500 Journal ofNeurology, Neurosurgery, and Psychiatry 1992;55:500-502

SHORT REPORT J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.55.6.500 on 1 June 1992. Downloaded from

Pure alexia and right hemiachromatopsia in posterior dementia

L Freedman, L Costa

Abstract visuospatial and ori- A 66 reasoning, topographic year old, right handed woman pre- entation. She was severely prosopagnosic, sented with pure alexia and right hemia- being unable to recognise famous and familiar chromatopsia (PARH) in the context of a faces, as well as her reflection in a mirror. A posterior dementia. PARH was accom- visual object was present confined to panied by , 2-D object two-dimensional stimuli. Verbal fluency, tactile agnosia, and environmental agnosia. Vis- naming, auditory comprehension, and oral ual fields were normal to confrontation were intact. Verbal memory was mildly testing. The pathological anatomy of compromised on measures of learn- PARH repetition involves circumscribed damage to ing and visual recognition memory was intact. the and lingual fusiform gyri and para- The summary memory quotient (MQ) was ventricular white matter ofthe left occipi- within the psychometric normal range tal cortex, two contiguous cortical regions (MQ = 96). functionally specialised for processing Examination of and colour percep- colour and word form information, tion indexed a pure alexia and right hemia- respectively. chromatopsia. The alexia was characterised by a letter-by-letter decoding strategy compli- mented by visual paralexic errors. Letters of Pure alexia and right hemiachromatopsia similar visual structure were mis- reflect frequently (PARH) disorders of reading and con- read. Colour perception was evaluated by tralateral colour perception, respectively.' Both having the patient name, match, and discrim- conditions result from damage to the left inate coloured tokens ( blue, green, yellow, usually secondary to infarction red) on free-field and half-field of the presentations.5 posterior cerebral artery.' The cortical The patient demonstrated intact colour per- areas responsible for processing colour and ception on all test on free-field letter parameters and information are functionally distinct yet left-field presentations. In contrast, there was anatomically contiguous being localised to the severe compromise (0%) in naming, matching, lingual and fusiform gyri and paraventricular and discrimination of all colours on right-field http://jnnp.bmj.com/ white matter of the left occipital cortex.' presentation. PARH are clinically dissociable,' 2 and rarely The patient was lost to follow up although occur simultaneously in the absence of a right correspondence with her physician several scotoma or superior quadrantanopia.34 We years later revealed relentless clinical deteriora- describe a patient with PARH and intact visual tion with development of dementia charac- fields (VF) which occurred in the context of a terised by a global visual and tactile agnosia posterior dementia. and severe visuospatial compromise. on October 3, 2021 by guest. Protected copyright. Case report Discussion A 66 year old, right handed woman was Our patient exhibited classical of PARH Department of referred for signs neurobehavioural testing because indexed by letter-by-letter reading, visual par- Psychology, The of a three Mississauga Hospital, year history of progressive visual alexias, and a defective ability to name, match, Mississauga, Ontario, anomia, alexia, and prosopagnosia. Serial neu- and discriminate colours presented to the right Canada rological examinations revealed normal find- L Freedman visual field. Colour perception was intact in the ings with intact visual fields. Serial CT of the left visual field and PARH was observed in the Department of showed no focal lesions, Psychology, University hydrocephalus, absence of any , colour anomia, or ofVictoria, Victoria, or posterior atrophy. An EEG revealed diffuse colour agnosia. British Columbia, slowing without focal features. Laboratory While pure alexia and right achromatopsia Canada investigations were negative L Costa and medical histo- can occur in isolation, they are usually accom- ry was remarkable for atrial fibrillation. Correspondence to: panied by other visual disorders. These can Dr Freedman, Departnent The patient was seen for neurobehavioural include object and colour 3 colour of Psychology, The anomia,' testing in November 1983. Intellectual evalu- agnosia,3 object agnosia,' and a Mississauga Hospital, 100 ation with the right superior Queensway West, WAIS-R indicated severe com- scotoma or quadrantanopia.34 While a com- Mississauga, Ontario, promise in visuospatial ability (PIQ = 69) with Canada L5B 1B8. plete right hemianopia often occurs with pure relatively spared verbal skills (VIQ = 91). it cannot Received 10 June 1991. alexia,3 co-exist with right hemia- Accepted 18 September There were severe impairments in construc- chromatopsia.' 2 Classical doctrine 1991 tional invariably praxis, matching of unfamiliar faces, had pure alexia accompanied by a complete Pure alexia and right hemiachromatopsia in posterior dementia 501

