Robert Rafal It reviews its anatomical basis and some of the dis the su rior tem s are affected in the right eases that cause it.It then details the indep nden the left.The of Balint's syndrome.It co ietal lobule is c min nthesis that attempts to sum 2.2 (Friedman-Hill,Robe Whal Blin pr 1995)sh th cted MR of th M) int des s syndro pariet part of the angul Anatomy and Etiology of Balint's Syndrome gyrus.A review of othe Balint's syndrome is produced by bilateral lesion of the parieto-occipital iunction.The lesions char parieta acteristically involve the dorsorostral occipital lobe and ieto-oc cipital jun n as (Brodmann area 19)and often but not invariabl syn (Coslett 991: Pierrot-D (Karnath.Ferber.Rorden.Driver.2000).the eillgny,Gray,Brunet,1986: angular spare the sup Verfaellie,Rapcsak,&Heilman,1990). Thus Balint's syndrome is associated with dis- 21 eases in which symmetric lesions of the paneto in 1909 (Husain Stei 1988 occipital junction are typical.For example,Luria supramarginal gyrus and the posterior part (1959)and Holmes and Horax(1919)have reported this syndrome after patients received penetrating wounds from projectiles entering laterally and traversing the coronal plane through the paneto occipital regions.Strokes successively injuring both hemispheres in the distribution of posterior parietal branches of the middle cerebral artery are anothe common cause (Coslett Saffran.1991:Friedman Hill et al.,1995;Pierrot-Deseillgny et al.,1986). Because the parieto-occipital junction lies in the watershed territory between the middle and the posterior cerebral arteries,Balint's syndrome is a common sequela of infarction due to global cerebral hypoperfusion.Another symmetrical pathology is the "butterfly"glioma-a malignant tumor origi- Figure 2.1 Figure 2.2 Balint's drawing of the brain of the patient he described. MRI of patient R.M. (Husain and Stein,1988)
It reviews its anatomical basis and some of the diseases that cause it. It then details the independent component symptoms of Bálint’s syndrome. It concludes with a synthesis that attempts to summarize what Bálint’s syndrome tells us about the role of attention and spatial representation in perception and action. Anatomy and Etiology of Bálint’s Syndrome Bálint’s syndrome is produced by bilateral lesions of the parieto-occipital junction. The lesions characteristically involve the dorsorostral occipital lobe (Brodmann area 19), and often, but not invariably (Karnath, Ferber, Rorden, & Driver, 2000), the angular gyrus, but may spare the supramarginal gyrus and the superior temporal gyrus. Figure 2.1 shows a drawing of the lesions in the patient reported by Bálint in 1909 (Husain & Stein, 1988). The supramarginal gyrus and the posterior part of the superior temporal gyrus are affected in the right hemisphere, but spared on the left. The superior parietal lobule is only minimally involved in either hemisphere. Figure 2.2 (Friedman-Hill, Robertson, & Treisman, 1995) shows the reconstructed MRI scan of the patient (R. M.) with Bálint’s syndrome described in the case report. The lesion involves the parieto-occipital junction and part of the angular gyrus of both hemispheres, but spares the temporal lobe and supramarginal gyrus. A review of other recent cases of Bálint’s syndrome emphasizes the consistent involvement of the posterior parietal lobe and parieto-occipital junction as critical in producing the syndrome (Coslett & Saffran, 1991; Pierrot-Deseillgny, Gray, & Brunet, 1986; Verfaellie, Rapcsak, & Heilman, 1990). Thus Bálint’s syndrome is associated with diseases in which symmetric lesions of the parietooccipital junction are typical. For example, Luria (1959) and Holmes and Horax (1919) have reported this syndrome after patients received penetrating wounds from projectiles entering laterally and traversing the coronal plane through the parietooccipital regions. Strokes successively injuring both hemispheres in the distribution of posterior parietal branches of the middle cerebral artery are another common cause (Coslett & Saffran, 1991; FriedmanHill et al., 1995; Pierrot-Deseillgny et al., 1986). Because the parieto-occipital junction lies in the watershed territory between the middle and the posterior cerebral arteries, Bálint’s syndrome is a common sequela of infarction due to global cerebral hypoperfusion. Another symmetrical pathology is the “butterfly” glioma—a malignant tumor origiRobert Rafal 28 Figure 2.1 Bálint’s drawing of the brain of the patient he described. (Husain and Stein, 1988). Figure 2.2 MRI of patient R.M
