Eminegletto visivo: criteri diagnostici ed evoluzione

Eminegletto visivo:criteri diagnostici ed evoluzione

Anna Dickmann

Università Cattolica del Sacro CuorePoliclinico A. Gemelli

Istituto di OftalmologiaDirettore: Prof. Emilio Balestrazzi

Site of excellence

Vasculopatie cerebrali Bosisio Parini 19.03.2011

Eminegletto visivo

• Deficit attentivo verso un emispazio

Incapacità di prestare attenzione o di notare stimoli provenienti da una metà del campo visivoN.B.:vie visive di base normofunzionanti


Eminegletto visivo• Ambito dell’Eminegletto Spaziale

(Unilateral Spatial Neglect - UNS)

• Incapacità di – riferire su – rispondere a – orientarsi verso

uno stimolo presentato dal lato opposto alla sede di una lesione cerebrale, quando questa incapacità non può essere imputata a difetti sensoriali o motorî


Negletto spaziale unilaterale• Non è una entità omogenea ed unitaria• Sindrome estremamente variegata• Parecchi deficit indipendenti interagenti tra loro

possono contribuire ai segni del neglect

– Deficit rappresentazionale (memoria)– Deficit motorio attivo intenzionale– Sensoriale inattentivo (visivo)


Eminegletto rappresentazionale

• Deficit di memoria rappresentazionale

Descrizione a memoria di un luogo notoCaso della Piazza Duomo di Milano(Luzzatti) neglect rappresentazionale “puro”

La memoria dello spazio extrapersonale è immagazzinata con un sistema egocentrico


Eminegletto MotorioIncapacità a muoversi nello spazio controlesionale pur essendo consci di uno stimolo da quel lato

Impossibile v isualizzare l'immagine.

X


N.B.: vie motorie integre

Eminegletto• Eminegletto sinistro

– Conseguenza di danno all’emisfero destro, spesso di origine vascolare

• Dall’80 al 17% dopo CVA destro neglect sinistro• Ma anche tumori e traumi

• Più raramente (2-15%) danno emisfero sinistro eminegletto destro generalmente più lieve

• Riportato un caso di neglect destro dopo stroke emisfero destro

• Le variazioni di dominanza cerebrale possono spiegare questa variabilità


Eminegletto spaziale • Soggetto normale

– l’emisfero destro dirige l’attenzione agli emispazi destro e sinistro mentre il sinistro solo a destra

• Lesione dell’emisfero destro– attenzione diretta

primariamente a destra con neglect dell’emispazio sinistro

• Lesione dell’emisfero sinistro– No neglect perché l’emisfero

destro controlla l’attenzione ad entrambi gli emispazi


Eminegletto - Sintomatologia

Inattenzione allo spazio di sinistra

– Mangiano solo il cibo nella parte destra del piatto



Fenomeno dell’Estinzione Stimoli visivi o tattili simultanei destra e sinistra

Sceglie il destro


Inattenzionea sinistra

Non può distoglierel’attenzione da destra

Competizione tra destra e sinistra


Inattenzione allo spazio di sinistra

Disegno a memoria/ copiatura

asimmetrico



Inattenzione allo spazio di sinistraIpocinesia del braccio

Al comando di alzare le braccia alza solo il destro



Inattenzione allo spazio di sinistraSe sulla sedia a rotelle (emiplegia)

Non riconoscono gli ostacoli a sinistra



Anosognosia

Inconsapevolezza del deficit



Asomatognosia

Non riconosce la sua mano sinistra


EmineglettoCorrelati neuroanatomici

• Lobo parietale– lesioni della

corteccia parietale posteriore

• Lobo parietale inferiore( IPL)

• Giunzione temporo-parietale (TPJ)


Neuroanatomia dell’attenzione

• Corteccia parietale posteriore

• Lobo frontale

• Giro cingolato


Neuroanatomia dell’attenzione• Lobo parietale posteriore (solco tra i lobi

sup e inf, ma anche aree adiacenti)– Informazioni auditive, visive, somatosensoriali,

vestibolari – rappresentazione sensoriale degli eventi

extrapersonali (eventi che accadono negli emispazi che circondano l’individuo)

• Interconnessioni– Corteccia premotoria– Campi oculari frontali– Collicolo superiore– Aree paralimbiche (attraverso il giro cingolato)



• Sostanza reticolare • Collicolo superiore



• Talamo • Solco intraparietale


Eminegletto

• Non lesione di una singola regione ma distruzione di un ampio network cerebrale per disconnessioni intra ed inter emisferiche