Table Clinical features in pure alexia with right hemiachromatopsia (PARH) J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.55.6.500 on 1 June 1992. Downloaded from Known/Presumed Anatomic Author(s) Patient age/Sex/Case Visual fields Associated Deficits Aetiology involvement Fusiform and lingual gyri, paraventricular white matter of Dejerine (1892) /M Normal None Vascular left occipital lobe (Autopsy) Partially resolved prosopagnosia, visual object Shuttleworth, Syring and Left homonymous agnosia, topographic Bilateral occipito-temporal Allen (1982) 70/Mt#l hemianopia disorientation, transient alexia Vascular cortex (EEG) Fusiform and lingual gyri, Damasio and Damasio Right superior paraventricular white matter of (1983) 14/M/#1 quadrantanopia None Vascular left occipital lobe (CT) Fusiform and lingual gyri, Right superior paraventricular white matter of 66/M/#2 quadrantanopia None Vascular left occipital lobe (CT) Fusiform and lingual gyri, Right superior paraventricular white matter of 71/Mt#3 quadrantanopia None Vascular left occipital lobe (CT) Prosopagnosia, visual object agnosia (2D), environmental Posterior cortical ?Bilateral mesiolateral occipital Freedman and Costa 66/F Normal agnosia dementia cortex

right hemianopia3 although this is no longer tricular white matter and the lingual and accepted in view of numerous reports of alexia fusiform gyri of the left occipital cortex. occurring without hemianopia. `When a par- Damasio and Damasio,' using CT, re-estab- tial right VF defect occurs with right hemia- lished the critical importance of damage to the chromatopsia, it is almost invariably a superior paraventricular white matter and lingual and scotoma or quadrantanopia.4 This association fusiform gyri in the development of PARH. results from the anatomical contiguity between While our patient had no focal lesions or the lingual and fusiform gyri and inferior lip of posterior atrophy on CT, a study using posi- the calcarine sulcus, the area responsible for tron emission tomography (PET) in another processing visual stimuli originating from the patient with PCD documented maximal hypo- superior aspect of the VF.4 Prosopagnosia, metabolism in the mediolateral aspect of the environmental agnosia, and a leftVF defect can left occipital lobe,8 roughly corresponding to co-occur with PARH following bioccipital the paraventricular white matter and lingual damage, although the right hemisphere lesions and fusiform gyri. do not contribute to PARH. In some instances Experimental studies using both humans of bioccipital damage, bilateral achromatopsia and monkeys have demonstrated functional occurs.4 In our case, PARH was accompanied specialisation within the with by prosopagnosia, 2-D object agnosia, and respect to colour and letter processing. Zeki4 environmental agnosia without a right VF has identified a select group ofneurons special- defect or extinction. ied for processing colour that are localised to Pure alexia occurring simultaneously with area V4 of the macaque. PET studies in right hemiachromatopsia is rare. Including the humans revealed selective activation in the present case, a review of the literature indexed lingual and fusiform gyri to multicoloured, but http://jnnp.bmj.com/ a total of six cases of PARH' 6 7 (table). The not achromatic (grey), displays. 0 Together clinical features of PARH shows that two with clinical data,' 2 these experimental results (33%) had accompanying prosopagnosia, further support the existence of a colour region object agnosia, and environmental agnosia. in humans localised to the lingual and fusiform Right VF function was normal in three cases gyri which is a homologue of area V4 in the (50%), with the remaining presenting with macaque. Similarly, with respect to reading, right superior quadrantanopia. The alexia in selective activation in the extrastriate visual on October 3, 2021 by guest. Protected copyright. one case was transient. The aetiology in five cortex (area 18) to letter strings or "visual (83%) cases was vascular, secondary to infarc- word forms" has been indexed by PET" in tion in the left posterior cerebral artery (one humans, while a pattern of impaired and case7 had bilateral PCA infarctions). improved metabolic activity in the left occipital The aetiology of PARH in our patient is lobe has been reported following the onset and presumably a focal degenerative disorder maxi- subsequent resolution of pure alexia.'2 mally affecting the posterior cortices. This posterior cortical dementia (PCD) has been 1 Damasio AR, Damasio H. The anatomical basis of pure previously described in a number of cases.8 alexia. Neurology 1983;33:1573-83. While all previously documented cases of PCD 2 Damasio AR, Damasio H. Hemianopia, hemiachroma- topsia, and the mechanisms of alexia. Cortex had alexia, none had accompanying right 1986;22: 161-9. hemiachromatopsia, although several had visu- 3 Benson DF. Alexia. In: Frederiks JAM, ed. Handbook of Clinical Neurology, Vol 1 (45). Clinical neuropsychology. al extinction. "The aetiology ofachromatopsia Holland: Elsevier 1985;433-55. is predominantly vascular,4 and we believe that 4 Zeli S. A century of cerebral achromatopsia. Brain 1990;113:1721-77. our case represents the first instance of achro- 5 Albert ML, Reches A, Silverberg R. Hemianopic colour matopsia occurring in an idiopathic demen- blindness. Y Neurol Neurosurg Psychiatry 1975;38: 546-9. tia. 6 Dejerine J. Contribution a l'etude anatomo-pathologique et The anatomy of PARH was uncovered by clinique des differences varietes de cecite verbale. Mem- oires Societe Biologique 1892;4:61-90. necropsy examination of Dejerine's patient' 7 Shutttleworth EC, Syring V, Allen N. Further observations which revealed involvement of the paraven- on the nature of prosopagnosia. Brain Cogn 1982: 502 Freedman, Costa

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