The spectrum of neuropsychiatric abnormalities associated with electrical status epilepticus in sleep

Electrical status epilepticus in sleep (ESES) is an electrographic pattern consisting of an almost continuous presence of spike-wave discharges in slow wave sleep. ESES is frequently encountered in pediatric syndromes associated with epilepsy or cognitive and language dysfunction. It can be present in various evolutionary stages of a spectrum of diseases, the prototypes of which are the 'continuous spikes and waves during slow wave sleep' syndrome (CSWS), the Landau-Kleffner syndrome (LKS), as well as in patients initially presenting as benign childhood epilepsy with centrotemporal spikes (BECTS). The purpose of this article is to review the literature data on the semiology, electrographic findings, prognosis, therapeutic options, as well as the current theories on the pathophysiology of these disorders. The frequent overlap of CSWS, LKS, and BECTS urges an increased level of awareness for the occasional transition from benign conditions such as BECTS to more devastating syndromes such as LKS and CSWS. Identification of atypical signs and symptoms, such as high discharge rates, prolonged duration of ESES, neuropsychiatric and cognitive dysfunction, lack of responsiveness to medications, and pre-existing neurologic conditions is of paramount importance in order to initiate the appropriate diagnostic measures. Prolonged and if needed repetitive sleep electroencephalographs (EEGs) are warranted for proper diagnosis.

Macrosomatognosia and microsomatognosia in migraine art

OBJECTIVES

To study macrosomatognosia and microsomatognosia occurring as migraine aura symptoms.

MATERIAL AND METHODS

Topological distribution of these body schema disturbances were assessed in a collection of 562 pictures submitted as entries to the 4 national Migraine Art competitions.

RESULTS

The said symptoms were illustrated by 18 artists. Macrosomatognosia was encountered more frequently than microsomatognosia and applied more often to single parts of the body, whereas microsomatognosia mostly affected the entire body. In partial macrosomatognosia, the head and upper extremities were the body parts most frequently involved, paralleling the extension of their representation in the sensory maps of the human brain.

CONCLUSIONS

The conscious perceptual experiences of whole body macro- and microsomatognosia argue in favour of the existence of an integrative neuronal network mediating whole body perception. Partial macro- and microsomatognosia suggest a reversible modification of cerebral maps of somatosensation during the migraine aura.

A componential analysis of visual object recognition deficits in patients with herpes simplex virus encephalitis

Five patients with a diagnosis of Herpes Simplex Virus Encephalitis (HSVE) underwent neuropsychological assessment to explore the integrity of their visual perceptual abilities. Selective deficits affecting different levels of the recognition processing were found; impaired recognition abilities were also influenced by selective task requirements, which resulted either in facilitatory or constraining effects on patients' performance. A theoretical model of object recognition (Humphreys & Riddoch, 1987) was taken into account to explain patients' performance. Further, the role of specific components of visual processing was evidenced in explaining the performance of patients affected by HSVE.

[Attention and neglect: neurological basis, assessment and disorders]

OBJECTIVE

Attention phenomenology is a wide subject, in this revision we will explain attention and its relationship with behavioral neglect.

DEVELOPMENT

Selective attention is the ability to throw the focus of awareness toward behaviorally relevant events in the personal and extrapersonal space. Severe alteration of these mechanisms constitutes unilateral neglect in patients with contralateral brain damage. Unilateral neglect is one of the most behaviorally devastating syndrome. There are different behavioral neglect: attentional (perceptual), intentional (motor), motivational and representational aspects of unilateral neglect. Left side neglect after right hemisphere lesions is more common (31 to 46%) than right sided neglect following lesions in the left hemisphere (2 to 12%).

CONCLUSION

One year after a cerebrovascular accident only 1/3 of the patients with unilateral neglect persist with this handicap.

[Right parietal lesions, spatial neglect and egocentric reference]

Using a proprioceptive "straight-ahead" pointing task, we determined the position of the subjective sagittal middle in thirty unselected patients with unilateral vascular lesions in the right hemisphere and twenty-two normal controls. Patients with extensive right parietal damage (n = 16) showed an ipsilesional (rightward) deviation of their egocentric reference, whereas patients with lesions that substantially spared the right parietal lobe (n = 14) showed a contralesional (leftward) deviation. No significant correlation emerged between the position of the egocentric reference and the performance on a neglect battery. These results can help explain some dissociations between left neglect signs and ipsilesional deviation of the egocentric reference, and raise some questions about the links among lesion location, neglect signs and egocentric frame of reference.