Eminegletto – Correlati lesionali

• CT - MRI• Estese lesioni dell’emisfero destro che

distruggono parecchi moduli funzionali• Localizzazione ancora controversa• Lobulo parietale inferiore (IPL) alla giunzione

con il lobo temporale• Eminegletto personale (egocentrico)

• Altra ipotesi: parte media e rostrale del giro temporale superiore (STG)

• Eminegletto extrapersonale (allocentrico)



• Transcranial magnetic stimulation (TMS)– A favore della corteccia parietale posteriore

• Functional MRI– Lesioni della giunzione temporo‐parietale destra possono determinare uno sbilanciamento dei lobuli parietali superiori (strutture importanti nell’orientamento attenzionale) con conseguente prevalenza dell’orientamento a destra



• Inattivazione elettrica temporanea di piccole aree cerebrali durante neurochirurgia– Contro il ruolo dell’STG– Ruolo della sostanza bianca

• Diffusion tensor MRI tractography (DT-MRI)– Lesione del fascicololongitudinale superiore– Disconnessione tra moduli corticali come

meccanismo generale del neglect


Eminegletto visuo-spaziale - Decorso

• Miglioramento maggiore nel primo mese post-stroke

• Può andare dalla guarigione completa alla persistenza completa

• Necessaria comunque una riabilitazione funzionale più lunga


Eminegletto visuo-spaziale - Diagnostica

• Diagnosi importante• Se presente

– cattiva prognosi di recupero funzionale dallo stroke

• Disponibili strategie riabilitative efficaci• Forse terapie farmacologiche


Eminegletto visuo-spaziale – Test diagnostici

• Cancellazione• Il paziente omette di

cancellare i simboli a sinistra – Asimmetria di

performance può variare da paziente a paziente

– Se cancellano tutto cominciano comunque da destra



• Bisezione di una linea orizzontale– Il paziente devia a destra– Più lunga è la linea più a destra viene divisa



• Bisezione di una linea orizzontale– D:D: emianopsia sinistra i paz emianoptici sn

deviano a sn

– Se emianopsia+ neglect massiva deviazione a destra



• Bisezione di una linea orizzontale

– Cross-over



• Errore nella copiatura della parte sinistra di un disegno– Anche se disegna a

memoria– Però se è bendato

disegna tutto



• Registrazione movimenti oculari durante un compito di ricerca



• Behavioural Inattention Test (BIT)

• The BIT was developed in 1987 by Barbara Wilson, Janet Cockburn and Peter Halligan.

• The BIT is divided into two subtests: Conventional and Behavioral.

• BIT Conventional subtest (BITC) • 6 items: line crossing, letter cancelation, star

cancellation, figure and shape copying, line bisection, and representational drawing.

• BIT Behavioral subtest (BITB) • 9 items: pre-scanning, phone dialing, menu

reading, article reading, telling and setting the time, coin sorting, address and sentence copying, map navigation, and card sorting. (Wilson et al., 1987).


Eminegletto visivo vs. Emianopsia

• Associazione possibile e relativamente frequente in considerazione delle aree di lesione

• L’emianopsia è un fattore aggravante per l’eminegletto?

• Di conseguenza il recupero funzionale è peggiore in presenza dell’associazione?


Eminegletto visivo vs. Emianopsia

• Emianoptici• Consci del deficit• Importanza dello

spazio cieco• Gradiente

attenzionale maggiore• Strategia di

adattamento

• Eminegletto• Inconscio dello spazio

a sinistra• Gradiente

attenzionale minore• Patologico


Rehabilitation Approaches


Grazie


Two mechanisms for Visual Field processing problem

Gradient of Neglect

• Neglect does not perfectly divide the entire visual field, rather it varies between individuals and the attended to or not attended to portions of the VF does not have sharp boundaries

Lecture 54A Disorder of Attention: Hemineglect

• Hemineglect: A disruption or decreased ability to look at something in the (often) left field of vision and pay attention to it. Thus, hemineglect is a disorder of attention in which one half of the perceptual world is neglected to some degree and cannot be attended to as completely or accurately as normal.


Drawings copied by a patient with contralateral neglect


Lect 54 Hemineglect, in conclusion

This order of attention which shows how the attentional system can be affected by brain damage, thus informing us about normal attention. In hemineglect, the patient is unable to direct attention voluntarily shift attention to the neglected side of space

The evidence suggests that this arises from an inability to disengage attention from a stimulus on the nonneglected side, hence disrupting the process of shifting attention to the opposite side.


