All three patients had a severe deficit in the storage of context-free information, along with a severe visual recognition memory impairment, as previously reported in a case study on a patient with pure progressive amnesia (Cognitive Neuropsychology 23 (2006) 1230-1247). Yet, spatial memory remained well preserved, and patients maintained totally independent in everyday life. In addition, a significant atrophy of the medial temporal structures was found. DISCUSSION: This specific pattern of impairment differs from other types of amnestic syndromes after medial temporal damage and raises the question of lesional topography, as well as possible compensatory phenomena. We suggest that pure progressive amnesia results from selective damage to the ventral subhippocampal route into the hippocampal formation leading to impaired context-free memory. Spatial memory may remain intact because the dorsal parahippocampal route into the hippocampus remains functional. Pure progressive amnesia may contribute to a better understanding of the neural systems involved in declarative memory and provide a better understanding into the nature of the memory impairment that characterizes the initial stages of AD.

Undifferentiation of somatic responses to emotions in a case of functional amnesia.

The term functional amnesia (FA) has been proposed for cases of memory impairment presenting with severe retrograde amnesia in the absence of cerebral injury or history of psychiatric disturbance. Emotional flattening has often been reported alongside FA, however the mechanism of such a modification is unknown. This study aimed to explore the emotional processing in a rare case of a patient with FA complaining of severe emotional flattening. We presented ecological dynamic video stimuli conveying strong peaceful and fearful emotions to the patient and 13 controls. We then explored their emotional responses considering both conscious emotional judgements and automatic psychophysiological responses (skin conductance) and facial muscular activity (corrugator supercilii). Both patient P.P. and controls perfectly recognized the emotions conveyed by the films. However, P.P. failed to show an increased skin conductance and corrugator activity as found in controls during fearful film extracts compared with peaceful extracts. Taken together, these finding demonstrate the presence of an emotional deficit, characterized by a failure to generate appropriate somatic responses to positive and negative stimuli. Although this altered somatic processing did not interfere with PP's explicit recognition of emotion, it modified his emotional experience, thereby constituting a possible explanation for his emotional flattening. This study therefore suggests that FA is not limited to a mnemonic impairment, but is a more complex disorder, involving also the processing of emotionally loaded experiences.

Evaluation of visual recognition memory in MCI patients.

BACKGROUND: Neurofibrillary tangles seen early in Alzheimer disease (AD) initially appear in a subregion of the perirhinal cortex. In the monkey, damage to the perirhinal cortex impairs performance on visual recognition memory tasks. The authors evaluated impairment of visual recognition memory as a potential early diagnostic marker of AD. METHODS: The authors developed a visual delayed matching-to-sample task (DMS48) designed to assess visual recognition memory in humans. Twenty-three patients fulfilling the criteria of amnestic mild cognitive impairment (MCI) (mean Mini-Mental State Examination [MMSE]: 26.6, SD = 1.6) were recruited. All underwent a full neuropsychological evaluation, which included the Free and Cued Selective Reminding (FCSR) test. Their performance was compared with that of 10 patients with mild AD, 20 patients with moderate AD, 20 patients with Parkinson disease (PD), and 40 age-matched controls. RESULTS: Control subjects and patients with PD performed close to ceiling. Patients with mild AD had very low scores, while patients with moderate AD answered at random. MCI patients obtained scores that were between those of control subjects and patients with mild AD (78%, SD = 16%). MCI patients who failed on the DMS48 had lower scores on free recall (p < 0.05) and received less benefit from cueing (p < 0.01) on the FCSR than the other MCI, suggesting a profile of genuine memory impairment related to medial temporal lobe lesions. CONCLUSION: The DMS48, a test of visual recognition memory, is impaired early in the course of patients with MCI. Further studies are necessary to determine whether the evaluation of visual recognition memory may contribute to the identification of patients with AD.

[The human perirhinal cortex]. / Le cortex périrhinal chez l'homme.

The perirhinal cortex is a structure that lies within the medial temporal lobe. In the present paper, we review current knowledge of the anatomical boundaries and functional correlates of this structure. In the past decade, numerous animal studies have attempted to understand the contribution of the perirhinal cortex to memory. Taken together, they suggest that the perirhinal cortex is crucially involved in recognition memory. This function appears to be independent from those assumed to be subserved by the hippocampus. In humans, data are scarce but tend to corroborate results found in the animal literature. The perirhinal cortex appears to support context-free (non-episodic) knowledge, such as general knowledge about the world and "item-specific" memories. Models of declarative memory that take into account the specific contribution of the perirhinal cortex are discussed, along with their potential application to early cortical neurodegenerative disorders.