[Four "alien" hands for two hands after a lesion in corpus callosum]

Callosal lesions, associated or not to internal frontal lesions, may produce different types of complex gestural behaviors. Four signs can be identified, each of which has been generally reported separately: the "alien hand" sign, the "diagnostic apraxia", the "wayward hand" and the "callosal apraxia". Some authors justify considering these signs as different entities, while others propose regrouping them either in an unique syndrome--the "alien hand"--or as two syndromes--the "frontal alien hand" and the "callosal alien hand". We present the observation of a patient who presented with the four mentioned syndromes in association. In this context, we review the clinical features of each of the four signs and the arguments supporting their individualization.

[Difficulties in face identification after lesion in the left hemisphere]

A 82 year-old right-handed man, without any intellectual impairment, suffered from an acute neurological deficit consisting in letter-by-letter reading, right superior quadrant hemianopia with achromatopia in the lower quadrant, and anomia. Cerebral MRI showed an infarct involving the ventral structures of the left hemisphere sparing the splenium of the corpus callosum and the thalamus. Neuropsychological examination revealed that the patient easily identified the objects, the animals and the famous places he could not name: his comments attested normal visual recognition. Conversely, when he was presented with famous faces, he always had a strong feeling of familiarity, but could not provide accurate information about the corresponding individual. Biographic information about personalities was not impaired in the semantic-biographic store, because it could be accessed from the names. Activation of face recognition units (where the visual description provided by the structural encoding and the stored sets of descriptions of familiar faces are compared), was effective, since the patient could distinguish famous faces from unknown ones. In a modular-sequential model of face recognition, this deficit is interpreted as a disconnection between face recognition units and person identity nodes (which are considered to contain semantic-biographic information about individuals). This kind of disturbance differs from classic prosopagnosia in which, characteristically, the patients are unable to experience a feeling of familiarity when viewing famous faces, and to perform a categorization between famous and unknown faces. Right hemisphere has a preponderant role in structural analysis of faces and in activation of face recognition units. The integrity of this hemisphere in this patient could explain the preservation of these two steps of processing. Left-hemisphere specific function in facial recognition enabled access to semantic-biographic store in a conscious, verbal and explicit way, after the right hemisphere had achieved basic visual analysis and activation of facial representation in memory. We compare the cognitive impairment in our patient to those encountered in classical prosopagnosic patients. This case illustrates the validity of the modular-sequential model considered. In addition it throws a light on the poor-known role of the left hemisphere in face recognition.

Tactile morphagnosia secondary to spatial deficits

A 73-year old man showed visual and tactile agnosia following bilateral haemorrhagic stroke. Tactile agnosia was present in both hands, as shown by his impaired recognition of objects, geometrical shapes, letters and nonsense shapes. Basic somatosensory functions and the appreciation of substance qualities (hylognosis) were preserved. The patient's inability to identify the stimulus shape (morphagnosia) was associated with a striking impairment in detecting the orientation of a line or a rod in two- and three-dimensional space. This spatial deficit was thought to underlie morphagnosia, since in the tactile modality form recognition is built upon the integration of the successive changes of orientation in space made by the hand as it explores the stimulus. Indirect support for this hypothesis was provided by the location of the lesions, which could not account for the severe impairment of both hands. Only those located in the right hemisphere encroached upon the posterior parietal cortex, which is the region assumed to be specialised in shape recognition. The left hemisphere damage spared the corresponding area and could not, therefore, be held responsible for the right hand tactile agnosia. We submit that tactile agnosia can result from the disruption of two discrete mechanisms and has different features. It may arise from a parietal lesion damaging the high level processing of somatosensory information that culminates in the structured description of the object. In this case, tactile recognition is impaired in the hand contralateral to the side of the lesion. Alternatively, it may be caused by a profound derangement of spatial skills, particularly those involved in detecting the orientation in space of lines, segments and complex patterns. This deficit results in morphagnosia, which affects both hands to the same degree.

[Impairment of visual recognition after a traumatic brain injury]

Impaired vision and cerebral blindness were observed in a patient who had suffered brain trauma. One year after the trauma, the impairment was characterized by low visual acuity, visual field restricted to central tunnel vision and impaired recognition of objects, line drawings, colors and faces. Vision improved six years after the brain trauma with more rapid recognition of objects and line drawings, increased visual acuity and broadening of the visual field. Reading was possible at this time. However, prosopagnosia remained very severe and was still the primary complaint of the patient. Improvement of visual function continuing for several years after a brain injury is discussed on the basis of cognitive and neurophysiological knowledge. The place of rehabilitation is discussed. Functional improvement is explained by extrastriate cortical afferences and the cortical network of visual pathways.