Unilateral Spatial Neglect SWAN

• Trattamento• Weinberg

– combination of visual scanning, sensory awareness, and spatial organization training is an effective treatment strategy for patients with right hemi‐ sphere lesions.

• Robertson et al29 – designed a strategy to decrease USN by facilitating activation of the sustained attention system. This strategy is based on the premise that sustained attention is a system that engages attention in prepara‐ tion for response in the absence of external stimuli



• Trattamento• Smania et al30

– used visual and movement imagery exercises to target the representational deficits seen in patients with USN.



• Trattamento• researchers31–35 have shown a reduction in USN following manipulation of sensory input that conveys perception of the head in space.

• A temporary remission of USN has been noted in several studies following vestibular stimulation through caloric irrigation.31–33

• UNS reduced temporarily through galvanic stimulation of the vestibular nerves.34 Rorsman et al34 found that galvanic stimulation applied duringvisuomotortasksdecreasedthe severity of neglect.



• Trattamento• Karnath et al35 found that lengthening of the left posterior neck muscles by trunk rotation induced a transient remission of left USN, presumably due to the sensory input that this supplied to the central nervous system.

• Modifications of the visual input to patients with USN have shown some success as a treatment intervention. Rossi et al36 used prisms……Rossetti et al concluded that the adaptation to the prisms affects spatial repre‐ sentation in the brain.


Unilateral Spatial Neglect SWAN• Trattamento• Several researchers39 – 41 have examined the effects of using an eye patch on USN.

• This eye patch is theorized to affect perception and attention by facilitating the direction of attention.

• Butter and Kirsch40 examined patients with a right CVA and left USN and found that placing a patch over the right eye improved performance on a standard test battery for neglect.

• Walker et al found no differences between the normal viewing condition and when the right or left eye was covered with a patch.Vasculopatie cerebrali Bosisio Parini

19.03.2011

Unilateral Spatial Neglect SWAN• Trattamento• Mirrors also have been used as therapeutic devices to facilitate attention to the neglected side.44,45 Ramachandran and colleagues44,45 placed a mirror…….

• “mirror agnosia.”



• Presenza di hemieglect rende difficoltosa la riabilitazione neurologica

• Terapia fondamentale non solo per la cura del deficit visuospaziale ma anche per gli altri aspetti della riabilitazione (p.es. ripristino motorio etc)

• Prende in considerazione sia approcci empirici che più razionali.

• Parecchi funzionano, anche se prove scientifiche di efficacia sono scarseVasculopatie cerebrali Bosisio Parini

19.03.2011


• The reported incidence of hemineglect in stroke patients is approximately 23%, ranging from 8% to 81%,



• Hemineglect may manifest as “ego‐ centric” (viewer‐centered reference frame) or “allocentric” (object‐ centered reference frame).



• Egocentric• unilateral extinction to double simultaneous sensory stimula‐

tion, thought to occur as the result of the inability of the left stimulus to compete for salience when the attention to the right hemispace contains an equivalent stimulus.7

• Asymmetric orienting response similarly oc‐ curs when a patient orients his or her gaze to the non‐neglected field when stimuli are presented to both sides.8 This obligatory shift in orientation may be because of both reduced attention to the neglected side as well as to an inability to disengage from stimuli in the non‐ neglected field.9



• Allocentric• Asymmetric drawing or copying and right‐shifted marking of

the midpoint on a line bisection test are examples of allocentric neglect. In such a deficit, the object is perceived asymmetri‐ cally regardless of its location in egocentric space



“sensory/perceptual” neglect versus “motor/exploratory” neglect.10Most manifestations of egocentric neglect are motor/exploratory, and those

with an allocentric base are generally sensory.The terms “intentional” and “attentional,” respec‐ tively have been applied to

this dichotomy as well.11,12 Unilateral limb hypokinesia is a demonstration of motor neglect that affects

peripersonal space or body perception.13,14Asomatognosia is an another example of this type of distorted hemi‐

inattention of self.15 For most patients the hemineglect syndrome clusters its individual deficits

according to the basic divisions described here. Any single element or combination, however, may be seen in a given patient