Balint's Syndrome nating in one parietal lobe and spreading across the Constriction of Visual Attention: corpus callosum to the other side Simultanagnosia Radiation necrosis may develop after radiation of a parietal lobe tumor in the opposite hemisphere in In their 1919 report of a 30-year-old World War the tract of the radiation port.Cerebral degenerative veteran who had a gunshot wound through disease.prototypically Alzheimer's disease.may the parieto-occipital regi ons Holmes Hora begin in the parieto-occipital regions,and there is observed that"the essential feature was his inabil- now a growing literature report ng cases of classic ity to direct attention to.and to take cognizance of Balint's syndrome that are due to degenerative dis- two or more objects"(Holmes Horax.1919. eases (Benson.Davis,Snyder.1988:Hof.Bouras ed that this difficulty"must be 1989,1990 Mende2 ecial disturbance or limitation of Turner,Gilmore,Remler,Tomsak,1990). attention" (p.402).Because of this constriction of visual a ention(what Bilint referred to chic field of g aze).the patient uld attend to The Symptom Complex of Balint's Syndrome of the size the fo Balint's initial description of this syndrome empha s draw sheet of paper an sized in his patient the constriction of visual atten d he recogn tion resulting in an inability to perceive more than at when it was n it te one object at a time,and optic ataxia,the inability to ing reach accurately toward objects.Balint used the term opticataxia to distinguish it from the tabetic ataxia of to b orb the first oject on which his eyes nate movements basedn ataxia is an inability to co 4919,p.390 Anoth rd overlappin ngur simila degree to which loc e pa n s lud e al patients have since been orted (Coslett&Saffran other objects from his or her attention can be quite 1991:Girotti et al. 1977 Luria 1959-Luria pra vdina-Vin 1963:Pierrot-Des Williams. to noting the simulta axia by Bal int,Holm and H fered thei s an exce of a type ligh processes which are concer the and association of sensatior (Holme 1919.p.285. Figure 2.3 Oerlhpingiguresusadiotefocimulaneousagnosia
nating in one parietal lobe and spreading across the corpus callosum to the other side. Radiation necrosis may develop after radiation of a parietal lobe tumor in the opposite hemisphere in the tract of the radiation port. Cerebral degenerative disease, prototypically Alzheimer’s disease, may begin in the parieto-occipital regions, and there is now a growing literature reporting cases of classic Bálint’s syndrome that are due to degenerative diseases (Benson, Davis, & Snyder, 1988; Hof, Bouras, Constintinidis, & Morrison, 1989, 1990; Mendez, Turner, Gilmore, Remler, & Tomsak, 1990). The Symptom Complex of Bálint’s Syndrome Bálint’s initial description of this syndrome emphasized in his patient the constriction of visual attention, resulting in an inability to perceive more than one object at a time, and optic ataxia, the inability to reach accurately toward objects. Bálint used the term optic ataxia to distinguish it from the tabetic ataxia of neurosyphilis; tabetic ataxia is an inability to coordinate movements based on proprioceptive input, while optic ataxia describes an inability to coordinate movements based on visual input. Many similar patients have since been reported (Coslett & Saffran, 1991; Girotti et al., 1982; Godwin-Austen, 1965; Kase, Troncoso, Court, Tapia, & Mohr, 1977; Luria, 1959; Luria, Pravdina-Vinarskaya, & Yarbuss, 1963; Pierrot-Deseillgny et al., 1986; Tyler, 1968; Williams, 1970). In addition to noting the simultanagnosia and optic ataxia reported by Bálint, Holmes and Horax emphasized spatial disorientation as the cardinal feature of the syndrome. Holmes and Horax offered their case “for the record . . . as an excellent example of a type of special disturbance of vision . . . which sheds considerable light on... those processes which are concerned in the integration and association of sensation” (Holmes & Horax, 1919, p. 285). Constriction of Visual Attention: Simultanagnosia In their 1919 report of a 30-year-old World War I veteran who had a gunshot wound through the parieto-occipital regions, Holmes & Horax observed that “the essential feature was his inability to direct attention to, and to take cognizance of, two or more objects” (Holmes & Horax, 1919, p. 402). They argued that this difficulty “must be attributed to a special disturbance or limitation