Memories are made of this: the effects of time on stored visual knowledge in a case of visual agnosia

We report the effects of the passage of time on the longterm visual knowledge for objects in a patient with visual agnosia (H.J.A.). The naming of real objects was found to have improved, although this was not associated with any change in H.J.A.'s basic perceptual abilities which were stable over a 16-year period. The improvement in object naming was attributed to better use of non-contour-based visual information (such as surface detail and depth cues). In addition, we demonstrate a deterioration in H.J.A.'s long-term memory for the visual properties of objects, and argue that this has occurred as a result of his having impaired perceptual input. The deterioration was only apparent in drawing from memory and in the verbal descriptions of items; with forced-choice testing, H.J.A. operated at ceiling; we propose that current tests of visual imagery may not be sufficiently sensitive to detect subtle impairments of visual memory. Our findings can be taken to indicate that perceptual and memorial processes are not functionally independent, but are linked in an interactive manner.

Category specificity in object agnosia: preservation of sensorimotor experiences related to objects

We report a case of semantic agnosia, characterized by category specificity. Object recognition, mainly involving visual representation, was severely impaired, whereas object recognition involving both visual and sensorimotor representations, was relatively well preserved. His ability to recognize gestures and produce appropriate gestural responses to objects was remarkable. These two factors lead the authors to form a hypothesis, in an attempt to explain the mechanisms involved in object recognition. It has been argued that manipulation of an object may give access to a certain amount of knowledge about it, and that preservation of sensorimotor experiences of objects might be important in recognizing some of them. This could account for the category specificity, described in object agnosia.

Alzheimer's disease with asymmetric parietal lobe atrophy: a case report

A 52-year-old, right-handed female presented with visuospatial dysfunction including left hemineglect, incomplete Balint's syndrome, and environmental agnosia, together with left-sided motor symptoms such as unskillful movement, dystonic postures, and myoclonus in the left hand, without significant dementia. Symptoms progressed to akinetic mutism prior to her death 10 years after onset of illness. Imaging studies such as MRI, SPECT, and PET studies showed severe, predominantly right-sided involvement of parietal and parieto-occipital areas. The motor signs might originate from the right parietal lesions such as area five or somatosensory area. Neuropathologic studies including immunocytochemistry showed tau-positive neurofibrillary tangles and abundant neuritic plaques with amyloid deposits, confirming the diagnosis of Alzheimer's disease. An analysis of serum apolipoprotein E revealed epsilon3/epsilon3 homozygosity. This case represents a variant of Alzheimer's disease conspicuous for progressive motor signs and visuospatial dysfunction with a striking laterality, reflecting asymmetric parietal involvement. Alzheimer's disease with asymmetric parietal atrophy is difficult to be clinically distinguished from corticobasal degeneration characterized by progressive unilateral motor signs and focal cortical signs.

Inversion superiority in visual agnosia may be common to a variety of orientation polarised objects besides faces

Selective impairment in recognition of faces (prosopagnosia) resulting from certain localized cortical lesions has been advanced as an argument for a face specific brain module. The argument is claimed to be strengthened by the discovery of an inversion superiority effect in the recognition of faces by a prosopagnosic patient (Farah et al., Vis Res 1995b;35:2089-2093). The present paper reports an inversion superiority effect in the recognition of faces and shoes in a visual agnosic patient. The finding raises the possibility that several classes of orientationally polarized objects, of which shoes and faces are examples, will exhibit inversion superiority.

Associative visual agnosia resulting from a disconnection between intact visual memory and semantic systems

We report the case of a patient (RC) who developed a severe visual agnosia, associated to alexia without agraphia, color anomia and amnesia, following an ischemic stroke in the territory supplied by the left posterior cerebral artery. Based on his proficient performance on tests evaluating analysis of elementary visual features, formation of viewer-centered and object-centered representations of visual stimuli and discrimination between drawings representing real and unreal objects, we concluded that the critical locus of deficit was a disconnection between the normally functioning visual memory store and the semantic system. RC's disturbance in visual processing of human faces paralleled his recognition disorder of other classes of objects. The possible contribution of neurobiological factors in determining RC's agnosic deficit is discussed.