Rehabilitation Approachesthere are often additional, more global deficits of cognitive function that

accompany hemineglect to make the treat‐ ment additionally challenging.Anosognosia is seen in hemineglect patients in up to 20% to 58% of cases.A lack of self‐monitoring because of the unawareness of the deficitPersonality changeInability to multitaskthey are often unable to reconcile logic of the situation with abnormal

perceptionsabnormal use information about stimuli depending on its context has been

demonstrated.23 Line bisection behavior on a given length line was shown to be altered by the introduction of different length lines—the perceived midpoint shifting leftward on that line when longer lines were mixed in the set and the perceived midpoint shifting rightward when shorter lines were mixed in. This “context effect” seems to be unique to right brain injury. Vasculopatie cerebrali Bosisio Parini

19.03.2011

Rehabilitation ApproachesPrima mette altre teorie sulla genesi (pag.186)

Clinically, global inattention often appears as part of the syndrome and establishes itself as the most significant limitation on intervention. The dopaminergic sys‐ tem mediates general attention,34 and its receptors seem to be asymmetrically lateralized to the right hemisphere.35

Poi qualcosa sui correlati lesionali


Rehabilitation ApproachesDa finire sull’efficacia del trattamento



• Neglect • “the failure to report, respond, or orient to novel or meaningful stimuli presented to the side opposite a brain lesion, when this failure cannot be attributed to either sensory or motor defects.



• Tre categorie di neglect• the memory and representational deficits,• the action‐intentional disorders (motor neglect)

• , and inattention (sensory neglect).1,3



• the memory and representational deficits,• descrizione della piazza del duomo a Milano



• the action‐intentional disorders (motor neglect)

• Occhi, testa, braccia, tronco



• the action‐intentional disorders (motor neglect)

• Concetto di emispazio• Tronco come punto di riferimento



• inattention (sensory neglect).1,3• A theory may adequately explain the neglect caused by a lesion in one anatomic area, but no one theory can account for the numerous variations of behavior associated with USN.


Unilateral Spatial Neglect SWAN• Mesulam: sistema limbico ha un ruolo nell’attenzione organizzato in due

componenti:• Giro cingolato anteriore rilevanza motivazionale dei molti input

extrapersonali• Giro posteriore monitorizza lo shift post‐saccadico verso l’attenzione visiva

overt

• Vie reticolari controllo e attivazione del livello di sorgenza del network attenzionale


Unilateral Spatial Neglect SWAN• Mesulam3 speculated further that motor planning and output are focused

in the frontal eye fields and the adjacent premotor areas. These regions are directly involved in overt and covert shifts of directed attention.3 …………The cortical and subcortical input to the frontal eye fields and adjacent motor regions directs the eyes, head, and limbs to scan and explore the environment.3


Unilateral Spatial Neglect SWAN• Mesulam’s model• The posterior parietal lobe, limbic system, and frontal eye fields/adjacent premotor areas are

self‐ contained local networks, and each has a role to play in attention.3,9,10 These local networks have extensive inter‐ connections with each other and the reticular activating system that form a larger neural network for atten‐ tion.3,9,10 The task of the larger network is to form a representation of the external environment, target spe‐ cific stimuli, and then explore those stimuli through visual scanning and motor acts.3,9,10 The posterior pari‐ etal lobe is primarily responsible for creating a sensory representation of extrapersonal events, and for targeting specific stimuli.3,9,10 The cingulate gyrus determines the motivational relevance of the extrapersonal sensory The cortical and subcortical input to the frontal eye fields and adjacent motor regions directs the eyes, head, and limbs to scan and explore the environment.3 Mesulam3,9,10 has developed a model of the neural networks involved in the distribution of attention (Fig. 2) input.3,9,10 The frontal eye fields and adjacent premotor areas regulate visual scanning, orient the head and eyes to explore the environment, and initiate motor acts for limb movement.3,9,10 Although it may be tempting to associate deficits with a lesion in one area, Mesulam3 cautions us against this. Mesulam3,9,10 contends there are no rigid boundaries of different types of USN because the attentional network is tightly interwoven. A specific behavior is not a product of one specific anatomic area, but rather a result of the many connections that are found within that area and with other more distant regions.3,9,10


BartolomeoCorrelati lesionali

• Transcranial magnetic stimulation (TMS)• Sembra più a favore del lobo parietale inferiore • Transcranial magnetic stimulation (TMS) transiently disrupts the integrated

activity of cortical networks in a relatively non invasive fashion. TMS over the left hemisphere decreased left extinction and neglect in right brain-damaged patients[55]. Temporary inactivation of the middle/rostral portions of the STG produced non- lateralized impairments in visual search tasks[56].In the same study,TMS stimulation of the central sectors of the STG did not modify judgment sof the lengthofhorizontal lines (Landmarktask), in contrast to inactivation of the posterior parietal cortex, which provoked lateralized effects similar to those shown by patients with neglect on the same task.