of attention” (p. 402). Because of this constriction of visual attention (what Bálint referred to as the psychic field of gaze), the patient could attend to only one object at a time regardless of the size of the object. “In one test, for instance, a large square was drawn on a sheet of paper and he recognized it immediately, but when it was again shown to him after a cross had been drawn in its center he saw the cross, but identified the surrounding figure only after considerable hesitation; his attention seemed to be absorbed by the first object on which his eyes fell” (Holmes & Horax, 1919, p. 390). Another useful clinical test uses overlapping figures (figure 2.3). The degree to which local detail can capture the patient’s attention and exclude all other objects from his or her attention can be quite Balint’s Syndrome 29 Figure 2.3 Overlapping figures used to test for simultaneous agnosia
Robert Rafal 30 Figure 2.4 shows the atte metric shap and asking her ts to draw familiar obi mpts of one of Luria's s.Whe n the patient's me what she saw.Sho ion was focused on the atte to dr a pa ting sim ple shanes until at one of the e obiect the orientation of th to the rest of the as lost on the Pa出 er is s implest e ery of two objects no pa pencil had no bject at a and,therefore.could n determ made was spe ng or ng spoke e reporte ob ervat t although thei watching a movie in which,after a heated argume lines or the angles quad no difficulty distinguishing shapes whose identity reeling across the room,apparently as a conse is implicitly dependent upon such comparisons quence of a punch thrown by a character she had Though he failed to distinguish any difference in never seen"(Coslett Saffran,1991,p.1525) the length of lines,even if it was as great as 50 Coslett and Saffran's patient also illustrated how percent,he could always recognize whether a patients with Balint's syndrome are confounded quadrilateral rectangular figure was a square or not in their efforts to read:"Although she read single .[Hle did not compare the lengths of its sides but words effortlessly,she stopped reading because 'on the first glance I see the whole figure and know the 'competing words' confused her"(Coslett whether it is a square or not'....He could also Saffran,1991.p.1525).Luria's patient reported that appreciate...the size of angles:a rhomboid even he"discerned obiects around him with difficulty when its sides stood at almost right angles was 'a that they flashed before his eyes and sometimes dis- square shoved out of shape'"(Holmes Horax. appeared from his field of vision.This [was]par- 919.D.394). ticularly pronounced in reading:the words and lines Holmes and Horax appreciated the importance of flashed before his eyes and now one,now another their observations for the understanding of normal extraneous word suddenly intruded itself into the vision:"It is therefore obvious that though he could text."The same occurred in writing:"[T]he patient not compare or estimate linear extensions he pre was unable to bring the letters into correlation with served the faculty of appreciating the shape of bidi- his lines or to follow visually what he was writing mensional figures.It was on this that his ability down letters disappeared from the field of vision to identify familiar objects depended"(Holmes overlapped with one another and did not coincide Horax,1919.p.394)."T]his is due to the rule that with the limits of the lines"(Luria.1959.p.440) the mind wher ossible takes cognizance of unities' Coslett and Saffran's patient"was unable to write (Holmes Horax.1919.p.400). as she claimed to be able to see only a single letter thus when creating a letter she saw only the tip of Spatial Disorientation the pencil and the letter under construction "lost"the p nstructed letter Saffran,1991,p.1525) omn to be a sym nosia and to be the care