Sleep EEG and developmental dysphasia

To determine the relation between developmental dysphasia and EEG anomalies during sleep, we compared 52 subjects with dysphasia with a control group of 20 children by using the ambulatory EEG method. Whereas 50% of the children with dysphasia experienced paroxysmal activity (PA), only two of the control group did. It is likely that paroxysmal abnormalities and language impairment are related to architectural dysplasia and neuron-migration disturbances. PA is frequent in subjects with receptive developmental dysphasia and may be the cause of language deterioration. When the occurrence of paroxysmal abnormalities during sleep is higher than 8% of total sleep time, we suggest the use of antiepileptic drugs.

Evidence for a disturbance of the body schema in neglect

Subjects with left neglect often fail to use and, in some instances, recognize the left side of the body. We performed a series of investigations to determine if this deficit is, at least in part, attributable to an impairment in the "body schema," an internal three-dimensional, dynamic representation of the spatial and biomechanical properties of one's body. First, subjects were shown a series of pictures of a single hand and asked to determine if the stimulus was a right or left hand. Subjects with neglect but not other subjects with brain lesions identified pictures of left (contra-lesional) hands significantly less reliably than pictures of right hands. On the basis of evidence demonstrating that the identification of pictured hands involves the matching of the stimuli to an on-line mental representation of one's body, these data suggest that neglect may be associated with a disruption of, or failure to attend to, the body schema. Data from subsequent investigations contrasting patients with left neglect and Gerstmann's syndrome argue for a distinction between a body schema and a "body image," or conceptual representation of the body which articulates with language.

Chronic auditory agnosia following Landau-Kleffner syndrome: a 23 year outcome study

We report a 27-year-old woman with chronic auditory agnosia following Landau-Kleffner Syndrome (LKS) diagnosed at age 4 1/2. She grew up in the hearing/speaking community with some exposure to manually coded English and American Sign Language (ASL). Manually coded (signed) English is her preferred mode of communication. Comprehension and production of spoken language remain severely compromised. Disruptions in auditory processing can be observed in tests of pitch and duration, suggesting that her disorder is not specific to language. Linguistic analysis of signed, spoken, and written English indicates her language system is intact but compromised because of impoverished input during the critical period for acquisition of spoken phonology. Specifically, although her sign language phonology is intact, spoken language phonology is markedly impaired. We argue that deprivation of auditory input during a period critical for the development of a phonological grammar and auditory-verbal short-term memory has limited her lexical and syntactic development in specific ways.

The evolution of alexia and simultanagnosia in posterior cortical atrophy

Early alexia and higher visual impairments characterize Posterior cortical atrophy (PCA), a progressive dementing syndrome most often caused by Alzheimer disease. Posterior cortical atrophy is rare, and the nature of the visual impairments in PCA are unclear. The authors observed two patients who had an insidiously progressive reading difficulty characterized by letter-by-letter reading and otherwise intact cognitive functions. Over time, these patients developed "ventral simultanagnosia" with preserved detection of multiple stimuli but inability to interpret whole scenes. Subsequently, they progressed to Balint syndrome with "dorsal simultanagnosia," optic ataxia, and oculomotor apraxia. Structural imaging was normal, but functional imaging revealed posterior cortical dysfunction. On a letter reading task, both patients had a word superiority effect, and on a whole word reading task, they could not read most words with missing or crosshatched letters. An inability to assess whole scenes progressed to an inability to detect more than one stimulus in an array. These findings suggest an evolution of PCA with progressive difficulty in visual integration beginning with letters, progressing to whole scenes, and culminating in Balint syndrome. These changes may reflect an extension of the pathophysiology of PCA from the extrastriate visual cortex to its occipitotemporal and occipitoparietal connections.

Multiple-domain dissociation between impaired visual perception and preserved mental imagery in a patient with bilateral extrastriate lesions

A brain-damaged patient is described whose pattern of performance provides insight into both the functional mechanisms and the neural structures involved in visual mental imagery. The patient became severely agnosic, alexic, achromatopsic and prosopagnosic following bilateral brain lesions in the temporo-occipital cortex. However, her mental imagery for the same visual entities that she could not perceive was perfectly preserved. This clear-cut dissociation held across all the major domains of high-level vision: object recognition, reading, colour and face processing. Our findings, together with other reports on domain-specific dissociations and functional brain imaging studies, provide evidence to support the view that visual perception and visual mental imagery are subserved by independent functional mechanisms, which do not share the same cortical implementation. In particular, our results suggest that mental imagery abilities need not be mediated by early visual cortices.