• Thiebaut de shotten• These findings run counter to a strong version of the STG

hypothesis [51], at least as far as line bisection is concerned. Importantly, however, the strongest deviations occurred in one patient upon inactivation of a white‐matter region in the depth of the IPL after most of the tumour had been removed.

• These results[56,63] thus seem consistent with the possibility that regions of the right temporal lobe are important for visual recog‐ nition and memory[64], but their relevance to neglect remains unclear.



• For the first time white matter pathways can be explored in detail in the living human brain, and the focus can shift from impairment of cortical modules to dysfunction of cortical networks [59 ]. A recent meta‐ analysis [62 ] of previous lesion overlapping studies demonstrated that the subcortical lesions of neglect patients invariably overlapped at or near the human homologues of superior longitudinal fasciculus (SLF) II and III. Disconnection between cortical modules may thus be a general mechanism of neglect[54 ].



• These results support models of neglect which postulate a dysfunction of large‐scale right‐hemisphere networks [66]. Parietal components of the network may determine the perceptual salience of extrapersonal objects; frontal components may be implicated in the production of an appropriate response to behaviourally relevant stimuli, in the online retention of spatial information, or in the focusing of attention on salient items through reciprocal connections to more posterior regions. The network approach may prove important for patient diagnosis because a particular form of white matter disconnection may have greater predictive value than the localization of greymatter lesions.


Left Unilateral Neglect as a Disconnection Syndrome

• We propose a reappraisal of the contribution of disconnection factors to the pathophysiology of neglect based on a review of animal and patient studies. These indicate that damage to the long‐range white matter pathways connecting parietal and frontal areas within the right hemisphere may constitute a crucial antecedent of neglect. Thus, neglect would not result from the dysfunction of a single cortical region but from the disruption of large networks made up of distant cortical regions. In this perspective, we also reexamined the possible contribution to neglect of interhemispheric disconnection. The reviewed evidence, often present in previous studies but frequently overlooked, is consistent with the existence of distributed cortical networks for orienting of attention in the normal brain, has impli‐ cations for theories of neglect and normal spatial processing, opens perspectives for research on brain‐‐behavior relationships, and sug‐ gests new possibilities for patient diagnosis and rehabilitation.



• Although neglect commonly results from lesions in the territory of the middle cerebral artery, posterior cerebral artery strokes can also give rise to neglect signs. Also in these patients, the presence o fneglect seems to correlate with inter and intrahemispheric disconnection [67 ]. Birdet al. [68

]


• Striato?


CorballisDifferent mechanisms for making

sense of visual information

1. Pick‐up mechanisms2. Filtering mechanisms3. Specialised parallel processing systems4. Use of imagination


CorballisAttentional scanning depends largely

on the right side of the brain• Damage to the right side causes “hemineglect” of the left side of space

• Damage to the left side has at most a temporary effect on spatial awareness

• Therefore the right brain deals with attention to both sides of space


3. Specialized processing systems


“What” and “where” in the brain

The dorsal (“where”)system

The ventral (“what”)system

Early visualanalysis


The dorsal (“where”) stream

• Codes for location in space

• Evolved in the context of navigation and environment‐dictated movement

• Largely unconscious


The ventral (“what”) system

• Codes for identity of objects

• Operates independently of location

• Single cells can be remarkably specific


Sparse coding

• The what system strips the information of “circumstantial attributes,” like colour, location, distance, movement

• This is called sparse coding—a trick that enables you to recognize the same objects in different guises

• Even orientation can be ignored …


Bartolomeo

• Imaginal neglect• Il neglect si può verificare in assenza di stimoli visivi– Descrizione a memoria di luoghiComunque solo una minoranza dei neglect mostra questo tipo di alterazione

Si può anche verificare il contrario (imaginal senza perceptual) magari dopo terapia o compensazione parziale


BartolomeoImaginal neglect

• Deviazione a destra anche di bisezione di una serie di numeri

• Fase REM• The complex relationships between perception and imagery in general [30], and concerning neglect in particular, are difficult to predict from the available theoretical models


Eminegletto Visivo

• Consiste in emiinattenzione verso tutto lo spazio di sinistra

• Mangiano solo il cibo a destra nel piatto• Non riconoscono con la sedia a rotelle gli ostacoli a sinistra

• Tendenza a fare molta attenzione a destra• Anosognosia (non sono consci del deficit)• Spesso negano la loro emiplegia


Eminegletto visivo: criteri diagnostici ed evoluzione

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