astonishing. I was testing a patient one day, drawing geometric shapes on a piece of paper and asking her to tell me what she saw. She was doing well at reporting simple shapes until at one point she shook her head, perplexed, and told me, “I can’t see any of those shapes now, doctor, the watermark on the paper is so distracting.” The visual experience of the patient with Bálint’s syndrome is a chaotic one of isolated snapshots with no coherence in space or time. Coslett and Saffran report a patient whom television programs bewildered “because she could only ‘see’ one person or object at a time and, therefore, could not determine who was speaking or being spoken to. She reported watching a movie in which, after a heated argument, she noted to her surprise and consternation that the character she had been watching was suddenly sent reeling across the room, apparently as a consequence of a punch thrown by a character she had never seen” (Coslett & Saffran, 1991, p. 1525). Coslett and Saffran’s patient also illustrated how patients with Bálint’s syndrome are confounded in their efforts to read: “Although she read single words effortlessly, she stopped reading because the ‘competing words’ confused her” (Coslett & Saffran, 1991, p. 1525). Luria’s patient reported that he “discerned objects around him with difficulty, that they flashed before his eyes and sometimes disappeared from his field of vision. This [was] particularly pronounced in reading: the words and lines flashed before his eyes and now one, now another, extraneous word suddenly intruded itself into the text.” The same occurred in writing: “[T]he patient was unable to bring the letters into correlation with his lines or to follow visually what he was writing down: letters disappeared from the field of vision, overlapped with one another and did not coincide with the limits of the lines” (Luria, 1959, p. 440). Coslett and Saffran’s patient “was unable to write as she claimed to be able to see only a single letter; thus when creating a letter she saw only the tip of the pencil and the letter under construction and “lost” the previously constructed letter” (Coslett & Saffran, 1991, p. 1525). Figure 2.4 shows the attempts of one of Luria’s patients to draw familiar objects. When the patient’s attention was focused on the attempt to draw a part of the object, the orientation of that part with regard to the rest of the object was lost, and the rendering was reduced to piecemeal fragments. Patients are unable to perform the simplest everyday tasks involving the comparison of two objects. They cannot tell which of two lines is longer, nor which of two coins is bigger. Holmes and Horax’s patient could not tell, visually, which of two pencils was bigger, although he had no difficulty doing so if he touched them. Holmes and Horax made the important observation that although their patient could not explicitly compare the lengths of two lines or the angles of a quadrilateral shape, he had no difficulty distinguishing shapes whose identity is implicitly dependent upon such comparisons: “Though he failed to distinguish any difference in the length of lines, even if it was as great as 50 percent, he could always recognize whether a quadrilateral rectangular figure was a square or not. . . . [H]e did not compare the lengths of its sides but ‘on the first glance I see the whole figure and know whether it is a square or not’. . . . He could also appreciate... the size of angles; a rhomboid even when its sides stood at almost right angles was ‘a square shoved out of shape’” (Holmes & Horax, 1919, p. 394). Holmes and Horax appreciated the importance of their observations for the understanding of normal vision: “It is therefore obvious that though he could not compare or estimate linear extensions he preserved the faculty of appreciating the shape of bidimensional figures. It was on this that his ability to identify familiar objects depended” (Holmes & Horax, 1919, p. 394). “[T]his is due to the rule that the mind when possible takes cognizance of unities” (Holmes & Horax, 1919, p. 400). Spatial Disorientation Holmes and Horax considered spatial disorientation to be a symptom independent from simultanagnosia, and to be the cardinal feature of the synRobert Rafal 30
Balint's Syndrome Drawing Copying Elephant head ears no walls body 政aw roof window feet feet "I can visualize it well...but my hands don't move properly" Figure 2.4 Drawing by the patient described by Luria(1959). drome:“The most pro hich 390-391 ra Patient曲Bat'y 1919.p This ger early lost in rome cann lly or by point I and then told to return to i mphsied that the defcct in his bed scussed I Ho tely started off in a wrong d localization was not restricted to visual objects in tion"(Holmes Horax,1919,p.395).This patient the outside world,but also extended to a defect in showed,then,no recollect on of spatial relation spatial memory:"Hle described as a visualist does ships of places he knew well before his injury.and his house,his family.a hospital ward in which he no ability to learn new routes:"He was never able had previously been,etc.But,on