Persistent recurrence of hypomania and prosopoaffective agnosia in a patient with right thalamic infarct

The authors report a 63-year-old man with a history of brief isolated manic episodes who became persistently hypomanic after a small right thalamic infarct. Detailed behavioral and neuropsychologic assessment were performed 18 months after the stroke and revealed a prosopoaffective agnosia as the foremost cognitive disorder, i.e., an impairment in the identification of emotional facial expressions with preserved discrimination of facial identity. Difficulties in reasoning on humorous material and other signs of mild right hemisphere dysfunction were present, but other perceptual, frontal and abstract-reasoning cognitive functions were unimpaired. Prosopoaffective agnosia has not been reported previously in thalamic lesions or in primary or secondary mania. The authors discuss the hypothetical relationships between a right hemisphere deficit in processing emotions and relapsing of the patient's hypomanic behavior.

[Dissociations between music and language functions after cerebral resection: A new case of amusia without aphasia]

We present the neuropsychological study of a patient, I.R., who sustained bilateral damage to the temporal lobes and to the right frontal lobe as a result of successive brain surgeries that occurred ten years earlier. The patient is 40 years old and right-handed; she had no special training in music or in language, representing, therefore, the large majority of listeners. Her performance is compared to that of four neurologically intact subjects who are closely matched in terms of education, sex and age. In the present study, we report I.R.'s performance on various tests aiming at assessing her general cognitive functioning with a particular focus on auditory aspects. The results show that, despite extensive damage to her auditory cortex, I.R.'s speech abilities are essentially intact (see Tables 1 and 2). The only impairments that are detected in the language domain are related to a short-term memory deficit, to some abnormal sensitivity to retroactive interference in long-term memory (see Table 3) and to articulation. These difficulties do not, however, affect linguistic communication, which is obviously undisturbed I.R. is not aphasic). Similarly, I.R. does not experience any difficulty in the recognition and memorization of familiar sounds such as animal cries, traffic noises and the like (see Tables 5 and 7). In contrast, I.R. is severely impaired in most musical abilities: She can no longer discriminate nor identify melodies that were once highly familiar to her; she can no longer discriminate nor memorize novel melodies (see Table 4). Her pattern of musical losses is compatible with a basic and severe perceptual deficit that compromises access to and registration in memory systems. The observation that the auditory impairment affects music and spares language and environmental sounds refers to a neuropsychological condition that is known as music agnosia. I.R. represents, to our knowledge, the fourth case of music agnosia available in the literature (Peretz et al., 1994; Griffiths et al., 1997). The existence of such cases suggests that music processing is not mediated by a general-purpose auditory architecture but by specialized cortical subsystems. Not only does I.R. suffer from music agnosia, but she is also impaired in the discrimination and recognition of musical instruments and of human voices (see Table 5). These latter two deficits probably do not result from the music agnosic condition. Rather, they seem to reflect damage to adjacent brain areas that are specialized in timbre processing (see Peretz. et al., 1994, for the relevant discussion). It is also worth mentioning that I.R. appears to be impaired in musical expressive abilities as well: I.R. can no longer sing a single note. Thus, her losses are rather general in the musical domain, hence justifying the classification of her case as amusia. Cases of amusia without aphasia are relatively frequent in the neuropsychological literature. However, all of these reported cases are anecdotal. Thus, in the present study, special focus is given to the measurement and direct comparison of performance in the language and music domain; in both domains, task characteristics and materials were as similar as possible. To this aim, the lyrics and the tune of the same popular song excerpts were used. The musical and the spoken parts were presented separately in a primed familiarity decision task and in a memory recognition task. In both situations, I.R. performs at or close to chance when she has to deal with music, whereas she recognizes easily and performs normally on the spoken material (see Tables 6 and 7). These results clearly argue for the autonomy of music and language in the processing of auditory information.

Anosognosia: examining the disconnection hypothesis

OBJECTIVE

To test the hypothesis that anosognosia for hemiparesis results from intrahemispheric disconnection.

METHODS

Using right carotid barbiturate injection as a model for anosognosia for hemiparesis, systematic attempts were made to modify deficit awareness by providing the left hemisphere with explicit information regarding left upper extremity function.

RESULTS

Experimental interventions failed to modify deficit awareness in 19 of 32 patients. In those patients who discovered their weakness, attempted movement of the weak limb seems more important than explicit observation of the extremity by the left hemisphere.

CONCLUSIONS

The results fail to support Geschwind's disconnection hypothesis for anosognosia for hemiparesis.