the other hand,he to give even an approximately correct description of had complete loss of memory of topography:he was the way he had taken,or should take,and though he unable to describe the route between the house in passed along it several times a day he never'learned a provincial town in which he had lived all his life his way'as a blind man would(Holmes Horax. and the railways station a short distance away. 1919,p.395). explaining 'I used to be able to see the way but I Holmes and Horax concluded that"The fact that can't see it now....'He was similarly unable to say he did not retain any memory of routes and topo- how he could find his room in a barracks in which graphical relations that were familiar to him before he had been stationed for some months.or describe he received his injury and could no longer recall
drome: “The most prominent symptom... was his inability to orient and localize correctly objects which he saw” (Holmes & Horax, 1919, pp. 390–391). Patients with Bálint’s syndrome cannot indicate the location of objects, verbally or by pointing (optic ataxia, to be discussed later). Holmes and Horax emphasized that the defect in visual localization was not restricted to visual objects in the outside world, but also extended to a defect in spatial memory: “[H]e described as a visualist does his house, his family, a hospital ward in which he had previously been, etc. But, on the other hand, he had complete loss of memory of topography; he was unable to describe the route between the house in a provincial town in which he had lived all his life and the railways station a short distance away, explaining ‘I used to be able to see the way but I can’t see it now. . . .’ He was similarly unable to say how he could find his room in a barracks in which he had been stationed for some months, or describe the geography of trenches in which he had served” (Holmes & Horax, 1919, p. 389). This gentleman was clearly lost in space: “On one occasion, for instance, he was led a few yards from his bed and then told to return to it; after searching with his eyes for a few moments he identified the bed, but immediately started off in a wrong direction” (Holmes & Horax, 1919, p. 395). This patient showed, then, no recollection of spatial relationships of places he knew well before his injury, and no ability to learn new routes: “He was never able to give even an approximately correct description of the way he had taken, or should take, and though he passed along it several times a day he never ‘learned his way’ as a blind man would” (Holmes & Horax, 1919, p. 395). Holmes and Horax concluded that “The fact that he did not retain any memory of routes and topographical relations that were familiar to him before he received his injury and could no longer recall Balint’s Syndrome 31 Drawing Elephant head ears nose eyes trunk feet feet body “I can visualize it well ... but my hands don't move properly” walls roof window door windows Copying Figure 2.4 Drawing by the patient described by Luria (1959)
Robert Rafal 32 ory.as well as those that have heen mes Horax,1919. p.404 Impaired Oculomotor Behavior Oculomotor behavior is also chaotic in Balint's cade ini iking distur ati d sr e app. c ey movem an ia in Balint's syndrome to execute smooth-pursuit eye ne The disorder of eye movement in Balint' syndrome is restricted to visually guided eye move as well as being off to the side.He groped for the comb until his hand bumped into it.Given a pencil ments.I he patient can program accurate eye move ments when they are guided by sound or touch and asked to mark the center of a circle,the patient When.however.requested to look at his own finger with Balint's syndrome typically won't even get the mark within the circle-and may not be able to even or to any point of his body which was touched he did so promptly and accurately"(Holmes Horax, hit the paper.In part this may be because the patient cannot take cognizance.simultaneously.of both the 1919,p.387. Holmes and Horax suggested that the oculomo circle and the pencil point;but it is also clear that tor disturbances seen in Balint's syndrome were the patient doesn't know where the circle is. secondary to spatial disorientation:"Some influence Holmes and Horax considered optic ataxia,like might be attributed to the abnormalities of the the oculomotor impairment.to be secondary to the movements of his eyes,but. these were an effec patient's "inability to orient and localize correctly in space obiects which he saw.When asked to and not the cause"(Holmes Horax.1919.D.401) "All these symptoms were secondary to and take hold of or point to any object,he projected his hand out vaguely.gene rally in a w ong directi dependent upon the loss of spatial orientation by vision"(Holmes Horax 1919.p 405).They and had obviously no accurate idea of its distanc described.similarly,the behavior of a patient with from him"(Holmes Horax.1919.p.391). Balint's syndrome when he was tested for smooth- Holmes and Horax again observed that the lack of pursuit eye movements:"When an object at which ess to a e he was staring was moved at a slow and uniform to vision.Thei ient was able to localize rate he could keep his eyes on it,but if it was jerked nd he did ha or moved abruptly it quickly disappeared"(Holmes based on kincsr &Horax,1919.p.387. he defec and th at tha Optic Ataxia exc en he att Figure 2.5 shows misreaching in Balint's syndr a spoon:if h held the Even after the pati nt sees the mb,he doe n't look succeeded in spoo accu directly at itand his aching is ina dept rately in it,..but when it was held by a observer
them, suggests that the cerebral mechanisms concerned with spatial memory, as well as those that subserve the perception of spatial relations, must have been involved” (Holmes & Horax, 1919, p. 404). Impaired Oculomotor Behavior Oculomotor behavior is also chaotic in Bálint’s syndrome, with striking disturbances of fixation, saccade initiation and accuracy, and smooth-pursuit eye movements. The patient may be unable to maintain fixation, may generate apparently random saccadic eye movements (Luria et al., 1963), and may seem unable to execute smooth-pursuit eye movements. The disorder of eye movements in Bálint’s syndrome is restricted to visually guided eye movements. The patient can program accurate eye movements when they are guided by sound or touch: “When, however, requested to look at his own finger or to any point of his body which was touched he did so promptly and accurately” (Holmes & Horax, 1919, p. 387). Holmes and Horax suggested that the oculomotor disturbances seen in Bálint’s syndrome were secondary to spatial disorientation: “Some influence might be attributed to the abnormalities of the movements of his eyes, but... these were an effect and not the cause” (Holmes & Horax, 1919, p. 401). “All these symptoms were secondary to and dependent upon the loss of spatial orientation by vision” (Holmes & Horax, 1919, p. 405). They described, similarly, the behavior of a patient with Bálint’s syndrome when he was tested for smoothpursuit eye movements: “When an object at which he was staring was moved at a slow and uniform rate he could keep his eyes on it, but if it was jerked or moved abruptly it quickly disappeared” (Holmes & Horax, 1919, p. 387). Optic Ataxia Figure 2.5 shows misreaching in Bálint’s syndrome. Even after the patient sees the comb, he doesn’t look directly at it, and his reaching is inaccurate in depth as well as being off to the side. He groped for the comb until his hand bumped into it. Given a pencil and asked to mark the center of a circle, the patient with Bálint’s syndrome typically won’t even get the mark within the circle—and may not be able to even hit the paper. In part this may be because the patient cannot take cognizance, simultaneously, of both the circle and the pencil point; but it is also clear that the patient doesn’t know where the circle is. Holmes and Horax considered optic ataxia, like the oculomotor impairment, to be secondary to the patient’s “inability to orient and localize correctly in space objects which he saw. When... asked to take hold of or point to any object, he projected his hand out vaguely, generally in a wrong direction, and had obviously no accurate idea of its distance from him” (Holmes & Horax, 1919, p. 391). Holmes and Horax again observed that the lack of access to a representation of space was specific to vision. Their patient was able to localize sounds and he did have a representation of peripersonal space based on kinesthetic input: “The contrast between the defective spatial guidance he received from vision and the accurate knowledge of space that contact gave him, was excellently illustrated when he attempted to take soup from a small bowl with a spoon; if he held the bowl in his own hand he always succeeded in placing the spoon accurately in it,... but when it was held by a observer Robert Rafal 32 Figure 2.5 Optic ataxia in Bálint’s syndrome